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Thread: Poor Dyno Results

  1. #1
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    Poor Dyno Results

    I had my Z8 dyno tested today and boy was I disappointed. I am interested in comments about what to do.

    Three years ago I put in the Dinan chip to change the engine profile. It eliminated the need for the sport button on the dash, it increased the number of RPMs per gear before the limiters would cut in and it removed the limit on the top speed.

    Last year I put a pair of Eisenmann racing mufflers on the car and it was supposed to increase the HP by about 4% - 6%. So I figured the car must be at around 415 HP now. Of course that is the engine and not to the tires. So I was guessing that maybe I would see 350 at the tires.

    The tests were run in 4th gear because of limitation on the dyno to not overpower it. The maximum RPMs in 4th gear was 5800 before the limiters cut in. So the maximum readings are at 5800 RPM where the car was at 100 MPH.

    Here are the results:
    1) Maximum HP at the wheels were 240 HP
    2) Maximum engine torque was 266 ft-lbs
    3) Air Fuel Ratio (AFR) was way too lean at 16.3

    My friend tested his modified Porche Turbo just before me, and he was getting 500 HP at the wheels. His AFR ratio was down around 12.9 at the maximum and was falling as the RPMs went up. On the Z8, the AFR was rising as the RPMs increased.

    It appears that the Dinan software is not supplying enough fuel to the engine at higher RPMs.

    I was going to contact Dinan and send them my results. I would like to have the profile changed and re-run the dyno test.

    I don't know much about engine tuning but these results are hardly what I expected. I am looking forward to what people who know a lot more about engines than I do, have to say. This is not the results I expected to see on the engine. I'd like to hear suggestions on what to do.

    There is a copy of the test results at z8.wirelessmarvels.com

    Comments?


    Jay in Southeast Florida
    Z8 #436

  2. #2
    Jay, the first thing to do is read up on the MAF's, these odd little things have a massive impact on the motors performance, and the change of muffler and chip really doesn't, so somewhere around 320-350rwHP is about what I'd expect.

    Steve Dinan will be able to give you some good feedback on dyno testing too, but a turbo car will always have a much better dyno readout than a normally aspirated car unless you have a huge 70mph airflow to the front of the car, and are at sea level in perfect cool thick air.
    Andrew Macpherson

    Expert Z8 Inspections, with full support for both Z8 sale and purchases.

  3. #3

    dyno test - performance chip

    Jay,
    I don't blame you for being disappointed. I'm not an expert on performance vehicles, but I'll share what I'm thinking.

    Your right, the AFR should have been closer to 12.5 (LBT). The lean AFR along with running a long time on the dyno may have heated up your exhaust system and increased your backpressure at the same time, further reducing your performance.

    Do you know what your sparks running at?

    Total exhaust system losses are usually 5-10% for run of the mill vehicles at reasonable temps, so getting a 4-6% improvement with mufflers may be a bit optimistic. Again, your muffler performance will be hard to determine if the car was running hot. How did they determine performance improvement? Cold Flow measurements?

    Advertised performance from BMW may be higher than what you obtain under real driving conditions. Prior to 2004 some companies would advertise performance under
    these optimal settings (LBT - Leanest Fuel for best Torque, MBT spark, minimal exh pressure) . Prior to my husband (sawbones) purchasing his Z8 I obtained the dyno engine hp/tq curves as tested here in Detroit. I'll have to find out if it was a fixed calibration with optimal fuel (LBT)/spark (MBT)/backpressure or run with the BMW control unit settings. There may be a difference in advertised engine hp/tq and actual and that would account for some of your losses.

    As a prior engine calibrator, I never been a fan of performance chips. We spend a ton of time mapping an engine under all conditions and optimizing the settings, I expect that BMW did the same. And I can't figure out why they would have messed with the AFR in order to change RPM limiters or speed limiters.

    Sawbones Wife
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    Andy Lytle
    2002 Z8 Silver/Black 23k
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    Testing the MAFs

    I checked the MAF link you referenced. Method 1 indicates that you can use hidden info from the dashboard displays to read fuel consumption while you are testing the car with a wide open throttle. Unfortunately the link indicates that this display is one of twenty test modes and it is not documented which test it might be. Further postings seem to report that some tests could screw things up so one needs to be cautious about what they select. Is there any further details on reaching the correct display to show the continuous fuel consumption they say should be examined to test the MAFs.

    So you really think that the difference between the 242rwHP figure I am getting and the 350rwHP figure you expect is the MAFs? We are talking about a 100rwHP difference. That is pretty significant.

    I am still bothered by the increasing and lean AFR. I put in a call to the technical service department for Dinan and am awaiting a return call from a fellowed named Brian. Dinan has a huge article about dyno testing on their web site. They seem to be stating that most dyno tests give false results. But even if my results were off by 5% to 10%, I am still getting significantly less HP than I expected. And Dinan does state that you will get better performance using their chip in lieu of the factory profile.

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    To: Sawebones Wife

    I drove the car to the dyno center which was about 30 minutes away. I was probably doing 80 - 100 MPH most of the way (don't tell the Florida Turnpike State Police). The car was turned off for about an hour once I got to the test center. They put it on the dyno and did 3 test runs. The numbers I reported were the maxim figures.

    We re-ran one of the runs with the AFR sensor moved to the other exhaust pipe to insure there was no problem with one of the Eisenmann mufflers versus the other affecting the back pressure. There was no difference in the test results between one exhaust and the other.

    So you agreed that the AFR is too lien. After viewing my friends test results on his Porche and seeing how the AFR ration went down as RPMs went up while mine kept increasing, something seemed wrong. If you want to see the actual graph of the results they are at z8.wirelessmarvels.com

    So how do I get the AFR profile to change from what it is doing? Do I need to go back to Dinan? Do I need to find someone who can do a custom profile? Are there places to go to have a custom profile created? I am sure to do the profile correctly it should be done on the specific enginer and not just generalized.

  6. #6
    Yes, the MAF's will cut back that much power if they are dirty, they are a real pain in our lives, and are the way BMW and many of the other German makers monitor airflow. If they get dirty they can't monitor it correctly, and they the Engine Management System drastically dials back the power. They are worth replacing every few years as a matter of course, because like everything they get residue build up over time. Some of the tests described are M5 specific because it has a far greater amount of info available through the dash, that info all came from the M5 site as the guys there have all covered far greater miles in a heavier car, and and M5 owners seem to be very performance minded.

    Also Dinan was trained in the hex-decimal code that the EMS uses, so his chip tuning is very on point. I wouldn't have any worry about the chip, it won't hurt anything, but on our motors the gain comes more in throttle feel and pick up in the midrange than an out and out power increase. I know from the interview I did with him here that we discussed dynos and he has had so many owners complain about their cars on a dyno that the only one he trusts is the one he uses, and it is in a full on wind tunnel!
    Andrew Macpherson

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    Replacing the MAFs

    The car is 7 years old and has 28,000 miles. I have only used it on the roads in New York and Florida. You think it is worth replacing the MAFs and re-running the tests? As I mentioned, it appears to everyone that reviewed the graph of the results (at z8.wirelessmarvels.com) that the Air Fuel Ratio should be decreasing at higher RPMs and not increasing as in the graph. Do you think this will change with new MAFs installed?

  8. #8
    I'm afraid the answer to that is outside my realm of knowledge, but all of us would be incredibly grateful if you would do a before and after MAF swap run, as I suspect you will find quite a difference. Please do keep us posted on your progress and learning.
    Andrew Macpherson

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    I spoke to technical support at Dinan. But before I called I suspected what I was going to hear when I read the fairly long report on the Dinan web site about dyno results that are inaccurate. Dinan reports thousands of downloads of their performance profile in M5/Z8 engines with no problem and they suspect my car is 'broken'. Dinan agrees that I should replace the Mass Airflow Sensor and re-run the dyno test on the same equipment. I am calling my local BMW dealer to order new sensors and will report the results to the group after I test the car again. After the new sensors are in, I need to drive the car for a while before restesting as the computer needs to adapt to the new sensor information it will accumulate.

    Dinan also suggested that the fuel pump pressure be checked. They had one Z8 shipped to them for testing with a similar problem to mine where the Air Fuel ratio was too lean, so I will have that checked also before I re-run the dyno test.

    Of course if I REALLY want to get crazy over this, I can ship the car from Florida to California and for $100 an hour and about 8 hours of work, Dinan will create a custom profile for my engine. It will only cost $4552 to get the car out there and back.

    Will let everyone know after the mods and the test is run again.

    Jay In South Florida
    Z8 #436

  10. #10
    Keep us posted Jay, sorry that you are the 'team tester' for this, but it will be great to get to the bottom of it for us all.
    Andrew Macpherson

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  11. #11
    Team Z8 RRZ8's Avatar
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    Jay, in march 2007 I had my Z8 tested (DynoJet model 248c) at a German BMW engine specialist tuner; Nowack Motorsport; result for my OEM Z8; 412 HP at crank; exactly 370 HP at rear wheels. I do not precisely know about enviromental adjustments regarding US spec, but 240 HP after a Dinan tune seems rather dramatic..... Can you give us more engine values regarding combustion? (how about Oxygen Sensor readings??)

  12. #12
    Z8 Addict Scott Pettit's Avatar
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    Are you replacing the MAS without determining that it is defective?

    Scott

  13. #13
    Team Z8 dwz8's Avatar
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    Quote Originally Posted by jmosk View Post
    The tests were run in 4th gear because of limitation on the dyno to not overpower it. The maximum RPMs in 4th gear was 5800 before the limiters cut in. So the maximum readings are at 5800 RPM where the car was at 100 MPH.

    Here are the results:
    1) Maximum HP at the wheels were 240 HP
    Which limiters kicked in at 5,800 RPM? Was that the max speed for the dyno?
    The engine should not restrict you from going up to 6,600 RPM (stock engine), and in your case, it should go above that RPM count due to the modification.
    At 5,800 RPM you are significantly below the RPM that is needed to reach the max HP.
    240 HP sound reasonable for 5,800 RPM, and it should go up to 360/370 HP at 6,600 RPM.
    Best regards, Dieter

    ....

  14. #14

    dyno results

    I looked at my performance curves and your peak Hp is at 6600 rpm so I agree that the lower rpm is the majority of your issue.

    Next - if your MAF is defective, I would hope that the "check engine" light would be on. If it is defective, then the AFR and spark and every other setting that is based on airflow calculations will be off. Under most driving conditions your car will use the Air/Fuel sensor (UEGO) to adjust the AFR to 14.7 and possibly/hopefully learn that the sensor is incorrect, turn on the light and enrichen the fuel to compensate. But at WOT, the engine should use the MAF and set a rich value of fuel to provide added performance and catalyst cooling.

    The dealer should be able to sort out the cause of the lean AFR.

    Do you like how it drives with the new chip/mufflers? If so, get the AFR resolved and enjoy your ride.

    Sawbones wife
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    Andy Lytle
    2002 Z8 Silver/Black 23k
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    Dinan is very clear about what their Stage 1 software does when installed in a Z8. It raises the rpm limit to 7270 rpms, removes the top speed limiter, and quickens the response of the electronic throttle control. It does not increase horsepower or torque output and they clearly state that fact. It also does not, in any way, alter the air/fuel ratio of the engine. The S62 motor in the Z8 makes its maximum horsepower at app. 6500 rpms (394). At 5500 rpms it should produce app. 366 horsepower. Maximum torque is produced at app. 4500 rpms (371) and at 5500 rpms it should put out app. 349 lb/ft. These figures are at the flywheel so you must compensate for drivetrain losses when comparing dyno results. There is also a great deal of variation in results from one dyno to another. Fouled MAFs will cause a significant loss of power and should be cleaned or replaced on a regular basis. Incorrect fuel/air ratios will cause a significant loss of power. Incorrect testing procedures on a dyno can cause a significant loss of power (inadequate air flow, tire slippage on the rollers, incorrect strap tension, failure to bypass ECU limiters, etc.). Altitude, ambient temperature, and relative humidity also affect dyno results and must be corrected for. The first thing you need to do is get your engine's performance analyzed by a BMW specialist to insure that everything is operating within specs. There is no need to guess. Then you can go back to the dyno shop and be confident that what you are seeing is a reasonably accurate representation of your engine's true power output. Just keep in mind that there are a myriad of variables involved in measuring power output on a dyno and any one of them can negatively affect your engine's performance. Also, your Eisenmann mufflers may add a few horsepower but not 4-6%. Dinan's mufflers on an M5 with the S62 motor add 6 hp. By comparison, if you install Dinan's cold air intake, 4:2:1 exhaust headers, mufflers, bored out MAFs, and Stage 4 software, you can get 28 additional hp from the S62 motor in an M5. These are real numbers, not flooby dust. Frankly, I'd forget about the dyno results (way too variable) and just get your Z8 tuned up properly.

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    Limiters definately cut in

    Quote Originally Posted by dwz8 View Post
    Which limiters kicked in at 5,800 RPM? Was that the max speed for the dyno?
    The engine should not restrict you from going up to 6,600 RPM (stock engine), and in your case, it should go above that RPM count due to the modification.
    At 5,800 RPM you are significantly below the RPM that is needed to reach the max HP.
    240 HP sound reasonable for 5,800 RPM, and it should go up to 360/370 HP at 6,600 RPM.
    No the limiters definately cut in just after 5800 RPM in 4th gear. The people running the dyno didn't know what was happening at first when they saw the engine power suddenly drop after 5800 RPM, heard the strange engine noise and smelled what was coming out of the exhaust.

    Are you saying that there should be no problem going to 6600 RPM in 4th without those limiters cutting power to the engine?

    If I was pegged at 5800 RPM what might be causing this?

    Jay in South Florida
    Z8 #436

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    I posted my dyno results on the chat room at get input from everyone on what might be causing me to only see 240 rwHP. Is there a way to insure that the MAFs are working correctly before replacing them? I was willing to replace them as there did not seem to be many other reasons why I should be seeing the results I saw. I will check the air filter and fuel pump in addition.

    Jay in Southeast Florida
    Z8 #436
    License Plate: MYBMW Z8
    Eisenmann Mufflers
    Dinan Performance Software

  18. #18
    I would suspect that when you change the MAF's that will cure that issue, the S62 has a lot of safety modes in the EMS. By the way you asked earlier if the MAF's going off would trigger the Check Engine Light, it doesn't, the EMS just adapts to it as it isn't a sudden change, it is a very slow one. However realizing that your reading was made at 5,800rpm explains everything.
    Andrew Macpherson

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    So you are saying that my BMW dealer should check out the engine performance and have them insure the engine is meeting all specifications? Are you saying that the MAFs can be cleaned rather than replaced? I didn't think that they can do anything about the lien Air/Fuel ratio I was seeing since that is under control of the computer.

    Jay in Southeast Florida
    Z8 #436
    License Plate: MYBMW Z8
    Eisenmann Mufflers
    Dinan Performance Software

  20. #20
    Team Z8 dwz8's Avatar
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    Quote Originally Posted by jmosk View Post
    No the limiters definately cut in just after 5800 RPM in 4th gear. The people running the dyno didn't know what was happening at first when they saw the engine power suddenly drop after 5800 RPM, heard the strange engine noise and smelled what was coming out of the exhaust.

    Are you saying that there should be no problem going to 6600 RPM in 4th without those limiters cutting power to the engine?

    If I was pegged at 5800 RPM what might be causing this?

    Jay in South Florida
    Z8 #436
    The engine's HP is listed as 400 HP / 6,500 1/min. Your rev limiter doesn't even kick in until over 7,000 1/min.
    The only issue that I can think of is that the folks at the Dyno shop didn't work with BMW certified setup, which disengages ABS sensors for a Dyno run. Alternatively, you can unplug those sensors to get the same effect.
    So maybe that has stopped the car to go to normal RPM ranges.
    Best regards, Dieter

    ....

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    What are the ABS sensors

    Quote Originally Posted by dwz8 View Post
    The engine's HP is listed as 400 HP / 6,500 1/min. Your rev limiter doesn't even kick in until over 7,000 1/min.
    The only issue that I can think of is that the folks at the Dyno shop didn't work with BMW certified setup, which disengages ABS sensors for a Dyno run. Alternatively, you can unplug those sensors to get the same effect.
    So maybe that has stopped the car to go to normal RPM ranges.
    Please explain - what are the ABS sensors that you say should be unplugged. Un

    Jay in Southeast Florida
    Z8 #436
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    Eisenmann Mufflers
    Dinan Performance Software

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    Looking into limiters

    The more I read on this topic, the more it is saying that the real problem is that I was not able to hit 6600 RPMs in 4th gear without the limiters cutting in. It sounds like that is where I should see the maximum HP. The 240rwHP at 5800 RPM may just be a point along the curve to the maximum HP and not the actual maximum at the wheels. So the focus seems to be finding why the car did not near 7000 RPMs in 4th gear. Before I replace the MAFs, I first need to find out why the limiters cut in just over 100MPH/5800RPM in 4th.

    Jay in Southeast Florida
    Z8 #436
    License Plate: MYBMW Z8
    Eisenmann Mufflers
    Dinan Performance Software

  23. #23
    ABS is what I've read in this thread too, and it seems glaringly obvious that the car is making the correct power at 5,800rpm, so it will also make the correct power at 6600rpm. If you want to continue to thrash your poor car in search of a number on a screen maybe call Dinan again and ask them, as I have no idea where these sensors are or how to unplug them.
    Andrew Macpherson

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  24. #24
    Z8 Addict Scott Pettit's Avatar
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    The ABS / speed sensors are mounted on the right rear wheel and the front left wheel. They look like a blasting cap and are partially inserted in a hole just behind the rotor. They are aimed at a "speed wheel", a wheel with sprockets that the sensor detects as each sprocket passes the sensor tip. Each sensor is held in place by a small bolt and its wire is connected to a junction box mounted to the body. Sensor replacement is simple-unplug the wire, remove the bolt and slide the sensor out of it's hole.

    For those of you who, like me, read their own OBD codes and love to spin a wrench, a faulty sensor code can sometimes be corrected by removing the sensor (you do not need to unplug the wire) and wiping the brake dust and dirt from the sensor (there are two exposed contacts on the tip), brushing / polishing the sensor tips with a fine wire brush and blowing dirt and dust out of the hole with a compressor.

    Been there-done that on my Z3.

    Scott

  25. #25
    What is the code, and can you post some pix please!
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  26. #26
    Z8 Addict Scott Pettit's Avatar
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    The code would depend on the fault and the brand of reader. On my Z3, I use a Peake tool which plugs into a port under the hood and only reads BMW codes. For the other cars, I use a standard OBD II reader. So, I can't tell you what the code is. If it stops raining today, I'll pull the Vette out so that I can get under the 8 and run the codes and try and get a picture.

    Scott

  27. #27
    Thank you - I have the Peake too, on the Z8 it plugs in both under and under the hood, which is handy!
    Andrew Macpherson

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  28. #28
    Sport Button On - DSC Off Z8-NL's Avatar
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    My Z8 was on a dyno once as well and because of the ABS sensors did pick up the fact that rearwheels were spinning and front wheels stationary it blocked at certain rpm as well. Guys operating that Dyno knew they had to by pass the system but did not know how so I left it there.

  29. #29
    Team Z8 dwz8's Avatar
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    Quote Originally Posted by jmosk View Post
    Please explain - what are the ABS sensors that you say should be unplugged. Un
    Scott described it perfectly. For a dyno run it is sufficient to unplug the rear ABS sensor as he described, that's it.
    Best regards, Dieter

    ....

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    The Saga Continues - Rev Limiters Cutting in at 5600 RPM

    Today I road tested the car bringing it up to the same speed as the dyno test and in the same gear and got some interesting results. At 5600 RPM in 4th (around 100 MPH), you could feel the power dip but I pushed it further and reached 6600 RPM. So I tried again and got the same result. BUT, I tried a 3rd time and at 5600 RPM the engine cut off. THEN, I could not bring the car above 3000 RPM in any gear.

    I brought the car to BMW and the fault indicator stated "129 - cat. protection due to empty tank or lack of fuel - additional information on catalytic converter protection function - Engine speed: 5460 RPM, engine load 49.6%, long. vehicle acceleration 0.4m /sec squared".

    That lack of fuel report seems to go along with what I observed on the dyno testing where the air/fuel ratio was going more lien as the RPM's increased. Maybe the mixture became so lean at 5460 RPMs that the engine shut down.

    So - I had the fuel filter and the air filter replaced. After two hours of labor, I took the car out on the road and EXACTLY the same things happened. I brought the car back in so the service manager and head technician could see the car unable to go above 3000 RPM. This condition goes away after you turn off the engine and then back on. It will work normally until you hit 5460 RPMs again, and then it cuts out again and locks up at 3000 RPM.

    Now here is an interesting observation which makes no sense to me - I was able to hit 6500 RPM in 2nd and 3rd gear. So how could this be? Why would the engine only cut out at 5460 RPMs in 4th gear and not in the lower gears? Unless the air/fule mixture is different at lower speeds than higher ones. I don't know.

    So I left the car at BMW at this point so they can talk among themselves to try to get to the bottom of this. And all because I decided to dyno test it.

    More to come.

    Jay in Southeast Florida
    Z8 #436
    License Plate: MYBMW Z8
    Eisenmann Mufflers
    Dinan Performance Software

  31. #31

    Dealer suggested Air and Fuel Filter changes?

    I don't know Jay - why did the dealer recommend the air and fuel filter? Your cat is getting to hot due to the lean fuel air ratio. The shut down occurs after the cat gets too hot, which is a function of time and rpm. The problem is still the air fuel ratio...

    No other fault codes? MAF sensor checked out? Do you still have the Dinan chip? Can you easily swap that out for the OEM chip?

    Lots of questions - wish I had answers for you.

    Sawbones Wife
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    Andy Lytle
    2002 Z8 Silver/Black 23k
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    www.golytle.com

  32. #32
    Z8 Addict Z8doc's Avatar
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    When I was on a dyno a few years ago after I got my Eisenmann mufflers installed, I did not have to remove or unplug the rear sensors and got some good numbers, but... I did have Dinan Stage 1 software already and had no problems with premature cut off at any RPM and reached the max that the Dinan software allows which is 7300 rpm and then the engine protection software allowed cut off and topped out in 6th gear. We got numbers close to what GM mentioned above and did try to limit the variables as best as possible by using high speed fans for airflow on a good cool air day as well. I agree this is something worthwhile if you are doing periodic systematic modifications but GMs advise is good as always and you can be confident that getting your Z8 tuned up and keep it that way is really all you need as the numbers everyone has gotten before you are pretty consistent.
    Best Regards,

    Jeff
    61995 Silver /// Rot - Original Owner
    Z8 Club of Germany e.V. #102

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    The dealer wanted to replace the fuel filter specifically becasue the fault was indicating that the fuel tank was empty or there was a lack of fuel. They suspected a clogged filter. This did not turn out to be the case. I agree that the more significant finding from the dyno test is that the Air Fuel ratio continued to get more lien as the RPMs increased which should not be the case. I think the engine is just being starved of fuel at higher RPMs and to protect the cat that is heating up as stated, it is shutting down power. They need to figure out why the AF ratio is doing what it is.

    Dinan specifically says that what is being observed with the AF ratio is not related to their software at all. But of course BMW is suspious of that since they no longer support Dinan software (although they certainly did at the time it was installed in the car more than 5 years ago). And I certainly have not had this problem over the last 5 years. You can't just replace a chip for the software change. The update consists of re-flashing an existing memory chip in the car with a new profile. So the Dinan software is actually downloaded into the car. We would have to download the standard software to run a test without the Dinan software. But I seriously doubt that this is the cause. There are thousands of M5 engines with this software in it. I would not be the only one reporting this problem if the cause was Dinan's software.

    With regard to unplugging the right rear and left wheel sensors during the dyno test since the front wheels are not moving while the rear wheels were at 100 MPH, I believe the duplication of the problem on the highway has proven that you don't need to unplug them for a dyno test. I see the same problem on the road that I see on the dyno.

    There are no other faults indicated by the car other than the catalytic converter protection fault due to lack of fuel. Nothing else has been checked on the car as of yet. The only thing the dealer has done so far to diagnose the problem was to replace the fuel filter. That was $500 to change that out. The MAFs will probably be 3 times that. And at this point that seems hit or miss. I am hoping someone at the factory has more insight based on these reports I have been giving them.

    Jay in Southeast Florida
    Z8 #436
    License Plate: MYBMW Z8
    Eisenmann Mufflers
    Dinan Performance Software

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    After giving this more thought, the observation I had that the engine has no problem at 6500 RPMs in 2nd or 3rd gear, but does cut out in 4th gear, is once again the Air Fuel ratio problem. In 4th gear at 100 MPH the volume of air hitting the car is certainly much larger than at 6500 RPMs in 2nd and 3rd gear. Just as people have reported here that a good dyno test requires that you are in a wind tunnel or at least have major fans blowing air across the car. The engine should have no idea what gear I am driving in. The only difference in 4th gear is that there is a lot more air.

    They need to get to the bottom of the Air Fuel mixture problem.

    Jay in Southeast Florida
    Z8 #436
    License Plate: MYBMW Z8
    Eisenmann Mufflers
    Dinan Performance Software

  35. #35

    Gear specific cut outs

    Jay,

    I have used gear specific RPM limiters in the past, but I doubt that is the problem.

    One of my co-workers dyno tested and tore down this engine - I'll send him this thread and see what he thinks.

    Sawbones Wife
    _________
    Andy Lytle
    2002 Z8 Silver/Black 23k
    Performance Package
    CDV Removed
    www.golytle.com

  36. #36
    I have both a low mileage '01 Z8 and a relatively high mileage '03 M5 daily driver. Both cars use the S62 engine. By the time the M5 had done 40k miles, the power had declined significantly relative to the Z8 despite the absence of any fault codes. Based on suggestions from the M5 board, I changed the MAFs. Afterwards, the M5 power (measured using the proven seat-of-the pants method) easily exceeded that of the Z8. The power fade occured slowly over time, and I never would have noticed it without being able to compare the two similar cars. MAFs wear due to both age and use but don't trigger fault codes until they are near failure. MAFs are very easy to replace yourself in about 10 minutes, and only cost about $80 if you shop around.

    Tyler
    '01 Z8 Titanium
    '03 M5
    '73 3.0CSL

  37. #37
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    Not out of the woods yet. Well after putting in a new fuel filter and fuel pump, it looks like things may have even gotten worse. I hit 5500 RPM in 3rd gear this time and felt the power leveling off. It was hard to get anything above 5500 RPM and then the Check Engine indicator went on. Shutting off the car did not eliminate the Check Engine light. So its back into the shop once again.

    More next week as we peel away the layers of this onion.

    Tyler - $80 for MAFS? I have a price from BMW of $422.44 each or $844.88 without installation. Part 13-62-1-433-566 "Hot-film A".

    Jay in Southeast Florida
    Z8 #436
    License Plate: MYBMW Z8
    Eisenmann Mufflers
    Dinan Performance Software

  38. #38
    Sport Button On - DSC Off Z8-NL's Avatar
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    would appreciate the address to buy the MAF's at around 80 USD

  39. #39
    I bought them for the M5 at Precision Tuning Motorsports, Bosch part number #06A906461A for about C$85 each. http://www.precisiontuning.ca/

    Importantly, the part number is for a VW. See attached thread for the debate on if it is identical to the BMW part or not.

    http://www.m5board.com/vbulletin/e39...-345-pair.html

    There are more threads if you want to do further research - just Google the part number above + Bosch + M5. Given the huge price difference and many positive user experiences, it was worth a try.

    Tyler

  40. #40
    Great link and great info, thanks so much, here are the MAF's as a simple plug in piece - http://www.bimmerzone.com/performance_MAFS.htm
    This is a much easier option than the old way of buying the whole air-tube assembly that required so much more work/time to remove/replace.
    Andrew Macpherson

    Expert Z8 Inspections, with full support for both Z8 sale and purchases.

  41. #41
    Sport Button On - DSC Off jpklecker's Avatar
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    Question

    You say they are easy to replace... where are they located under the hood and how do you access them?
    John Klecker - 2002 Topaz / Crema (61782)

  42. #42
    You can see them outlined in red here...
     
    Andrew Macpherson

    Expert Z8 Inspections, with full support for both Z8 sale and purchases.

  43. #43
    Sport Button On - DSC Off jpklecker's Avatar
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    Thanks Andrew; sorry for the dumb question... obviously they are very easy to access and replace.
    John Klecker - 2002 Topaz / Crema (61782)

  44. #44
    The most difficult aspect of replacing MAFs yourself is finding the correct 5- or 6-point Torx security bit for the screws holding the sensors to the mount. Some cars use the 5 and some use the 6, and these bits are not generally carried at your local Home Depot or hardware store.

    I used needle nose pliars and just gripped the screw gently and twisted. The screws came out very easily, but were slightly scuffed in the process so I touched them up with some black paint.

    Later, I found a source for the bits:

    http://www.tdiparts.com/catalog/prod...c5a9773e32bbe9

    Tyler

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    I think it is fixed now

    The check engine light that came on after the fuel pump was put in, was still indicating a fuel problem. So this time the MAFs were replaced. And now it is looking good. Hit 6600 RPM in 3rd and 4th without a problem. No dip in power at 5600 - 5800 RPM any more and it accelerates smoothly right up to the top. So it is back to the dyno test shortly to repeat the test of a few weeks ago. I will report the new results as soon as we run the test. Beside the HP measurement, I am especially interested in seeing the Air Fuel Ratio with the new fuel pump, fuel filter, air filter and MAFs. I think there will be a major difference at the high end and expect to see the mixture getting more rich instead of more lien like last time.

    More to come shortly.

    Jay in Southeast Florida
    Z8 #436
    License Plate: MYBMW Z8
    Eisenmann Mufflers
    Dinan Performance Software

  46. #46
    Team Z8 RRZ8's Avatar
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    Quote Originally Posted by macfly View Post
    You can see them outlined in red here...

    Andrew, off topic; where's the PP?

  47. #47
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    Quote Originally Posted by jmosk View Post
    The check engine light that came on after the fuel pump was put in, was still indicating a fuel problem. So this time the MAFs were replaced. And now it is looking good. Hit 6600 RPM in 3rd and 4th without a problem. No dip in power at 5600 - 5800 RPM any more and it accelerates smoothly right up to the top. So it is back to the dyno test shortly to repeat the test of a few weeks ago. I will report the new results as soon as we run the test. Beside the HP measurement, I am especially interested in seeing the Air Fuel Ratio with the new fuel pump, fuel filter, air filter and MAFs. I think there will be a major difference at the high end and expect to see the mixture getting more rich instead of more lien like last time.

    More to come shortly.
    Jmosk, my oxygen sensors are absolutely positive; mixture is definitely rich (average reading about 0,6-0,7). On the dyno my (completely OEM S62 engine produces 412 HP at the crank)

  48. #48
    Andrew Macpherson

    Expert Z8 Inspections, with full support for both Z8 sale and purchases.

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    It's getting better 240 Hp --> 315HP - Limiters still cut in

    Well as Macfly predicted, it appears that there was a problem with the Mass Air Flow sensors. They were replaced along with the fuel pump, fuel filter and the air filter. There is a new dyno graph at z8.wirelessmarvels.com.

    You can see on the original graph, also at that site, that the Air/Fuel ratio became more lean as the RPMs increased (14.2 --> 16.3). It became so lean at high RPMs that the engine reported it was starved out of fuel (fault registered in the computer). But, the new graph shows the Air/Fuel ratio becoming more rich as RPMs increased, just what I was expecting to see and reported in prior postings. Now the ratio went from 13.0 --> 12.0.

    The Rev Limiters still cut in around 5800 - 6000 RPMs so we did not acheive maximum horsepower. From prior posts in this thread, the technician attempted to disconnect the ABS from the right rear tire then we re-ran the test. The rev limiters still cut in at 5800 RPM. On the way home I saw the brake pad light on the dash board. Unfortunately, the postings described that the ABS sensor was on the right rear wheel, but it did not have a picture of the wire to disconnect. Obvoisuly the technician pulled the brake pad sensor off instead of the ABS sensor so it made no difference.

    I called Dinan and they said that they disable the ABS controller on their Z8 dyno tests. They do this under the hood. But looking at where the unit is located, it would take a lot of work to disconnect it. But the shop forman at my local BMW dealer said we can remove fuses 8, 14, 17 and S6 to disable the ABS. So I will plan one more dyno run in the next few weeks with these fuses pulled and we will see how much more HP we can get with another 1000 RPMs.

    It was great to see that this round of repairs brought the power up around 80 HP.

    Jay in Southeast Florida
    Z8 #436
    License Plate: MYBMW Z8
    Eisenmann Mufflers
    Dinan Performance Software