| 12-06-2017, 11:05 PM | #1 |
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Acceleration issues and weird noise
Hey gents,
I have a f82 M4, my car has developed some weird symptoms that frustrates the shit out of me. I have a few performance mods: *Stage 2 tune flash *downpipes catless *M-performance exhaust system (but the no X pipes) *BM air filter Recently my car has been acting up on idle (it stutters) and car vibrates at idle. I decided to keep driving it as the workshop could not identify what was the problem...no error codes....as you might have guessed the problem only got worse. On power the car pulls hard then bogs, then pulls and bogs (continuous cycle), in particular in higher gears (4-5-6-7). I thought the problem was the injectors, so I get a brand new set of 6 and fitted them, also new spark plugs (OE), new engine mounts all round....none of this helped! Getting feedup, I asked them to remove the flash tune, so I can run it stock to assist with finding the issue...that was yesterday, so today I picked it up and shop asked me to drive it, if any issues on stock trim error code would come up but they asked me to also be aware that without cat I might have a cell check light come up soon (I don't care) as the this error code wont effect the actual performance. So I went ahead to drive it (80km) distance, it went well for about 5-mins, after getting on the express way, I had one good acceleration spurt in 3-4th and then I backed off due to congestion. I thought the problem went away, then as soon as I opened it up....it just started sputtering, a very distinctive noise (burrrrrrrp burrrrrp) without really accelerating (70% throttle felt like 5% throttle) in conjunction with this burrrrp noise. I had to drive it with very little throttle input, it would gradually pickup speed but lets say the acceleration is on par with a push bicycle with 0.1hp. On idle, it would just vibrate hard.... i am not sure if my explanation is understandable, so i did my best to take a video....you may have to listen closely as it seems the burrrrp sound is difficult to capture with my iPhone while driving. -----can anyone help???? Now i am thinking, high pressure fuel pump? Coil--? Map-sensor? no error codes at all! such a pain in the ass! |
| 12-07-2017, 09:27 PM | #3 |
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Yea----
did some more driving, low rpms.....(never going more than half throttle or high rpm) car runs fine.... it seems only in mid-high range rpm with TPS more than 50% will the problem occur and effect it during idle. driving low rpm, little throttle on idle it runs fine.... so weird.... is it the high pressure fuel pump? |
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| 12-08-2017, 01:12 AM | #4 |
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No error codes what so ever....
based on my experience with diesel applications, the symptoms is like the fuel pump...(fuel delivery). but on these M cars, you have so much going on so I'm lost. |
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| 12-08-2017, 06:44 AM | #5 |
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Its your tune. Your throtte plate is closing and opening erratically when you feel that slow down speed up thing just like the stock car does. This is one of the issues that was completely fixed with BM3. What tune are you running?
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| 12-08-2017, 04:35 PM | #6 |
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It’s a flash tune.
But the thing is....this video was done on ALL stock condition. Meaning I removed the flash tune to run the factory tuning maps to try to identify the issue. With the tune previously the car preformed better than as stock.... with the same issues but not as pronounced as it is with all stock setting. Do you really think it’s the tune? If so then I don’t understand why the symptoms is worse as stock.... |
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| 12-08-2017, 11:33 PM | #7 |
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viewing live data/ logging it will help point you in the right direction. but always start simple... dont go throwing parts at it and not check for boost leaks or loose connections
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| 12-13-2017, 02:28 AM | #9 |
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sorry I wont disclose the flash tune brand as I don't think it is fair.
I also think it is irrelevant as the problem is ALOT more apparent when reverted back to stock...... but if anyone actually knows what the issue is that I am having I would be extremely appreciative! |
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| 12-14-2017, 10:45 PM | #11 |
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it is misfiring!
no engine check light, but when scanned with OBD2 tool, the following error codes come up: 140001 140004 140010 140101 140110 140601 140604 140610 150102 180001 !!!! will be checking the coils then will proceed to compression test.... does anyone have any idea whats happening? |
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