[335xiE90]

I recently started experiencing surging in 1st and 2nd gear at lower RPMs. It almost feels like I suddenly forgot how to drive a manual.

I just replaced the spark plugs with one-step colder plugs, initially gapped at .022 and then tightened to .020, but I didn’t notice any difference between the two. I’m also running brand new coils and a new LPFP. I'm seeing no codes in MHD.

Does anyone have suggestions on what I should be logging to help diagnose the issue?

[Cmanns05]

Reset throttle adaptations ( Follow procedure carefully).

If no help reset the Throttle, Vanos, and Lambda together.

[Cmanns05]

Log the usual stuff, and upload to datazap. Make sure STFT, AFR and throttle are included.

Also if tuned, helps to go back to stage 0 or a stock map. Test

[335xiE90]

I'll try those suggestions tonite. THANK YOU!

[335xiE90]

I did the resets with no luck, flashed to stock and its just as bad. I'm going to try and get a log some time this week.

[335xiE90]

Here's a 2nd gear log. https://datazap.me/u/matthew-pinola/...14-15-21-22-23

[whyzee125]

Try uninstalling MHD entirely then reinstalling. My car has been slowly developing this about once per year since I've owned it and this keeps it away for about a year.

Some say that inlets seem to cause this due to the scaling in the tune and others say it's the catalyst monitoring that gets more sensitive with tuning--if it's the latter, supposedly there's a software update that will eliminate it.

I've always had other bigger issues arise that need my attention more so haven't gotten around to figuring this one out yet, but it's common LOL.

What tune and mods are you running?

[Cmanns05]

Originally Posted by 335xiE90

Here's a 2nd gear log. https://datazap.me/u/matthew-pinola/2nd-gear?log=0&data=14-15-21-22-23

Okay your STFT are horrible, the banks are basically doing the exact opposite of each other. Looks to start as soon as you go into boost.

No codes during a pull like this? Check for obvious vacuum leaks, could also be a faulty o2.

DO NOT do pulls any further. Youre leaning out cylinders and these engines will let go. Trust I just replaced mine for a bad o2 while logging for my tuner.

INPA or ISTA has tools tou can download to check o2s for free. Smoke machines on Amazon are very affordable. Time to roll up the sleeves and start checking.

Would be smart to pull your plugs see if the injectors for 4,5,6 are leaking. Or are clogged.

[lookalikehuuh]

Originally Posted by Cmanns05

Okay your STFT are horrible, the banks are basically doing the exact opposite of each other. Looks to start as soon as you go into boost.

No codes during a pull like this? Check for obvious vacuum leaks, could also be a faulty o2.

DO NOT do pulls any further. Youre leaning out cylinders and these engines will let go. Trust I just replaced mine for a bad o2 while logging for my tuner.

INPA or ISTA has tools tou can download to check o2s for free. Smoke machines on Amazon are very affordable. Time to roll up the sleeves and start checking.

Would be smart to pull your plugs see if the injectors for 4,5,6 are leaking. Or are clogged.

errr.... are we looking at the same log here?

I don't see his car leaning out at all, and STFTs don't really look bad at all... I would say they are bad if they were like in the 20s or 30s... something like that.

The only thing that I see in this log is the timing corrections on multiple cylinders. This could be because of the colder spark plugs... I personally don't recommend people go to colder plugs unless they have upgraded twins, or single turbo. For anything stockies can produce the OE plug I found has the best results. None of that would explain the surging though.


I agree with Wyzee... a full uninstall of MHD is probably in order to get the software reset back to baseline.

[Sgop335]

well, he is talking about the separation between the stfts, which is not that bad but yea pointing towards an impending issue in one of the fuel injector(s).
Honestly there is a log, but did the op actually see any surging during the above log? rpm seems kinda clean. But its not running lean or anything for that serious warning! lol

[335xiE90]

Alright everyone I flashed back to stock and it still surging. The weird thing is it does not do it when the car is cold. It's mainly felt during initial acceleration in 1st gear then in the lower RPMS in 2nd gear.

160k miles
Stage 2+ tune for 65k miles
VRSF DP
VRSF 7.5 IC
Index 12 Injectors
Eldor Coil Packs
1 Step Colder Plugs

Newly replaced:
Cam Ledges
Both VANOS solenoids
LPFP
Oxygen Sensor (Upstream/Rear)

[335xiE90]

I got some logs of if stumbling in 1-2 gears but datazap is down. I'll post once their site is back online.

[335xiE90]

I got two logs when the car was really surging. STFT values are all over the place. The car is parked until I sort this out.

https://datazap.me/u/matthew-pinola/...x3&sizes=50x50

https://datazap.me/u/matthew-pinola/...x3&sizes=50x50

[whyzee125]

Try not flashing back to stock, but uninstalling MHD entirely.

[335xiE90]

Originally Posted by whyzee125

Try not flashing back to stock, but uninstalling MHD entirely.

Sadly that didn't work. I did however purchase upstream/front oxygen sensor. The other upstream is relatively new (10k miles). Here's to hoping that o2 sensor is the culprit.

[lookalikehuuh]

Originally Posted by 335xiE90

Sadly that didn't work. I did however purchase upstream/front oxygen sensor. The other upstream is relatively new (10k miles). Here's to hoping that o2 sensor is the culprit.

I wonder if its the newer one that is causing the issue... wouldn't be the first time new parts aren't as good as the originals... What brands O2s are you purchasing, and from where?

Bosch voltage regulators... im looking at you...

Do you have a log with MHD removed entirely? I think that would be a good baseline for us. Also some LTFT data might be useful. Also of note, the STFT are pretty close in these newer logs.

[335xiE90]

Originally Posted by lookalikehuuh

I wonder if its the newer one that is causing the issue... wouldn't be the first time new parts aren't as good as the originals... What brands O2s are you purchasing, and from where?

Bosch voltage regulators... im looking at you...

Do you have a log with MHD removed entirely? I think that would be a good baseline for us. Also some LTFT data might be useful. Also of note, the STFT are pretty close in these newer logs.

This is the one that is installed now - https://www.fcpeuro.com/products/bmw...ve-335is-17102

This is the one I just bought - https://www.fcpeuro.com/products/bmw...nt-bosch-17098

No logs for when MHD was removed. Ill get some tonite and ensure I include LTFT.

[335xiE90]

This is a log completely stock with no MHD - https://datazap.me/u/matthew-pinola/...=50x50&sc=3-21.

[lookalikehuuh]

Originally Posted by 335xiE90

This is a log completely stock with no MHD - https://datazap.me/u/matthew-pinola/...=50x50&sc=3-21.

Oh man those LTFT are crazy high... car is adding a ton of fuel. Are you sure you don't have some type of issue with an intake leak or maybe an issue with your MAP sensors (though this is less likely)?

I think some people have found air leaks around the valve covers, intake systems, or broken vacuum hoses when their vehicles behave like yours. Do you have a smoke tester that you might be able to use? If you don't this might be the best time to invest in one.

[335xiE90]

Originally Posted by lookalikehuuh

Oh man those LTFT are crazy high... car is adding a ton of fuel. Are you sure you don't have some type of issue with an intake leak or maybe an issue with your MAP sensors (though this is less likely)?

I think some people have found air leaks around the valve covers, intake systems, or broken vacuum hoses when their vehicles behave like yours. Do you have a smoke tester that you might be able to use? If you don't this might be the best time to invest in one.

I recently replaced the cam ledges, so a leak is a definite possibility. Im scoping out smoke machines on Amazon now to test for leaks. I'll report back once I get it tested!

EDIT: I ordered a smoke machine, it will be here tomorrow. What should the LTFT values be?

[lookalikehuuh]

Originally Posted by 335xiE90

I recently replaced the cam ledges, so a leak is a definite possibility. Im scoping out smoke machines on Amazon now to test for leaks. I'll report back once I get it tested!

EDIT: I ordered a smoke machine, it will be here tomorrow. What should the LTFT values be?

In an ideal world, they would be near 0. But this world isn't perfect, still I would perfer to see them +/- 5.

[335xiE90]

Alright folks. A smoke test showed my charge pipe and map sensor needed new o-rings. Once I did that a smoke test showed no leaks. But I ran into the same exact issue, once the car gets warmed up it starts surging in first gear badly. Not sure if it helps, but here's yet another log. https://datazap.me/u/matthew-pinola/...=50x50&sc=3-21. Could the surging be caused by a bad HPFP? I'm pretty sure I'm running the original still.