Need help with surging

eastsidaz · 03-17-2026, 05:25 PM

Quote:

Originally Posted by 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.

Yes, Rail pressure barely gets over 700psi even at 4000rpm. 700psi at idle is normal and increases with RPM so it's no good.

Weird thing is rail pressure was ok in earlier logs

lookalikehuuh · 03-18-2026, 12:24 PM

Quote:

Originally Posted by 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.

yeahh... this is weird... Rail pressures were perfectly fine before but now I would expect them to be around 1500ish+ while you are on throttle.

Fuel trims are still extremely high, we are approaching 30 when you combine the LTFTs and STFTs. Its somehow acting as if there is unmetered air coming into the combustion chamber.

335xiE90 · 03-19-2026, 11:56 AM

I'm going to reset adaptations again tonite and try and get a 2-3 gear log.

335xiE90 · 04-06-2026, 05:20 PM

Alright. So in the last 2 1/2 weeks I've replaced the boost solenoids, MAP Sensor and coolant temp sensor. All of them went out, one after the other. Does anyone have any ideas on narrowing this down a bit? The car ONLY does this when the oil temp is > 160. It drives perfectly normal with a cold engine.

TunafishE93 · 04-06-2026, 06:03 PM

Whats your blow off valve situation?

335xiE90 · 04-06-2026, 06:48 PM

Quote:

Originally Posted by TunafishE93

Whats your blow off valve situation?

I'm running a tial BOV.

TunafishE93 · 04-06-2026, 08:37 PM

How close are you to target boost, the last graph with seeable surges doesn't have that parameter.

335xiE90 · 04-08-2026, 08:14 AM

Quote:

Originally Posted by TunafishE93

How close are you to target boost, the last graph with seeable surges doesn't have that parameter.

I'm going to try and go out saturday morning to get some new logs. I will make sure to log target boost as well!

TunafishE93 · 04-08-2026, 08:24 AM

Quote:

Originally Posted by 335xiE90

I'm going to try and go out saturday morning to get some new logs. I will make sure to log target boost as well!

What turbo do you have?

335xiE90 · 04-08-2026, 12:54 PM

Quote:

Originally Posted by TunafishE93

What turbo do you have?

Factory turbos w/ 160k miles!!! They have some wastegate rattle and i plan on replacing them VERY soon. I just want to resolve this surging issue first.

335xiE90 · Today, 11:47 AM

Big update. I was driving the car and it was doing it's normal surging in first gear, but something new happened. It started smoking like crazy. Come to find out the ground wire on the #1 coil backed itself out and shorted out on the coilpack. I think this really has to be the issue at this point because there's literally nothing else that could be causing this from all the research I've done.

Anyhow, I plan on picking up a new wiring harness for the coils this weekend if all goes well.

03-19-2026, 11:56 AM	#25
335xiE90 Private 38 Rep 97 Posts Drives: BMW 335xi Join Date: Jul 2022 Location: Massachusetts iTrader: (0)	I'm going to reset adaptations again tonite and try and get a 2-3 gear log.
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04-06-2026, 05:20 PM	#26
335xiE90 Private 38 Rep 97 Posts Drives: BMW 335xi Join Date: Jul 2022 Location: Massachusetts iTrader: (0)	Alright. So in the last 2 1/2 weeks I've replaced the boost solenoids, MAP Sensor and coolant temp sensor. All of them went out, one after the other. Does anyone have any ideas on narrowing this down a bit? The car ONLY does this when the oil temp is > 160. It drives perfectly normal with a cold engine. Last edited by 335xiE90; 04-06-2026 at 05:28 PM..
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04-06-2026, 06:03 PM	#27
TunafishE93 Major 557 Rep 1,306 Posts Drives: BMW 335i Join Date: Dec 2019 Location: NV iTrader: (0)	Whats your blow off valve situation?
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04-06-2026, 08:37 PM	#29
TunafishE93 Major 557 Rep 1,306 Posts Drives: BMW 335i Join Date: Dec 2019 Location: NV iTrader: (0)	How close are you to target boost, the last graph with seeable surges doesn't have that parameter.
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Today, 11:47 AM	#33
335xiE90 Private 38 Rep 97 Posts Drives: BMW 335xi Join Date: Jul 2022 Location: Massachusetts iTrader: (0)	Big update. I was driving the car and it was doing it's normal surging in first gear, but something new happened. It started smoking like crazy. Come to find out the ground wire on the #1 coil backed itself out and shorted out on the coilpack. I think this really has to be the issue at this point because there's literally nothing else that could be causing this from all the research I've done. Anyhow, I plan on picking up a new wiring harness for the coils this weekend if all goes well.
	Appreciate 0 Quote