[f22n55]

Hello everyone, I’ve had my 2016 m235i for over a year now. It has Catless downpipes, charge pipe, intercooler, tune, full straight pipe, and a possibly touched turbo not sure. Maybe more mods I’m not aware of. I got my ofhg and coolant hose replaced last January for oil leaks. Since then I have had boost preassure codes too low, too high etc among more boost related codes. The car will very intermittently die on cold start. Choke up terribly like it’s gasping for air on semi warm/cold starts. And feels like limp mode but smooth? Transition shifts gears too quickly. Doing 40 and in 8th gear almost immediately. This problem goes away and drives amazing for a week or a month than comes back and the car feels TERRIBLE. I’ve spent well over 4k trying to diagnose the issue but that resulted in different mechanics throwing random parts at it. I’m at a loss and don’t know what to do. Anything helps I’ve tried posting everywhere but here hopefully someone will have some insight ask me for any helpful info if anything. Thank you!!

[qx]

Not sure this is the right forum but w/e. Which parts were replaced and did you get it smoke tested?

[f22n55]

Originally Posted by qx

Not sure this is the right forum but w/e. Which parts were replaced and did you get it smoke tested?

Tmap sensor, vacuum line next to the Maf on the Intake. And possibly another sensor this was months ago so can’t remember. But yes had the intake smoked and the highly reputable shop who installs big turbo kits couldn’t find anything

[qx]

Originally Posted by f22n55

This problem goes away and drives amazing for a week or a month than comes back

Maybe try wiggling the charge pipe a bit when it's happening, could be coming loose sometimes?

[3002 tii]

If you’re tuned, flash back to stock and see if codes go away.

[thesanmarinoblues]

Aftermarket intake? I see those codes on the F8x section pretty often and the recommended fix is to run a stock intake.

[f22n55]

Originally Posted by qx

Maybe try wiggling the charge pipe a bit when it's happening, could be coming loose sometimes?

I had a CTS intake, reverted it to stock a month ago but had these boost preassure codes from before ever even getting the intake

[f22n55]

Originally Posted by 3002 tii

If you’re tuned, flash back to stock and see if codes go away.

It’s tuned but I don’t have the software, bought the car tuned

[qx]

I had similar trouble when I had vacuum leaks and failed boost converter on my n55 pwg f25. Fixed leaks and replaced vacuum pump diaphragm, boost solenoid, and valve cover (pcv)

[qx]

You can test most of this with a $20 brake bleeder

[f22n55]

Originally Posted by qx

I had similar trouble when I had vacuum leaks and failed boost converter on my n55 pwg f25. Fixed leaks and replaced vacuum pump diaphragm, boost solenoid, and valve cover (pcv)

What codes were you getting?

[f22n55]

Originally Posted by qx

You can test most of this with a $20 brake bleeder

Wouldn’t a smoke test debunk a leak though? Atleast a obvious one where spraying brake bleeder wouldn’t show the cause?

[qx]

Do you have ewg or pwg? My pwg wasn't being controlled correctly. It was just a thought, might be on the right track but again your intake was smoked (though problem is intermittent)

[f22n55]

Originally Posted by qx

Do you have ewg or pwg? My pwg wasn't being controlled correctly. It was just a thought, might be on the right track but again your intake was smoked (though problem is intermittent)

Mine is ewg, all this started when I got my OFHG and upper coolant hose replaced for oil leaks.

[XutvJet]

You said the boost pressure codes started AFTER they did the OFHG and coolant hoses. To do that work, they would have had to remove the intake system, various sensors, and possibly the CP. When issues crop up after fixing something, it's almost always a reinstallation error and they broke something. You've likely got a vacuum leak going on somewhere.

More importantly, you need to figure out how to get a stock tune back on the car and then buy a license and tune from there.

Sorry to be very blunt here, but these cars are not ones to buy modded and not be able to troubleshoot yourself you're wealthy and can throw money at them. I be going through the intake system with a fine tooth comb including verifying that they got the intake manifold on correctly and didn't pinch a runner gasket.

[f22n55]

Originally Posted by XutvJet

You said the boost pressure codes started AFTER they did the OFHG and coolant hoses. To do that work, they would have had to remove the intake system, various sensors, and possibly the CP. When issues crop up after fixing something, it's almost always a reinstallation error and they broke something. You've likely got a vacuum leak going on somewhere.

More importantly, you need to figure out how to get a stock tune back on the car and then buy a license and tune from there.

Sorry to be very blunt here, but these cars are not ones to buy modded and not be able to troubleshoot yourself you're wealthy and can throw money at them. I be going through the intake system with a fine tooth comb including verifying that they got the intake manifold on correctly and didn't pinch a runner gasket.

I’ve reinstalled the intake myself, visually checked chargepipe which seems good, replaced a vacuum hose next to the maf. And a shop changed either the tmap or map sensor. The car has been smoke tested and they couldn’t find a leak that way. So I’m really not sure how to proceed. The dealer who messed up the job mention “I may need a new engine harness” cause I kept getting a low oil preassure code for about a month. Took it to my guy and he saw that they used a aftermarket oil filter. Once that was fixed these boost preassure codes popped up.

[XutvJet]

Originally Posted by f22n55

I’ve reinstalled the intake myself, visually checked chargepipe which seems good, replaced a vacuum hose next to the maf. And a shop changed either the tmap or map sensor. The car has been smoke tested and they couldn’t find a leak that way. So I’m really not sure how to proceed. The dealer who messed up the job mention “I may need a new engine harness” cause I kept getting a low oil preassure code for about a month. Took it to my guy and he saw that they used a aftermarket oil filter. Once that was fixed these boost preassure codes popped up.

Web searches of most of your codes point to codes typically thrown by intakes (especially the POS CST intake), common "tuner" codes, and evidence of a vacuum leak. Just because a smoke test isn't finding a leak doesn't mean one isn't there, especially when the engine is moving around in its mounts while driving, after extended warm up, etc. Perhaps your intake manifold is leaking? Rough running like you've noted is typically some sort of vacuum leak.

You really need yank the unknown Stage 2+ tune off the DME and run something else that you can control, monitor, and datalog.