[335i E92]

Evening all

Might seem like a stupid question, however as some of you guys now when I had my Evolve stage 2 a few months ago it was only reaching 12psi when target was 14. Not only this, it was running rough an felt down on power.

I've recently had a couple of leaky injectors replaced that were badly gunked up with carbon. The difference it made to the power was huge, lots more grunt and midrange.

Not had time to dyno it again yet but was curious if the faulty injectors could have caused the underboost as they were in a terrible state?

The injectors were that badly carbonised that it was restricting the fuel flow on both injectors, would the DME automatically reduce the boost if it detected major fuelling issues hence why I wasn't quite hitting target?

Hunted high and low for boost or vac leak and found nothing!!

[phil200tdi]

I think I have the same problem. I guess the dme will pull boost and timing based on misfires caused by poor fueling.

What codes were generated? I'm not getting any..

I'm going to try getting the injectors ultrasonically cleaned and tested to identify which (if any) are at fault.

[335i E92]

I didn't get any codes either, I'm actually going back in to woods on Sat to get the last of the faulty injectors replaced. When i went in last w'end it was clear looking at the plugs which injectors were at fault but they needed to order another injector in so hopefully I'll notice a bigger improvement in power when the last faulty one is removed.

I'm pretty sure this is why I was under boosting, I remember the 1 wot in 3rd gear straight after the stage 2 software and it was oscillating quite badly as though the DME was trying to alter the boost levels to compensate for the irregular fuelling from the injectors.

Makes sense to me, I'll report back on sat once the last injectors been replaced.

[335i E92]

Any other thoughts guys?

[fastloop]

Have you had your HPFP replaced? It took a very long time before my one actually started to throw codes and even then it was few and far between. However you could feel the car was down on power and had some minor misfires that would pull timing after being on full boost for a few seconds. None of these were severe enough to throw any proper misfire codes, but you could feel that something wasn't right. After the HPFP was replaced and the intake was cleaned the car was back to it's former self.

Is you car making 14 psi now or are you still only seeing 12? How do you measure this, have you got a boost gauge or are you reading this info off the DME using BT? Also is the car running smooth now, but just appear to run lower boost?

[335i E92]

Pretty sure it's not hpfp!!

When I got the evolve stage 2 it highlighted that i had a problem somewhere, running rough terrible mpg, black smoke on start up and the under boost situ.

I had a leaky injector replaced last week that made a huge difference to the car, we also identified a 2nd faulty injector but had to order that one in which is being fitted on sat.

Hoping that when I replace the 2nd injector on sat that it will be 100%. Not dyno'd the car since it was at Evolve and was missing boost target so I can't say what boost I'm hitting now, i just now it feels much stronger!!

I'm just trying to establish if its plausible that the DME would pull boost if it detected fuelling issues hence the 2psi under boost or if I'm looking for a separate issue beyond the fuel injectors?

As I said I've checked for boost leaks and can't find anything suspect just wanted opinions if this was possible.

Will be going back on the dyno in a few weeks to see for sure!!

Cheers

H

[m1bjr]

DEM will indeed manipulate boost and timing to save the engine.

Although with major fuelling issues I would expect at least some O2 sensor codes on a hot engine.
The throttle plate is manipulated for boost fine control too I believe.

You can be under target for many reasons.
Knock is a common one.

[335i E92]

Originally Posted by m1bjr

DEM will indeed manipulate boost and timing to save the engine.

Although with major fuelling issues I would expect at least some O2 sensor codes on a hot engine.
The throttle plate is manipulated for boost fine control too I believe.

You can be under target for many reasons.
Knock is a common one.

Thanks Steve

Pretty much what i wanted to hear, hopfully after my trip to Woods tomorrow the car will be fighting fit and hitting boost targets. Will post up the dyno results in a few week.

Cheers

H