S3 BAM BOOST ISSUE

[Budd]

Yeah i thought that. Two fins to the left of the white fin has a really bent tip which just always looked out of place where as my new one received yesterday are all identical and facing the same way. The cartridges are from same seller and same melett manafacture.

Still waiting to get logs a bit later hopefully. I have a feeling its still over boosting tho

 

[Budd]

New cartridge and still... completely lost now

 

[<tuffty/>]

is this with the actuator directly connected and by passing the N75 completely?

<tuffty/>

 

[Budd]

No thats just a run with new turbo. I shall do what you said a bit later hopefully if i can get a joint or long piece of hose. I also tested the actuator fitted to the turbo while it was out and worked smoothly. Cracked at 5psi

 

[Budd]

well boost to actuator showed this.. was unable to get a 5k run unfortunately. Hope its good enough. Boost gauge showed 4 psi

 

[<tuffty/>]

In that case based on what we've seen so far and of course not being able to see the car I reckon its most likely your map...

Chances are it was aggressively mapped on a dying turbo and now that you have refreshed it the ECU isn't ready to deal with it...

Note that these ECU's are tuned by 'boost' they are tuned for load request.... so typically you lift the load request tables which means that the ECU will increase the boost to meet the 'load' (or cylinder fill required) by volume... its clever to know to drop duty cycle when its met the boost needed to generate the air flow being asked... however on aggressive maps the control can over shoot as its PID based so typically on a tired turbo you need to increase the load request more to get the turbo to boost high enough...

A fresh turbo will easily attain the boost the dying one couldn't especially on spool so the boost will over shoot until the ECU realises then tries to reign it back in... if the overshoot is minimal then the ECU can control it quickly enough but if its past its operating parameters (4psi more than it can actually see) then it will use protection routines to cut boost quickly...

Of course this is realistically the explanation for the higher than expected boost... there are other factors that we haven't touched on yet... the cutting out could also be related to fuelling... its entirely plausible that due to the higher boost the cuts you get are from it simply not having enough fuel or more likely fuel pressure to support the boost its producing..

At this point I would be considering running on actuator only until you can get it booked into a dyno that knows 1.8t's and what to look for...

Have seen all sorts in my time so this is one of those times where one issue highlights another

<tuffty/>

 

[Budd]

Well that confirms my suspicions then tbh. Been great advice. I shall now get it booked it for a map. This has had me going mental being as it was my first motor ive actually torn apart so much. Thought it may have been something i have done but i have gone over everything 1000 times and replaced most parts. Fingers crossed its that then. Next will be wrapping and airing out

Been a great help. Thanks very much. Will hopefully update soon with some positive news

Also last question i promise lol..do my maf readings look a little low at all??

 

[<tuffty/>]

They will do in that last log as you are only running 4/5psi....

I wouldn't worry to much about MAF readings at the moment but I would prepare yourself in case a new MAF is required... they fail pretty regularly but to to under read...

If the MAF hasn't been changed in your lifetime and you don't have a record of when it was then its not a bad idea to replace it... they are service items IMO but obvs you don't need to change them every 12 months...

Once on the dyno with a decent map it will become apparent if the MAF is on its way out

<tuffty/>

 

[Budd]

Great. Il leave it to the mapper then. Thanks