2008 MS3 Stalling / Violent Shaking in Boost

[08Speed3]

Year/Make/Model: 2008 MS3
Mileage:240000km body / 150000km engine
Location: Alberta Canada
Concern: Car stalling at idle / wont go into boost
DTC's: secondary o2 heater
Modifications: Turboback exhaust Catless DP, Autotech HPFP, 70mm intake, ebay TIP, HKS SSQV
ECU/Tuning Software: Accessport. Does have a China Turbo on it right now, only 10000kms old and still builds boost fine.
Tuner: Justin
Is the concern intermittent? no
Can you duplicate the concern? yes
Recent Repairs: New Denso MAF, New MAF Pigtail, New Bosch OEM MAP sensor, New set of coils, New NGK plugs at .028, New air filter, New battery, Injectors cleaned and flow tested
Correction:


This car...
It was fixed for awhile, running fine after I replaced the MAF a month or so ago. Was running 100% no issues until last week. On my way home car died going around a corner, maybe 15mph engine just shut off completely and coasted to a stop. took key out and it restarted right away.
after that happened, car didnt want to go into boost, ran fine in vaccum but as soon as you load it up a bit and it starts to build boost car violently shakes until you let off, I got it back home and pulled the plugs to check, looked fine, gap was still good. put everything back together and swapped the coils with another set I had. Car actually ran great all day thursday, built target boost of 22lbs, didnt hiccup once. Let car sit all weekend and got in it this morning and started it up to warm it up a bit. Car idles for 30 seconds then dies on the driveway. Started it back up and took it down the street, went maybe 2 kms down the road and it felt a bit off, very slight hiccups like a small misfire and when i went to merge onto a busier street car started to accelerate, build a bit of boost, then shook violently like before and when I let off it died. Coasted to a side street and sat for a minute. Car fired back up drove fine in vaccum, so I started datalogging and recorded it happening. Leaned into the throttle a bit and it did it again, bucked hard until I let off, but stayed running this time. Went right home and parked it and took my beater truck to work.

Ideas Floating around my head are maybe CKP sensor dieing, maybe bad grounds, Cam sensor maybe? Any tips on diagnosing? I've thrown so many parts/ sensors at this car to fix it lately its really discouraging. It does have a shitty newer china turbo on it, but it doesnt burn oil and it seems to build boost just fine, but I guess I cant rule out that either. That wouldn't explain the dieing at idle though.
Thanks for reading....

 

[Enki]

Check your hoses, looks like you have a bunch of airflow when you should have none (throttle closed).

Also please tell me you aren't running a crackle tune.

 

[08Speed3]

Check your hoses, looks like you have a bunch of airflow when you should have none (throttle closed).

Also please tell me you aren't running a crackle tune.

Lol, no crackle tune. I did run one years ago when I had a focus st, but I smartened up.i am running full VTA though so it always spikes rich for a second when the throttle closes. I just have the regular full pro tune from Justin.
I will go over it all tomorrow, I just had the intercooler off a few days ago checking the plugs and made sure everything was tight but I will go over it all again. I found a CKP sensor local for cheap too so I might go pick that up tomorrow just to see. I have a feeling just from stalling while idling it’s losing some sort of signal, I could definitely be wrong though. Wouldn’t be the first time.

 

[Enki]

Logging the stall while idling will likely tell us more.

 

[08Speed3]

Ok, I got a update. I started it to log the idle and it never stalled when I am logging it of course...drove it to work and same symptoms though, doesn't like building boost at all, drive able as long as you stay out of boost, idle was rough, part throttle a little jumpy but its been like that forever so didn't account it to anything, maybe the VTCS delete if anything. Went and picked up the Crank Position sensor and threw it on not expecting much and it seemed to clear everything up surprisingly enough.

Idle smoothed out, part throttle feels much better, and its back to being able to make full pulls and they feel better then before. LTFT values even got better. Night and day. Its been a few days now trouble free.
Probably made this thread a little pre-mature in a bit of a frustrated state since I had the crank sensor on my mind already, apologies.
Always appreciate the help on here when something comes up.
Thank You!

 

[Easter Bunny]

Fingers crossed it was that easy. Keep us posted