90T, intermittant low end sputtering

[GringoEJS]

OK, we almost have this car running like a champ. However, it still takes it 6 seconds or so of cranking to get it to fire up, then it needs to warm up a few minutes to become "mostly reliable" (before it warms up, if you push the gas, it will sputter). Anyway, the problem is that some days, it can be driven with nearly no issues. Boosts nicely to 5000 rpms with no problems. Then there are the other days, when out of the blue, it will just sputter and hesitate, clear up, then sputter some more. Doesn't matter if it is 1st, 2nd, or 3rd gear. It seems to clear up after 2500 rpms when it is acting up. Then it will run great. Timing is on, because 60% of the time, it runs really strong, plugs are new and gapped correctly, coil packs, CPS, and ECU have all been swapped out.
So...I searched without any new info, and I am just looking for help for new leads to track down. Ideas?

 

[tlo86]

how does your cold start injector look

 

[GringoEJS]

We swapped the complete upper intake manifold with a known good one and the same thing. Once the car is warm, it is still random on when it will run smoothly and when it will bog under 2500 rpms in any gear.

 

[IwantMKIII]

i don't know to what degree your sputtering problem is but i used to have a mystery sputtering acceleration problem a while back. No one figured it out. I later realized i got it to stop after i changed the lower IC pipe, my guess is the contracting and expanding of it form the turbo caused the issue.

Keep in mind this was my ONLY rubber pipe on the IC system at the time, your problem could be anywhere if the problems are related

 

[GringoEJS]

Bump to the top...

Still an issue. I have to apply about 5% throttle while starting to get it to fire up after cranking over for 10-15 seconds. I then need to warm the car up if I expect it not to bog EVERYTIME I step on the gas pedal. Then once I take it out on the road, it is hit or miss if it stumbles while driving. It might run perfectly through every gear for 2 miles, or it might stumble and sputter at 25mph for a block. Sadly, we have put less than 50 miles on it in the last 2 years because we don't trust it. It would be nice to have this car as a daily driver, like it was before we did the turbo conversion.

Also, pretty much anytime the car is floored, it will bog.

 

[IwantMKIII]

ever check TPS?

 

[GringoEJS]

I swapped the throttle body once, and then the complete upper intake manifold afterwards. The check engine light has not come on once since we swapped the manifold (2 months ago). Because it runs so sporadic, I guess it must be electrical...

 

[jdub]

The check engine light does not come on with a code 51 (TPS)...it is stored while active, you have to check for it.

 

[MKIIINA]

how are your grounds? tps would be the other option i would check too