Ok, so here's my issue.. Thought I had a wiring harness issue earlier which was causing the 3Bar sensor to not communicate information effectively from the sensors to the turbo.. or vice versa.. which is causing a stutter when the injectors hit that 900PSI ( about the time boost tends to pick up from personal observation...) .. I can hear pressure building up in the turbo.. and even when I push in the clutch.. what sounds like the BPV getting the blow off.. but under gentle acceleration, I am getting a definite surge / stutter issues...

so my thoughts to this point are.. Vacumn problem?

Wiring Harness / Electrical...

have I gotten any Codes to pop... yes, I have I was getting MAF codes.. Under Boost Codes and system too Rich Codes primarily.. but I attributed this to the fact that the system assumed all was normal while under gas.. but the sensors couldnt make that change due to Direct Inject.. so it gave me the codes.. so I cleared them...

I cheecked the wiring harness and the 3 Bar Sensors .... ended up re-wiring the lower Sensor harness but to no avail.. still getting the boost issues... so it now leads me to think there is a vacumn issue possibly...

but I wanted to post it to the group to see if anyone ever had the same issue, ( probably! ) .. and what they did to fix it..

other notes to rule out any ideas that could take me in the wrong direction:

No Aftermarket Parts other than... BPV, GMS1 upgrade.. Full HP tune on top and a K&N .. all parts have been on vehicle including tune for well over a year... with no issues til this week...

Thanks all...

 

Ohh FYI.. I'm definitely getting an exhaust pop now as well due to the additional pressure in the system I think... but also part of the problem

 

The three most common causes of vac issues on these cars is:
1) Boost/vac leak caused by a cracked IC or leaking pipe connection. This usually is accompanied by a P0101 code.
2) The EVAP solenoid on the intake manifold is stuck open. See YouTube for video on how to check it.
3) The vac tank is leaking. You can bypass it to check. Search for vac tank bypass on this site.

We used to have an issue where the coldside pipe nipple that holds the vac/boost source tube broke off, but that is so easy to see that you would have seen it when you went to re-wire your TMAP sensor.

 

Hello MajorCB,

We are sorry to hear of the concerns you are experiencing. We understand that you are seeking advice from your fellow forum members, and although we may not be able to provide technical information, we'd be happy to look further into this and document your concerns. Please send us a private message with your VIN if you'd like our assistance.

Thank you,

Andraya R.
Chevrolet Customer Care

 

Thanks to both of you for the responses... so yes, I did get a P0101 code twice.. so my thoughts about the Vacumn issue seem to be front on the list.. I went over the car today.. checking the Vac tubes from the Turbo.. ( as best as I could with limited visibility and a high powered flash light ) .. worked my way around to the intake manifold... down under the car to check for cracks in the intercooler.. visibly I could find nothing.. all the connections except for one clamp located at the bottom of the car next to the 3Bar Sensor on the lower charge pipe.. so I adjusted that and got it tight again..

I pulled off the Forge BPV ( man what a pain ) and found the O-ring seemingly crushed.. pulled it out it retained its shape once more.. but to be completely sure about it not being an issue.. I replaced it with the stock version again just to be sure. now as far as the EVAP solenoid, I wasn't getting any codes for it..

I recently ( about 6 months ago replaced the entire system from back to front to deal with possibly over filling the gas tank... but I could un plug and check to see if its been stuck open.. though I would think I would be getting codes prior to its breakage? ) .. makes me also wonder about the cleanliness of the fuel..

as far as the Nipple you speak of .. well on my air box the plastic nipple attached to the PCV ( I believe ) has been broken off.. not sure if any effects or not on boost.. up til a week ago, it was a non issue... and its been broke for a month or so.. been thinking about just doing the repair myself over paying for the new entire thing that the dealer wants to charge me close to 200bucks for.. but not sure if conventional hi temp plastic epoxy/cement would be enough to hold it

tonight I will unplug the Evap Solenoid... see if that does anything.. at least eliminates one on the list. then move to doing a leak test.... the Vac Tank is something I am not sure about and would appreciate some additional information on that.. perhaps a photo of its location.. and what to check...

thanks a bunch for the replies.. will continue to analyze and get back soon

 

Ohh.. I wondered.. if P0101 code happens.. could it be the MAF ?

 

The pvc nipple being broke could be causing your p0101, but normally it's a boost leak not the maf. You could get zzp's upgraded tube ZZPerformance - LNF Cobalt Upgraded Intake Tube #ZZ-LNFUPITT

I strongly recommend an actual boost leak test, not just visual. I did a boost leak test this weekend and had a leak on my hot side pipe connection, it visually looked fine, but was leaking pretty good at 20psi

 

ECaulk- Thanks for the post, I will be getting to Lowes to buy the necessary materials to do the boost leak test this week. I have the regulator on the air line so I should be good to go once I get it built.

one thing is for sure.. I am not even able to eclipes 5lbs of boost / or 900psi before the turbo and the entire engine starts to stutter.. I can hear the turbo spool.. and seemingly alot of air moving.. but it just doesnt do anything.. then , release the clutch and the exhaust goes popping.. just assume that to be what's built up in the system .. then while trying to hold RPM in 4th gear at 40-55mph / 2000-2300RPM, then it wants to stutter or bog down.. that's when I get the MAF code.. or Low Boost, code.. system Rich etc. codes...

As for the braided PCV hose coming off of the Air Box, I will look into the replacement for it .. as mentioned, its been broke for some time and have had no issues with being able to boost until this past week, so not sure what would have changed or if that hose could be the source of the problem.. but I will look at its replacement, so thanks for the link.

 

Ok so as I suspected and as you did too.. I did the pressure test and whamo.. looks like its definitely coming out of the intercooler... passenger side .. on the top side of the black plastic piece before it even touches the plastic charge piping.

so now its looking like im having to purchase a new intercooler... ( I has Sad ) ... so the question now is.. which intercooler is best and most closely related to the stock CFM as I do not have access to a tuner near by.. I have a full HP tune.. the other question is... if I get a intercooler with slightly more CFM... would a re-tune be required... I would have to think.. if a intercooler had say 10 more CFM.. would there be a requirement to re-tune? or is there some kind of break down that says... ohh you only got an intercooler with 20% more CFM .. a re-tune is not really needed. where is the line in that sand if you will?? anyone know?

also .. for the money and most stock looking appearance.. what's best .. MPx? ZZP? .. I am looking for ease of install here.. direct fit.. so I think MPx might be the way to go. unless anyone has something else to say about it.


thanks again all for the continued feedback

 

Zzp is supposed to be a direct fit.

 

well before I go spend the money.. I am gonna take a shot at a self repair on the intercooler.. if the break isnt bad.. I am gonna try some high strength epoxy, the stuff that holds airplanes together, and cut some tin can aluminum and try a patch.. I know it seems pretty "ghetto" to do it this way.. but I'd rather take the southern approach and save some money before shelling out the dough.