DMarotta

Is it remotely possible that a dirty airfilter could cause me to get absolutely no boost? I mean, I can be up at 5000 RPM with no boost, floor it and get no boost?

I took the car to the dealer and they said it was due to a dirty air filter. Anyone care to chime in?

GDZHHR

Sounds like a load of BS to me. How bad good your filter be? Did they show it to you?

RaineMan

What dealer did you take it to? Parks, City, Steve Moore, etc?

I can tell you the guys at Parks have no clue... City did all the service on my Cobalt SS/SC and seemed to know their way around.

I personally know one of the techs at Steve Moore.

DMarotta

I went to Steve Moore. He said it was the filter and I called BS. The Cust Service rep went into some story about the code it threw said it was the filter. While driving home it "appeared normal" with the new filter, however my boost never went over 15 PSI. I should be seeing 20+ PSI since I have the GM stage II kit.

As I was driving home the boost went out again. No code this time. I pulled a U-turn and went back to the dealer. I took the Cust Service Manager out for a quick ride to show him I was not nutz. They have the car again and i am in a loaner.

I am starting to get a little miffed wth this issue as it has happened several times since Feb march time frame and each time they say they fixed it. However about every 90 days I end up back at the dealer. The Cust Service rep I deal with is Kenny. Nice guy, he is as puzzeled as me. Who is the tech you know mabey he is the guy looking at my red HHR SS?

Anyone want to take a shot a what may be wrong?

ChevyMgr

You tell them to check this PI. They can find it in SI under PIP#4720.

https://www.chevyhhr.net/forums/show...31&page=11#107

DMarotta

Thanks Chey Mgr, I actually had PIP #4720 done about 30 days ago (or alledgedly had it done)

This time the tech gave me a sheet referencing "DCT P2178: Fuel Trim System Rich at Cruise or Accel"

Quote from the invoice: P2178 Found long term fuel trim at -24%, Replaced dirty air filter, reset trim and test drove now at -16% Spec Tolerance is 0% to -20% at idle.

After I took the Cust Service Mgr for a ride an showed him the issue. I turned the car off, then restarted it. Boost returned but only to about 15 PSI and if I went WOT I can cut the boost out again so this is now reproducible. There is no CEL code.

The only thing on this not showroom stock is the GM stage II and new rims (same tires)

RaineMan

Hmm, that does sound like a tricky one.

Maybe your ECU needs to be reflashed? I've seen some of the Cobalts conveniently "forget" tuning info and try to reset to the stock program... which means plenty of trouble if you are running Stage kit parts.

The lack of codes is also a concern. The computer on these things is so finicky it should be popping codes all over.

The guy I know is Jason Praefcke, he's a DSLSJA member. The last time I talked to him he was working there as a tech. I don't know if he's certified on the LNF, but it can't hurt to ask.

Good luck!

More_Torque_More_HP

I would have them check the PI again and very closely check the wiring for chafing. The other possibility is the intercooler "leaking"

The reason the PI was put out was that a "chafing" wire can reduce boost and not set a code. the chafed area causes a poor signal, but the signal still exists so the code is not set.

XXL

There's your problem!