I have searched and read about the possible 5psi issue threads (including the new service bulletin thread), I would just like some opinions. Only mods are GMS1 and K&N SRI. I drive a ton of highway on my 08 (at 100k) and I just finally seem to have gotten over the flutter problems. Well now, I'm experiencing the 5si mode issue (and throwing the SES light). It resets when the car is shut off and then can go back to the 5psi mode, but sometimes it'll go over a week and run fine and light goes out. I didn't do a leakdown test but from what I see, all piping is connected. So what should I do to solve this issue? I know I'm gonna be paying out of pocket at the dealer. First off, is the SRI playing into any of this? Also, could this be a tune issue. For example, if I ordered a Trifecta tune would it at least keep it from going into the 5psi mode? Aside from that, I dunno if I should see if a local shop (that has experience with EVos and turbo vehicles) would be a better bet or just bite the bullet and take it to the dealer. I just don't wanna pay for them to trial and error and still not fix the problem. Tjis car has been in and out of the dealer more than any other vehicle I've ever owned. Totally ridiculous. Thanks guys, looking forward to your answers.

 

hmmm in for results, but it could be loose sensors, how was the stage kit wired?

 

Car's either hitting overboost protection or going limp mode for some reason. Possibly poorly wired sensors, but it doesn't sound like that's the issue.

 

I don't know if this will help any but I noticed some guys experiencing it while/after racing or driving hard. The 2 times I threw a code, I was barely boosting, if at all. Once was on the highway cruising at normal speed (not accelerating) and the other was in traffic on a 25mph street.

 

The installation of the GMS1 sensors is historically the cause of this.

 

Your local Evo "tuner" probably isn't going to know jack about how the SS T/C is set up. Its much more advanced than a Mitsubishi Evo, those can be controlled with a simple external manual boost controller.

I would bring it to the dealer and have them diagnose it. They will be able to pinpoint the problem, they have all the resources available from GM as well as the ability to contact the engineers if they get stumped by a really difficult problem.

If I had to make an educated guess, I'd say check the wiring where the GM Stage 1 T-Map sensor is spliced into the stock wiring harness. If the connection was not properly soldered, it probably has a poor connection.

 

That should be covered under powertrain dude... my turbo got covered under powertrain at 40K

 

I'm over 100k so I'm out of warranty. I suppose I'll go down tomorrow and have them drive it and make an appointment to get it in again (which usually takes 2 weeks). It seems like my dealer is so clueless. I've already had them re-wire these sensors, one was already supposedly replaced etc etc.

 

damn on an 08?? im about to turn 47K

 

Yep. All highway. The car looks new still. Thats what is weird cause like i said, it's not like i'm hammering this car at max boost all day. 95% of its life is cruising at 2k rpms on the highway, not boosting.

 

Look at your GMS1 Sensors... If it's not fixed by Oct 1st I'll come look at it when I'm in Pittsburgh.

 

Wow over 100k, what kind of maintenance have you done to the car. I'm at 47k and wondering what I should do to make it last forever lol.

 

When the car goes into 5PSI mode it's called mechanical boost mode by GM . If the computer is having trouble controlling the wastegate it will resort to this. Mine did it new once and it was the wastegate actuator had a loose connection.....but some have broken nipples ...here is the tsb with a pic so you can check it . Or it could be the Stage 1 connections ....just thought this will give you something to rule out anyway


ervice Information 2008 Chevrolet Cobalt | Cobalt, G5 (VIN A) Service Manual | Document ID: 2206771
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#PIP4520: Low Boost / Power And/Or DTC P0299 Or P0101 - keywords actuator boost CAC charge control cooler driveability DTC ECM engine gas lnf low maf MIL reduced reducedpwmde SES wastegate - (Nov 4, 2008)


Subject: Low Boost/Power and/or DTC P0299 or P0101


Models: 2008-2009 Chevrolet Cobalt SS Only

2008-2009 Chevrolet HHR SS Only

2007-2009 Pontiac Solstice GXP

2007-2009 Saturn Sky Redline

With Engine RPO LNF Only




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The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Condition/Concern:
A technician may encounter a vehicle with a low boost/power condition and/or DTC P0299 and or P0101 setting. This may be the result of a cracked or broken fitting at the turbocharger assembly.

Recommendation/Instructions:
It has been determined that the nipple for the turbocharger wastegate actuator may be damaged causing this condition. If this concern is noted please inspect the area on the underside of the turbo compressor housing for the wastegate actuator solenoid valve. The nipple (see CALLOUT #1) may have been damaged causing a loss of boost pressure. It may be necessary to remove the charge air duct for a closer inspection. See eSI "Turbocharger Wastegate Actuator Replacement" for solenoid replacement procedure.





This solenoid is available separate from the turbocharger and should be replaced as a sub assembly. Do not replace the turbocharger assembly.

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.

GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information.

WE SUPPORT VOLUNTARY TECHNICIAN CERTIFICATION


Š 2009 General Motors Corporation. All rights reserved.

 

man hop this dont happen to me 62k and climbing

 

Maybe this was just coincidence, or possibly not even the problem, but after I cleaned my K&N filter and sprayed the MAF sensor with carb cleaner, mine quit going into 5psi mode, which it was doing daily...dealer couldn't find an issue and the GMS1 was installed well.

 

OK I'll spray mine tomorrow. I've done it a few times since I got the SRI but it's been a little while. I made an appointment to drop it off this week. I'll bring up some of the info you guys have posted and hopefully we can pin-point the problem. I'll update with any info.

 

Hey rukkee is this only for 08s and 09s or can this happen on 10s as well? My car will randomly start jerking during partial throttle or cruising on the highway and it seems like when im cruising the car will accelerate on its own. It will lurch forward as if i was accelerating. The bpv goes crazy and is constantly letting off pressure when the car starts jerking. Also, the a/f gauge starts jumping all over the place. Dealer doesn't know what's wrong with it. Could this be the problem?

 

bump

 

I had the same issue with my 09 ss. I have the GMS1 and K&N SRI. I was at 5 PSI and had turbo flutter like a bitch. After taking it to the dealer and having them tell me nothing is wrong, I started doing research on here. Its either the GMS1 Kit was installed like crap, and the sensors, wires arent installed correctly, or you have a hole in the bottom of the chargepiping. I ended up having a hole in my chargepiping, the dealer replaced it, and I have had no issues since.

 

I guess Ive gotta get out more lol, Ive got an 08 with 32,000 miles.

OP, I had this problem numerous times. The issue was the GMS1 MAP sensors install. The first time I brought it back they replaced the lower MAP sensor. The second time it happened I insisted they solder the connections rather than use butt connections. They did, and since then I havent had a problem. That lower sensor being where it is, if the heat sealing butt connectors are not applied right the wires can be exposed to the elements and they will cause the issues with the sensor. Once the sensor goes, your ECU will get erratic readings which will cause erratic and/or reduced boost.

 

Its either the sensor wiring came undone somehow or the MAF. Ive seen a bad MAF or a code for it cause the same thing. Try just resetting the ECU to start, Ill bet that cures it

 

I still need to spray my MAF. i will try to do that today. Just disconnect the battery to reset or is there another way you recommend?

The weird thing is, i was on the phone with the dealer today. The car has only gone into this mode once since alst week when I posted this. They said if it doesn't act up when the car is down there, they wont do anything to it (despite the stored codes) so I dunno if I will waste time leaving it there tomorrow if it doesn't act up. I may just wait til its acting up and drive right to the dealer. I know they replaced a GMS1 map once and just rewired it recently to cure flutter. i really think its that the sensors need soldered, given that I go long spans (and consider my mileage per day) when the car runs fine. i think an actual hardware problem (such as boost leak or wastegate issue) would make the car go into the 5psi mode more often. i could be wrong though. If it acts up and I can get the dealer to drive it, I will insist they solder the sensors, as 80vetteL82 said.

 

Let us know what happens with the car seeing im having the same problems as you and the service manager doesnt want to solder the wires.

 

If I'm right, I get the cookie.

 

I started taking videos of my problems and would shove my phone in the service managers face.

This is a very common problem with bad install on the GMS1.

Freaking sucks the converter harnesses where not out with the kit itself. Would have paid an extra hundred to not deal with it.