80vetteL82

So I finally got my car in to have the problems with the GMS1 addressed. Like others i my car occassionally would boost only 5psi (typically hits 24-25), and would run rough at light throttle. I also started getting a CEL when the symptoms started. I forget the CEL number but when I scanned it at my shop it came back as an air intake tract problem. These symptoms typically started right after hitting the road, not after a long a drive. It usually resolved after letting the car sit for a couple hours or sometimes more. I was also getting very erratic idle intermittently, and the car would boost 5+psi at idle!

So I brought it to the dealership yesterday to have the issue addressed and also have the power steering recall done. I called yesterday evening to check on it and was told the recall was done, but they were still trying to diagnose the other problem and would need to keep it over.

I called today around 4 to see if they figured it out. They told me they've decided its the boost pressure sensor, and they special ordered it for tomorrow. He told me they had trouble diagnosing because they don't see "many of these turbos, or whatever it is." Lol this was reassuring, granted he's only the service writer so hopefully the tech knows a LITTLE more.

So what do you guys think, does this sound right? I was expecting it to be the MAP sensor wiring, I don't know much about the boost pressure sensor... maybe the sensor didn't like the 25psi the GMS1 was making?

Thoughts?

Thanks!

Cobalt_Daddy

Gms1 should only make 20.5psi iirc, not 25..

09SS

It depends on location. Some cars require more or less boost to make the numbers GM decided upon.

DoMiStIc_RuSh_06

iTrader: (1)

Mine makes 20-22 depending on the weather.

DirtyBalt09

iTrader: (2)

Dat one dem der turbo cars? Dont see many fancy things like that...

80vetteL82

Nope it holds 24-25, I can read the gauge lol. There's another user on here with GMS1, TommyP I believe, who actually posted a picture of his boost gauge showing 25psi on GMS1.

Lol I'm 15mins from Boston, not in the middle of the sticks. It would be nice if these guys were educated on a product they sell and warranty.

JerseyBeastBalt

i took my car for a similar gms1 problem and it ended up being a crack in the evap canister

naskron

Mine has been doing this every once and a while. I haven't taken it in yet but i thought of what the op wrote was one of my guesses. I noticed that when i got out of the car and took a look under the hood when it was doing it last couple of times, after about a minute or so i heard something click, when i got back in the car it was back to normal. Maybe it was the boost pressure sensor or silinoid clossing or sumthin. Just what i noticed...

80vetteL82

Well, I got a call from the service writer today. According to him they got the "wrong part." Now, I dont know if that means they got something other than they ordered, or if it means they got what they ordered but it turned out that wasnt the problem.

Either way, he said they MAY be able to get the right part for tomorrow but he didnt sound to confident. Personally I dont think they know what the hell is going on with the car!

On the plus side I got a free rental in the mean time....



Its actually really nice. The interior is very comfortable and the ride is very quiet. Its pretty peppy too... its AWD powered by a 3.6L DI engine.

Stay tuned and hopefully there will be some answers from the dealer soon...

Cobalt_Daddy

i only spike 21psi .. odd. im only a few hundred feet from sea level tho.

FasterIsBetter

Sucks man, you should run the hell out of the rental car while you have it. At least try to make it resemble the feel of your TC, lol.

80vetteL82

So, I got the car back the other day. The recall was done, and the GMS1 issue addressed. So far the CEL has not returned, although it was intermittent so Ill have to give it some time and see if it comes back. The car does seem to be running better now. Funny thing also happened, so far Ive only noticed a peak boost of 20-21psi! I wonder if that sensor being screwed was causing the turbo to over spin because I was definitely reading 24-25psi before. At some points before it almost seemed slower when it was boosting that much....like the turbo was spinning real hard but it wasnt getting any where....I dunno.

Either way, its running good now and will hopefully stay that way.....

BTW here are the codes I couldnt remember...

P0236
P0106

They supposedly traced it to an "intermittent opening in the intake air temp pressure sensor" .....

EDIT: Like everyone else I was thinking it was going to be a MAP sensor issue from installing the kit wrong, especially seeing code P0106 is a MAP sensor code. When they told me they were replacing the "boost pressure sensor" I was a little confused....well turns out they didnt! I just looked at the service slip and the part they replaced was # 52206797, looked it up and guess what it is??? A GMS1 MAP sensor! lol so I guess thats what it was after all!

ULTRAKHAN

I had exactly the same thing 24-26 PSI boost then at times no more than 5PSI. I would clear the codes and 24-26 again.
Took it in to the dealer said they didn't find anything just played around with the wastegate.
Now I get a 20-22 PSI and no more faults or sporatic 5psi boosting.

crashher0

iTrader: (2)

Dont mean to dig up an old post but it was the first one on the google machines search for GMS1 5lbs of boost problem. 2 weeks ago I had GMS1 installed everything worked fine for 2 weeks. On my drive home from a 3 hour trip my car shuttered and felt like it had water in the line, sputtering all weird. Figured it was just water since it was raining when i filled up maybe a drop or two got in the tank on accident. but it would only build 5lbs of boost no matter what i tried.

Ever since that day when I will start the car and it will run fine 2 miles down the road it sputters and will only build 5 psi when i shift the turbo shutters when it spins down. instead of the notorious psheww sound when shifting it goes psh-shew-shew-shew-shew. It will do this till i let it sit for few hours.
DTC codes are P0100 and P0238

After that happened the first time i trifecta tuned it thinking it was just my aftermarket intake and its still doing it whether i have the tune on or off.

Is this the same thing you were experiencing? I had the GMS1 installed by a chevy dealer but if the map sensors are bad i feel like i could re-splice their splices and put new map sensors on... Don't want to drop 150+ on new sensors with the kit only being in after a week.

80vetteL82

Yeah, sounds like your MAP sensor. My car is actually doing the same thing again. Its a recurring issue. I may tear into it myself and see what the MAP sensor connections they crimp connected look like.

crashher0

iTrader: (2)

Yep it was the lower map sensor. I've seen p0236, p0238 and today p0237 so I put the car on ramps and found the lower map sensor half plugged in. So I pulled it out cleaned off a little then made sure it snapped into the locking place took it for a spin and everything worked perfectly fine. The only code I threw was a p0100 from my intake.