I decided to re-read the thread, I need a comment from everyone on this. WHAT WERE THE ENVIRONMENTAL CONDITIONS OUTSIDE WHEN THE PROBLEM 1ST STARTED?!?!?! (Rain, Dry, Humid, Hot, cold)

 

Mine conditions were dry humid and hot. Haven't gone into limp mode in a while but still missing power

 

My conditions were. Hot and Humid as well. Also did it on a Hot Rainy Day (again High Humidity). I noticed Mr. Duncan was watching this thread. Lets give him as much info about the problem as we can and maybe together we might find a solution.

 

Map sensor finally died. Replaced it now car is running fine.

 

After all, it is Houston, Texas in the summer.

It seems to happen mainly after a fill up , and for sure after a start - I do not remember it ever " going out" while driving after it had worked fine before.

I disconnected and then reconnected the upper sensor (engine off ) and my problem went away for ~ 2 months.

Then, this past Sunday, I got a CEL.

I did not write the codes down (dummy me ) , but they referenced boost sensor rationality, I think & misfore on cylinder 4 for sure.

I cleared them, and did the pull off/put on on both sensors this ttime.

I checked w/ the reader yesterday - no more codes, no impending codes, and nothing out of the unusual.

A bad sensor - or a misfire - couldn't just disappear on it's own.

I did notice on the Saturday before the CEL that I was feeling a miss while on cruise at highway speeds.

Strange car - I guess complex = potentially problematic. Still fun as all get out, though.

Britt

 

Had my MAP sensors replaced for the second time a couple weeks ago. Taking it back in today with the same symptoms (intermittent limp mode, bucking at lower rpms, occasional rough idle and surging on start up). I'm going to have them look at the lower sensor to see if it is flush and also see if they can check the connections to see if it's not them.

I find it hard to believe that I've gone through 3 sets of faulty sensors, there's got to be something else going on. I'll let you know what they find. At least I'm getting a rental this time.

 

It is not the sensors. It is the connector or wiring harness. Have it soldered and sealed properly. Also check for a rub thru near the AC compressor. If it is rubbing protect the wire with the plastic conduit. Also check for the proper o-rings. If you have replaced them the o-rings may have not been transfered. The O-rings should be blue. Finally check to make sure you do not have a boost leak.

 

Thank you. I'll be sure to relay the message!

 

I havent actually checked the dealers work, but they said they replaced the sensor and soldered the wires and it has been fine for the past month. they also said they changed the size of the o-ring for the lower sensor.

 

I haven't gone into limp mode for quite some time, but the other day during a NLS I got a CEL for basically 5 errors. Random misfire, 1, 2,3, and 4 cylinder misfires. Car continued to run just fine when it happened... :\

 

Problem came back! But this time upper map sensor blown. Dealer ship ordered a new one. Drove the car to the gym with no problems. Then drove home and low boost again. Turned ignition on and off a few time to see if it would go back to normal. It didn't and I got an engine light. Brought the car back to the dealership. Catalytic converter fried!!!
Now they will test all wiring, solder connections check sensor installation. Now I have to wait for another week for cat to come in. Will post findings after I pick it up next week.

 

Anyone hear an odd wiggling noise coming from the engine when WOT and at 20+ PSI?

 

Are you guys still having issues that originally had issues?

 

Did it last Saturday (10/23 )- first time in a while. No codes, no warning - just power off vis a vi the 5 psi boost.

Stopped the car, unplugged & reconnected both sensors, back to good.

I have noticed several times now a lack of response at low speeds & partial throttle - almost like the drive by wire disappeared then reappeared and the car is dropping back to idle.

Related ? Who knows.

My car may have been mad 'cuz I cheated on it - we went to the Mark of Excellence Test Drive and played w/ some Z06's & CTS-V's, coupe & sedan.

Get me a supercharged CTS-Vsedan for 35K and I'll live w/ it being an auto.

Britt

 

mines been at the dealer for the past 3 days only had like 6 psi after they installed it ha

 

It's official, keeping warranty isn't worth the troubles when HPTuner and Trifecta can up it and not worry about the sensors.

 

Had the lower wires soldered and it worked ok for a while except I was getting 15-17 lbs of boost constantly. I also heard loud whooshing noises. Finally a CEL came on. It was throwing 3 codes and the techs at work saw a TSB on a radiator bolt puncturing stock charge piping. So they get the new pipe 4 days later put it in and go and road test it. They say all is well....so I road test it behind them and Im stomping on it and still only 15-17 lbs of boost with my stg 1(always held 20 constantly right after I got it installed and worked fine for months!). As its making boost in 3rd gear it hits a brick wall and immediately got into vacuum and falls flat on its face. Throws an underboost code and the Tech 2 scanner has an asterisks where boost pressure sensor info should be. any info on that??? Help.......there is very limited info on diagnosing cars with stg 1 issues besides the stuff we always hear. Solder your lower Tmap next to the ac compressor and check for leaks. I have done both. I am so fed up with the GMStg 1 I am thinking about going back to stock and selling this thing!

I am so pissed it can work awesome for 6 months now its bugged out and something always wrong week after week for 6 months. UNACCEPTABLE!



AND ON TOP OF IT ALL I SELL CHEVROLETS AND HAVE FOR 4 YEARS. IVE SOLD 2 OF MY FRIENDS SS COBALTS AND THEY ARE WAITING FOR MY FINAL FIX IF ANY TO GET THE STG 1 INSTALLED.

 

Sounds like a bad map sensor to me? If it not showing any boost on the tech 2.

 

According to Onstar - no CEL shown. After I got a chance to pull over, I wiggled the lowers - noticed there was water on the wires (A/C, I presume ) and disconnected/reconnected the upper.

Problem went bye bye.

Too bad there is not a right angled plug that would allow the wires to go to the driver's side of the lower TMAP, thus giving more room.

Hope the helps someone w/ a diagnosis - Britt.

 

I've been reading this and I find that the issues I've been having with mine look A LOT like what you guys are experiencing. Except that I got UP to app. 24-26 psi & I'm stock.
But as far as the irregular boost, limp mode etc go : quite similar. I don't what to make of this, I am getting extremely annoyed with this car and GM altogether, period.

https://www.cobaltss.net/forums/08-1...-stock-235405/

 

Sounds like you have a boost leak or Vacuum leak. The first place I would look is the vacuum cannister connected to the charge air by-pass valve. The diaphragm inside can split causing the problem you describe. The tank is mounted under the intake manifold on the side of the block.

Also, check the intercooler for cracks and leaks.

 

It is when the engine breaks, just ask mkulrey13

https://www.cobaltss.net/forums/2-0l...s-help-235552/

 

99% of the time it has been the crimp connections to the TMAP sensor near the AC Compressor.

 

What a shame that someone deleted that thread. I'm assuming mkulrey did. There was a lot of useful info in there.

Anyhow, I think GMS1 is the way to go if you need to keep your warranty. If you can't afford to pay for a new motor, then do not get a custom tune, and do not get an aftermarket intake. It's as simple as that. I never had a lick of a problem on GMS1, and I bet I run the car harder than 99% of the people on this board.

 

Glad you brought this back up-some of the issues described here mirror symptoms referenced in the service bulletin on same (https://www.cobaltss.net/forums/2-0l...st-mod-191361/) (post #128)

The way my car responded positively to the cannister(tank)delete led me to believe there might be a leak(I had experienced excess lag and 1 underboost episode).However dealership couldn't find code or replicate issue so they wouldn't test tank. I even showed them the bulletin and alluded to my "test"-not sure how smart that was but w/e. For reference it was hot when this happened.
I would be interested in testing the tank myself; any pointers are appreciated.