Hi all, first post long time reader. Some background on the car. I bought it brand new in 2010 so I'm the only owner and have always taken proper care of the car, oil changes air filter, tire rotations spark plugs etc. I had the stage 1 installed at the dealer while the car was still under warranty and ever since the stage 1 install the car acted a little "funny". What I mean by funny is, when it was cold outside (winter, I live in Ohio) the car would have a lumpy idle. It would wander for a bit and then settle. Never had any problems with drivability or anything though. I did take the car to the dealer to have UT looked at and was told there was nothing wrong with it, they re-downloaded the new ecu map so I moved on. The stage 1 was installed prior to the quick connect kit so the wires are spliced for both of the map sensors. I've looked at the connections and don't see any issues with them. So about 4 months ago everything went haywire. The car would surge under acceleration almost like a big gust of wind came up and pushed me, primarily in 1st and 2nd. Then I would lose all power and wouldn't be able to accelerate much past 30 in 3rd gear. It threw cell codes for multiple cylinder misfire on all 4 cylinders as well as a MAF sensor malfunction so I stored it for the winter. Now rhat it's getting warm out I'm trying to fix it. I've read multiple things about what it could be but nothing is definitive.

Things I've read:
Fuel filter - bought a new one watched some videos and can't find the damn thing, any ideas?
MAF sensor - replaced it still happening
Ignition coils - replaced all 4 still happening
Spark plugs - replaced all 4 for the second time still happening (ac delco iridium plugs properly gapped)
Cam sensors - have not replaced yet but are on the list

I'm quickly running out of ideas and don't want to take it to the dealer and spend an arm and a leg. So really I'm just looking for additional advice outside of the, "hey go install those other sensors", on things I can look at or try that way I can get this issue resolved. All help is aprecited. If you need more info, please let me know.

 

I'd be willing to bet your problem is the MAP sensor connections. I'd solder the connections.

 

^ this. How much boost will it hold? How many miles on the car? I think the filter is in the tank with the fuel pump if I remember correctly. My gms1 tune hunted around at idle also. Have you ever cleaned your valves?

 

Looks like I'll be soldering the connections this weekend then. In the end it wouldn't hurt I guess, to eliminate that as a possibility. I was dreading that the fuel filter would be in the tank. Looks like they sold me the wrong one so I'll be returning that. The car has 85k miles on it and I've never cleaned the valves. Is that the old sea foam through the brake line trick?

 

To clean the LNF valves you are looking at

https://www.cobaltss.net/forums/how-...nifold-304187/

https://www.cobaltss.net/forums/how-...emoval-304188/

Takes about 8 hrs the first time you do it. But it's very much worth it.

 

Another potential issue could be the primary o2 sensor, you have 85k miles they usually last in stockish form around 80-100k miles

 

That's a great idea buddy. Good luck to you.

I highly doubt your intake valves are gunked up bad enough to cause any noticeable issues. GM's PCV system is definitely lack luster but it's nowhere near as bad as BMW's and VW's.

Definitely put it on your list of thins to do. I'd suggest the primary 02 as ECaulk said as well. I changed that sucker every time I swapped to a different turbo.

Keep us posted!

 

It's funny you mention gust of wind. I have that exact feeling with no codes or other issues. Some of it appears to be tune/cam table related.

I also have not tried changing my intake and exhaust cam selenoid that's on top of the valve cover. It's a 5 min job, just need to purchase the selenoids.

 

Mine only had 34,000 miles on it (20,000) driven by a woman, and my valves were bad enough that it effected the idle significantly and part throttle.

 

Check your MAF code again, if it's P0101 there is a chance you have a boost leak.

If you can get a scanner on it, it could be crazy fuel trims.

Also, check you evap purge selenoid.

 

My evap purge solenoid did go bad not too long ago so that has been replaced. Cause a very crappy idle that always wandered. Also replaced the trunk monkey (can't remember what it's called) not too long ago. I'm starting to realize how many things this could be and all I'm seeing are $$$ for parts.... I'll be honest I was hoping for one of those hey I had the same thing this is what I replaced and it worked fine.

 

With cars it's sometimes a crap shoot as to what went wrong. Lots of sensors on computer controlled cars. If you ever want to pull the trigger on hp tuners it can help some in diagnosing issues as you can datalog and check out some of the data to help diagnose.

 

So I drove the car to work today to test this theory (7 miles). My car has a built in lcd display that will show me several things 1 being air to fuel ratio. Watching that as I'm driving, anytime the car would lose power, I would drop to 16-18 air to fuel which 18 is as high as the guage goes and then when power returned it'd spike to 12. I only get the "surge" when im medium throttle with no boost (don't have much of a chance to boost with all the stops i make to work). Would this indicate an issue with the primary O2 sensor? I'm trying not to replace both if it's not needed.

 

Cruising around your car should be at 14.7 for most of the time. When you left off the throttle it will spoke because it goes into fuel cut off. It does sound like your fueling may be off. Can you log fuel trims? If your long term fuel trim is messed up you may have a boost leak. I'd probably do a boost leak test anyway

 

So the moral of the story for me here is, post on the forums before buying a bunch of parts to try and fix your car. Replaced the bank 1 o2 sensor with an ac delco replacement, unplugged the battery and reset the computer and she's running fine right now. Was a pain in the ass to get to though, had to pull the fuse box, which I've done before when my shift linkage broke and worked it with a breaker bar but all is well. Still haven't soldered the map sensor connections so that will be on next weekends project list but I appreciate all of the feedback from everyone. The only question that I still have, should I be worried about the lumpy/wandering idle that is far more apparent when it's cold out? Any known fixes to that issue or should I start another thread?

 

Just for reference. You don't have to pull the fuse box. You just have to squeeze your hands in there and find the nut and work your socket onto it. Helps having an 02 socket.

So to your lopey idle. Have your valves been cleaned before? Do you have a video of the idle? Do you let it warm up properly before hitting the gas? I usually don't start driving till the idle settles down.

 

^ this. After I cleaned my valves it helped smooth out the idle. Also, someone can correct me if I'm wrong but I think gms 1 retains the cat warmup unlike an hp tune where you can turn it off. If you are higher miles, your cat may be slightly plugged if you don't regularly do some spirited driving. Partially plugged cat will make it even worse.

 

So I'm resurrecting my old thread here. I thought I had the issue fixed, for all I know this may be a new issue. After replacing the bank 1 O2 sensor everything cleared up and about 2 months ago I seafoamed the car. Just this last week I started throwing cel codes again, multiple cylinder misfire on all cylinders and maf sensor (which I replaced already). The issue is a little different now though. The car will stumble as if it wanted to die, but only for a second, then it'll drive fine the rest of the way but it won't boost at all in any gear. Any thoughts or ideas? Replace the O2 sensor after the cat?

 

What are the new codes you are getting?

02 after the Cat has nothing to do with drivability.

I will say, that replacing the cam selenoids fixed the surging issue I was having. But mine wasn't as extreme as going into limp or low boost mode.

Are you sure you don't have a boost leak?

 

P0100
P0300
P0301
P0302
P0303
P0304
P0420

I'm not sure if I have a boost leak or not, but will likely have to test that as well.

 

p0420 is a catalyst code (prob why you mentioned the secondary O2 sensor). I could see a clogged cat causing misfires, have you checked that out?

You can check the solenoid valves by measuring the resistance across the leads. >25ohms and it's bad. However, I'd expect a p0010 or p0011 code for that issue.

 

P0100 is the main focus here i think.

Check the wiring to the MAF sensor
Clean the MAF sensor with proper cleaner.
Check the EXH fuse in the under hood fuse box.
If you have an aftermarket intake switch back to stock. (also make sure your intake is attached properly)
Check for boost leaks including your intercooler if it's stock.
Replace MAF sensor ACDELCO 2134332
Replace both cam selenoids Genuine GM 1265540 and Genuine GM 12655421
Clean both MAP sensors.
Last is possible bad computer.


This is the order of operation I would go in. Starting with the things that are easy going to harder.

I know this seems like a lot, but it's only $100 in parts and will nail down an issue.

 

I'll put my old map sensor back in from when I switched it out last time thinking that was the issue. How hard is it to change the cam sensors, I'll have to try that this weekend.

 

It's a 5-15 min change. Very easy. Easier than an oil change. They unbolt and you pull the electrical connector off.

 

So I'm once again reviving this thread. I thought I had everything fixed, threw a P0106 and P0420 code last night. Figured what the heck, clean the MAP sensors and see what happens as that is what I found while searching. Now to the fun part. The Cold Charge Pipe bolt was rusted, and well, is now headless. I've been searching for about an hour now, and haven't really found any good how-tos on how to remove the lower charge pipe on either google or through the many forums that I frequent. Can one of you fine patrons, point me in the direction of a proper how-to? I haven't had to do anything major on the car as of yet, so if it's as simple as jack the car up, remove these 2 bolts, feel free to tell me that as well.