Thanks for the info. I just ordered the ZZP one anyway. I don't want to deal with that crap.

 

Update.

Installed the ZZP charge pipe. Reused old couplers. Did a boost leak test before putting the turbo coupler on and all checked out okay.

Car will only boost to 17 maybe 18, and fuel trims went right back to 15. I can't catch a break. I would have thought the spitting soapy bubbles leak I had before would have been it. I double checked and re tightened the clamps and no luck. I did reset the trims before taking it out.

Can the pcv check valve go bad and leak? When I put my hand over it while the engine is running there is a definite tone change. I wonder if air is entering the system there.

I remember powell saying that GM has an upgraded pcv valve out now? (Was in his pcv instructions)

That or I will be pulling the bumper this weekend. I have to get this fixed before I can install the intake so that I can then install the pcv separator.

 

Oh My I Was Certain This Was Going To Be It. Thats Possible Too, I Think In Order To Remove It, You Have To Cut Something At The Valve Cover Since The Thing Is Crimped In On That Side. Still, I Feel Theres A LEak On The ChargD Side Since It Goes Negative Under Boost. 17-18 Psi Seems Low For gms1.

 

Alright, I was thinking on my drive to work. When you say boost 17-18 psi. Is that a spike to 17-18 psi towards the upper RPM or is that held 17-18 psi and does it spike to 20psi?

The reason im asking is, maybe the problem is you have a stock tune with GMS1 sensors? Did you buy the car from the dealership the way it is? Or have GMS1 installed on it?

Im thinking could it be possible that someone trades in a GMS1 tuned cobalt SS and the dealer goes 'hey this doesnt feel normal." And flashes it back to stock tune. I dont know what happens when you use 3 bar MAP sensors with a factory tune, im assuming nothing but I do think if the car recognizes the sensors as the 2.5 bar MAP sensors and they are actually 3.0 bar sensors that could cause something.

Im short on ideas now since you made the boost leak tester and did not see anything outside of that couper. If it is the PCV valve, I will be shocked and apologetic since you did mention it in an earlier post.

The last thing I could think of would be to really check the GMS1 tune (You have GMS1 or no?)
Somebody with HPtuners in your area should data log your car and send it to a reputable tuner so they can pour over the data and find out whats causing the high LTFT. And... if its holding 15 LTFT without changing, maybe it can just be tuned out? You probably dont want to go that route and find out whats causing the initial problem though.

PCV valve makes sense cause you have a positive LTFT most of the time and its on the vac side. Okay I got another idea and this might sound sticky and stupid but its temporary lol. Wrap the PCV valve to the intake using duct tape making sure to seal any gaps, make sure its sealed good so that theres no possible way for air to get by. If you have another idea without using tape, go with it as long as it makes a tight seal. Drive around and see if the LTFT comes down.

 

LTFT does not go negative per say, but dips at least 2 percent. Right now it is hovering at 13.6 and then throttle puts it to 12.2. Idling in neutral will put it as high as 19.

Got the car used with 24000 miles on it from a Ford dealer. So I'm not sure they would have touched it. They had no idea it had GMS1 or they would have asked for more haha. I only found out by reading this forum and then checking the sensors and stickers that I do indeed should have GMS1.

PSI under WOT (say in 2nd gear) will climb rapidly to 17PSI and then will jump to 18 nearing the end of the gear. I am at sea level (I work literally a mile from the sound) so would it be possible to say that my car does not need to boost that high? Regardless, my LTFTs should not be that high. I have seen 19psi before but I have not seen it since I put on the ZZP charge pipe (more volume to try and compress?).

I am going to try the tape suggestion tonight after the car cools down a bit.

 

Just Saran wrapped the entire check valve and then covered it in tape. At idle nothing changed but we will see on my work drive tomorrow.

 

k, Im still thinking its plausible that the car is not on GMS1 then if you only hit 18 psi as a spike towards the end, When its hot out you'll see higher PSI on the boost gauge and when its cold you will see lower PSI (14-16ish)

Whats your temp like in the area? Im assuming you dont have any sort of boost leak, your boost leak tester would have found that, even on the intercooler (you could still pop the bumper off and look at it).

I certain wont factor out that its possible the dealer switched the tune back to stock file. OR the previous owner had GMS1 then he HPtuned it and traded in with factory parts installed. The dealer then could say "Oh this doesnt feel right." and flash it back to stock tune (not GMS1) or the previous owner flashed it back to stock. Again I dont know what happens when you have 3 bar MAP sensors on a factory tune, could be this.

If nothing comes of this, its time to meet up with a local tuner and datalog to see if there are any answers there. They would be able to tell you if its GMS1 or factory tune. They should also be able to see how many times the cars been "flashed" or tuned previously.

 

First of all, stock tune with 3bar maps would throw a cold almost instantly.

I still don't see how you could have such a high positive LTFT without a leak.

With stock intake the LTFT is around 0 and with K&N you should see +5 to +10

What you are talking about is a good size leak.

 

He's checking that now. Postive LTFT screams vacuum side. He made a boost leak tester to check the charged side and found a leak on the factory charge piping. He replaced the upper charge pipe with a metal one from ZZP, problem still there. Its not a big leak, otherwise a code would be thrown and he'd be making 1-3 psi for boost.

As for there being other possible leaks, theres the intercooler and lower charge pipe. Im assuming he sprayed the soapy water on everything and the only thing he could visually see was the upper charge pipe leak. He does notice that at boost the LTFT drifts back down which is why I suggested a leak on the charged side to begin with.

Also im the only one responding here... you have any suggestions? I gave him some decent ideas to solving this mystery. The other possibilities could be the Purge Valve solenoid is stuck open (would result in a CEL)? or a vacuum line somewhere out of sight has a tear (would eventually result in a CEL)?


Wired,
If you still see high LTFTs, another step before seeing a tuner is actually taking the bumper off and doing the boost leak test again, spray the crap out of the intercooler (especially that small crack/ scuff you saw by the condenser bar) and lower Charge pipe.

 

I will be removing the bumper this weekend.

 

This suggests 0 improvements at the PCV.

If you werent in washington, I'd come help you out. Ive done the intercooler swap before. Its not bad taking the bumper off.

https://www.cobaltss.net/forums/how-...nstall-298667/

^When I did my TR8, pic are really bad. I didnt realize my Droid Potato didnt have at least a 1.3 megapixel camera.

You can kinda follow that for taking the bumper off

 

Where is the threshold for a CEL? I'm looking at the CEL list and I'm reading it as 1.23 Lamda. Which I assume is +23%

I agree about the purge valve. It's too common of a problem and I have had one stuck open and one stuck close. For the price it's stupid not to change it.

 

I had a CEL pop at -21%. It was due to a pencil tip sized hole on the lower charge pipe. I completely missed the vac line being disconnected there and that resulted in a CEL, not for the vac line but the tiny hole. My LTFTs creeped negative pretty much immediately. In 2 to 3 days I had a CEL. I did all highway driving too.

As for the Purge valve, you would get a CEL when it doesnt open or close when its suppose to give a Emmissions CEL unrelated to a lean or rich AFR CEL.


We also have to take into consideration that he replaced the whole intake system with a K&N intake and the problem still existed. If there was any leak in the intake system other than the PCV valve then he would have seen an improvement.

JUST GOT ANOTHER IDEA.

Take out the BPV, check the diaphragm for a tear. (should result in negative fuel trims and a boost leak as well but you never know.)
Becareful taking it out and disconnecting the vac line. The vac pressure holds the BPV together when assembled. You dont want the spring to shoot out and dissappear.

 

Thanks for the help. I really appreciate it. Just to make sure its known, these are positive fuel trims I am having.

The saran wrap and tape over the pcv check valve did not solve the problem. LTFTs did not move however I did not reset them before leaving for work.

I want to get this fixed so I can install the intake so that I can install the powell pcv system I have sitting in my garage. Stock airbox leaves too little room for it.

 

yes I understand. + fuel trims usually mean unmetered air is getting into the system. Leak under vacuum.

- Fuel trim is metered air leaving the system. Leak in charge piping or charged side.



If there was a leak at the PCV valve, a drive to work would have instantly made the fuel trims drop back to normal.

P.S.- if there was a tear in the BPV diaphragm (located right on the turbo under that skin colored cap held by three bolts), then metered charged air would leak back into the intake tube, this should only cause a negative fuel trim and a pretty bad boost leak so its probably out of the question.

 

I just gotta ask. The PCV valve is located inside the intake manifold, between the intake and the head. There's no way you took the intake manifold off and removed the PVC valve and wrapped it in Saran Wrap. Did you?

 

I think he means the vent from the valve cover to the intake. The one thats held on by that stupid spring clip which doesnt quite make a good seal.

 

Really need to change the purge valve to get it off the list. Such an easy change.

We will continue to help, just have to start knocking stuff out.

 

Yes I meant the pcv vent check valve that connects to the intake.

Cudajoe, I thank you a ton for the help so far. I just wanted to make sure new comers knew that we were talking about positive trims.

Ill check the evap solenoid blow test and see if there is a broken seal there. I can also stop to get a new one as I'd like to diagnose without just buying all new parts. Already spent 200 which didn't work (which I would have done myself anyway as that leak looked bad. Plus it looks cool haha)

 

Evap purge valve passed the blow test and the owing looks good.

 

when you take the bumper off this weekend, spray the intercooler good, also spray anywhere there is a vacuum line connected to the system (for boost leak test). Car doesnt have many miles, but it doesnt mean the previous owner damaged something. I wonder if you have the vacuum tank deletion?

That was a thing a while back to remove the plastic tank under the intake manifold and block/bypass the vac lines.

https://www.cobaltss.net/forums/2-0l...ss-mod-208802/

 

Good call. Bypassing the vacuum tank is a free thing to knock another thing off the list.

 

You are running the GMS1 tune with a K&N intake?

There is likely no problem with your car, especially if the fuel trims return to normal when you put the stock intake back on.

My long term fuel trim would creep positive until the DTC was triggered with the K&N untuned. Either get a tune or put the stock intake back on. It seems pointless to be looking for a nonexistent problem.

 

I was thinking vacuum tank for the vacuum line down to the cold side pipe next to the MAP.

 

I know you didnt read the entire thread based on your response. He's got GMS1, thats it. Everything else is stock. Stock airbox, GMS1 tune. +15 LTFT. When he's in boost the LTFTs dip in the negative direction. He hit +10 LTFT hold 5psi in 5th gear acceleration. (Probably from the leaky upper charge pipe).