Can anyone help me with this issue? I had my brother, a mechanic, spend about 40+ hours diagnosing this issue. The car is idling at 2k after only an intake and fuel injection cleaning using BG products. Here is a quick list of everything we did so far.

Service Rendered:



BG Air Intake System Cleaner



BG Air Intake System Cleaner is an extremely effective solvent/degreaser formulation that quickly removes sticky, heavy deposits which accumulate in the air throttle body assemblies and plenums of modern, multi-port fuel injected engines. Cleanup reduces harmful exhaust emissions and restores engine performance. Catalytic converter and oxygen sensor safe. BG Air Intake System Cleaner is designed to be used with the BG 9210 Inject-A-Flush® Apparatus.

Part No. 206

11 oz. (325 mL) can



BG Fuel Injection System Cleaner



BG Fuel Injection System Cleaner is a specially formulated blend of solvents, high molecular-weight dispersants and deposit control additives which will quickly, effectively and safely clean fuel injectors and help remove upper engine deposits. This product is designed to be used with the BG 9210 Inject-A-Flush® Apparatus and BG 44K® Part No. 208. BG Fuel Injection System Cleaner contains deposit control additives which “pre-soak” rock-hard valve deposits. This allows the powerful cleaning ingredients in BG 44K® to provide even more effective cleanup. Not harmful to any fuel system components including gaskets, hoses, metals, fuel tank bladders, fuel pumps, O-rings, etc. Catalytic converter and oxygen sensor safe.

Part No. 210

11 oz. (325 mL) can





http://www.bgprod.com/products/fuelair.html





After BG fuel service, Cobalt SS has undesired high idle, erratic idle, poor fuel economy. DTC P0507 set. No Other DTCs Set.



Diagnostic Steps:

Check for Vacuum Leaks, Inspect PCV:



Tests performed/Test Result:

Smoked Engine through throttle body intake & brake booster vacuum hose – NO LEAKS Present.

Inspected PCV operation – Valve Operates Normally





Engine Sensors/Circuit Tests:

MAP sensor holds vacuum

MAP sensor values confirmed with analog Vacuum Gage

MAP sensor circuit testing: Map sensor signal circuit tested, MAP 5V reference circuit Tested



MAF sensor swapped out with Known Good MAF sensor

MAF sensor signal circuit tested for short to ground/short to voltage/any additional resistance



O2 sensor swapped with Known Good 02 sensor

Back pressure test performed – 0 back pressure



ACC Pedal swapped with factory Pedal



Alternator/Generator Testing:

L Terminal Voltage within range

L Terminal Turns ON/OFF

Vehicle Voltage within Range



Fuel Pressure: 58 PSI



Throttle Position is consistent with throttle command.

No Throttle DTCs set in ECM.



Swapped Spark Plugs with AC Delco 41-103



Engine Coolant Temp Confirmed


IAT Confirmed



All above tests passed and didn’t reveal any problems.



Snap-on Solus Pro Scanner revealed MAF Performance Test Failed. – POSSIBLE Problem





Cobalt SS acts like its running Rich, or a has Vacuum leak. Increasing engine load will sometimes correct Engine Idle until the throttle is actuated again. Other DTCs may still be in ECM due to unplugged sensors during diagnostic. The Only DTC sets during normal Engine cycle is P0507 Idle Speed High. Possibly ECM isn’t calculating MAF frequency correctly, or Fuel Injectors dumping too much fuel?

 

im gonna go with that last idea. injectors are adding too much fuel. Try swapping injectors and see if the issue remains?

 

It's probably something to do with how your software (aka tune) relates with your hardware (aka powertrain components). I had all sorts of issues with my mods in my Grand Prix; That's why I stopped doing performance mods when I bought my balt.

 

I am meeting with Vector today to reflash and see if they can see anything.

 

sounds like there is a tune issue..stock injectors in the car should not be doing that with ur stock idle rev limiter which is if i remember 850, dont quote me..i dont have my tunes open...post up with details after theylook at it

 

I had this issue last summer and spent $600 taking the car places and "fixing" it. I did everything you have listed adn changed my tune I dunno how many times. Nothing fixed it. Sprayed Carb cleaner trying to find leaks, nothin. BUT..... Only thingwrong was a vac line was loosely seated. Enough to not be detected but during operation would cause a bad idle.

It took a 5 cent ziptie to correct my issue. Make sure every vacuum hose is snug. Not just if it's seated on but tug and see if they slide right off. There should be resistance. If not, ziptie the end. Fixed my bad idle.

 

Kirk at Vector is out for a week. Just my luck. GM has the car now. Get ready to be raped. Already paid $95.00 to have them look at it. I hope it is the ECM and they just reflash it. I can get Vector to add the tune again for free later.

This was not it because we did 2 smoke tests and it showed no leak. That would be nice tho.

GM couldn't help cause my ECM is locked and "it needs to be stock to diagnose further". Typical bull ****.

I made an appointment with Vector for when Kirk returns. Does anyone have any other suggestions?

Did you know Chris isn't with Vector anymore?

 

Tune issue.

 

anyone else have ideas? i plan on getting it back to stock and taking a test drive. then we'll see what happens.

 

I wouldn't be quick to suspect your injectors, as your PCM(ECU) should be able to cut fuel pressure to compensate. Check your fuel trims for a pretty clear indication on weither its cutting/adding fuel. In my opinion, injector cleaners tend to do more damage than good, but to each his own.

 

this may sound crazy but if you can get your hands on another maf put it in and disconnect your battery completely both terminals...then put back on after 2-3 min....start car and let idle for 2 min so the computer can run system ck's and reset your maf then see what happens....if you of course didnt try that already.....the maf's in the cobalt's are very tempermental and if you contaminated it in any way...which you very well could have then it wont send the correct signal.... therefore changing idle speed..by afecting other sensors.....just a thought

 

read the first post

 

YA YA I KNOW I realized it after i typed all that >>>>>>plus read my post again I put in there "if you havent already tried that" so I covered my behind....lol

 

bump

You're right Chris doesn't work for Vector anymore


I also got the same issue as you do...
seems like anyone that cleans their throttle bodies gets this problem

I got Vector's Power Flash Cable and Kirk just updated my tune for a first try and it didn't fix my problem


Was he able to fix yours??

 

Yes, he was able to. He flashed it back to stock, but that didn't help. So I asked him to flash it with the latest GM file, which was more updated than the one I had. That did the trick. Then I had him put on the tune and I am all set.