Coblasts

Came across this (updated Aug ,27,08)

Subject: Engine Misfire Due to Injector Control Circuit Short on AC Line Bracket - keywords accelerate acceleration drive gound load loss miss no P0200 P0201 P0203 P0204 P0300 P0301 P0302 P0303 P0304 under #PIP3536 - (09/08/2005)



Models: 2005-2006 Chevrolet Cobalt SS

2004-2006 Saturn Ion Redline

Addition I think it explains it better

Condition/Concern:
Some customers may comment on a severe engine misfire and a SES Light. Upon inspection, DTCs P0300 - P0304 may be found due to misfires on cylinders 1 and 4 or cylinders 2 and 3.

Recommendation/Instructions:
If this concern is encountered, inspect circuits 406 (IC Control for 2/3 Coil) and 423 (IC Control for 1/4 Coil) for an intermittent short to ground or poor connection on either end. Depending on the model, these circuits may short on the AC lines near the AC compressor, on the transmission mount, or on the transmission lines where they enter the transmission. If there is no problem found with these circuits, inspect the ignition control module ground to ensure that it is clean and tight.



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The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Condition/Concern:
On rare occasions, a SES Light and engine misfire may be experienced due to a chaffed injector control circuit. As a result, any of the following DTCs may be stored: P0200, P0201, P0202, P0203, P0204, P0300, P0301, P0302, P0303, or P0304

Recommendation/Instructions:
If the SI diagnosis does not isolate a cause for the concern, inspect the fuel injector harness for a potential short to ground at the air conditioning line bracket at the rear of the head, above the transmission. If signs of a short to ground are present, repair and reposition the circuit/harness as necessary.


Subject: SES Light On or Various Driveability Concerns - keywords backfire cold DTC G103 hesitate idle INT intermittent light low MIL rough stall start SES various warm #PIC3457A - (12/07/2005)



Models: 2005-2006 Chevrolet Cobalt

2005-2006 Pontiac Pursuit




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The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Condition/Concern:
A customer might comment about a SES light on or Various driveability concerns intermittently.

Recommendation/Instructions:
The first thing to check is Ground G103 for it being loose, If it is tight then proceed with current diagnostics.

Note: This ground is located behind the left front head light assembly on the top of the frame rail.

Found this as well
02-06-05-004b Info - Misfire DTCs P0300, P1380, P1381 and Catalytic Converter Damage Due to Installation of Alarm Systems - (Feb 14, 2006)

Another

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Subject: Cylinder Miss On Left Turns And Cylinder 4 Miss On Right Turns - Possible Fuel Contamination - keywords CEL contaminated controls cylinders gas injector intermittent MIL misfire P0300 P0301 rail rust #PIP3333A - (07/12/2007)



Models: 2004-2008 Chevrolet Aveo

2004-2006 Chevrolet Cavalier

2005-2008 Chevrolet Cobalt, Cobalt SS

2006-2008 Chevrolet HHR

2004-2008 Chevrolet Malibu

2007-2008 Pontiac G5

2006-2008 Pontiac G6

2005-2006 Pontiac Pursuit (Canada Only)

2004-2006 Pontiac Sunfire

2003-2008 Pontiac Vibe, Vibe GT

2003-2008 Saturn Ion, Ion Redline

2007-2008 Saturn Aura, Aura Hybrid

2004-2008 Saturn Vue

2007-2008 Saturn Vue Hybrid

with a 4 Cylinder Engine

(RPOs L61, L91, LAT, LE5, LNK, LSJ, LV6, or LXT)




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This PI was superseded to update models. Please discard PIP3333.


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The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Condition/Concern:
On rare occasions, an intermittent engine misfire may be experienced on cylinder 1 during/following a left turn or on cylinder 4 during/following a right turn. The misfire may / will typically last up to 10 seconds. A SES light and DTCs P0300, P0301, and/or P0304 may also be present if the misfire lasts long enough.

This may be the result of fuel contamination and is more likely to occur on vehicles with a returnless fuel rail because it is easier for fuel contaminates to become trapped in a returnless fuel rail since they do not have a fuel return line that returns fuel back to the fuel tank. As a result, any fuel contaminates that make it to the fuel rail tend to gather over the #1 fuel injector inlet when turning left and tend to gather over the #4 fuel injector inlet when turning right, causing this concern. The cylinder next to the fuel feed line (1 or 4 depending on the model) may also experience some random misfires at idle as contaminates enter the fuel rail from the fuel tank.



Another one I read:
Missfires caused by aftermarket alarm systems due to the mechanical relay they use in there unit for disarming the car.

Heres some stuff to check

1)Operate the engine at idle.
Observe the Heated Oxygen Sensor (HO2S) parameters with a scan tool.

2)Visually and physically inspect the following items:
The vacuum hoses for splits, kinks, and proper connections

3)Inspect for the following conditions:
The HO2S for proper installation
Ensure that the electrical connectors and wires are secured and not contacting the exhaust system.

4)Inspect for the following conditions:
-Missing, loose, or leaking exhaust components
-Vacuum leaks at the intake manifold, throttle body, and injector O-rings
-The air induction system and air intake ducts for leaks
-The crankcase ventilation system for leaks
-The evaporative canister purge pipes for obstructions or plugging.

5)Still could be your Maf
Observe the manifold absolute pressure (MAP) sensor pressure parameter with a scan tool.

Worst case
6)If conditions were not corrected, a worn cam, worn intake or exhaust valves, or other engine mechanical failure may be at fault.

7)Test for fuel contamination. Small amounts of water can be delivered to the fuel injectors and cause a lean exhaust indication. A lean exhaust indication can also be caused by too much alcohol in the fuel. Refer to Alcohol/Contaminants-in-Fuel Diagnosis .

8)The system will go lean if an injector is not supplying enough fuel.

9)A lean condition could be present during high fuel demand due to a fuel pump that does not pump enough fuel, a plugged fuel filter, or a restricted fuel pipe.

jeremie

i've only seen this concern one time. it doesnt happen too often.

rukkee

iTrader: (3)

Thanks for posting those . I've check all of them in Service Information and it's a pretty big issue . My car has a random misfire at idle , it won't set a code or flash a light but it shows up on a tech2 misfire graph. Alot of people have complained about this in the past , this will give them some things to check.

Cobaltss/TC

The same thing can be caused by improper spark plugs see that more often then the wires shorting!!!!!

07SSCharged248

nice find....

srcobaltss

only if i knew what all that ment and how to check..i'm having a misfire problem thats leading to other problems..

emiller

Anyone else having misfire problems with their 08 SS TC?

07cobalt07

I've got the same problem with intermettent (sp) misfires at idle. I notice it more after warming up the engine.

WickedSS2005

iTrader: (1)

subscribed for home

cobaltR

I sometimes notice misfires also...but not horrible ones....ocassionally at idle or when I'm at a lower rpm and give it alittle boost. Its alittle annoying but it hasnt affected any wot runs.

07cobalt07

Shoot, I keep taking mine to the dealership and they keep telling me that they cannot duplicate it. They told me to bring it in when it happens again. So, I'm sure I'll be taking it by there tomorrow. Let you know what happens.

brett5

i really only get misfires when my plugs are about shot...like now again at 5000 miles the ngks are shot i'm swithching back to autoliites

superbrowndude

iTrader: (2)

I'm having a misfire at low rpm and a knock reading at 3.6max at low speeds to. I'm not sure how long this has been happening,I just started monitoring it now. After I filled up with gas today,it took the dic a few min to tell me how much fuel kms I would have. That's never happened to me before,I use octane 94. My A/Frs are sitting around 14.4-15, there like that all the time. My mods are in my Sig,tell me what u guys think.

Brenticus

iTrader: (2)

Mine misses at idle due to a rich tune. Hoping to get that resolved in a couple of weeks.

trey ss

good info sir

SS/TCNick

iTrader: (5)

I'm getting a misfire at low Rpm's and after I give it a little boost. The dealership said they couldn't find what was wrong with it and to bring it in if it happenes again. Well it is and I took my tune off b/c I was sure it was the tune messing up but it's not, still getting a misfire any help please? Not on much if anyone can help p.m. me thanks a lot

guitarenvy

You've got other issues if your going through plugs like that.

SS/TCNick

iTrader: (5)

Lol I know I have other problems to but the dealership doesn't even know why its having misfirers :/

blackss2.0

Anyone ever find a common solution for this or do I really have to check everything those bulletins say?

LP08SS

iTrader: (2)

ive been having misfiring problems too! i thought maybe my tune would have taken care of it but about 2 weeks after i got another bunch of misfire codes

blackss2.0

I've had misfire in cylinder one for like a year and a half now. Thought it was due to my tune but now i'm starting to think it may have to be why my air fuel is 10.9-11.0 on wot when after I got it tuned it was 11.8-12.3. Sticky injector maybe?

LP08SS

iTrader: (2)

Could be .... why dont u switch your injectors around and see if the condition follows the suspicious injector 5to the cylinder u put it in?

dufcobalt

I got misfire on #3 cylinder on idle after I put 2.9" 60lbs plug new injectors new... a/f idle are crazy 13.5 to 15.5 and at wot 10.0... I dont know what causing misfire .. someone has an idea?

ECaulk

iTrader: (6)

Did you tune for the pulley and injectors?

dufcobalt

yes hptune