SS Low RPM Misfire
Thread Starter
Member
Joined: 02-10-2013
Posts: 98
From: Fullerton,Ca
SS Low RPM Misfire
I have a 2008 SS manual and it developed a low RPM misfire. 45k on vehicle.
I took it to a shop and they diagnosed a bad injector. I replaced all 4 with the new ZZ Opel injectors. It did not help. If I get the RPMS above 2500 the misfire is gone. I have codes PO300, 301, 302, 303, AND 304.
The shop was confident that #4 cylinder was the culprit because it showed the most misfiring. I put new plugs in and swapped the coil packs from 1 and 2 to 3 and 4 to see if the misfire on #4 would go away and it did not.
Any ideas anyone? I have had the car almost 1 year and I put 10K troublefree miles on it up to now.
I took it to a shop and they diagnosed a bad injector. I replaced all 4 with the new ZZ Opel injectors. It did not help. If I get the RPMS above 2500 the misfire is gone. I have codes PO300, 301, 302, 303, AND 304.
The shop was confident that #4 cylinder was the culprit because it showed the most misfiring. I put new plugs in and swapped the coil packs from 1 and 2 to 3 and 4 to see if the misfire on #4 would go away and it did not.
Any ideas anyone? I have had the car almost 1 year and I put 10K troublefree miles on it up to now.
Senior Member
Joined: 12-24-2007
Posts: 2,873
From: Seville. OH
The codes are showing a misfire on all cylinders. I would first check fuel supply.
Maybe a compression test just to rule out engine problems.
Did you Have all of these codes before the injectors were replaced?
Maybe a compression test just to rule out engine problems.
Did you Have all of these codes before the injectors were replaced?
Deceased
Joined: 06-30-2010
Posts: 25,739
From: Kannapolis NC
Can't rule out the plugs either, are you using the proper AC Delco 41-108 Iridium plugs?
Switching to other brands, especially some of the "Performance" brand plugs, will almost guarantee misfires.
And as mentioned above, a fuel pressure test and compression check are in order.
Switching to other brands, especially some of the "Performance" brand plugs, will almost guarantee misfires.
And as mentioned above, a fuel pressure test and compression check are in order.
Senior Member
Joined: 04-26-2009
Posts: 669
From: City of Champions
http://www.enclaveforum.net/index.ph...1647;topicseen
Nope, it doesn't matter... all DI motors (early or late-model) will be affected with carbon on the intake valves.
Here's another thread from the Camaro forum:
http://www.camaro5.com/forums/showthread.php?t=241547
Pay attention to what member SC2150 says, otherwise, read the following GM TSB, although physically cleaning the carbon is the only way to remove ALL the carbon:
Service Information
Home Publications Number Search New Bulletins Bulletin Search Feedback Help| Document ID: 2863222
#PIP5029: Engine Misfires Due To Major Carbon Deposits On The Intake And/Or Exhaust Valves - (May 29, 2012)
Subject: Engine Misfires Due To Major Carbon Deposits On The Intake And/Or Exhaust Valves
Models: 2008 - 2012 Cadillac CTS, STS
2008 - 2010 Chevrolet Cobalt SS, HHR SS
2007 - 2010 Pontiac Solstice GXP
2007 - 2010 Saturn Sky Redline
The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
Condition/Concern:
Some customers may complain of a MIL and engine misfire. In some cases, the misfire may be more apparent on a cold start, may count on a single cylinder or several cylinders, and may or may not be felt by the driver. Upon inspection, the technician will find one or more misfire codes (DTC P0300, 301,302,303,304) stored in the ECM and SI diagnosis may or may not isolate the cause of the misfire depending on whether the intake/exhaust valves are sticking at the time of the diagnosis.
This may be the result of major carbon build up on the intake and/or exhaust valves as shown below so the misfires should not have appeared until the engine has accumulated around 5,000 miles or more.
Nope, it doesn't matter... all DI motors (early or late-model) will be affected with carbon on the intake valves.
Here's another thread from the Camaro forum:
http://www.camaro5.com/forums/showthread.php?t=241547
Pay attention to what member SC2150 says, otherwise, read the following GM TSB, although physically cleaning the carbon is the only way to remove ALL the carbon:
Service Information
Home Publications Number Search New Bulletins Bulletin Search Feedback Help| Document ID: 2863222
#PIP5029: Engine Misfires Due To Major Carbon Deposits On The Intake And/Or Exhaust Valves - (May 29, 2012)
Subject: Engine Misfires Due To Major Carbon Deposits On The Intake And/Or Exhaust Valves
Models: 2008 - 2012 Cadillac CTS, STS
2008 - 2010 Chevrolet Cobalt SS, HHR SS
2007 - 2010 Pontiac Solstice GXP
2007 - 2010 Saturn Sky Redline
The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
Condition/Concern:
Some customers may complain of a MIL and engine misfire. In some cases, the misfire may be more apparent on a cold start, may count on a single cylinder or several cylinders, and may or may not be felt by the driver. Upon inspection, the technician will find one or more misfire codes (DTC P0300, 301,302,303,304) stored in the ECM and SI diagnosis may or may not isolate the cause of the misfire depending on whether the intake/exhaust valves are sticking at the time of the diagnosis.
This may be the result of major carbon build up on the intake and/or exhaust valves as shown below so the misfires should not have appeared until the engine has accumulated around 5,000 miles or more.
Thread Starter
Member
Joined: 02-10-2013
Posts: 98
From: Fullerton,Ca
I just did a compression test. Engine was warm.
1--110
2--106
3--118
4--50
I think I know where the culprit is, but even my highest of 118 is low. I am going to do a leak down test. What compression reading have any of you guys been getting, assuming
you had a reason to check?
1--110
2--106
3--118
4--50
I think I know where the culprit is, but even my highest of 118 is low. I am going to do a leak down test. What compression reading have any of you guys been getting, assuming
you had a reason to check?
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