Help! 02 WS6 Misfire on all cylinders
11-13-2014, 08:41 PM
#1
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Join Date: Jun 2002
Location: Katy, TX
Posts: 4
Help! 02 WS6 Misfire on all cylinders
Hello,
Sorry if this is not the correct section (please move if needed), but I am hoping someone could steer me in the right direction. I just purchased a 2002 WS6 Trans Am with 35,355 mile. I had it shipped from NY to Houston and took it straight to a mechanic to get inspected to make sure everything was ok. He called me the next day and asked me if I could call the previous owner and ask him if he had made any modifications to the intake or the cams because he was getting a misfire code on all the cylinders (P0301-P0308). He said that it misfires worse in the mornings when the engine is cold and less so when it is warmed up. I bought it from a dealership who didn't have any information on the vehicle. I was able to look up last service date from my Carfax report and it shows the following:
07/16/2010 32,230 Clark's Auto Repair
State inspection completed
Engine/powertrain computer/module checked
Spark plug(s) replaced
Spark plug wires replaced
Air filter replaced
Decarbon service completed
Fuel injection system flushed/serviced
No service since then:
06/12/2012 EASTERN REGION 34,701 Auto Auction REPORTED AT AUTO AUCTION
06/20/2012 MARLTON, NJ 34,640 Motor Vehicle Dept.TITLE
07/13/2012 EASTERN REGION 34,757 Auto Auction REPORTED AT AUTO AUCTION
07/16/2012 EASTERN REGION 34,768 Auto Auction REPORTED AT AUTO AUCTION AS DEALER VEHICLE
I am almost positive that the car has been sitting in a lot since 2012 untouched (it has Falken tires with 95% tread left that are rotted from sitting on flats)
I had them change the plugs and wires (NGK V-Power spark plugs and MSD wires), check for a vacuum leak, clean the MAF and check the fuel pressure (he was getting 60PSI). He also said the little amount of gas that was in there was clean. He plugged the computer in and showed me the misfire readings, and the misfire count was pretty even across all 8 cylinders. He still believes that the cam was modified.
Any other ideas before taking the car apart to see if it has indeed been modded? Any help would be appreciated. Thanks in advance.
Sorry if this is not the correct section (please move if needed), but I am hoping someone could steer me in the right direction. I just purchased a 2002 WS6 Trans Am with 35,355 mile. I had it shipped from NY to Houston and took it straight to a mechanic to get inspected to make sure everything was ok. He called me the next day and asked me if I could call the previous owner and ask him if he had made any modifications to the intake or the cams because he was getting a misfire code on all the cylinders (P0301-P0308). He said that it misfires worse in the mornings when the engine is cold and less so when it is warmed up. I bought it from a dealership who didn't have any information on the vehicle. I was able to look up last service date from my Carfax report and it shows the following:
07/16/2010 32,230 Clark's Auto Repair
State inspection completed
Engine/powertrain computer/module checked
Spark plug(s) replaced
Spark plug wires replaced
Air filter replaced
Decarbon service completed
Fuel injection system flushed/serviced
No service since then:
06/12/2012 EASTERN REGION 34,701 Auto Auction REPORTED AT AUTO AUCTION
06/20/2012 MARLTON, NJ 34,640 Motor Vehicle Dept.TITLE
07/13/2012 EASTERN REGION 34,757 Auto Auction REPORTED AT AUTO AUCTION
07/16/2012 EASTERN REGION 34,768 Auto Auction REPORTED AT AUTO AUCTION AS DEALER VEHICLE
I am almost positive that the car has been sitting in a lot since 2012 untouched (it has Falken tires with 95% tread left that are rotted from sitting on flats)
I had them change the plugs and wires (NGK V-Power spark plugs and MSD wires), check for a vacuum leak, clean the MAF and check the fuel pressure (he was getting 60PSI). He also said the little amount of gas that was in there was clean. He plugged the computer in and showed me the misfire readings, and the misfire count was pretty even across all 8 cylinders. He still believes that the cam was modified.
Any other ideas before taking the car apart to see if it has indeed been modded? Any help would be appreciated. Thanks in advance.
11-14-2014, 06:46 AM
#2
Administrator
Join Date: Nov 1998
Location: Hell was full so they sent me to NJ
Posts: 70,648
Re: Help! 02 WS6 Misfire on all cylinders
If it's been sitting for 2+ years with bad gas, replace the fuel, and clean the injectors. Change the fuel filter. The fuel pressure should be 58psi (60psi is OK), but if he's measuring it at idle, there's very little load on the fuel system. Or did he measure fuel pressure out on the road, with engine under a significant load?
Were there any other codes?
Were there any other codes?
11-17-2014, 06:07 AM
#3
Registered User
Join Date: Jun 2006
Location: upstate New York
Posts: 439
Re: Help! 02 WS6 Misfire on all cylinders
Yes, I'd run a couple tanks of fuel through it first, drive it a bit, check and maybe change most of the fluids: Diff, trans, coolant. Probably needs to run through a few heat cycles before trying to chase down an intermittent problem. Couple cans of Techron or similar wouldn't hurt, I would be concerned about varnished up parts in the fuel system.
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