Need help troubleshooting 2004 GTO after cam swap
07-26-2008, 07:01 PM
#1
Need help troubleshooting 2004 GTO after cam swap Hi guys I need some help on this one.
I've been tuning LS1 cars for years now but I have a 2004 GTO M6 that has a major problem. I think its more of an electrical problem than anything. Car ran perfect before the cam swap.
The guy came to me for a basic tune to get his car running better, he swapped in a 232 236 114lsa cam with supporting valvetrain parts, cold air kit and different catback. He currently has the stock manifolds but getting LTs next month.
With the stock tune or my basic tune, the car is gutless, a mini van can out run this thing.
- It has major misfires on cyl 1
- You can smell raw fuel when its at idle
- LTrims on bank 1 is at +25 at idle and bank 2 is at -6
- When driving it goes in and out of closed loop
- Injector bank 1 is about double of bank 2 (ms)
- Sounds like half the engine is running/firing
- It has Ignition coil codes for cyl 1,3,5,7
I checked all the wiring and all looks fine, didn't see any pinched wires.
Both injector fuses are fine, ohmed them out with my DVM.
I'm out of ideas of things to look for, any help would be apreaciated.
Bill
I've been tuning LS1 cars for years now but I have a 2004 GTO M6 that has a major problem. I think its more of an electrical problem than anything. Car ran perfect before the cam swap.
The guy came to me for a basic tune to get his car running better, he swapped in a 232 236 114lsa cam with supporting valvetrain parts, cold air kit and different catback. He currently has the stock manifolds but getting LTs next month.
With the stock tune or my basic tune, the car is gutless, a mini van can out run this thing.
- It has major misfires on cyl 1
- You can smell raw fuel when its at idle
- LTrims on bank 1 is at +25 at idle and bank 2 is at -6
- When driving it goes in and out of closed loop
- Injector bank 1 is about double of bank 2 (ms)
- Sounds like half the engine is running/firing
- It has Ignition coil codes for cyl 1,3,5,7
I checked all the wiring and all looks fine, didn't see any pinched wires.
Both injector fuses are fine, ohmed them out with my DVM.
I'm out of ideas of things to look for, any help would be apreaciated.
Bill
07-26-2008, 07:28 PM
#2
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Have you done a compression check and a leak down on cyl 1 vs other cylinders? Have you pulled the valve covers off or checked the plug?
1 cylinder on 1 bank is 25% right? So if 1cyl is not having a combustion cycle and just pumping air, the o2 sensor notices this and shows a 25% leaner mixture (plus whatever the stft's are- up to 50) then the other bank. If there is a problem on one bank, such as what you have, the fuel trims will make matters much worse.
Its good that you narrowed this down to cylinder 1. Note all the things that affect that 1 cylinder: injector, pushrod, valve spring, lifter, valves, rings, spark plug, plug wire, coil.
If this were something like an exhaust leak, you could clear the fuel trims and the car would drive perfectly fine until it learned the mixture again. If this were a vacuum leak and you cleared the fuel trims, it would drive worse until the trims learned the mixture again.
Are you able to clear the fuel trims with your scanner? If so, clear them and see how the car feels, and keep clearing them. Or put the car in open loop and test it. It doesn't sound like an electrical problem. If the car was fine before the cam swap, I would look at the obvious things that have been changed- springs, pushrods, lifters, plugs etc....
I hope this gets you on the right track, if you need any additional help you can call me @ 813-495-8778
Jeremy
1 cylinder on 1 bank is 25% right? So if 1cyl is not having a combustion cycle and just pumping air, the o2 sensor notices this and shows a 25% leaner mixture (plus whatever the stft's are- up to 50) then the other bank. If there is a problem on one bank, such as what you have, the fuel trims will make matters much worse.
Its good that you narrowed this down to cylinder 1. Note all the things that affect that 1 cylinder: injector, pushrod, valve spring, lifter, valves, rings, spark plug, plug wire, coil.
If this were something like an exhaust leak, you could clear the fuel trims and the car would drive perfectly fine until it learned the mixture again. If this were a vacuum leak and you cleared the fuel trims, it would drive worse until the trims learned the mixture again.
Are you able to clear the fuel trims with your scanner? If so, clear them and see how the car feels, and keep clearing them. Or put the car in open loop and test it. It doesn't sound like an electrical problem. If the car was fine before the cam swap, I would look at the obvious things that have been changed- springs, pushrods, lifters, plugs etc....
I hope this gets you on the right track, if you need any additional help you can call me @ 813-495-8778
Jeremy
07-26-2008, 08:01 PM
#4
I swapped coil pack #1 with coil pack #3 problem didnt follow.
The guy came by at 9PM last night and was trying to figure it out till 11PM in my driveway.
I can clear the Ltrims, put it in closed loop, open loop, doesn't make a difference.
It is bank 1 cyl 1 that is having major misfires.
The exhaust manifolds were never taken off, all he did was remove the intake, coil packs, valve covers, front timing cover, etc for just a cam swap.
I'm thinking he has 2 problems, maybe the intake has a leak on cyl 1 and some other issue.
The thing that gets me is that it has coil pack codes for the whole bank 1 (drivers side)
Jeremy, I think I'll give you a call in a few...
Bill
The guy came by at 9PM last night and was trying to figure it out till 11PM in my driveway.
I can clear the Ltrims, put it in closed loop, open loop, doesn't make a difference.
It is bank 1 cyl 1 that is having major misfires.
The exhaust manifolds were never taken off, all he did was remove the intake, coil packs, valve covers, front timing cover, etc for just a cam swap.
I'm thinking he has 2 problems, maybe the intake has a leak on cyl 1 and some other issue.
The thing that gets me is that it has coil pack codes for the whole bank 1 (drivers side)
Jeremy, I think I'll give you a call in a few...
Bill
07-26-2008, 08:13 PM
#5
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Sorry i ment to say switch the whole assmbly for 1,3,5,7 with the one for 2,4,6,8. and see if you get codes to switch.
Then swap plug # 1 to say #6 and see if the misfire follows then the same with the plug wire.
Then swap plug # 1 to say #6 and see if the misfire follows then the same with the plug wire.
07-26-2008, 08:52 PM
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07-26-2008, 09:35 PM
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Well that is a good point, are they coil codes or misfire codes?
Swapping the entire bank coil pack from side to side would have been a good fast diagnostic.
Swapping the entire bank coil pack from side to side would have been a good fast diagnostic.
07-27-2008, 04:36 PM
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Might check that all the spark plugs are secure (torqued down) as well. A loose plug will bring the engine way down on power and create the lean bank as well as DTC's.
07-28-2008, 07:29 AM
#13
I talked to the car owner yesterday and for some reason he thinks he installed the cam 180 degrees out, is that even possible?
He said he is going to tear everything apart and "reinstall" the cam making sure cyl 1 is at TDC and its dot to dot.
He said he is going to tear everything apart and "reinstall" the cam making sure cyl 1 is at TDC and its dot to dot.
07-28-2008, 09:38 AM
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It's easier to pull all the spark plugs to make turning the engine by hand easier. Look for timing tape that is close to the same diameter as the harmonic balancer. It will help get close on the degrees. Again if off a tooth it will be big numbers.
good luck!
Robin
07-29-2008, 08:51 PM
#16
***UPDATE***
Car is up and running perfect.
The cam was installed 180 degrees out!!! (from what car owner told me) Still don't know how that was possible but it did run.
After he "reinstalled" the cam, I highly suggested replacing the front cover seal and using a new crank bolt, which he decided to do after I explained why.
Thanks to all that tried to help me out, you learn something new everyday!
Car is up and running perfect.
The cam was installed 180 degrees out!!! (from what car owner told me) Still don't know how that was possible but it did run.
After he "reinstalled" the cam, I highly suggested replacing the front cover seal and using a new crank bolt, which he decided to do after I explained why.
Thanks to all that tried to help me out, you learn something new everyday!
