04 GTO Ran fine one day and now it's running like it has a big cam
10-07-2011, 04:15 PM
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04 GTO Ran fine one day and now it's running like it has a big cam I've got a 04 GTO LS1.39k miles.K&N AIS.Magnaflow catback.Nothing else is done to it.It has always run perfect.Day before yesterday I jumped on it.It ran to 4000 rpm and would go no farther. I've changed plugs.The old one's didn't look bad.Compression is 160lbs on the drivers side and 105 -120lbs on the passegers side. Missfire on 4 and 6. Swaped plug wires,injectors,and coils off another running LS1.That did nothing and the other LS1 is running fine with the swaped parts in it. It seems to be running worse since we've changed everything? The whole car is shaking. Broken valve spring maybe?What am I missing? Blown headgasket? Thanx.
Last edited by EVIL_Z06@yahoo.com; 10-07-2011 at 08:03 PM.
10-07-2011, 05:17 PM
#2
Someone might of swapped your ls2 for an ls1. I think that's the problem. If it's an ls1 it's an 04. Anyway, have u gotten the MAF sensor checked out? Intake leaks? Don't keep swapping parts just because u "think" it's the problem. Find a good tech near you to help.
10-07-2011, 05:42 PM
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Sorry it's a 04 built in September.Ck'd ground wires,Ck'd for vacume leaks at the intake manifold. Removed MAf and cleaned it.Wouldn't the MAF throw a code? I'm getting PO304 and PO306 missfire codes. We've shut down injectors 1 by 1. It's easy to do a process by elimination if the parts are availible. Ck'd fuel pressure regulator.60 lbs of fuel pressure.
10-07-2011, 05:49 PM
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Thanx I was headed in that direction. Pulled valve covers, no broken springs,Rockers in tact pushrods r straight. This is got me stumped. Thought it had a blown head gasket on the rt bank.It had low compression 105 to 120.Pulled the head and changed the gasket,had the head ck'd out.They took .008 of it. Still have a misfire code on 4 and 6?
Last edited by EVIL_Z06@yahoo.com; 10-15-2011 at 10:28 AM. Reason: Still have codes
10-07-2011, 08:35 PM
#6
Sorry it's a 04 built in September.Ck'd ground wires,Ck'd for vacume leaks at the intake manifold. Removed MAf and cleaned it.Wouldn't the MAF throw a code? I'm getting PO304 and PO306 missfire codes. We've shut down injectors 1 by 1. It's easy to do a process by elimination if the parts are availible. Ck'd fuel pressure regulator.60 lbs of fuel pressure.
10-07-2011, 08:41 PM
#7
if you got low compression on one side Iwould say blown headgasket, if you have low compression its not going to be electrical so stop waisting your time replacing plugs wires and looking into air fuel problems.
if its got low compression then its getting out somewhere. my bet is a blown gasket between the 4 and 6 cyl
if its got low compression then its getting out somewhere. my bet is a blown gasket between the 4 and 6 cyl
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10-07-2011, 08:57 PM
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if you got low compression on one side Iwould say blown headgasket, if you have low compression its not going to be electrical so stop waisting your time replacing plugs wires and looking into air fuel problems.
if its got low compression then its getting out somewhere. my bet is a blown gasket between the 4 and 6 cyl
if its got low compression then its getting out somewhere. my bet is a blown gasket between the 4 and 6 cyl
10-15-2011, 03:56 PM
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Compression on the rt bank after the head gasket still is 105-115 ? were gona do a wet test now and see if it's rings.130-149 wet.
Last edited by EVIL_Z06@yahoo.com; 10-15-2011 at 07:18 PM.
10-15-2011, 04:13 PM
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have you checked the coils, spark plugs and spark plug wiries
I came the same problem, and found two coil is not functioning and one spark plug wire needs replacement
I hope this will help
I came the same problem, and found two coil is not functioning and one spark plug wire needs replacement
I hope this will help
10-17-2011, 12:25 PM
#16
Ignore all the posts saying to check for spark and fuel and power and grounds. This is simple- you have low compression so you either have bad rings, valve(s), or head gasket problems. The fact that it is on 4 and 6 would indicate a gasket problem which is probably best case scenario. Losing spark or fuel won't give you low compression numbers.
10-17-2011, 12:40 PM
#17
Like stated before, the likely cause is a clogged catalytic converter. Unbolt the passenger side converter from the manifold and drive it. If the power restores, you're converter is clogged. Contact your local GM dealer and find the vehicle's in-service date. All vehicles sold in the US have an 8 year/80K mile warranty on catalytic converters. Depending upon when the vehicle was sold, you may still be covered.
