Flashing SES code. Changing out heads. Need advice.
02-23-2009, 04:53 PM
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Flashing SES code. Changing out heads. Need advice. I recently was driving on the highway in my 99 T/A and got a flashing SES code. Car runs REALLY rough and lacks HP bigtime. Very choppy idle (althought he needle stays constant...). Pulled a P0500, p0138, and P0158 (Random Misfire, Rear O2s). Checked all the Plugs, wires, and coils. Changed the O2 sensors back to factory. No change. 
Took it to Pontiac and they ran a diagnotic and compression test. They found 0 compression in cylinder 1 and cited bad mechanicals in the heads or hole in the piston. I found a reputable shop on the outskirts of town saying they have a used but in nice condition set of 243 LS2 heads off a GTO with Gold PRC Springs on it. He would remove both heads replace all the gaskets (including the head gaskets, intake gaskets, valve seals, etc..) and put new lifters in all for $1250. Still not 100% sure that the complete lack of compression in cylinder 1 isn't a hole in a piston instead of a head problem (although I don't run nitrous), but I can't afford to tear it down twice. He also said he'd switch out the springs with regular LS6 springs if I'd rather have those.
3 questions
Is it possible no compression in a cylinder is caused by something electrical or the head gasket?
Does that 243 GTO set of heads sound like it will work well on a 99 T/A fairly well w/o a custom tune?
Is this a good deal for everything?
P.S. My casting I currently have on my heads is in the 800's, but I don't remember the exact number.
.
Took it to Pontiac and they ran a diagnotic and compression test. They found 0 compression in cylinder 1 and cited bad mechanicals in the heads or hole in the piston. I found a reputable shop on the outskirts of town saying they have a used but in nice condition set of 243 LS2 heads off a GTO with Gold PRC Springs on it. He would remove both heads replace all the gaskets (including the head gaskets, intake gaskets, valve seals, etc..) and put new lifters in all for $1250. Still not 100% sure that the complete lack of compression in cylinder 1 isn't a hole in a piston instead of a head problem (although I don't run nitrous), but I can't afford to tear it down twice. He also said he'd switch out the springs with regular LS6 springs if I'd rather have those. 3 questions
Is it possible no compression in a cylinder is caused by something electrical or the head gasket?
Does that 243 GTO set of heads sound like it will work well on a 99 T/A fairly well w/o a custom tune?
Is this a good deal for everything?
P.S. My casting I currently have on my heads is in the 800's, but I don't remember the exact number.
.
Last edited by smgbad; 02-23-2009 at 05:07 PM.
02-23-2009, 05:12 PM
#2
sounds like bad catalytic converters....i would def have someone else check out the compressoin, but this time unbolt the headers/manifolds...not from the head but anywhere between the manifold and the cat. no compression is NEVER an electrical issue as compression is determined by all mechanical parts, but having no compression on one cyl will cause the engine to idle very bad...and it will be rythmic and the computer will be able to pick that up, normally shut the injector down and throw a code. It should be code P0301. That would be Cyl 1 misfire. You would also see no activity whatsoever on that cyls injector with a scan tool.
Just my .02
Just my .02
02-23-2009, 06:51 PM
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The only codes thrown were P0300, p0138, and P0158 . Random Misfire (which confuses me as to why it wasn't specific to Cylinder 1 since that was the major misfire cylinder), and the other two codes are the laft and right rear 02 sensors. I changed the new O2 sensors back to stock GM ones and no change. The O2 sensor codes went away though... So you're saying to try unhooking the pipes after the headers and starting it then to see if the compression comes back? ::sorry... confused::
Also, THere's some white smoke (not too terribly much) that smells bad coming out of the back, but not blue smoke. If it was a ring or hole in the piston, wouldn't there be tons of blue smoke?
Also, THere's some white smoke (not too terribly much) that smells bad coming out of the back, but not blue smoke. If it was a ring or hole in the piston, wouldn't there be tons of blue smoke?
02-24-2009, 08:35 AM
#6
maybe burning water...head gasket maybe. But yah if your cats are clogged enough, the air wont come out of the cyl right, and cause alot of funny things to happen. i would def have another shop check the car out.
