1995 Pontiac Grand Am quad 4 has compression fuel and spark

Tiny
RAIDER197
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  • 1995 PONTIAC GRAND AM
Engine Mechanical problem
1995 Pontiac Grand Am 4 cyl Two Wheel Drive Automatic 100k miles

Help! I'm banging my head against the wall trying to figure this one out. I purchased a 1995 Grand Am for my son and installed a good cylinder head on it. It ran fine for about a month now it wont start. New coil housing, plugs, crank sensor, tried new fuel pressure regulator, tested ignition module at NAPA, checked for a shorted sensor, took readings from sensors (crank, cam, map, maf, mat, temp, tps) checked resistance on injectors. I seem to have plenty of fuel squirting out of the injectors and good strong spark at all of the plugs. I am thinking too much fuel or spark and fuel at the wrong time. But when removing injectors and plugs then cranking, it seems to be going through the proper sequence. I did scan the PCM with an Auto x-ray scanner and got a code 34 (Map, Maf) but I dont think this would prevent the engine from running. Even with starting fluid it wont pop off at all. I thought water in the gas or plugged converter/tail pipe but that seems ok as well. I did reset the PCM too and that did not work. The engine has 150 psi in each cylinder. Which is what it was right after head replacement. Ughh, Someone smarter than I please help!
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Monday, March 24th, 2008 AT 7:23 PM

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Tiny
SERVICE WRITER
  • MECHANIC
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IT would be worthwhile to follow the MAP trouble tree for the code 34. This may lead to the the source in a roundabout way. One of the test results lead to a bad ecm.
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Monday, March 24th, 2008 AT 7:39 PM
Tiny
RAIDER197
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It ended up being that the valve timing was off. Even though it fared well on a compression test. The chain was a 2-4 nothes off. So my compression test to verify timing was a failure. Do not rely on a compression test. Tear side of engine down to verify. Replaced chain and tensioner now it runs like a new car. The quad four is not junk after all !
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Monday, April 7th, 2008 AT 9:08 PM

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