RE: 5.7L Engine Miss. Very Frustrated! Tried Everything.
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RE: 5.7L Engine Miss. Very Frustrated! Tried Everything. - 8/15/2006 10:24:15 PM
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firered89
Posts: 10
Joined: 8/8/2006
Status: offline
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well, i finally called a shop, and im going in tomorrow morning. he said more thank likely, its something very minor and he would have to drive it to tell. i hope all goes well. he also said if it happens more when your going up hill, its probably your spark plug wires...this might be my case...ZT.
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RE: 5.7L Engine Miss. Very Frustrated! Tried Everything. - 8/24/2006 11:53:19 PM
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ffp444
Posts: 1
Joined: 8/24/2006
Status: offline
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I DON'T KNOW IF YOU ARE STILL HAVING THIS PROBLEM, SEEING THAT YOUR POST WAS IN MAY. HOWEVER, I WOULD LIKE TO HELP. I HAVE A 97 Z-71 WITH 5.7. I INSTALLED A NEW GM CRATE MOTOR IN 10/04. SEVERAL MONTHS LATER, I BEGAN TO HAVE A MISSFIRE IN CYLINDER 8 AND 6. CYLINDER 8 MISSFIRE WAS CONSTANT, WHILE CYLINDER 6 WAS JUST EVERY ONCE IN A WHILE. THIS PROBLEM WOULD ONLY OCCUR AFTER THE ENGINE WARM-UP PHASE. THE ENGINE RAN PERFECT WHILE COLD. I WAS ALSO HAVING AN OIL CONSUMPTION PROBLEM. I PULLED ALL OF THE SPARK PLUGS TO FIND THAT 6 AND 8 WERE OIL AND FUEL SOAKED. A COMPRESSION TEST REVEALED 6 AND 8 WERE LOWER THAN THE OTHER CYLINDERS, BUT THEY WERE STILL IN SPEC. WHILE REMOVING THE INTAKE MANIFOLD, THE BOLT CLOSEST TO 6 AND 8 CAME LOOSE WAY TO EASILY. ONCE I REMOVED THE INTAKE, THE GASKET AROUND 6 AND 8 HAD BEEN PULLED DOWN BY ENGINE VACUUM SECONDARY TO THAT LOOSE BOLT. THIS ALLOWED FOR THE MISFIRE IN THOSE 2 CYLINDERS WITH 8 BEING THE WORST. THIS ALSO EXPLAINED THE OIL CONSUMPTION BECAUSE OF THE GAP CAUSED BY THE DISPLACEMENT OF THE INTAKE GASKET. I BELIEVE THAT THE EXPLANATION OF THE ENGINE ONLY MISFIRING WHILE WARM: WHILE COLD, THE INTAKE SITS FLAT ON THE GASKET, CREATING A GOOD SEAL. UPON WARM-UP, THAT ALUMINUM EXPANDS AND CAUSES A GAP, ALLOWING CONDITIONS FOR A MISFIRE. MY SOLUTION: WHEN I INSTALLED MY CRATE MOTOR,
I WAS VERY PRECISE WITH MY TORQUE SPECS, BEING A FORMER BMW MASTER TECH. HOWEVER, WHEN I TORQUED MY INTAKE BOLTS, I USED JUST WHATEVER LOCTITE I HAD IN MY TOOL BOX. I BELIEVE THIS IS WHY THE BOLT BACKED OUT. BE SURE TO USE THE APPROPRIATE HIGH TEMP LOCTITE SO THIS DOES NOT RE-OCCUR AND OF COURSE, TORQUE TO PROPER SPECS IN A STAR PATTERN. HOPE THIS HELPS.
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RE: 5.7L Engine Miss. Very Frustrated! Tried Everything. - 8/27/2006 8:55:40 AM
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chevyblues
Posts: 24
Joined: 8/27/2006
Status: offline
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This is a reply to the start of the thread.
My '95 Z-71 is having similar problem. Runs ok, but lacks a little power, until warmed up good. Then has very poor acceleration and sometimes feels like it is even missing. I too suspected EGR valve or EGR solenoid. EGR valve holds vacuum with engine off, but doesn't hold with engine on. The lines hold vacuum all the way to the EGR valve. I replaced both the EGR valve and the EGR solenoid. Nothing changed. It was also overheating a bit with the A/C turned on. For grins, I changed the thermostat and the fuel filter. Doesn't overheat any more but still have the power problem.
The only thing I have been able to do to get the engine to run ok again was to disconnect the vacuum line to the EGR Solenoid and plug it.
chevyblues
< Message edited by chevyblues -- 8/27/2006 9:15:19 AM >
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