RE: 5.7L Engine Miss. Very Frustrated! Tried Everything.
Login  | |
|
RE: 5.7L Engine Miss. Very Frustrated! Tried Everything. - 8/15/2006 10:24:15 PM
|
|
|
firered89
Posts: 10
Joined: 8/8/2006
Status: offline
|
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.
|
|
|
|
|
|
|
|
|
RE: 5.7L Engine Miss. Very Frustrated! Tried Everything. - 8/24/2006 11:53:19 PM
|
|
|
ffp444
Posts: 1
Joined: 8/24/2006
Status: offline
|
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.
|
|
|
|
|
|
|
RE: 5.7L Engine Miss. Very Frustrated! Tried Everything. - 8/27/2006 8:55:40 AM
|
|
|
chevyblues
Posts: 24
Joined: 8/27/2006
Status: offline
|
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 >
|
|
|
|
|
RE: 5.7L Engine Miss. Very Frustrated! Tried Everything. - 8/30/2006 4:30:06 PM
|
|
|
dartlord2001
Posts: 4
Joined: 5/4/2006
Status: offline
|
Hey
This is the one that posted the orig. thread. as I said before,I had a guy check my truck with a scanner and he found no problems.I found an advance auto parts with an OBD I scanner.They checked it and their scanner showed a code 42.The printout says Ign System problem-Elec spark timing circuit fault.They said a knock sensor could cause this but they didnt know that for sure.My Haynes manual says knock sensor problem would be code 43.I have tried to locate the elec spark control on the motor but I cant find it.The Haynes manual shows it right by the TBI on the right side but its not there on mine.I cant find the 4 wire plug for it either.Is anyone familiar with this?The truck is a '94 W/5.7L
Thanks
|
|
|
|
|
RE: 5.7L Engine Miss. Very Frustrated! Tried Everything. - 8/30/2006 9:58:58 PM
|
|
|
chevyblues
Posts: 24
Joined: 8/27/2006
Status: offline
|
I have a Chilton (8055) 28624 for 1988-98. The illustration and description put the knock sensor on the block to the front of the starter motor. There some testing instructions. If I had a scanner, it would be yours. Basically it says, you can check the time with timing light and then tap on the front of the engine block. Timing should retard. If not there is a problem with the sensor or the circuit. If replacing, the installation needs to be done to not insulate it from the block.
--------
chevyblues
|
|
|
|
|
RE: 5.7L Engine Miss. Very Frustrated! Tried Everything. - 8/31/2006 11:58:38 PM
|
|
|
bradstump
Posts: 16
Joined: 8/31/2006
Status: offline
|
I had the same problem with a '96. after warming up, it would miss, spit, and sputter under acceleration. Mine was fixed with a fuel filter. Believe it or not, it started again about 3 weeks later. I replaced it again and it never acted up again. I figure I got some bad gas and it just stopped it up.
|
|
|
|
Contact Us |
Advertising |
Automotive Directory |
Archive |
About Us |
Link To Us |
Chevy Links |
Legal |
Privacy Policy |
© Chevrolet Forum
Chevrolet Forum .com is not affiliated with or endorsed by Chevrolet Motors Division or General Motors.
|
Printable Version
