Need help: Car starts to miss or hesitate as it starts to warm up... need opinions!
08-16-2001, 07:06 AM
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Car: 2002 SOM z28
Engine: LS1
Transmission: T-56
Need help: Car starts to miss or hesitate as it starts to warm up... need opinions!
The car started doing this over a 1 week period... it starts off OK, but as I drive and it warms up to operating temps (about 160F) it starts to miss and hesitate under light/med throttle.
My first thoughts were plug wires, so I changed those. I also checked a few of the plugs which look relatively clean (and are not that old). I also took apart the carb an cleaned it out really well. I also checked my timing, but it is still at 8* (where it likes it...). My fuel psi is about 7 and my float level appears correct.
I do suspect a blown power valve... that is the next thing to change. I first thought I'd ask to see if anyone else has had this same problem and what they had to do to fix it. I am supposed to go to a car club gathering and would really like to represent the 3rdgen crowd...
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1984 z28 w/ a 357 cu in. monster engine which is looking like the posterchild for Edelbrock with the exception of the Holley 750vac... all the suspension stuff... 9-bolt posi disk is in...
-=ICON Motorsports=-
My first thoughts were plug wires, so I changed those. I also checked a few of the plugs which look relatively clean (and are not that old). I also took apart the carb an cleaned it out really well. I also checked my timing, but it is still at 8* (where it likes it...). My fuel psi is about 7 and my float level appears correct.
I do suspect a blown power valve... that is the next thing to change. I first thought I'd ask to see if anyone else has had this same problem and what they had to do to fix it. I am supposed to go to a car club gathering and would really like to represent the 3rdgen crowd...
------------------
1984 z28 w/ a 357 cu in. monster engine which is looking like the posterchild for Edelbrock with the exception of the Holley 750vac... all the suspension stuff... 9-bolt posi disk is in...
-=ICON Motorsports=-
08-16-2001, 02:52 PM
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Car: 2002 SOM z28
Engine: LS1
Transmission: T-56
What are signs that the MSD box might be going? I would figure that those things either work or they don't (much like a blown amp). And would that explain why the problem starts more once the engine is hot and not while it is still cold?
08-17-2001, 01:44 PM
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Car: 2002 SOM z28
Engine: LS1
Transmission: T-56
How does a "how can my stock LG4 beat a turbo Eclipse" post get 6 replies, yet a serious tech question gets none! I should have picked a better title... lol------------------
1984 z28 w/ a 357 cu in. monster engine which is looking like the posterchild for Edelbrock with the exception of the Holley 750vac... all the suspension stuff... 9-bolt posi disk is in...
-=ICON Motorsports=-
08-17-2001, 02:00 PM
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Car: 1985 Trans Am
Engine: 350
Transmission: T5
Axle/Gears: 3.70
Don't cry Ray. It's not very manly. 
Honestly Ray I would undo the MSD box and try it. If anything you can atleast rule that out if you still have the problem.
[This message has been edited by Karps TA (edited August 17, 2001).]
Honestly Ray I would undo the MSD box and try it. If anything you can atleast rule that out if you still have the problem.
[This message has been edited by Karps TA (edited August 17, 2001).]
08-17-2001, 02:26 PM
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Car: 2002 SOM z28
Engine: LS1
Transmission: T-56
Hey Brandon... Don't you dare come crying to me next time you need someone to hold your hand through rebuilding an alternator or fittings for your fuel pump... don't you have Ewoks to chase away from your car or something!
08-17-2001, 10:37 PM
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2 words.....SPARK PLUGS and dont go by "theyre not very old" because a bad plug show the exact signs you speak of...I know I fought this gremlin before...runs great when cold but as it is warming up it goes to hell...plugs are cheap, try it
Brian
Brian
08-18-2001, 11:14 AM
#7
Bio,
Hmmm... let's think about this. Holley four, running lean at part throttle, missing under moderate load... it all sounds normal to me.
Do you have a Quadrajet you can bolt on to try?
If you couldn't tell, I'm not a big fan of Holley carbs. I know that makes me the odd-ball, but that's just the way I am. Check the metering blocks for deposits and buildup. The power valve really shouldn't be a factor at moderate throttle openings.
And don't disregard Blueiroc's advice - I've never seen ten bucks worth of new spark plugs do any harm to an engine.
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Later,
Vader
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"Let the bodies hit the floor!"
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Hmmm... let's think about this. Holley four, running lean at part throttle, missing under moderate load... it all sounds normal to me.
Do you have a Quadrajet you can bolt on to try?
If you couldn't tell, I'm not a big fan of Holley carbs. I know that makes me the odd-ball, but that's just the way I am. Check the metering blocks for deposits and buildup. The power valve really shouldn't be a factor at moderate throttle openings.
And don't disregard Blueiroc's advice - I've never seen ten bucks worth of new spark plugs do any harm to an engine.
------------------
Later,
Vader
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"Let the bodies hit the floor!"
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