"Miss" When Warms Up
#1
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Joined: Aug 2003
Posts: 482
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From: Chesapeake, VA
Car: 1991 Formula Firebird
Engine: L98 with headers/exhaust
Transmission: 700R4
Axle/Gears: 3.23 10-bolt
"Miss" When Warms Up
Hey...just want to pick your brains for advice.
I just picked up a mint 1991 Formula 350. The car runs great upon start-up, but as it gets progressively hotter, it runs rougher with a pronounced "miss". The previous owner had the distributor replaced and I just changed the plugs and wires, which were in bad shape. I was thinking the coil would be my next move, but I'm open to suggestions. Thanks in advance! Ben
I just picked up a mint 1991 Formula 350. The car runs great upon start-up, but as it gets progressively hotter, it runs rougher with a pronounced "miss". The previous owner had the distributor replaced and I just changed the plugs and wires, which were in bad shape. I was thinking the coil would be my next move, but I'm open to suggestions. Thanks in advance! Ben
#3
Thread Starter
Member
Joined: Aug 2003
Posts: 482
Likes: 0
From: Chesapeake, VA
Car: 1991 Formula Firebird
Engine: L98 with headers/exhaust
Transmission: 700R4
Axle/Gears: 3.23 10-bolt
Re: "Miss" When Warms Up
Well, I've had a head-gasket go before and the Formula has none of the symptoms. The plugs looked/smelled "wet" with fuel, which I thought backed the ignition theory... I replaced the coil last night with no improvement.
Any ideas?
Any ideas?
#5
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iTrader: (2)
Joined: Mar 2003
Posts: 465
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From: Heart of Dixie
Car: 1987 Camaro Sport Coupe
Engine: 355
Transmission: 700R4
Axle/Gears: 7.5 inch 342
Re: "Miss" When Warms Up
I would run a cylinder leakdown test. Or pull the plugs and put pressure tester on the radiator. see if you get any water.
#7
Thread Starter
Member
Joined: Aug 2003
Posts: 482
Likes: 0
From: Chesapeake, VA
Car: 1991 Formula Firebird
Engine: L98 with headers/exhaust
Transmission: 700R4
Axle/Gears: 3.23 10-bolt
Re: "Miss" When Warms Up
Thanks for the replies, guys. I think it is the injectors. I'm really pressed for time so (don't laugh) I'm having the Pontiac dealership do a diagnostic on the Formula. It barely made a 7-mile trip...
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#9
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iTrader: (1)
Joined: Jan 2006
Posts: 924
Likes: 6
From: Sweden
Car: 1989 IROC-Z
Engine: 350 TPI
Transmission: Th700R4
Axle/Gears: 3.27
Re: "Miss" When Warms Up
Yeah it could be the ignition module and/or pickup coil to.
Had similar problem, runned good cold, but a as soon as the car got running temp and the sun hitting the hood, the dist started to miss, and was really hard to start sometimes when it was hot. Turned out to be a really bad ignition moule and a "on the way" pickup failure..
Got new parts from MSD (warranty) and im on the road again.
Had similar problem, runned good cold, but a as soon as the car got running temp and the sun hitting the hood, the dist started to miss, and was really hard to start sometimes when it was hot. Turned out to be a really bad ignition moule and a "on the way" pickup failure..
Got new parts from MSD (warranty) and im on the road again.
#10
Thread Starter
Member
Joined: Aug 2003
Posts: 482
Likes: 0
From: Chesapeake, VA
Car: 1991 Formula Firebird
Engine: L98 with headers/exhaust
Transmission: 700R4
Axle/Gears: 3.23 10-bolt
Re: "Miss" When Warms Up
***Update***
The dealer found 10psi at the fuel-rail, so they replaced the fuel pump and that seems to have fixed it. They are taking it for an extended road test to make sure there are no other issues. I need to get some diagnostic tools for the 3rdGen...
The dealer found 10psi at the fuel-rail, so they replaced the fuel pump and that seems to have fixed it. They are taking it for an extended road test to make sure there are no other issues. I need to get some diagnostic tools for the 3rdGen...
#13
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Member
Joined: Aug 2003
Posts: 482
Likes: 0
From: Chesapeake, VA
Car: 1991 Formula Firebird
Engine: L98 with headers/exhaust
Transmission: 700R4
Axle/Gears: 3.23 10-bolt
Re: "Miss" When Warms Up
Got the Formula back yesterday and it is running fantastic. Thanks for the input guys!
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