7 cylinders running at 400 degrees???
Thread Starter
Junior Member
Joined: Oct 2006
Posts: 80
Likes: 0
From: Mechanicville, New York
Car: 91' z28
Engine: rebuilt 350
Transmission: stock
Axle/Gears: stock
7 cylinders running at 400 degrees???
91 z28 tpi 2000 miles on new 350. Car has been stalling out and very hesitant lately so i decided to take it to the chevy dealership. They told me that 7 of the cylinders are running at 400 degrees and 1 cylinder at 200 degrees. What does this mean and what can happen and what causes this?
Senior Member

Joined: Mar 2004
Posts: 923
Likes: 2
From: Bakersfield, CA
Car: 91 Z28
Engine: 383 SuperRam
Transmission: ProBuilt 700r4
Axle/Gears: G92 3.23
Re: 7 cylinders running at 400 degrees???
they probably put an infared thermometer on the exhaust ports. the one at 200 degrees would indicate a rich cylinder, check your ignition (plugs, wires, cap, rotor) if the colder cylinder plug is fouled, you could have a bad injector, check the injectors too, if they are the stock injectors, they are probably bad. you shouldn't drive it if you have a misfiring cylinder.
Joined: Jul 1999
Posts: 10,950
Likes: 26
From: Orange, SoCal
Car: 1990 Pontiac Trans Am
Engine: 355 TPI siamesed runners
Transmission: Tremec T56
Axle/Gears: 12-Bolt 3.73
Re: 7 cylinders running at 400 degrees???
Yes, sounds like a bad injector, or possibly a bad spark plug or spark plug wire. Do an ohms test on each injector. They should all be around 14 ohms or more. Any less than 12 ohms and its bad.
Thread Starter
Junior Member
Joined: Oct 2006
Posts: 80
Likes: 0
From: Mechanicville, New York
Car: 91' z28
Engine: rebuilt 350
Transmission: stock
Axle/Gears: stock
Re: 7 cylinders running at 400 degrees???
tested the injectors and they are fine. Chevy says after 2 days of trying to find the problem put in a new ecm chip and now she is working like the day i bought her. thanks for the input guys.
Senior Member

Joined: Mar 2004
Posts: 923
Likes: 2
From: Bakersfield, CA
Car: 91 Z28
Engine: 383 SuperRam
Transmission: ProBuilt 700r4
Axle/Gears: G92 3.23
Re: 7 cylinders running at 400 degrees???
well if that fixed the problem great. but that doesn't explain the one cold cylinder. the injectors work in banks, 1,3,5,7 together and 2,4,6,8 together. so if it were an ecm issue either bank 1 or 2 would have problems, not just one hole. might have been mis diagnosed on the cold cylinder.
Thread Starter
Junior Member
Joined: Oct 2006
Posts: 80
Likes: 0
From: Mechanicville, New York
Car: 91' z28
Engine: rebuilt 350
Transmission: stock
Axle/Gears: stock
Re: 7 cylinders running at 400 degrees???
ill have to find out some more about that thanks for the comment.
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