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Old 08-05-2021, 02:08 PM
169mph 169mph is offline
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Join Date: Sep 2020
Location: League City, TX
Cobra Make, Engine: Backdraft w/ 427IR
Posts: 84
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Originally Posted by twobjshelbys View Post
This is a fuel injected 8-stack from Roush. I had the same engine. It's quite finicky.

After it warms up does the idle stay at 1150?

Do you have the dual fuel pumps? Have you checked pressure? I added a pressure gauge at the end of one of the fuel rails.
Thanks for the response.

It usually idles at 1050-1150 rpms. The rpms start dropping after it's been running for a few minutes. They'll drop until the engine almost stalls then they go back up normal for about 20 seconds and then the RPMs drop again. It's a cycle. Eventually the engine stalls. I keep the RPMs up when I go for drive but that gets old quick.

I have a Walbro 255 in-tank fuel pump, which I plan to switch to an aeromotive 340. I going to replace the fuel filter downstream of the pump when I switch fuel pumps.

I had issues with backfiring when decelerating in the past but after replacing the exhaust flange gaskets it rarely happens. Could an intake manifold vacuum leak cause the idle issues?
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