302 Jasper EFI detonation problem
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Freshman User
Joined: Mar 2003
Posts: 43
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From: San Diego
302 Jasper EFI detonation problem
Gents,
I have an 86 F-150 with a 302 EFI jasper semi-performance motor with about 20k miles. It seems to run well on regular gas, idles well and no detonation. When towing loads I get detonation even when running premium fuel. I'm running this engine with headers and a dynomax 1 cat exhaust system, a flowmaster single chamber, and a K&N, but with the stock EFI computer. I wonder if the reduced back pressure of these mods has caused the computer to lean out the mixture too much for the engine. Any thoughts? I've considered running one step cooler plugs and maybe going with a cooler thermostat. Maybe some sort of electrical fix would be best? Any help would be appreciated, thanks!
Loren
ps timing checks good on this engine
I have an 86 F-150 with a 302 EFI jasper semi-performance motor with about 20k miles. It seems to run well on regular gas, idles well and no detonation. When towing loads I get detonation even when running premium fuel. I'm running this engine with headers and a dynomax 1 cat exhaust system, a flowmaster single chamber, and a K&N, but with the stock EFI computer. I wonder if the reduced back pressure of these mods has caused the computer to lean out the mixture too much for the engine. Any thoughts? I've considered running one step cooler plugs and maybe going with a cooler thermostat. Maybe some sort of electrical fix would be best? Any help would be appreciated, thanks!
Loren
ps timing checks good on this engine
Cargo Master
Joined: Jun 2001
Posts: 2,571
Likes: 22
From: Oxford, Indiana
302 Jasper EFI detonation problem
I wouldn't mess with the t-stat, but a cooler plug might be a good place to start. Also, check to make sure that your EGR valve is operating properly. The computer is calibrated to determine fuel mixture under the assumption that the EGR is functional. If it is not working, it can ping under load.
New User
Joined: Mar 2003
Posts: 7
Likes: 0
302 Jasper EFI detonation problem
I Have a Jasper Motor in my truck and never had problems with detonation. I am running a Mustang computer with superchip and 12* base timing with 93 ocatane gas. But before I messed with it there was never a problem. I would check your timing with the spout disconnected. It should be 10* (stock) if you want to run 87 octane gas.
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