1985 F150 Computer Question
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Senior User
Joined: Jun 2002
Posts: 330
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From: Chandler,Arizona - USA
1985 F150 Computer Question
I have the 300 I-6, 4X2, with a C6 transmission. The computer was replaced as well as the idle speed control to stop the stalling problem the truck was having. Since the new computer was installed, performance has been reduced significantly. I also went the route of replacing the computer to get the truck through emissions(Arizona). I was wondering if replacing the distributor with a distributor and vacuum advance from say, a 1983 truck, and hooking a Duraspark Ignition Module, then disconnecting that dang blasted computer, would be feasable with this truck? Would it be able to pass emissions? Would performance suffer? Also, how would one hook up the idle speed control in this type of set up? I had a 1983 for 16 years and I kick myself for selling it to my friend...who absolutely loves the truck.
Thanks for your information.
Thanks for your information.
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Joined: Jan 2001
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From: Nebraska
1985 F150 Computer Question
Yes, converting to Duraspark would make it a lot simpler without all the electronics, but I don't know about passing emissions. What kind of performance problems is your truck having?
If it is stalling, try adjusting the curb idle screw. This screw is actually an anti-diesel screw. It's supposed to be set at <500 rpm. The idle speed control motor *should* only drop the throttle down on it after shutdown to prevent dieseling. What I found with mine was it would drop down on it in normal driving such as at a stop sign. (Why, I have no idea. Everything else works the way it should.) I adjusted the screw to ~750 rpm and it works fine.
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1995 F-150 Supercab XLT 155" 4x4 M5OD 302
1986 F-150 4x4 NP435 300
If it is stalling, try adjusting the curb idle screw. This screw is actually an anti-diesel screw. It's supposed to be set at <500 rpm. The idle speed control motor *should* only drop the throttle down on it after shutdown to prevent dieseling. What I found with mine was it would drop down on it in normal driving such as at a stop sign. (Why, I have no idea. Everything else works the way it should.) I adjusted the screw to ~750 rpm and it works fine.
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1995 F-150 Supercab XLT 155" 4x4 M5OD 302
1986 F-150 4x4 NP435 300
Thread Starter
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Senior User
Joined: Jun 2002
Posts: 330
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From: Chandler,Arizona - USA
1985 F150 Computer Question
Thanks for getting back to me. About the performance problems. Since the computer was replaced, the truck no longer stalls. However, power wise, performance has suffered. The truck has no pep when taking off from a stop. It has 3:55 gears by the way. In the past, this truck had no acceleration problems whether from a dead stop, or entering a freeway and accelerating to 70mph. When using the passing gear, which works at speeds under 55mph, the truck goes slower than a herd of turtles stampeding through peanut butter. The remanufactured carb is about 9 months old. This all started when the computer was replaced. I have not had the timing checked. A friend suggested that the timing should be checked. Thanks again! Paul
