86 302 Efi
New User
Joined: Feb 2001
Posts: 6
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86 302 Efi
Hey Motorheads I have a good one for you. I have an 86 302 EFI and have had it in the shop several times on a problem. They first told me I need to change the EGR Valve,EGR POS Sensor, throttle POS Sensor, and the ambiant air temp sensor. I also had the fuel injectors cleaned by a shop that uses the 3 step process (whatever that means). I changed out the sensors and took the truck back in they said everything looked and ran excellent. My problem is that when the truck is warmed up it still idles rough and when you are stopping (IE stop light) it doesnt die but it tries to then it re-adjusts and usually idles fine (slightly rough) until the next light. Any suggestions short of raising the radiator cap and pulling a new truck under it would be greatly appreciated.
Freshman User
Joined: Mar 2001
Posts: 48
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86 302 Efi
you mention something about when the truck warms up it has this problem,so when its cold its okay i guess.if you have this a temperture control switch you might check it, im talking about vacuum control or you might want to check the map sensor theres a way to test the map sensor if you have a book.
map sensors could cause your engine to run rough if they dont work right.ihad a ford 400 once and i thought it was the carb that was causing my problem, but in turn it was the map sensor.
i know yours is a efi but you never know, and now i have a 87 bronco 351w ho holley four and i just rebuilt my carb on it because it was letting to much gas into the carb even after you cut it off.on yours that thottle control sensor makes sense because it sends a message to the computer letting it know what speed your at or if your idling,and to much gas there at the wrong time could cause your problem.
good luck .
map sensors could cause your engine to run rough if they dont work right.ihad a ford 400 once and i thought it was the carb that was causing my problem, but in turn it was the map sensor.
i know yours is a efi but you never know, and now i have a 87 bronco 351w ho holley four and i just rebuilt my carb on it because it was letting to much gas into the carb even after you cut it off.on yours that thottle control sensor makes sense because it sends a message to the computer letting it know what speed your at or if your idling,and to much gas there at the wrong time could cause your problem.
good luck .
Senior User
Joined: Aug 2000
Posts: 473
Likes: 1
From: Richmond, CA
86 302 Efi
I have an 89 Bronco 5.0 EFI, that ran fine when I first bought it. But a few months later I started to have the same problem with idleing. At stops and parked sitting in idle I couldn't get the idle below 1500 RPMs. The idle accually fluctuated between 1400 and 2000 RPMs.
While I had my rear-end in the shop for complete rebuild, I had a chance to find out why idle was bad. It turned out that all the gaskets in the top end were shot and needed to be replaced.
replaced the valve cover gaskets, upper intake gasket, throttle body gasket, and EGR valve gasket. After I put it all back together, it idles at a consistant 800 RPMs.
Had too much air and vacuum leak.
While I had my rear-end in the shop for complete rebuild, I had a chance to find out why idle was bad. It turned out that all the gaskets in the top end were shot and needed to be replaced.
replaced the valve cover gaskets, upper intake gasket, throttle body gasket, and EGR valve gasket. After I put it all back together, it idles at a consistant 800 RPMs.
Had too much air and vacuum leak.
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