Stumped by this 'newer' engine

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Apr 28, 2005 | 06:56 AM

great90wt

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From: Grand Junction in SW Mich

Stumped by this 'newer' engine

I've got a bit of a problem with a 302 I just changed the head gaskets on. It is in an '87 F150 with fuel injection. I'm more used to older engines with carbs. The engine starts quicks and idles fairly smoothly as it warms up. It has a few hitches but nothing really out of the ordinary. Give it some throttle and it roars up smoothly. The problem starts when it is warm. It loves to just stall whenever it is not getting throttle. Driving down the road, its file. Stop for a moment, or just slow for a turn, and it stalls. Starts right back up and keeps going until I let off throttle again. I've heard it could be vacuum and I've checked the connections and replaced any busted pieces of that hard vac line. Could it be the coil going that fast? Something else? The truck has 176,000 miles on it, are my cat's shot and causing too much backpressure at idle when warm? Thanks for the help!

Apr 28, 2005 | 10:24 AM

ronclark

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From: Fleming Ga

Was it doing this before changing the gaskets?

Apr 28, 2005 | 11:49 AM

great90wt

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From: Grand Junction in SW Mich

Not really. As soon as the gasket blew, it would stall constantly, but I thought that was a symptom of the blown gasket. Before the blow, it ran fine.

Apr 28, 2005 | 12:32 PM

MustangGT221

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From: Topsfield, MA

I wouldn't say it's the cats being shot, as that situation hasn't changed since the head gaskets were changed. You had those cats when the engine was running correctly, so I don't see them as being the problem.

First place to start, is computer diagnostics. Check the computer codes (lots of threads on how in the 87-96 forum) and see if you have any codes stored. That'll be the first step.

Apr 28, 2005 | 12:57 PM

ronclark

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From: Fleming Ga

Check for vacumn leaks around the intake manifolds. Try spraying carb cleaner or wd-40 around the intake where it connects to the heads and around the gasket between the upper and lower manifold and see if the RPM picks up or the engine levels out. Else check to see that you connected everything up properly, and no codes in the computer.

Apr 28, 2005 | 01:19 PM

Peter94

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From: St. Peter

Does it have the ignition control module on the distributor? I know those can be wrecked by getting hot, maybe thats what the problem is. Wonder if there's a way to check it out?

Apr 28, 2005 | 01:58 PM

garsten

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From: Tucson, AZ

first, make sure the idle speed control got reconnected and the connection is good. then i would remove the isc and clean it out and verify things are moving freely inside. spray carb cleaner should do the job quite nicely. my truck wants to sometime idle rough at lights when warm...i need to clean mine...i'll keep you posted when i do and if my problem is corrected. cheers, garsten