Hi, I'm new to the forum and hoping for some advice. I have a 1991 Ford F-150, it has low mileage and until last week ran like a top. My problems started while driving, a noticeable loss of power immediately followed by an engine light. When I made a stop, the truck would barely move in drive. ( auto transmission ) I put it in low gear and had decent pickup but still felt sluggish. Manually shifted through the gears to get it home. At home I noticed that the overdrive button wouldn't light up. The next day when the engine was cold I started it up. The tach went straight to 1000 rpm and had a very erratic idle, before that it went right to 2000 rpm and stayed until it warmed up then dropped to about 700 and ran very smooth. I've tried to pull codes with no luck, can't even get them when I tried jumping the eec plug and counting the flashes. The guy at the parts store said it sounded like the tps, made sense, changed it, no changes. I find it hard to believe that it's my transmission because of the change in the idle and the poor running condition. I'm leaning toward the solenoid pack but I'm no mechanic. I don't want to just throw money at it, so thought I would try here. Seems like a lot of knowledge on this sight so I'm hoping someone can steer me in the right direction. Thank you and sorry for the long post.

 

Does the check engine light flash when you try to retrieve codes? I think you have an engine problem not a trans problem, or more accurately you likely have an EFI control system problem which could be a bad PCM itself.

 

No flashing light. Would a bad pcm explain why I can't pull codes ?

 

Yes. And so can corroded pins on the data link connector. Clean them with contact cleaner and/or a small fingernail file. If still no go, pull the PCM then inspect it for signs or leaking capacitors and other damage.

You might as well do both....

 

I pulled the ECM out this morning, definately has leaking capacitors. Would you suggest replacing the ECM or changing the capacitors. Also, are the leaking capacitors consistent with the issues I'm having ? I saw no other problems on the board. Thanks

 

Those capacitors are usually for power supply filters, and if they've failed, the ECM will get unstable power, is it not function properly. So yes, it can cause all sorts of performance problems.

If you're handy with a soldering iron, them replacing the blown caps would be a cheap fix you can try. If that doesn't work, you can then replace the whole ECM.

 

Depends on how much damage the leaking caps. have caused.

Yes

 

Put in a new ECM today, everything's back to normal. Thanks to everyone for your help. I wish I could buy you guys a beer !!!

 

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