Truck:1992 F150

2W Drive, 3 inch body lift and ProComp shocks, 32 in BF Goodrich tires w/ Eagle alloy wheels. Powerstop crossdrilled frt. rotors

5.0L, March under-drive pullies, BBK 56mm Throttle body, Motorsport 9mm plug wires, Fluid harmonic balancer, Hooker equal length shorty style Super Comp headers w/ a custom dual exhaust. Mellings (sp) hi-flo oil pump, Edlebrock hi-flo H2O pump, Black Magic fan, Permacool oil cooler w/ fan.

E4OD, just rebuilt w/ major upgrades. Four pinion planetaries, race clutches w/ one extra clutch per pack, 2500 stall converter, B&M shift kit, heavy-duty pump, B&M deep pan.

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Anyway now you know the good stuff here's the bad.

My truck for the last 6 months acts very irratict, crazy if you will. I'll be driving as normal (like this morning) and all of a sudden my RPMs won't come down. And they get worse and worse. Even when at a stop the truck wants to launch forward w/ a lot of power (as if power-braking). We're talking 2000-3000 RPMs w/out my foot on the gas. As you can guess this is a MAJOR problem. Either I'll end up wrecking it, burn up my newly built trans or my engine or all of the above. I had it in the shop w/ a so called drivability expert for over a week and they couldn't give me an answer. BTW once the truck has cooled down it seems to drive fine again. And the problem is not consistent. It happened today but may not happen again for over a week.

Someone HELP!

 

Are there any C.E.L.'S? Did you check for codes? sounds like lost tach signal to computer. Let us know.

 

when you start talking computers and gasoline engines I start getting lost. I had it w/ a drivability "expert" for a week. they claim they didn't know what's up.

to answer your question…I have no way to check this myself and don't know very much about the computer's working. I'm more of a nuts & bolts guy.

 

Sounds like a real severe vaccum leak. Check all your lines. As far as the computer goes you should pull the codes. Click the CLUB FTE MEMBER link under my username.

<----- Over here. I have a link on my website there that will show you how to pull codes with a paper clip. Or you can go the easy route and buy a 30 dollar code reader at Kragens or other parts store.

 

It's 1992 so you have a speed density system, the bigger throttle body is sucking in too much air and the computer can't compensate, call superchips and tell them what it is and they will burn you a chip to help handle the new flowm okay new thought! Replace the TPS. If you go to your local auto parts store they can normally pull the codes there for free. I am willing to bet it's a dirty IAC or a failing TPS (Idle air control, throttle position sensor.)

 

Your second idea seems more logical. I had the BBK throttle body on it for a long time before this nonsense started,

Well I've always been courious about those gadgets that claim to pull the codes from your vehicles computer. If I can pick one up for $50 +/- I will. But would it tell me if any of the problems listed above are in fact the cause?

 

Henry,
You can get a Haynes manual for your truck, and the code scanner under $50. Let us know how it goes.

 

Save some money and pull the codes with a jumper wire and the check engine light. Someone linked to the procedure above.

 

The code reader is definitly worth the 30 bucks I paid for one. Sure beats counting the flashing light to read your codes. And it comes with a detailed book listing the various tests and codes.

 

i once had a problem with a car that it wouldn't idle down either was a toyota celica 5 sp then i remembered i took floormats out and vacumed i looked down and the floormat was on the gas pedal keeping it from commin all the way back up. All that costed me was bout 5 min of serious worrying.

 

um…yeah. That's not the problem here. Thanks though.

 

So I found a couple of vacuum leaks, fixed those. Also I replaced a number of sensors that could cause such a problem. Seems to run fine now.