I have a 93 F150.
I have replaced some of the things that Autozone told me too, the last was the Throttle Position sensor or whatever. Anyway, it ran fine for a while. I only drive it on the weekends and sometimes it sits for a couple of weeks without driving. It has almost 200K on it. I bought it used. It started missing and then backfiring and now I can barely get it started. It will build up when you let off the gas and then blow out the tail pipe like a shotgun was going off. I changed the rotor button and distributor cap, cleaned the EGR valve and checked it, cleaned the barely used spark plugs. When i replaced the dist cap i crossed a wire and it still didn't act any better when i fixed that. I am stumped!!! It isn't throwing any codes..... It starts like it is way out of time. I was told the timing is hard to adjust or impossible on this model. I tried moving the dist anyway a little each way and no help. I NEED HELP BEFORE I SHOOT IT!!!
Also is it possible to put an old school 302/289 in the place of this monster??

Thanks for any help

"Wise men talk because they have something to say: fools talk because they have to say somethng"..........PLATO

 

First off this is a very easy engine to time. All you do is pull out the SPOUT jumper, hook timing light to number one plug wire. Loosen the hold down bolt, start it and turn the distributor until the pointer points to 10* BTDC. Tighten the hold down bolt and recheck. Take you light off and put the SPOUT back in.
The only things I can think of if you already changed the TPS are the ECT or the ACT sensors.
The O2 sensors may also cause this problem but I would think that it would give a code where the ECT and ACT would not.

 

my guess is the timing chain jumped a tooth

 

I agree, it sounds like the valve timing is off. You should run a compression test on it to give you a better idea of whether it's a mechanical problem or an EEC IV problem. I'd like to know what the manifold vacuum is at idle, too.

 

Thanks for the help, though I have a couple of questions. Not the smartest mechanic on the block but not the dumbest either. I have heard about the "spout" but I don't know what the heck it is, please explain. Also if it jumped a tooth on the timing, what are my options? And lastly it won't idle so I can't do a compression at idling.

THANKS

 

The SPOUT (SPark OUTput) is a signal from the PCM Computer to the TFI Module or ICM Module which ever the case may be. This is the signal from the Computer that adjusts the spark advance. When you pull out the SPOUT jumper you break the signal going to the module. The module will then default to run the engine at base timing (10* BTDC).

If you jumped timing it would mean that the chain is too loose and you have to pull the cover and replace the chain and gears.