Sorry for the long one today, but here goes. Ok, I was on here about 2-3 months ago looking to find some advice on how to fix my 1993 f-250 under the "MAP sensor connector problems. It is a 5.8l V8. When I was on here last the issue was that the truck wouldn't run right whenever the Manifold Air Pressure sensor was plugged in, and whenever unplugged, would run perfectly fine, but the drive was slow and clunky and it was obvious this was not a permanent solution. Since I've posted, I was able to source a new PCM from rock auto, I've redone my entire spark system, and even replaced the fuel pressure sensor. I went through various tests with the truck and a multi-meter to verify everything was working fine.

The problem is, I have no idea what it could be and I am back to square one with this truck. The PCM seems to fix the continuously running fuel pump and the dysfunctional brakes, but it was still having the issue that it wouldn't run at all unless the MAP sensor was unplugged, the other piece of useful information I gained is that the truck likes to stall if starting fluid is sprayed while running. under normal circumstances I'm told the idle should surge instead of stall. I don't know what I should do now though, because when I was going down the road with it two nights ago, I lost power and stalled, but when I tried to start again, I was blowing white smoke from the oil cap. When I tried cranking it again at my house, it sounded like my engine was making a weird houffing noise like the sound a horse would make when it's exhausted. Did I blow my rings, valve seals, what could've caused this? Was it bad injectors? Please help me.

 

I should also like to add that the other weird symptoms my truck was exhibiting were an oil gauge that was bouncing in tune with the idle of the truck when at idle and normal at increased RPM, and on the new PCM I would get codes for my EGR valve.

 

Wait. What? There is no way the engine computer fixed the brakes.

If the engine was about the stall and then the engine speed went back up then of course the oil pressure gauge needle move up and down. What EGR codes? During what test and which phase of the test?

 

Well as far as the brakes go, I had a PCM that I bought from E-Bay and it made my brakes act funky, as if the truck was off. When I got the new PCM, they were normal. The oil pressure gauge would only bounce when I was at idle, in park or at a stop light are two scenarios. The EGR codes were 334 and 565 KOEO, I never tried to do KOER because I was worried I might mess up the relearn procedures after installing the new PCM.

 

Impossible. The brake system has no electrical connection to the engine computer. There is no “relearning” process and you need to repair engine off faults before moving onto the engine running test.

Is the “fuel pressure sensor” actually fuel pressure the regulator on the fuel rail? What fuel pressure do you have? Is there spark?

 

There is a brake light switch that is used by the EEC-IV.

 

Yes, correct. The Brake On/Off(BOO) switch.
The brake light switch has nothing to do with the mechanical brakes.

I suppose if your engine ran sooo poorly, and you had zero vacuum, then you would notice no power brakes.

White smoke is either antifreeze burning, oil burning, or brake fluid burning.

Time for a compression test.

 

I do agree with you 99% but I can't say the OP is wrong. If he believes the brakes are fixed with the EEC-IV replacement, the only thing that have caused this is the brake signal going into the EEC-IV. With bad ECU's you never really know what going in there. He could have bumped something during the installation, I don't know/care but I am glad the brake work.

 

I've already replaced the fuel pressure regulator. I will admit I haven't done any sort of fuel pressure tests before hand, or compression tests for that matter. However, I will do a compression test now since I've lost power. Beforehand I thought that since there was a tiny amount of vacuum in my oil system (I put my hand over the cap) that I didn't have any blow by. Now I guess I do? Also as for the brakes: they're not the main issue, I just felt like it was worth mentioning. Yes, I have spark, and yes I have fuel pressure.

 

Then why did you replace the fuel pressure regulator? You can have some pressure but not enough for the engine to run.

Too much fuel can cause an engine to stall. The whole truck lost electrical power while you were driving? Is the rotor in the distributor turning when you rank the engine?

 

no, the truck would stick crank and still had electrical power, but the engine wouldn't turn over.

 

Wrong thread

 

Point of interest, white smoke can also be trans fluid burning if you have a C6. If the diaphragm in the modulator dries out and cracks, the vacuum line can suck trans fluid up. Mine smoked like a mosquito fogger and burned a quart before I figured it out. $33 modulator, one bolt and five minutes. I kinda enjoy the E4OD posts. Makes me feel better about 14 mpg highway (downhill).

 

Engine cranking is the engine turning over.

We do not know what problem you have.