I am wits end...'92 f150 300CID 4wd E4OD. Truck started running rough while towing a trailer, I have checked/cleaned/and or replaced the following: air filter, fuel filter, EGR valve (cleaned), EGR vacuum solenoid, EGR valve position sensor, vacuum lines,idle control valve, throttle body. I keep getting a code 33 from the OBD1.....EGR valve position sensor indicates and open or closed EGR valve..I have pulled off the EGR valve, cleaned it (wasn't clogged at all) checked the diaphram and checked the valve seat itself....no leaks and open and closes fine. If the truck is COLD, it runs better and get worse as it warms up in a few minutes until it doesn't want to run at all. I have also checked the fuel pressure and its around 45 psi on both tanks. WHAT AN OLD FART TO DO???? Please give me some suggestions...Thanks (No black smoke from the exhaust either!)
Ray D. Whitlock
Powhatan, Virginia

 

Hook up a code reader and pull the diagnostic codes...might give you a hint as to what's going wrong.

 

To isolate the EGR as the culprit, block off with a piece of soda or beer can. Bolt egr back with gasket in place. This will isolate an intake leak associated with the EGR. If truck isn't better, I'd bet on PCM problem. Nearly identical problems I had with mine, as I had 2 capacitors go bad, leak out, and ruin the PCM.

Are you counting flashes or using a code reader?

 

shouldn't a 92 be a 3 code?

 

I thought the same. Perhaps he'll post with the appropriate answer. Mine is 3-digit and its a '92.

 

I am counting light flashes on a SUNPRO code reader...keep getting a 2 digit code #33.

 

Is there any way to check the PCM?

 

Pull it out and open it up. Driver side, pull lower plastic kick panel out, behind it there. Need 10mm socket to loosen bolt holding it in under the hood, near driver side fenderwall.

 

Well now, I have been nominated, elected, and hold the position of ******* OF THE YEAR! (All by myself I should add! LOL!!!) It IS 3 digit codes....I was counting 111 (Beeps and light flashes) it was being sent twice as...as the code 33. Code 111 being system pass per the 'puter...NOT! I disconnected the battery to erase the codes and clear the computer for a fresh start. Started the engine and ran it with difficulty for 5 minutes so spitting and sputtering. The KOEO codes were as follows:

<TABLE border=1 width="87%" align=center><TBODY><TR><TD>111

</TD><TD>
</TD><TD>System checks OK

</TD></TR></TBODY></TABLE>

<TABLE border=1 width="87%" align=center><TBODY><TR><TD>552

</TD><TD>(O)
</TD><TD>AIRB solenoid/circuit failure – Solenoids

</TD></TR></TBODY></TABLE>

<TABLE border=1 width="87%" align=center><TBODY><TR><TD>558

</TD><TD>(O)
</TD><TD>EGR vacuum regulator solenoid/circuit failure – EVR or PFE or Solenoids

</TD></TR></TBODY></TABLE>

<TABLE border=1 width="87%" align=center><TBODY><TR><TD>621

</TD><TD>(O)
</TD><TD>Solenoid/circuit failure – shift solenoid 1 – Transmissions

</TD></TR></TBODY></TABLE>

<TABLE border=1 width="87%" align=center><TBODY><TR><TD>631

</TD><TD>(O)
</TD><TD>Overdrive Cancel Light circuit problem – Transmissions

</TD></TR></TBODY></TABLE>

<TABLE border=1 width="87%" align=center><TBODY><TR><TD>654

</TD><TD>(O)
</TD><TD>Transmission selector not in PARK – Transmissions

</TD></TR></TBODY></TABLE>

I cannot honestly believe all this is bad at one time AND showing a system pass code!!! The egr vacuum regulator has been replaced as well as the egr position sensor. So now, is the PCM/main computer taken a dump and throwing all these codes.....or am I screwed like a cheap lady of the night?? HELP ME PLEASE SOMEBODY!!!! Getting ready to pull out the bottle of EARLY TIMES!!!

 

The EEC-IV computer was bad....Took it out, no burnt smell or anything that looked out of the ordinary. Took the cover off and the soldered side of the circuit board look good....the component side looked ok but I noticed 2 of the capacitors were slightly off color from the other light blue ones...1 wire was burned off each capacitor!!!. There was a slight bit of goop on the circuit board under them as well. I went to the NAPA warehouse in my area and they happened to have 1 EEC-IV computer with the correct calibration. Put that sucker in and the truck ran like new. Let it run for a few minutes and then checked the KOEO codes....Some codes were stored but it ran fine. Erased these codes and ran it again for about 15 minutes. Second check for codes, I got a 111 system pass and no other codes!! Apparently when this computer was rebuilt, the original codes were not deleted. Cost from NAPA $98.00 and some change with a 12 month 18K warranty.
In retrospect, about 6 months ago the ammeter started showing a surge in charging (New alternator, not rebuilt about 6 months old) and the headlights would brighten a bit. Never did have any issues with charging or bulbs being burned out. After the replacement EEC-IV was installed, this issue was gone as well. SO......if your gauges start acting goofy, take it as a warning that the EEC may be getting ready to take a dump. Also, if you vehicle starts running like crap, stops and runs fine for a bit and then starts running like crap again. Check the codes, if you get a system pass code AND multiple trouble codes. Put your money into a replacment EEC-IV Unit before you start spending a boat load on sensors and components because the codes say they are bad. Be sure and get the correct one with the SAME calibration code for your vehicle. Its stamped or on a sticker on the EEC-IV unit itself.

I hope this saves at least one person some time and headaches that I experianced!!!!

 

Good to hear you got it back up and running. Sorry to hear it was the PCM, but I'm glad my experience led you into the right direction.

 

good to know that you fixed it. ALSO don't worry I did the same exact thing you did with counting the codes too. You aren't alone hahaha