I keep getting code 33 in both KoEO and KoeR.
The truck runs great when cold but wheh I restart warm it runs like I am having problem with the MAP (hard idle and choppy idle). I replaced the EGR but still am gettin codes, 12, 13 and 33 in the KOER tests.
HELP! i checked the data page but could not access as the links were bad. We are going to test the EGR solenoid and see if its bad but if you have any ideas please let me know.

Thanks,
Tom

p.s. 86-B2, 2.9 F.I., 4x4

 

Ok, we did the "blow" test throught he EGR solenoid and it seems good. I still can't figure this out. When it is warm and you shut off the engine then re-start, it runs bad like when I had to replace the MAP sensor. But, I am not getting the MAP code.

Tom

 

Since you have an idle problem and the 12 & 13 are IAC related I would focus on those codes. If you don't have the pinpoint tests for the IAC I can email them to you.

For the EGR, My 2.9 didn't have EGR but the EVP seems to be a common fault.

 

Thanks Ken00,
Actually, I think the Solenoid may be bad as we were able to blow air through it. I have the resistance tests for the IAC so we will try those tomorrow.
We didn't get codes 12 and 13 yesterday until we replaced the EGR.
Again, this is odd as when its cold it runs perfect. Then after abot 10 miles if you stop for a few minutes then restart it runs like crap, you can hardley get 55 miles per hour out of her.
The test we have for the IAC is resistance 7-10 ohms = good.
Do you have a different tests?

Tom

 

You're getting a KOEO 33? I would start with that code.
Note that a KOEO code (I'm assuming you're properly distinguishing between KOEO and memory (CM) codes) is set with the engine not running. This means a KOEO 33 can't be set by the EGR valve, or the EVR solenoid. 1st thing to check is the wiring and such between the PFE sensor and the EEC-IV computer. Make sure the sensor is getting +5 V Vref, and has good connections to the computer. If the wiring checks out and you can't get a proper signal from the PFE sensor (Mine gives me 3.2 V KOEO measured from pin 27 to ground), it's probably the sensor that's bad.
And additional note, it is normal for the EVR solenoid to show a constant vacuum leak even when "closed." It is designed that way.

 

I am also getting code 33 with KOER. I am certainthe solenoid is bad as air travels freely when poer is suppied and when power is not supplied both in cold a normal operating temperature. there is no difference. I have a better volt meter on its way now so I will check the voltage at the PFE sensor tonight as soon as my meter get home.

Thanks for the reply and the suggestion,
Tom

 

OK, do over...Doh...in the immortal words of Homer Simpson. Upon reading the directions for our tester more thoroughly... with the idle set at 800 rpm, and warmed up, here are the results:
KOEO self test codes = 11 (pass) then 10 separator code, then 33 as continuous memory code.
KOER self test codes = nothing, then goes to cylinder (shows a 6) then 10 and you goose the accelarator, then it goes to "Diagnostic Trouble Codes" gives 33 and 13. 74 comes after those (brake switch code).
The EVR Solenoid allows the same amount of air though it as we blow in. no restriction, and no difference with or without 12V power.
Thoughts are original EGR valve had so much carbon build up that it never closed. Now with new EGR it can't open because solenoid can't operate to tell it to open. Rough idle due to NO2 not being at the proper ratio?
IAC valve terminals resistance test = 0 - needle swings to continuity instead of 7-13 resistance.

So, are we looking at two bad parts then?
Mr.shorty, Should I still do the PFE test since it was a continouse code or is that a mute point?

Thanks again,
Tom

 

Everything I suggested above assumed the 33 was a KOEO code. SOP is to resolve KOEO codes, then KOER codes, the any remaining CM codes. You're passing the KOEO test, so we move on to the KOER test.

KOER 74 is usually a result of not pressing the brake to actuate the BOO switch right after engine id is output. Probably not contributing anything, but some of us just hate to see anything but pass codes.
KOER 13 is usually more symptomatic than diagnostic. After all, we already knew the engine was running rough .
Which leaves us with the KOER 33 (and the CM 33, but it's usually easier to diagnose from the KOER test. It passed the KOEO test, which means the sensor gave a reasonable baseline output with the engine off. It also means that, electrically, the EVR solenoid responded properly, as far as the computer can tell (which means the circuit is intact, but it couldn't really tell if it opened or closed). From your description, it soundslike the EVR solenoid might be stuck open. This would cause full engine vacuum to be applied to the EGR valve, causing it to open too wide, and cause driveability problems. I expect the computer is seeing this as the PFE sensor voltage stays lower than it should, maybe even dropping below the KOEO value. Normally, the PFE sensor output should increase when the engine starts. Here's what I would do:

Hook up a voltmeter to the PFE signal wire as I suggested above. Note the KOEO output, then start the engine and see what the signal does. If it does behave as theorized (PFE signal drops below KOEO value), then I would spend more time withn the EVR solenoid. 1st, make sure the EVR circuit is intact, and there are no shortsto ground between te solenoid and the computer. 2nd, Using output state test and while monitoring voltage drop across solenoid, make sure the computer can command the EVR solenoid to open and close. If the computer can tell it to open and close, and it oesn't close, then it's probably stuck open, and may just need to be replaced.