First off I have been lurking here and another X forum since I got this truck but this is my first post here.

Just picked up this ride about 3 or 4 weeks ago. It has a few small problems like A/C that is not cold (no matter right now as winter seems to be coming early in Wisconsin) the cruise control doesnt work (kind of a bummer) but this was interesting. Pulled the dash trim to install the radio from my old car. Noticed a wad of paper stuffed into the bulb slot for the CEL, took it out and what do ya know the bulb indeed comes on after a few short time driving. Pulled the code and came up with the following:

KOEO
111 - Pass

C
332 - EGR valve opening not detected
337 - EGR valve pressure transducer/position sensor circuit above max voltage
543 - fuel pump circuit open; battery to PCM

I visually inspected the EGR area of the engine and found a vacuum line had come off of the DPFE. The line was just a little too short and a bit stretched out on the ends so I replaced it. Reset the codes with my reader and took it for a drive. CEL came on again. Pulled the codes a second time. This time it passed on KOEO, and gave a C 332 again.

Have not run KOER test yet as the book with my code reader says to fix problems listed in the KOEO test first.

Funny thing is the other day I was trying to determine if this truck came with factory keyless (got no remotes with it) so I pulled off the jack cover to look for the module. I think it's the right module for keyless. Anyway, getting off topic, back in that compartment was what looks to be a brand new EGR valve. Could the EGR be causing the problems? Guess since I have it I will try to swap it out when I have time, but I can't take the car through emmisions until that light is gone. Just trying to save myself the $70-$90 I have been quoted for the DPFE sensor.

Sorry for this getting long winded, but would this also account for the harder than normal starting when cold? The truck starts real quick when it was warm out or after it's already warmed up, but now that it's getting colder if it sits all night and I try to start it in the morning it takes a while to crank over. I should add that this truck sat for about 6 months without running and it fired right up first try.

Thanks for any help.

 

What they mean when they say "resolve KOEO codes first" is to resolve the 1st set of codes that are output during the KOEO test. The second set of codes are call continuous memory (CM) codes, and they are the last set that you resolve last. I think your next step should be to run the KOER test.
I would also carefully check all the vacuum lines to the EGR valve to make sure everything looks good.

 

After reading around some I had a feeling you would be the one to answer this. I have checked all the vacuum lines and aside from the one I have already replaced they are all in good shape. I will double check and pull KOER codes tomorrow. Would it be of any benefit to change over the hard plastic vacuum lines to rubber ones? The plastic one from the EGR itself seems to be much longer than neccesary.

 

Well I did the KOER check today. It gave me the following codes, hopefully because I was off in my timing of pressing the brake and turning the wheel. I tried this by myself and never bought the extension cable for my reader, it costs as much as I paid for the scanner. I cant say as I noticed the CEL blinking when I tried the brake and wheel, but the scanner was holding it's 6 cyl reading while I tried, perhaps I tried to soon? Was I to wait untill after the engine ID was off the screen? Having always had obd 1 chevy cars I never had one that I used a KOER test, not even sure they have one.

KOER
412 - unable to control RPM during high RPM self-test
411 - unable to control RPM during low RPM self-test
538 - insufficient change in RPM/operator error during Dynamic Response Test

my Haynes manual has 3 differnt things for a 538 but 2 of them refer to 1995 and later models.

I wasnt able to change out the EGR today. Will try to get to it next weekend as I have to be out of state for work all this week.

And just to add, of course it's still giving me the original 332.

 

KOER 412 and 411 are usually more symptomatic than diagnostic. Basically they mean that the engine was running rough. If it's never been done, you might pull the IAC valve off of the upper intake and clean it out.
KOER 538 is usually a result of missing the dynamic response test (aka goose test). After the computer goes through the low speed and high speed tests, right before it outputs the codes, it will give you a brief cue (some scanners use a code 10 for this) to goose the throttle.

Have you cleared the CM codes to see which codes come back? What driveability symptoms are you experiencing?

 

Yes I cleared codes again after running the KOER test and I'm still getting the original 332. When I get back into town next weekend I will pull the IAC and clean it out, pretty sure it has never been done.

As for driveability, aside from the rough starting/idle when cold I described above, it has run the same for the few weeks I have had it. Doesn't seem to be runing badly and mileage seems to be about 19-20mpg. I drive mostly freeway during the week. I was told it was tuned up not too long ago, but after seeing the air filter that was in there I may be doing another tune up when I have the time for it.

 

Apply vacuum directly to the EGR valve while the engine is running... upon applying vacuum the engine should die (or come close to it).. if you notice very little or no change in idle, your egr is restricted somewhere.. remove the valve and check for carbon buildup in the valve itself, in the line going to the valve, and in the port in the engine. If you still can't find anything you may have to remove the intake to find further blockage.

If the engine DOES die or come close to dying after applying vacuum, try replacing the DPFE.

Good luck.

 

Your bigger issues are being answered by one more capable than me, but as for your cruise control, if it's still inoperative after your drivability issues are resolved, take a look at the controller. I was fortunate to have my 92 Exp to rob the part from while diagnosing my sisters 94 Exp. I had already checked the switch responses at the connector for the controller, and on a whim, I traded controllers. It worked! I didn't price a new one, but I spent 20 bucks at a salvage yard for a replacement. You access the controller by emptying out your glove box, squeeze the sides together to release the tabs, and rotate the box all the way down. Then look up under the dash and you'll see a box (about 3x3 inches...mine was green). You may have other issues, but this worked for me.
Good luck.

 

Well tested the EGR today as per Mazda's suggestion. Using a hand vac pump with the engine running I gave it some vacuum. The engine didn't die, but sure did bog down and buck around some. Can't say how close to killing it was but it was definitly running rougher than normal. Released the vacuum and it evened back out again. So going on that I found an advanced auto that had a DPFE sensor in stock. Picked it up and got it all installed, until I went to plug it in, then found the electrical connection was different. The one I need is special order.

Being as I have to go back out of state for 3-4 more days I will have to come back to this most likely next weekend. I did take off the IAC and clean it up. I havent had a chance to try the KOER test since the cleaning, so not sure if that cured the RPM problems. Will find out tomorrow morning when I start the car is cleaning the IAC helped with the cold starts at all. This morning before cleaning it took a bit longer than normal to start.

sjwoody: Thanks for the tip, cruise is the next thing I look into once the CEL problem is taken care of. Perhaps next spring. Cold weather is here already and I dont have a garage to work in.

 

Yes you tested it properly... the DPFE is a high failure item on these... almost always a "low egr flow" or "egr not opening" code is a result of this. Basically your EGR is working properly, the computer just isn't detecting it. A remote possibility is a failed EGR solenoid... not applying vacuum to the EGR when it's supposed to, but that's very rare, and usually sets a different code.

Also disregard the fuel pump circuit code... that code shouldn't set a light and if it were true the vehicle wouldn't be running...

Good luck.. keep us informed

 

Well, replaced the DPFE the other day, along with replacing both vacuum lines to it, and clearing the codes. The CEL came back on again, but I havent had time to pull the codes again and see if it's still the same code or not. Hopefully I will have some spare time this weekend to pull the codes and change the EGR with new one I have. I have to get an EGR gasket too, cuz the valve I found in the truck wasnt in a box it was just sitting in the rear compartment.

And cleaning the IAC didn't help the cold start problem, it still seemed to be there. Although maybe in my head, it seemed to start a little better in the morning after I changed the DPFE. Maybe it just wasnt getting that cold at night. The mystery on that issue shall continue.