Rough Idle and Pulling 3 Codes

[aeraceranthony]

Vaccum lines were good. The voltage was at 6, so I will replace it Friday, clear codes, and give you an update. Would this cause the rough idle though? Its really rough when I have it in park, but when I throw it in drive, its not as bad.

 

[fastpakr]

If it's causing weird behavior of EGR, then that's at least a possibility. Replace the sensor, fire up the KOEO test and kill the test as soon as continuous codes begin (that will clear them). Restart and run the test, and see what you get. If you get an all clear on KOEO, see how it does with KOER. Good luck! You're well on the way to getting it fixed.

 

[aeraceranthony]

What do you mean by killing the trest to clear the codes? Unplugging the scanner during the test? Can I reest everything by unpluging the battery for a few hours?

 

[fastpakr]

Sorry, forgot/missed that you were using a real scanner. Yes - just unplug it. Disconnecting the battery for a few hours (IIRC it only takes about 10 minutes) will also clear any fuel trim settings, etc. Not necessarily a bad idea in this case.

 

[Toms01PSD]

I would advise against just "unplugging" it. And i've never heard of it clearing the codes either. Disconnecting the battery will only turn the light off depending on whether it is stored in the memory or not, if it is, it will be on still, if not it may come back on after driving for awhile. That's why we road test vehicles.

 

[fastpakr]

I would advise against just "unplugging" it. And i've never heard of it clearing the codes either. Disconnecting the battery will only turn the light off depending on whether it is stored in the memory or not, if it is, it will be on still, if not it may come back on after driving for awhile. That's why we road test vehicles.

Ending the KOEO test during continous memory code output is actually the official method for clearing stored codes. The computer builds and maintains a fuel trim table as the engine runs based on sensor feedback that is used in closed loop operation. If it were operating with bad input (which we know to be the case here) clearing it will force it to reset those tables and re-learn immediately rather than slowly adjusting. Obviously he needs to run the tests again as soon as he reconnects everything to determine whether the replacement DPFE sensor has solved the issue in that circuit. I certainly suspect so, given that we've demonstrated that it was giving false readings even at KOEO.

 

[Toms01PSD]

Ending the KOEO test during continous memory code output is actually the official method for clearing stored codes.

Hmm never heard that before. And don't you just love those fuel trim tables.

 

[aeraceranthony]

Ran a KOEO scan, pulled the scanner. Ran it again, and no codes. So stopping the scan half way through does clear all codes. I also disconnected the battery for a half an hour to be safe. Replaced the new EGR pressure unit. Ran the car for about 5 miles. Its still running rough. Idle is still at 650. Ran a KOEO scan again and getting code 33 (ALL - (O, M) EGR did not open/ respond during test or if memory code, did not open intermittently - EVP EVR PFE). The sequence is 33, long pause, one beep, long pause then 33 again.

Ideas?

 

[fastpakr]

So you got 33 for KOER, not continuous, right? Let me look that up...

Edit - not thinking clearly. 33 can't be right. I think you got 111 on KOEO and then on continuous, not 33. That's a pass code for both. 2 digit codes don't exist on a '94.

Go ahead and run KOER tests.

 

[aeraceranthony]

Ran the KOER test twice, all I got was 536 both times. ((O,R,M) Brake On Off open or shorted to ground - BOO ) But I didn't run the brake test.

 

[fastpakr]

There's a basic brake function test in the KOER test. When the light flashes in the middle of the KOER process, push the brake test and goose the throttle. That should clear the 536 code.

 

[aeraceranthony]

Alright. I turned the steering wheel (have power steering) and pushed the gas after the one flash/beep.

I still cant find any leaking vaccum lines which can really be the only be the real cause of my rough idle. Other than that, the truck runs great and gets the milage it should (17 city).

Any ideas of the rough idle? Should I just drive it more and run a KOEO and KOER in about 25 miles and see what I get?

 

[fastpakr]

There's a sequence for testing various systems to troubleshoot a rough idle when no code is set. I'll try to get a chance to copy the fundamentals here tomorrow.

 

[aeraceranthony]

Things I have done so far:
Cleaned the MAF
Replace the plug wires(Taylor)
Replace the Cap and Rotor(Taylor)
Replace the Coil(MSD)
Replace the plugs(E3)
Replace the Fuel Filter
Replace the Air Filter
Oil change(04/25/09)
Replace the EGR Pressure Sensor(04/25/09)

There is no knocking or pinging. I am still wanting to do a compression test, just don't have the tools for it yet. Will probably run seafoam in the next week.