Stumbling!

[Joe_SHO]

My '94 Automatic has been stumbling (missing) for the past few months, particularly at idle and if you add just a little gas while cruising. High RPM's seem fine, (though I'm sure I still lose power up there.) It seemed to start right after I installed amp wiring. The positive cable off the battery is pretty corroded, and I think that might be part of the problem, but crossing my fingers for something easier to replace. Codes indicate knock sensor and egr, but I don't imagine either of these could cause this problem? Please correct me if I'm wrong.

So far I've replaced fuel filter twice, regapped plugs (they are Motorcraft double platinums less than 10k old), cleaned battery terminals, cleaned air filter (Accel Kool Blue), and cleaned MAF sensor.

Every time I try something it seems to run well for a few miles then it goes back to missing.

I am running out of ideas. The car is still 100% driveable and gets me around 20 mpg, but the stumbling just bugs me, as I'm sure it would any of you or anyone else who takes pride in knowing their vehicle is running at its best.

Thanks for any input. -Joe

 

[rubydist]

when you pull the plugs, does one look worse than the others or are they all the same?

what egr code do you get? its possible that the "add just a little gas at cruising" problem is related to the egr, but not the idle (unless the egr won't close all the way)

I'm thinking a plug, wire, or coil pack problem is a possibility. lots of times you will get a miss w/o getting a code for that. could also be related to the dis or the tps.

 

[hamburglar]

I have the same thing and no codes get pulled....
I'm going to take the car to utah and want to get it fixed...
TPS maybe?

 

[TYSHO]

What's the history on the spark plug wires?

If it is missing, you need to start with the ignition system.

 

[Joe_SHO]

I installed a Screamin' Demon ignition coil and new wires the same time I did the plugs about 10k ago. I'll try throwing the OEM one back in. Thanks for responses.

EDIT: Going back to OEM did nothing. I'm suspecting vacuum because I can hear a sucking when I tap the throttle, but all my vacuum lines seem to be in place. Intake silencer is gone so that may be the reason for the noise also.

 

[rubydist]

what exactly are the codes you get?

 

[93rev2sev]

Please describe the method you used to clean the maf sensor. Don't rule it out just yet.

 

[frosho]

what exactly are the codes you get?

This. It's hard to pinpoint the problem if you don't provide us with the codes.

I'm gonna take a stab at it and guess that the EGR passages in your intake are clogged up, which will give a code 332 if I remember correctly. Follow this link for a guide to cleaning them - http://www.shotimes.com/php-bin/mod...le=article&mode=thread&order=0&thold=0&sid=86

Again, that's just a guess. Post the codes and you'll get better answers.

 

[Joe_SHO]

Please describe the method you used to clean the maf sensor. Don't rule it out just yet.

Removed two security torx screws. Pulled the sensor out of the housing and sprayed it thoroughly with MAF Sensor Cleaner. Allowed time to dry then reinstalled. The only way I know to be honest.

I will get specific codes asap once I get a chance to borrow a code reader.

Thanks again for all the suggestions. -Joe

 

[93rev2sev]

That's the proper cleaning procedure. I think a lot of people remove the housing and spray through the screen; which cleans the screen pretty well...

I'd get to the yard and see if you can find a couple of MAFSs.

 

[rubydist]

you don't need a code reader, you just need to be able to count.......

 

[kevinspann]

you don't need a code reader, you just need to be able to count.......

That might be too much to ask for some of the people here...


Pulling codes:

http://www.shotimes.com/php-bin/mod...le=article&mode=thread&order=0&thold=0&sid=83

 

[Joe_SHO]

Threw in the MAF Sensor from my parts car. No change. But, are all SHO MAF Sensors interchangable? The one from the '92 had different numbers on the bottom.

 

[frosho]

Yes, they're interchangeable.

Still waiting on those codes...

 

[Joe_SHO]

Koeo: 337
koer: 337, 538

 

[rubydist]

337 = dpfe circuit above maximum.
538 = operator error on test.

you will want to make sure the dpfe is connected properly, and if that code remains, change the dpfe.

when you run the test, you have a relatively short time window to do the operator required things like hitting the gas, turning the wheel, etc. and you failed to do so properly.

 

[Joe_SHO]

when you run the test, you have a relatively short time window to do the operator required things like hitting the gas, turning the wheel, etc. and you failed to do so properly.

I'll blame the female. She didn't know where the O/D button was and didn't turn the wheel far enough. Thanks though!

-Joe

 

[shobhakti]

I have an ATX that was running as you described in your opening post, with a 332 code. I know from past automatics that the internal intake orifices that go to the EGR clog up. I took off the manifold and tore it apart. The long internal sample tube(from the TB to the EGR) was full up to half way and had to be scraped out with a screw driver! I'll have it back together in a day or two and report if this alleviates the poor performance and the 332 EGR code. I have to clean everything first, new gaskets and such.