I am hoping someone can help with this. All I want to do is read the darn codes on my son's '93 Explorer (4L-6, 4X4). I got one of these:



Actually, this is the second one as I thought the first one was faulty. Same thing with this one. It does not do anything. I think the little LED is supposed to come on when you plug it in, it doesn't. I tried grounding the single lead to the negative battery terminal, and nothing. Any tips or tricks on getting this to work? AS this is the second code reader doing the same thing, it must be something truck related. I have followed the instructions to the letter, is there something I'm missing?

 

When you turn the scanner, do you hear anything in engine clicking (if KOEO test) or do the RPMs change (if KOER test)? Does anything appear on the display?

 

When you turn the key to run does the check engine light come on?

Is it not starting, or?????

 

There is no clicking. The truck starts fine and will run until it heats up, then it will hardly run. I drove it about 3 miles the other day, then it died at a light. I barely got it off the road. After it cooled back down, I was able to drive it home. It now seems to be running real rich. I tried the volt meter method of pulling the codes. I got a code 33 I believe, but then the needle on the volt meter goes up and stays up as there is a slight whine from somewhere. Codee 33 would be an EGR problem. Would that cause the syptoms I'm getting?

 

I have an identical unit that we use on the 92, did you read the manual, there are steps you have to go through to get the codes, dont have my manual handy, but if you dont have one I will send the routine

 

33 is EGR not opening or not fully closing. Sounds like the EGR is stuck open & that will cause it to stall, but that should make it lean not rich. Go figure.

WIth the engine warmed up try revving it & watching the diaphragm in the EGR, you should be able to see or feel it moving above about 2000 rpm's.

 

aquanut - I followed the manual step by step with no luck. The guy at the parts store recomended the manual method, so I traded the reader in on a Hayne manual that details the procedure. Now I'm not so sure that there might be a problem with the computer. Even with the voltmeter, it seems to do basically the same thing. I did get distinct needle swings to come-up with the 33 code. But after those, the needle on the voltmeter just stayed up as I got the hum from somewhere. Damn all this fancy crap!

So, it starts fine. Idle is a bit rough and I'm getting some black smoke from the exhaust. I'm leary of driving it for any period of time as it died the last time. I'll check and see if I can see the EGR Diaphram moving.

 

If the check engine light comes on with the key on & engine off, you should be able to pull codes. I have no idea what thats about.

Since your getting the black smoke, try this: run it a few seconds & shut it off.

Pull the vacuum hose off of the fuel pressure regulator. If you find gas, thats why it's rich..

 

I agree with 87xlt, I would be looking for a bad FPR.

 

Checking fuel pressure is a good diagnostic step, but I think I would still focus on why you can't get codes. There appears to be some electrical fault preventing you from running a complete test.

Out of curiosity, what does the CEL do? The CEL should flash with each sweep of the needle (meaning you can pull codes without the voltmeter, just need to jumper STI to SIG RET). Does the CEL do the same as the voltmeter (blink-blink-blink, blink-blink-blink, bliiiiiiiiiiiiiiii......)? Side note: your '93 should be outputting three digit codes, not two digit codes. I expect that '33' you were getting would end up being a 33x code. Still an EGR code, but which EGR code.

What is the "humming" that you get in the middle of the KOEO test? Possibly a relay, maybe even the EEC relay, going crazy?

Some things I would do (you'll almost certainly want a wiring diagram if you don't have one already):
1) Check continuity of the wires between the self-test connector and the computer
2) Check the computer's power leads for a steady +12 V. Make sure the computer's grounds are all solid (it seems as these vehicles age, the ground connection coming off the "pigtail" on the negative battery cable goes bad).

 

OK,
I checked everything possible with no luck. I figured I'd take it into the shop to get the diagnostics done, then do the repairs. I have not used repair shops very often, and only once in the 9 years we have been in Texas. I took the thing into Lambs Automotive. $89 for thier diagnosis. They were having a heck of a time too. They followed the process outlined in Alltrade I think it was. Replaced the PCM relay and still did not get proper codes. Ended up replacing the PCM. With the PCM, relay and labor dropped about $500, but the damn thing is working. They were able to pull codes and told me the DPFE needed to be replaced. Gave me a quote of $210 for the DPFE +$25 labor. I picked it up without letting them milk me for anymore. Picked up a DPFE for $62 at OReillys (Wagner lifetime warranty). Took about 5 minutes to replace. Another reminder of why I don't care for auto repair shops...

 

Yeah Mrshorty I was thinking the same thing. A 1993 has 3 digit codes so your reading a 33 was an error ..not sure why or what you did or if your volt meter is bad.

Do you have the old PCM? What were the part numbers and 4 digit codes on both of them? If you do have an EGR valve, for a 1993 that means it's a california emissions car. Ford had a TSB to change the PCM's in 1994 or 1995. So there might be a better on out there for you. I doubt your shop knew about this TSB. I only do because the dealer changed mine under warranty. I can send you this TSB if you PM me an email addy.

I am a little suspect at the shop's diagnosis. PCM's rarely go bad and should only be changed if all else is verifed to be OK. Running rich is usually, not allways, a bad O2 sensor or bad fuel pressure reg as mentioned. If you were running that bad with black smoke coming out, I guarentee you there would be something told off a good scanner. Either a rich bank code or just monitor the 02's real time and see if they are switching. Scanners do give a lot of clues.

A bad DPFE can certainly make a car stall at idle - has no real affect with the throttle open. And I don't see how it will cause a rich condition to give you black smoke.

As far as the PCM relay, all that does is power up he PCM. If the car is running, the PCM ha power. Why on earth did the shop think the relay needed to be changed?

See why I'm learly of their work? Wish I had caught this post last month...could have helped you a bit more.

 

Thanks for the input MrSki. Unfortunately, the damage has been done. The truck runs fine now, I'm just a bit lighter in the pocket. I'll chalk it up to a learning experience. Although I've worked on cars for 35 years, I'm clueless with this emissions stuff.

My thought was that since I could not get a code read out of the thing. Aftyer trying 2 code readers and the analog volt meter, that something was probably messed up with the computer. I checked all the wiring and connections and all was fine.

It does run fine now and thats what matters I guess. I don't have to worry about this truck and can spend more time with my '53!

 

And that's what a lot of people want is to just get it fixed. No problem. But if you want that TSB to check the PCM codes, let me know. It's a simple e-mail.