black smoke

[hotshot31]

I would agree

 

[dogfriend]

I would check fuel pressure on the fuel rail. It sounds like you are running way rich. If the fuel pressure is too high, it could cause this.

EGR stuck open would act similar to a vacuum leak - it would lean out the A/F ratio.

The other thought that I had was a problem with one of the sensors is tricking the PCM into giving too long a pulse on the fuel injectors. MAF, Intake Air Temp, or Coolant Temp sensors - check the connections to these sensors.

 

[MrShorty]

I would double check your code interpretation. A '94 should be outputting three digit codes.

From what you describe, the engine appears to be running rich. The primary purpose of the engine management system is to control the fuel/air mixture. If you're new to fuel injection, you might take the time to find Glacier991's "primer on computerized engine controls" thread.

If the one code is correct, then the computer is seeing a fault in the EGR system, but I would take the time to verify that you've properly interpreted the codes. You might review my "notes on pulling ECC-IV codes" in the EEC-IV forum if you need help with the test protocol.

I would probably also put a fuel pressure gauge on it. A leaky diaphragm is only one failure mode of the FPR.

 

[hotshot31]

ok ya'll I dug out the hanes book I got for my other one & ran the tests 3-4 times today after I cleaned the air filter,maf sensor, new plugs,inspected the vac & elec. plugins & drove it around for awhile... it gave me the same codes but the prob is one of the codes only relates to the engine running which I didn't do....just did the key on test & the codes it gave me was 327,157,158...so my quest is does that mean my maf sensor is bad or what ??

 

[MrShorty]

one of the codes only relates to the engine running which I didn't do....just did the key on test & the codes it gave me was 327,157,158

Which code do you believe is only a KOER code? According to my code lists, 327 and 158 can be any type of code (KOEO, CM, or KOER), and 157 can be either KOER or CM.

When diagnosing several EEC-IV codes, SOP is to resolve KOEO codes first. You didn't state which codes came before the separator pulse (KOEO codes) and which came after (CM codes), so the first thing I would ask you to do would be to determine which code(s) is (are) coming from the KOEO test.

Because KOEO codes are set with the engine off, they are almost always electrical faults, so the next step is to look through the appropriate circuit until you find the fault.

 

[hotshot31]

I only did the KOEO test & thats the order the codes came.....I might be mistaken but I thought 157 was only a code for the KOER test....so does that imply my MAF is bad ?

 

[MrShorty]

With maybe a few exceptions, codes by themselves can't imply that a part is bad. Codes point to a problem with the circuit, of which the sensor is only one part.

If that's the order the codes came out, and I assume that the 327 and the 158 are KOEO codes and the 157 is a CM code (which could easily be wrong. you have to figure out which of those codes are KOEO and which are CM codes), then I would first resolve the KOEO 327 code.

KOEO 327 indicates that the EGR sensor's signal wasn't correct during the KOEO test. KOEO codes are almost always electrical in nature, so I would focus on the DPFE sensor circuit. The DPFE on these goes bad quite frequently, so I'd probably inspect the circuit and, if the circuit checks out, then replace the DPFE.

After any repairs are made, repeat the KOEO test to see what codes have been resolved and what remain, then work on the next KOEO code.

 

[hotshot31]

ok cool...I'll check it out ..thanks

 

[Exploderpilot]

differential pressure feedback egr

 

[Exploderpilot]

here's a basic ford setup, i think this should be similar to the explorer.

 

[mawrazen]

I have a 94 EX with 239+K miles. Used to get 14 mpg my new personal best is 23.67 mpg this week.

Could be a vacuum leak, or bad tranny modulator valve.

Also try:

Seafoam
TPS mod
Throttle cable mod

Good luck!

 

[hotshot31]

sorry about taking so long to get back to ya'll but I've had a few fires this week so I've been a lil busy....ok heres what I've done so far I've replaced the MAF sensor, cleaned my IAC sensor,checked my hoses. I've also done a KOEO & a KOER test after I had ran it around town. the good news it the smokes quit far as I can tell, but its giving me codes 326,116. the 326 code I'm guessing is a hard fault code & the 116 is a memory one. I ran around it for probably 30 minutes or so, so would the 116 mean that my Engine Coolant sensor is bad?...by the way thanks for all the great help.....yea I'm also going to run some seafoam through it today & see if that helps with the EGR before I take it off

 

[mikeinri]

Hey hotshot,

I don't know how I missed this post. I had the EXACT same problem (soot and smoke coming out of the tailpipe, plus CEL) with my 94 several years ago. I've also run into a bunch of EGR/DPFE issues earlier this year.

As for the soot and smoke (assuming you still have this problem), I took my truck to a Ford Dealer (I ignored the CEL for months, then was on vacation in FL, towed a boat from RI at the time the soot happened). Long story short, they replaced MAF, TPS and O2 sensors and cleaned the intake system. Problem solved. Their explanation was that one of the sensors went bad, I ignored it and the computer tried to compensate. With the engine running so poorly, it fouled other sensors. So, you will want to be sure to clean the system and think about replacing the O2 sensors, since they're at the end of the line (in the exhaust).

As for the EGR issue, have you searched this site? Search for "code 327 from hell" and you will see what I went through. I agree that it's most likely the DPFE. Whatever you do, make sure you buy the new part from Ford. There is an upgraded model available (comes with a new adaptor that you have to splice in). I used an aftermarket one, got a few weeks out of it, then had to go with the Ford part. Don't waste money like I did. BTW, correctly troubleshooting the EGR system requires a vacuum pump (I skipped this and went right into part-swapping).

In general, when dealing with codes, remember this. You can go to AutoZone, and they should be able to read them for you. Not all stores will want to work on Gen 1 Explorers (they claim they don't have or know how to use the specific reader for these trucks).

Even if AutoZone doesn't read them for you, if you bring in your codes, they can enter them into their system and print out a long register tape printout, which details the troubleshooting procedure, down to how much voltage you should see on each colored wire in a harness.

Hope this helps. BTW, welcome to the forum!

Mike

 

[MrShorty]

the 326 code I'm guessing is a hard fault code & the 116 is a memory one. I ran around it for probably 30 minutes or so, so would the 116 mean that my Engine Coolant sensor is bad?

Mine and BrooklynBay's code lists indicate the opposite: 116 would be a hard fault code and 326 would be a memory code.

My experience with a KOEO 116 indicates that it is caused by operator error the vast majority of the time. Namely, the operator performed the KOEO test while the engine was cold. If this is the case, or if you are uncertain if the engine was warm enough, repeat the KOEO test after running the engine up to normal operating temperature. If you're still getting a KOEO 116, then test the ECT with a volt/ohm meter. The ECT is a simple thermistor and should be pretty easy to test.