Howdy Folks-

New to this site- a guy in our building turned me onto to you. This site rocks.

So here is the deal-

I drive a 1993 Ford Explorer/V6. Manual. 4x4.

Problem: Engine light came on and mileage has dropped dramatically.

Went to shucks and used their Diagnostic tool.

Ran 2 Tests:
KOER: Results: DTC 90
KOEO: Results: DTC 157 and then DTC: 998. Not sure if I ran first test of this set correctly so ran it twice more and got the 998.

The engines 'pulsates', more so when warming up.

Is this the 02 sensors?

Any advice woudl be extremely welcome.

Thanks In Advance!!

FYI- Last summer I replaced the entire cooling system. This winter I replaced the clutch, Tranny and 4x4 gear box.

Also, engine has knocking noise when warming up- is it time to call it quits on her? Really don't want to as she is my mountain beast. Grin.

Thoughts....

 

Check those codes again...there will be three digit codes or there will be two digit codes, never a combination of the two. Here is a link to help you pull the codes yourself: EEC IV Self Test hookup
Just leave out the voltmeter/test light in the diagrams and count the blinks on the check engine light.

 

998 (R) Did not pass Key On Engine Off test yet (Get 111 in KOEO first) . You have to do the KOEO test FIRST.

90 SERIES FUEL/AIR INJECTION CODES ON VEHICLES WITH DUAL OXYGEN SENSORS REFER TO THE LEFT OR FRONT SENSOR. EXCEPT: 1984-1988 3.8L ENGINES: RIGHT SENSOR - not sure if one of your O2 sensors is faulting or not. May want to start fresh with the KOEO test first, then go from there.

157 (R,M) Mass Air Flow signal is/was low or grounded - MAF. Check your MAF sensor connection and ensure the intake hoses, etc. on either side of it are tight and leak free, as well as at the throttle body itself. Also check for vacuum leaks.

The O2 sensor(s)/MAF situation could be causing your warm-up knock, but not sure. Is it rod knock or is it lifter noise? The 4.0s are notorious for valvetrain (pushrods/rockers) wearing out. Let us know what your retest results are.

 

Thanks for the response!

Never used the device before and the people at schucks gave me No instuctions on how to use it. Once I figured out how to turn it on I played with it until I thought I had figured it out.. Didn't realize what KO stood for- makes a big difference. I did have the key off.

Heading out of town today so will run tests monday and let you know the results.

Ill check vac sys before I leave- may get lucky.

My mechanical skills are ok. Shade tree mechanic..

Thanks again for the info!

 

There are two different tests: Key on, engine off (KOEO) and Key on, engine running (KOER). It can't run a test with the key off. Don't dig too far into these codes without being sure you ran the test and counted the blinks correctly.

I wasn't aware of this. Is it something with the newer computers? I can run a KOER test with active codes in the KOEO test without any trouble, but I have an 87.

 

OBD-I and OBD-II can be different. Different OBD-I or OBD-II can also be different. Most later-model OBD-I systems almost require the KOEO test be done first. These are usually MAF-equipped vehicles, not MAP-equipped. I can run any of the tests in no specific order on my '87 as well. It's just better to do the KOEO first with the engine warmed up and go from there.

 

That's interesting. I've always done the engine off test before the engine running test anyway, but didn't know that it really mattered.

 

Yep. Certain EEC-IV and EEC-V computers are fickle about that sort of thing, so I am understanding. I am going to assume from what I've found, it's more prominent in MAF-equipped and/or DIS/EDIS vehicles than the EEC-IV/TFI ignition equipped vehicles (our '87s are the latter of all mentioned, EEC-IV with TFI ignition).

 

I see this has quite a bit of current activity so I’ll ask this question in hopes someone can help me out with this one.

Similar to the initial problem with the first person I’m trying to help a person with his 1993 Ford Ranger Super Cab 4X4 4.0 liter AT. It appears to be running very rich (black smoke), and pulsing while idling. Basic overdue tune up and air filter did nothing.

Ran the codes with an expensive brand new code reader and found
KOEO DTC 111 & 157
KOER DTC 090, 157, and 998


My gut feeling is to start with replacing the O2 sensor and then go with a MAF.

Please respond with whatever you know, it may help.


PS, don’t forget to watch the race at Talladega tomorrow!

 

You may need to clear the 157 code for KOEO. I don't see how you got 111 on KOEO and then got a 998 on KOER, unless you did the tests backwards (KOER first, KOEO second) or the 157 CM code is causing that. In both your situations, the MAF may require cleaning and 'tuning' (slightly loosen the clamps, rotate up to 45 degrees either direction to see what gives the best results). Could always be a bad MAF or dirty/wet connections. May also want to check the entire engine harness for problems. Not sure if either O2 sensor is faulting (IIRC, there are two on the 4.0s), but that is also something to check. If you replace one, I would personally replace both, just to keep from having to replace the other one after the fact. Can always keep the 'good' one as a spare.

 

Thanks for the reply so fast.

So I went (before the race) and took the MAF out, cleaned it up really well and then cleared the codes via my scanner.

I then drove the truck for twenty minutes, came back and the scanner read;
KOEO – 111 and 157
KOER – 090 and 998

Much of the black smoke is gone, so it appears that the rich running is now gone.

Oh yea, I did a “wiggle” test with the scanner; nothing was picked up so the wire connections appear to be okay.

What would be my next recommended steps?

Thank you; and what a flip by Carl Edwards yesterday! Too bad that NASCAR can’t get out of the restrictor plates and let the drivers race. Sure car would be more likely to go airborne, but they could slap another “aero package” to control them using down force. Obviously the opinions of the drivers as well.

 

Might be time for a new MAF sensor or to go through your wiring harness from the sensor to the computer.... a 157 indicates problems with it, and you probably won't clear that 998 until you get that 157 cleared. Not sure why you just get a code 90, but I would look at all of the O2 sensors. Could be that the rich condition has made them dirty.

Yeah, I saw that flip on TV... holy smokes! From what I saw, he connected with a couple of other drivers like he had lost traction. At least they're still racing... could be worse... they could shut down the sport until the gas prices go down and the economy picks up! I think those cars are engineered the way they are on purpose... can't have a race without a show I forget, what track was that at?