Check engine and O/D

[Boobala]

Okay, I'm not sure what is happening here. The CEL comes on and the O/D light will flash.

When the engine is cold, the lights do not come on until I start driving. If it is warm outside, the lights come on quickly. If it is cold outside it take a little while.

Also, the engine will briefly hesitate when accelerating. When stopping the engine will sometimes stall because rpms will drop very briefly.

When it gets really cold outside, I can can hear/feel something in the drive train bump( possibly the torque converter?).

An ideas? Possibly the throttle position sensor? EGR? How might I troubleshoot either? Any thoughts would be greatly appreciated on my 120k mile 95 xlt.

Thanks, Jeff

 

[Billy177]

may be your tps but get your codes read and go from there

 

[MrShorty]

A '95 is still OBD-1/EEC-IV, so you can perform the EEC-IV diagnostics with nothing more than a jumper wire. Most manuals (Chiltons, Haynes, www.dalidesign.com/hbook/eectest.html, etc) have a basic description of the "quick test" (aka pulling codes).

 

[Boobala]

I read the codes using a jumper and watching the Check Engine Light. These are engine running codes. Here's what I get:
412 - Unable to control RPM during High RPM Self-test
116 - Coolant temperature sensor out of self-test range
114 - Intake air temperature sensor out of self-test range
336 - EGR circuit higher than expected
538 - (3 different possibilities)
1. Insufficient change in RPM/operator error in Dynamic Response Check
2. Invalid cylinder balance test due to throttle movement during test (1995 models)
3. Invalid cylinder balance test due to CID circuit failure (1995 models)
536 - Brake ON/OF (BOO) circuit failure/not activated during the KOER
632 - Transmission control switch (TCS) circuit did not change states during the KOER

Go back to the start of the thread for a description of the behavior of the problem.

I did notice when performing the Engine Running Test, when I barely engaged the throttle, the CEL came on and then went away after letting off. I think this was telling me to hold the throttle full open for 1 second. But since it happens when the throttle changes position the least bit, would this possibly be looking like a TPS problem.

Your thoughts on this is GREATLY appreciated. Thanks.

 

[Boobala]

Any ideas???

Anyone have any thoughts on these codes? I'm getting real nervous about damage I could be doing the drivetrain somewhere when the hesitation occurs at higher speeds.

 

[Billy177]

sounds like you have a whole mess of prolblems. first off with so many codes i would have them actually read using a code scanner to be sure that they are right. if indeed thay are i would definatly get a new tps and i would also check all the connections because the coolant and air temp sensors are out of range. you may have a harness disconnected or something like that.

 

[boominXplorer]

Yeah get a new TPS and clean your MAF and IAC. When your TPS goes you have many problems.

 

[MrShorty]

Actually, I'll bet there are only two meaningful codes in that whole list.
412 - real code. indicates problems with the PCM's ability to control engine RPM. Check TPS/IAC/vacuum leaks/etc.
116 & 114 - triggered if test is run on cold engine. PCM expects engine to be at operating temperature when KOER test is performed. If engine was at operating temperature, then a fault is indicated in the ECT & IAT
336 - EGR fault. EGR problems are often traced to the DPFE sensor. Be sure to diagnose before replacing parts.
538 - option 1 is correct. cylinder balance test only applies to SEFI engines (you have port EFI). Almost always indicates that operator failed to "goose" the throttle at appropriate point in KOER test.
536 & 632 - Like 538, almost always indicate that appropriate switch not actuated at appropriate point during KOER test.

Unless the KOER test was perfromed correctly, the only two codes I see are the EGR code and IAC code. The next step would be to get the appropriate circuit "pinpoint" tests and go from there.
If you're up to it, someone posted a link to a file called "gtest.pdf" in the explorer forum at FTE (www.ford-trucks.com/forums). Run a search over there for "gtest.pdf" (be sure to set search options back far enough, it was posted last summer) and you should find it. The file contains a near complete article (~200 pages) from Mitchell for the EEC-IV diagnostics on a '95 Ford Explorer. I posted the link here, but the search engine here doesn't like to find it.

Good luck.

 

[Boobala]

gtest.pdf

Wow. I downloaded the "gtest.pdf" and that's gonna be some reading material for the bathroom. I think I'll be able to follow it through though.

I tend to agree there are only a couple of meaningful codes there. I want to try the KOEO and KOER tests one more time. It seems if I don't complete the KOEO tests first the KOER may not report correctly.

Thank you guys for your help. I'll update the thread as I go or as I break stuff and need more help.

Great website. I hope to be able to learn enough so I can help out somebody here at some point.

If anyone needs the 'gtest.pdf' let me know and I can send it. I had a bit of a time ripping it off the russian server it was stored on.

 

[MrShorty]

I meant to mention in my previous post, that you should always diagnose any KOEO hard faults before dealing with the KOER codes.