95 4.0 OHV 172000 miles

[peakcomp]

Just started having a check engine light on, almost instantly from the vehicle start. It was going on and off for a while as the vehicle was driven...now, it remains on.

Attempted to pull codes, but scanner says it can't connect to the computer. Schucks says my PCM is probably bad. ?

The vehicle runs kind of sluggish, seems not to have acceleration power and the tranny seems to shift kind of stiff.

Why can I not pull codes? Is there a way to get the code to know where to start to fix it without having Ford charge 79.00 to diagnose the code?

And how to determine if the PCM is at fault?

Please advise,

and Thank you in advance for your help.

Ken

 

[imp]

Do you know for certain that your scanner is working properly? Has it detected and displayed codes in the past on this engine? Try disconnecting a sensor, perhaps Throttle Position Sensor while engine is running, or maybe Mass Air Sensor, look to see3 if MIL light illuminated, shut off engine, then try code check. If you can pull code(s), viability of scanner confirmed, must look further.

Check if EGR valve is stuck open (affects idle adversely), though that should generate a DTC.

Check if Idle Air Control valve is freely movable; some can be manually moved after removal from throttle body. IAC position is NOT sensed by PCM, so trouble there generates no direct DTC.

PCM at fault? Maybe, but not very often, on pre-OBD-II systems. Can you beg, borrow, steal, or otherwise obtain a known good PCM and try it in your truck? imp

 

[EricM9104]

Last tune up? Run a check on your MAF and TPS (threads posted on here)

 

[peakcomp]

I used the Schucks scanner, not sure what or anything about it. Haven't tried to pull codes in the past.

Where is the EGR valve and how would one check on whether it is stuck open?

IAC was cleaned today, and is movable...seems fine. Didn't help, still CEL on.

Ken

Do you know for certain that your scanner is working properly? Has it detected and displayed codes in the past on this engine? Try disconnecting a sensor, perhaps Throttle Position Sensor while engine is running, or maybe Mass Air Sensor, look to see3 if MIL light illuminated, shut off engine, then try code check. If you can pull code(s), viability of scanner confirmed, must look further.

Check if EGR valve is stuck open (affects idle adversely), though that should generate a DTC.

Check if Idle Air Control valve is freely movable; some can be manually moved after removal from throttle body. IAC position is NOT sensed by PCM, so trouble there generates no direct DTC.

PCM at fault? Maybe, but not very often, on pre-OBD-II systems. Can you beg, borrow, steal, or otherwise obtain a known good PCM and try it in your truck? imp

 

[peakcomp]

Last tune up, well partial tune up (spark plugs and fuel filter last month)...Cleaned MAF sensor today..no improvement..CEL still on.

TPS? Sensor? Location?

Ken

Last tune up? Run a check on your MAF and TPS (threads posted on here)

 

[peakcomp]

Unable to pull codes, used CEL jumper short..

Was able to use the CEL to 'flash' my codes at me. I think this is what I get..a little hard to distinguish the codes when flashing.

Code 117 and Code 176???

Ken

 

[BurnTheLight88]

code 117 - ECT sensor is/was low or grounded (engine coolant temp sensor)

Code 176 - Oxygen sensor not switching - system is/was lean Left or Front HO2S

Neither of these sound like you'd be getting those codes with your description of the problem. As for the scanner, I'm guessing that it's for OBD-II, and if your light flashes codes, its OBD-I.


For a full list of the codes: click me

 

[peakcomp]

Ya, I'm kind of confused as to if my 1995 Explorer is OBD I or II...it has a Diagnostic port inside under the steering column...which leads me to believe OBDII..but, its pre-96!

Ken

code 117 - ECT sensor is/was low or grounded (engine coolant temp sensor)

Code 176 - Oxygen sensor not switching - system is/was lean Left or Front HO2S

Neither of these sound like you'd be getting those codes with your description of the problem. As for the scanner, I'm guessing that it's for OBD-II, and if your light flashes codes, its OBD-I.


For a full list of the codes: click me

 

[XLT]

1995 was the in between year. Not a obd I and not an obd II. It has the obd 1.5 from my understanding.

I hope this link helps.

 

[BurnTheLight88]

It should still have the OBD-I port under the hood I believe, so if you buy an OBD-I reader, which are relatively cheap, it should plug into there and not under the dash (or you can count the light flashes using a jumped, it takes a while to get the hang of though). Under the dash is an OBD-II port I believe, but only 3 wires go into it, so it's not compliant with OBD-II readers.

 

[Joe Dirt]

The port under the dash has nothing going to it- it's a dead plug, you need to use the harness under the hood.

Check my video: