Check engine light on but no codes

[green95]

This is getting aggravating. My 95 ATX is getting crappy gas mileage and the check engine light is on. It will go on and off while I'm driving and sometimes it just stays on. It will not come on until it is warmed up and the car always reaches normal operating temperature. HERES THE REASON FOR POSTING THIS: My scanner says there are no codes and that the system passes. I've tried 2 different scanners and both say the same thing. I searched the forum and have made a list of potential problems. Does anyone know why the light comes on when there aren't any codes in the computer or am i not doing something right? Before I start throwing parts at it, what should I replace first? Thanks in advance.

 

[Vnuk1]

Have you tried the old school paper clip method for pulling the codes?

 

[green95]

No I haven't tried that yet. I plan to on Sunday (my day off), but do I run the risk of messing anything up?

 

[jmpSHO]

I would say you have a bad PCM, if you have access to one try swapping it and see if there is a change.

 

[shotime1994]

What kind of scanner are you using?

 

[joesho_gb]

Risk of damaging something, as long as you follow the instructions, you should be fine.

As for the crap gas mileage and all, when the CEL comes on, do you notice the car surging or feeling like it's missing at low RPM's (like below 2100 rpm)?

I ask, because it may be an O2 sensor. They don't throw codes until the engine is at normal operating temp.

 

[jmpSHO]

Anytime the CEL comes on it sure store a code.

 

[joesho_gb]

Yea, it should. Stupid question, but is the ground wire for the keep alive memory good? If it's loose, that might be why the codes aren't being saved.

 

[shotime1994]

Well it also could be a dpfe sensor they will throw codes when the engine is warmed up.

 

[green95]

I have been using an Actron OBD 1 scanner. Battery is good in it and its brand new.

As far as the car surging when the light comes on, nothing. Nothing at all changes when the light comes on. It still keeps driving the same and has plenty of power. Last night i did notice that when i step on the gas hard enough for it to downshift, I can see the exhaust in the mirror. This morning it gave me a hard start. Turned over longer than usual and then fired up.

As far as the Keep alive memory wire, where is that wire? Thanks guys for all the help so far.
:thankyou:

 

[joesho_gb]

Well it also could be a dpfe sensor they will throw codes when the engine is warmed up.

Oh good one, forgot about that.

As for the Keep Alive Memory, as long as you have the stock battery setup, on the negative battery terminal, you should have two wires hooked into it.
The large one is obviously the electronics ground, but there should be a smaller gauge wire, 12 or 14 gauge, black. It runs along the passenger fender, goes around the strut tower, then eventually goes into the firewall to the main computer.

Check the connectors at the battery. I actually wired mine directly into the Chassis when the connector on the terminal connector was replaced.

 

[projectSHO89]

Yea, it should. Stupid question, but is the ground wire for the keep alive memory good? If it's loose, that might be why the codes aren't being saved.

That small ground wire off the negative battery terminal is for the PCM ground. It is not exclusive to the KAM function.

If that ground wire is in poor shape, you'll usually have a dim CEL along wing PCM-related running problems and ignition system problems.

 

[green95]

So I hooked my scanner up again, and the light didn't flash on the scanner BUT the CEL did flash. I started the test over and this is what I got pending I didn't miss count....

176 This code flashed twice in 2 sets
332 This code flashed twice in 2 sets
543 This code falshed once in 2 sets

The next time I did the test this is what I got:

565 This code flashed twice.

I may have miss counted the check engine light but I don't think I did on the second test.

Matt

 

[shotime1994]

332 is your dpfe sensor. 176 is your o2 sensor. Both those codes will come on when the engine is warmed up.

 

[green95]

Where can I get a new DPFE sensor and where is it located? I can't find one through autozone or advance. I did find the oxygen sensor there and the guy there was telling me that '332' is for the EGR valve? Is that correct or is it the dpfe? Could both of these codes explain the gas mileage?

 

[shotime1994]

Ford sells a new style dpfe sensor with a pig tail. It is located at the back of the intake held on by two screws there is vacuum lines a harness on it.

 

[rubydist]

176 - HEGO sensor indicates system lean (LH).
332 - EGR valve opening not detected.
543 - Fuel pump secondary circuit failure.
565 - CANP solenoid circuit failure.

176 is telling you that the front o2 sensor is not switching - this is typically a o2 sensor going bad.
332 is telling you that it doesn't sense the egr valve opening - this could be a bad dpfe sensor, but also is commonly caused by clogged egr passages.
543 is commonly set because the engine was stalled at some point and can typically be ignored.
565 is telling you that the charcoal canister purge solenoid is not working. This will result in a saturated charcoal canister and a gas smell around the car all of the time especially when it is warm outside. You can replace that purge solenoid, or shotimes has a modification that allows the canister to be purged all the time, which eliminates the smell without any adverse results.

 

[green95]

I do smell gas when I shut the car off. I'm going to replace all that it says I need, but need a little help as to the location of these parts. I found the DPFE on the back/right side of the intake. Is the charcoal canister purge solenoid the round part with a vacuum hose and another hose bolted to the bottom? Its to the left of the master cylinder and bolted to the intake?

 

[rubydist]

The purge solenoid is on a vacuum line that runs to the intake just after the throttle body, and it is located somewhere on the right side of the abs controller.

 

[green95]

I followed the vacuum line down past the ABS controller, and I found a small (very old) canister. The part number was hard to read but I believe this is it

E4TF-9C915
Does that sound correct and is that the right part?
I was going to attach a picture but couldn't upload it.