engine codes, need some advice. been chasing this for over a year.

[missouriman]

94 explorer 4.0
I read through the fac's and plan on checking the fuel pressure, and regulator.
I have had this problem since we bought it, I am sure this is why it was traded off.
this problem occures on long trips, not around town. it can go 6 months with out a code, then when we go on a road trip the check light comes on at around 250 miles. We made it 750 miles one time.
the motor blew about 6 months after we bought it. it was rebuilt. the problems occured before the rebuild as well.
we have replaced the mafs, fuel relay, canister purge valve.
we have had it in the dealer ship twice, several other shops and no one has found what is causing this.
check light comes on for a few min, then go's out, comes back on. the power go's down, the milage go's down. Some times the gas peddle has no response untill half way down, then it takes off as if you had stomped on the gas.
I have been using the Ford code reader available at auto zone for around 45.00.
codes that came up after this last road trip are.
565- canister purge solenoid circuit fault. (this one is very consistant and I have replaced that valve, but don't know how to test it)
10- shift from one type of reading to the other
172- HEGO Sensor fault lean
173- HEGO Sensor fault rich
176- HEGO Sensor fault always lean
177- HEGO Sensor fault always rich
542- fuel pump secondary circuit fault.

I have not been able to figure it out and I don't want to keep guessing.
thank you for your time and any input that you may have.
we really don't want to trade the truck off, due to the new motor and 450.00 hitch and trailor wireing we just had put in.
you can also email me at
missouriman35@hotmail.com

 

[marragtop]

Could be the throttle position sensor, but it should throw a code for that. If you clear the codes, do they stay off until the next road trip?

 

[missouriman]

yes, they stay off and it runs fine. that is the strange part.
I think that when it gets 3 or more codes it go's to a safe mode setting.
I have been clearing the codes on the road trips and diconnection the battery for a minute or so. then we are good for 250 miles more.
just getting really tired of it.

 

[92 green sport]

I agree, replace the tps sensor. If you haven't replaced the o2 sensors maybe it would be a good idea to do those too.

 

[mschacht]

Mine was doing most of what your problems are. An added item on mine was, on long trips when i pulled off to fuel up, the idle would not got down below 2000 rpms. Sometimes a vapor lock would happen. I changed both o2 sensors. Mine had 2. I have not had the problem since. When I had the codes read, it never said o2 problems. I had a good mechanic that had been around the block a few time and had experienced in this problem before. Good luck

 

[MrShorty]

A few thoughts:

KOEO 565: As your code descriptions indicates, the fault is in the CANP solenoid circuit. The CANP solenoid is one part of that circuit. My experience with these suggests that the fault almost has to be either a full open or a short to ground in the CANP circuit. Shouldn't be too hard to track down with a voltmeter and a wiring diagram. Note that KOEO code can't be "cleared" by disconnecting the battery or otherwise. KOEO codes represent "hard faults" that can only be cleared by fixing (or the fault fixing itself) the fault.

CM O2 sensor codes: These are an interesting group. For one, the fault appears to effect both sides, rather than just one of the two sensors. Two, the codes are internally contradictory. From other symptoms/indications (the condition of the spark plugs, maybe) is the engine running lean or rich? Does it pass the KEOR test? O2 sensor codes can be soem of the more difficult to diagnose, and yours don't seem to show up very often, which makes it even harder.

CM 542: This, like the KOEO 565, almost has to be an intermittent full open/short to ground in the fuel pump circuit (or possibly the fuel pump monitor circuit). In the absence of a KOEO 542, this fault would appear to be intermittent, which will make it a little more difficult to locate. When you've cleared codes in the past, did you always wait until the CEL came on before checking again, or did you try clearing and pulling codes even though the CEL hasn't come back on (if that makes sense)?

Not sure where I would begin with this. SOP would be to resolve the KOEO code, then see if the other CM codes come back after getting it to pass the KOEO test. If the O2 sensors are due to be replaced, you might replace them as a matter of maintenance (if you believe O2 sensors should be replaced periodically) and see if the problem stays away.

 

[missouriman]

I used the code reader to clear the codes, then recheck them.

I will look over the wireing and see if I can find the short on the purge valve.
I would surely have thought that one of the 6 or so places I have had it into would have done that.

 

[93FoRdExPlOrEr]

....

....

 

[missouriman]

well went to the auto store to get the tps, o2 sensors, a few relays that are in line with the purge valve and the counter guy said. whoa..
that is to much stuff. take it to (this local garage) they are the experts with fords and these weird problems. so made an appointment for the 19th.
I will post up what they find.
thanks for the advice and your time.

 

[missouriman]

why are there lines, vs view and last reply.
have I been deleated or moved?

ok, moved this looks like a pretty remote thread area..

 

[missouriman]

A few thoughts:

KOEO 565: As your code descriptions indicates, the fault is in the CANP solenoid circuit. The CANP solenoid is one part of that circuit. My experience with these suggests that the fault almost has to be either a full open or a short to ground in the CANP circuit. Shouldn't be too hard to track down with a voltmeter and a wiring diagram. Note that KOEO code can't be "cleared" by disconnecting the battery or otherwise. KOEO codes represent "hard faults" that can only be cleared by fixing (or the fault fixing itself) the fault.

CM O2 sensor codes: These are an interesting group. For one, the fault appears to effect both sides, rather than just one of the two sensors. Two, the codes are internally contradictory. From other symptoms/indications (the condition of the spark plugs, maybe) is the engine running lean or rich? Does it pass the KEOR test? O2 sensor codes can be soem of the more difficult to diagnose, and yours don't seem to show up very often, which makes it even harder.

CM 542: This, like the KOEO 565, almost has to be an intermittent full open/short to ground in the fuel pump circuit (or possibly the fuel pump monitor circuit). In the absence of a KOEO 542, this fault would appear to be intermittent, which will make it a little more difficult to locate. When you've cleared codes in the past, did you always wait until the CEL came on before checking again, or did you try clearing and pulling codes even though the CEL hasn't come back on (if that makes sense)?

Not sure where I would begin with this. SOP would be to resolve the KOEO code, then see if the other CM codes come back after getting it to pass the KOEO test. If the O2 sensors are due to be replaced, you might replace them as a matter of maintenance (if you believe O2 sensors should be replaced periodically) and see if the problem stays away.

I have been looking at the wireing diagrams and trying to figure out if the constant, purge valve fault is part of the fuel pump secondary circuit???

I sure like my 46 dodge, 6 wires to the harness, only takes 3 to make it run.

 

[MrShorty]

Cannister purge solenoid circuit and fuel pump circuit are different. The only thing they share (kind of) is a common power supply (the EEC relay).

The electrical on those old cars sure was simpler, wasn't it.

And I wouldn't call this a "remote thread area" yet. The EEC-IV forum was created just a few weeks ago. It really hasn't been around long enough to get a lot of exposure.

Be aware that, the overall intermittent nature of the main problem could cause the tech at the shop trouble. If it doesn't act up for him, he may not do any better than you at pinpointing the problem. Not saying not to take it in, but don't get all upset when he comes back with "it didn't act up for me, so I couldn't pinpoint the problem" and then charges you the diagnostic fee. Be sure to help him by giving him/her (hate to assume that all automotive techs are men) as much information as you can (when it acts up, what seems to trigger the CEL, etc.).

 

[missouriman]

thank you for all your help.
hate to trade it off due to this problem.
new motor, radiator
new hitch and wireing
new brakes and tires.

sigh.

 

[sprint29]

Hi Missouriman,
I saw a problem like this on a Ranger once. It turns out the truck had been in a wreck at sometime or another and when it was repaired, a wire was stripped by a sheet piece and wasn`t caught at the time of the repair. The wire would short out, cause the condition, ( chk eng lite,run bad,etc.) and then when you would try to diagnose the problem it wouldn`t show up. What a headache. If your Ex has been in a crash, it might not be evident. It wasn`t on the Ranger. Found out when looking for the cure. Hope I can help. SEEYA

 

[Runnin'OnEmpty]

MissouriMan, my hunch is that you have an intermittantly faulty fuel pump. (Say that 3 times fast). That would explain the decreased power followed by engine 'taking off', the CEL on and off, O2 codes, fuel pump circuit codes, in fact about all of them except for the purge circuit code.

You might try checking the fuel pressure at the rail, idleing with the vacuum hose both on and off. If you have a return line, you can clamp the hose for a second or two, and see if the pressure increases. I'm betting you have a pump motor that's struggling to keep the fuel pressure up.....

ROE

 

[missouriman]

Well after 3 hours in the shop. nothing found, fuel pressure checked out, anything that could be tested was.
fuel filter cleaned.
no vacume leaks.
nodda, we had driven to wyoming and had a check light on the way home.
still at square one.
uggg.

 

[MrShorty]

Was the tech able to get the CEL to come on during operation for him? Given the intermittent nature of the problem, I'm wondering if the fault was even present when he was looking.

 

[missouriman]

no, he had no codes show up during the test.
odd because we drove from rapid city south dakota to gillet wyoming in order to get the light to come on and it did.

he got no codes, with my little checker I got the purge valve code.
the valve it self and the ciucit running it also checked out.
may be I will try a junk yard pcm???

 

[MrShorty]

When he says he got "no codes" do you know if that meant he really got nothing at all, or did he get all pass codes? If he really got nothing at all, then something must have been wrong with his expensive scanner (wouldn't be the first time I've heard of someone having trouble getting codes with an expensive scanner. One of the reasons I prefer the poor man's method of getting codes). If he got all pass codes, then he must have done something to temporarily fix the KOEO 565 you've been consistently getting.

This might be one that will require you to have a scanner with youon the next trip to Gillett so you can be looking at the outputs as you drive (see Glaciers "primer on code readers and scanners thread")

 

[missouriman]

you know, he didn't say.
but he was supprised when I picked my scanner off the seat and said that I had been using this one, ( i have two, forgot one on a long trip and needed to reset everything so bought a second one)( they both read the same codes tried that). and suggested that we hook it up. it showed the purge valve code, he seemed a bit shocked.
what kind of scanner, where and how much? getting ready to go to the other side of wyoming for x mass. (new years we have x-mass so everyone can get off to get together).