Check Engine Madness!!!!!!!!!!!!!!!!!!!

[Triton46]

OK, took the Explorer on a 320 mile weekend trip. Ran great all the way there and back...except for the check engine light. I did notice though that it came on after 20 miles whether the AC was on or off. We stopped once on the way there and after 20 more miles the Check Engine came on. Then on the way home it came on after 20 miles and stayed on the whole time. I cleaned the MAF about three weeks ago but this problem keeps cropping up. On the way down I got 220 miles to the 1/4 left mark on the gas guage and about 240 to the 1/4 mark on the way back. So whats up with this thing? Could it be the FPR? Ive got one on order with carparts.com. HELP!?!?!?!

 

[FMNavajo]

Triton46,
I would lean towards the FPR and O2 sensor. Was it pinging at all? How was the acceleration at speeds? Whens the last time the plugs and wires were changed? It could just need a simple tune up. Another thing to check is the #5 spark plug to see if it has more carbon build up then the others, if so, you might want to consider retorquing the lower intake manifold. check this if you seem to be burning oil fast.

Just some questions to help determine the problem,
FM

 

[Triton46]

Acceleration was awesome, better than I remember in a long time. There was no pinging, I filled up with 89 (which usually pings under heavy acceleration with the AC on) and got no pinging.

I think it had a tuneup back at 60000 or maybe 90000, I just got the car from my parents. Is this a typical FPR problem (ie no pinging, great acceleration, lousy MPG)?

 

[FMNavajo]

The FPR won't hurt but I'm starting to think it's just a sensor, O2 or otherwise. You might want to look for someone with a code reader and find out why the check engine light was on. These codes will be saved until the battery is disconnected. Maybe someone else has seen this problem and will type something in here for you.

Good luck,
FM

 

[kilroy]

What year is it?

I took a trip a few weeks back to Michingan pulling my horse trailer, and on the return trip with the cruise on, my check engine light came on, and it was the O2 sensor. I reset the code, and it has been fine ever since. How many miles are on it, any oil burning, and when was the last time the O2's were replaced?

 

[Triton46]

Its a 1991 with 92000 miles on the clock. The O2 sensor was replaced a few months ago. Before this replacement, the Check Engine would come on if you went 1 mile down the road and got worse and worse until it was on almost all the time. I disconnected the battery and reconnected and that fixed nothing. Finally had the O2 sensor replaced and all was well for a few months. Then a long 180 mile trip and it came back on. Anyone in Greensboro, NC with a code scanner? I may take it by Ford in a few days and let them read it...and take some money.

Anyone know if this is the FPR? What is the usual lifespan of an FPR? I have one coming tomorrow from carparts.com. Great price on it $60 - 33% came out to about $45 and shipping and handling. Get this deal while you can, ends in August.

 

[kilroy]

All you need to scan the codes on a 91 is a papaer clip, and you jumper some pins on the diagnostic connecter under the hood. Which pins, I can't remember, but there may be a website that will tell you, do a search for trouble codes, and scanning, and you should be able to find one. If you can wait a day, I could dig out my old book, and get the codes for you that you read off the dash.

 

[Triton46]

Not sure about the paper clip idea, Im only half a shade tree mechanic at best.

Anyone know how long a FPR will last? I got out of the truck the other day while it was running to get the mail and I could smell the rotten egg smell. Ive heard others talk about it, but never knew what it was until then. Also sometimes when I shut it off there is a strong gas smell.

How much will Ford charge to read the codes?

 

[Triton46]

I drove to Harrisburg, Pa this weekend with new FPR in a box in the back awaiting the help of my girlfriend's father to install. The night before I cleaned the MAF just in case that was the culprit. Hit the road and 40 miles down the road CHECK ENGINE. Stopped to eat, got 20 miles down the road CHECK ENGINE. Here is where it gets interesting, I was then positive it was the FPR. When we left the restaurant we got 100+ miles away with no check engine...then it came on and remained on until we pulled into Pa. Total trip is 400 miles.

This morning we took the old FPR off following directions from the Explorer fixit bible web page (cant remember the address but will post later). Kudos to everyone who submits to that page as the directions were right on for what to do. Depressurized the tank, rigged the hoses for AC out of the way, drained coolant and removed hose, removed air hose. The FPR was a little difficult to unbolt but once it was undone it popped out of the engine. Note: The main gas line going in has a cap around it, we proke a prong taking it off because we weren't sure what it was. Then the gas line is attached metal to metal, with a safety (you can push it into the fuel line, but you can't easily pull it out). Anyone who has done this knows what I mean, we used pliers, screw drivers, and small crow bar and it finally popped off. New FPR from carparts.com ($49) went on easily, tightened bolts and replaced all the hoses and fluid. Put the fuel relay back in place and she fired right up. The Explorer runs fine (not that it wasnt before) the true test will be our journey home...will the mysterious CHECK ENGINE reappear???? Tune in Monday to find out....

 

[Triton46]

I can sum it up in two words CHECK ENGINE. The FPR change did not work and I still have a check engine light. My next move is too find out what codes are in the computer. Three questions:

1) Where can I find a good scanner or how much does Ford charge?
2) Does anyone know where software and hardware connections for a laptop scanner can be found?
3) What else could be wrong with this thing? I had the oxygen sensor changed about two months ago...

 

[kilroy]

Trak auto or pep boys has a scanner for around $30. The system is too old for a laptop setup, it's not interactive, more like a dumb terminal.

 

[Triton46]

OK guys more weirdness. Last night before leaving Pa on my 400 mile trip back I checked all hose and wire connections and disconnected the battery (turned on headlights) for 15 min to reset the computer.

I woke up this morning and let the car warm up for a good 15 min to relearn the default parameters. Then we took off. For the first 100 miles there was no CHECK ENGINE, then we went another 100 miles. At 200 miles we decided to stop and eat, no CHECK ENGINE, I started slowing down to tak the offramp and as I braked around the corner on it came. *NOTE this happened on the way up, no CHECK ENGINE for 100 miles and I tapped the brakes and on it came.* So we ate then filled up, after restarting the car there was no CHECK ENGINE, we went 50 miles down the road with no CHECK ENGINE, pulled into a rest stop slowed down and braked on the offramp...no CHECK ENGINE. We parked and still no CHECK ENGINE. After stretching and walking around we took off, got 30 to 40 miles away (NO CHECK ENGINE) and pulled over to...ahhmmmmm...try and avoid getting a ticket. We pulled into a gas station for about 10 min...while we were talking the CHECK ENGINE light came on about 8 min after we stopped and had the car sitting in neutral. We took off for the rest of the 150 miles home with the CHECK ENGINE light on. We never stopped again and the CHECK ENGINE light stayed on the whole way. What could this be? If it was sensors, shouldn't it have gone off somewhere on the first 200 miles while we were doing 70 to 80mph. Why did it come on while braking and why when I was parked? This is very odd. I will post Engine codes when I get a chance to pick up a voltometer from K-mart. Please someone advise on what this could be...loose connection, bad O2 sensor, short in the system....

As I said before, the FPR was changed this weekend and everything seems improved. No more gas smell and the MPG went from 15 to 17 on the highway to 17 to 19.

 

[kilroy]

That sounds more like an EGR valve problem then anything else. I had a 92 Vic that was like that, and there was a module for the EGR system that I had to replace. I measures presures before and after the egr valve, and sometimes they get clogged. Usually EGR problems show up on deacceleration.

 

[Triton46]

Kilroy,

91 through 93(?) dont have an EGR I beleive.

Could this be a differential pressure feedback sensor (DPFE) or do I even have one?

Ill read the codes tomorrow and see what it says. Should I set the voltmeter on DCV, ACV, DCA, or OHM (10, 1250, or 500)? Thanks.

[Edited by Triton46 on 09-04-2000 at 08:13 PM]