I saved mine also. I hope that's all it is. If so, I could've had this one straightened out months ago. Thanks for all of your effort. -Al

 

Selbona,
Are you using a code scanner and are you getting EGR codes on the first set of "engine off" codes? That is what really pointed to the wrong position sensor.

I drove it today with the new EGR sensor. I pushed the pin back in until I get the replacement. The CEL came on for a couple of minutes and went off.

Code scanner gave two stored codes:
35, EGR position voltage too high, and 41 EGO sensor signal voltage low "lean." This is a different EGR code and I only got an O2 code once or twice before. Any one know if these two could be related?

On the engine running test, I got no codes. It may be hard to find what is going on with this.

Is the EGO sensor something that should be replaced at intervals?

 

from the website http://www.freeautomechanic.com/diag...blecodes7.html - there are two conditions associated with code 41.
41 HO2S circuit indicates system lean (right HO2S).
41 No HO2S switch detected (right HO2S).

If code 35 is valid, it suggests that too much exhaust gas is being introduced according to the computer's look-up tables and calculations?

If I'm thinking right, the exhaust gas should compete with the air - thus too much exhaust gas should result in too little air - resulting in a rich condition. So I would lean (ar-ar-ar) toward the second definition provided in that the O2 sensor isn't changing as the computer thinks it should = bad O2 sensor.

At any rate, there is a possibility that the codes are related. You have done a lot of work on this, changed a lot of stuff. Perhaps its time to erase the codes, and zero the computer out and remove any 'learned' adjustments by pulling the battery negative cable for about 20 minutes - essentially start fresh. Then see if codes pop back up and go from there.

 

I cleared it all out and removed battery cable when I added the new sensor yesterday. I did get 35 on a KOEO test with the first set of codes. I pushed the loose pin in with some pliers and the code left. I didn't reset it after that.

I will reset it all when I get the replacement position sensor and see what happens. The truck is acting like it did when it first began to show CEL, a short time after I bought it. The light came on every couple of weeks, and only stayed on for a few seconds. I am not sure if the O2 sensor was replaced I will try to check it out too.

I still have a hard time trusting the EGR position sensor, after I had this much problems with the same brand, especially since Advance Auto did not show any other applications for the truck.

 

Red Truck,

I am using a code scanner and I'm getting the low voltage EGR codes in the key on engine off test. However, I've never gotten an O2 code, although I highly suspect a lean fuel mix. I only say that because of the way the truck is running when I hit the throttle and the really, really bad gas mileage. I am at a total loss with this thing. I'm going in search of a factory EGR position sensor instead of the one I bought from Advance. After that, I'm pulling the intake, cleaning it, replacing all of the vaccuum lines and installing a new EGR. While I'm at it, I'm dropping the metal gas tank and replacing it with a plastic one. I'm also replacing the fuel pump, fuel filters, and injectors after I blow the lines out with compressed air. If that doesn't stop it, I have no idea what else to do. I talked to the guys at the Ford dealership. After about 5 minutes it became clear that I knew more about this truck than they did, so this website is my only resource. I've also bought headers for this truck and am considering doing away with the catalytic converters. If I do that, I don't think the O2 sensors will have an effect on the EGR issue, but I'm not sure. I have another post on here to help determine that. I'll stay in touch over the next week and let you know what happens. I love this truck if I can just get the little aggravating things fixed on it. Thanks. -Al

 

If I understand correctly, two sets of codes are sent on KOEO. The first set are faults present at the time of scanning. These indicate voltage problems with sensors etc. and the computer not receiving the expected signals. If you are getting codes here, other than the 1-1 pass code, they may be related to a bad or wrong position sensor, egr stuck open (should be reading closed)or bad solenoid.

There will then be a separator code. The next set are stored codes, usually produced during operation. Codes here may indicate more mechanical problems like vacuum lines, manifold gaskets etc.

I would suggest that you look at less expensive maintenance items first. Fuel filter, plugs and wires etc. I have had some problems with very simple stuff that made vehicles run horrible. I changed plugs in a mustang and cracked one. It only "missed" on pulls.The last thing I checked was the plugs, since I had just changed them.

I have also had problems with both cheap and expensive plug wires. I had put new plugs and wires on a Ranger and it took a 15 minute "missing" spell on the interstate, would only do 45 in 70mph traffic. I put back motorcraft plugs and wires and no more problems.

The EGR can cause some rough running, if it is not closing right or at the right time. I didn't do a lot with mine b/c it was changed before I bought it.

Have you checked the ignition module? I think they may test those at Advance Auto. I wonder if my fast idle may be something ignition. Doing a code scan, I went through the timing test I noticed that the timing advance section matched my fast idle. The next time it happened I stopped, and removed the spout connector. Fast idle stopped.

Another thing to consider is the computer itself. I had a ranger with 28k miles and still under warranty. It began running rough at cruising speeds right after I bought it. I took it to a dealer shop, nothing showed. I changed plugs, wires, filters. It kept coming back. The truck would leave a black/blue smoke trail and felt like it was shaking apart. After 5 or so trips to the dealer shop, they replaced the computer and EGO sensor under warranty. Problem solved. The tech said that the computers rarely tell on themselves. I bought one for my 92 for $40 off a junkyard on car-part.com.

When I had my current 92 f150 checked out at the dealer shop, the tech told me that the egr codes it showed should not cause a lot of running problems. What I have done tends to back that up. I saw more difference after fixing vacuum leaks than anything.

Have you taken your truck to a good, local independant mechanic? There are some good ones around who have more experience with these older trucks than a lot of dealer techs. After warranties run out, a lot of models don't end up at the dealer.

Just a few thoughts. I'm not an expert but have worked through a few things. Hope your problem shows up without costing you a lot of money and work.

 

Red Truck,

Re-check your vaccuum lines. When I was replacing the fuel injector o-rings today, I found another broken vaccuum line. It was the one line I didn't replace before because I ran out of hose. After I got everything put back together, I didn't have a CEL anymore. I drove it for about 20 miles and it never came back on, so I think it might be fixed. I know there can't be another leak, because now every line has been replaced. I also removed the lower intake and cleaned that. It was gunked up pretty bad with carbon deposits. I don't know what fixed the problem, the clean intakes, the vaccuum line or the new o-rings, but it's fixed... I think. Also, my understanding of the code reader is the same as yours. It's pretty confusing. I think the OBD-II is supposed to be easier to understand, but unfortunately we're stuck with OBD-I. I also found a small crack in what looks like a freeze plug in the rear of the throttle body. I have no idea what it is or what it plugs up, but it is cracked. I don't know if that will ever cause me any problems or if it could be the cause of the previous one, but right now everything seems okay. I'll let you know if I find anything else. -Al

 

I had replaced my ignition module a couple of months ago in an effort to eliminate the problem by replacing every possible component except the motor. -Al

 

Great! I am still fighting with the EGR position sensors. I got the new one from NAPA and it began sending codes. My old one is working okay. I get a CEL every couple of days now. The last time I ran it, 2 trips about 15 miles, nothing showed.

I have my truck torn apart to replace the radiator support. I hope to finish while I'm off work over thanksgiving. I ordered a light gray EGR sensor off ebay and also ordered an O2 sensor. I got a signal a couple of times for that.

When I get it back together, I will see what happens. I will keep you posted. How bad were the o-rings and lower intake? I've not been into those yet. My next step will be replacing the vacuum lines, if this is not cleared up. I've gone through my lines very well. It looks like if that were my problem it would show up more consistently, but you never know.