Hello everyone,

I am fairly new to this board and have found a lot of useful information. Unfortunatly after 2hours of reading I haven't found the answers to my problem:

The truck is a 1995 F150 Sport, 300 (Y code, federal) 6 cylinder, 5-speed, and 160,000 miles. I have an intermitten check engine light for a month but usually only at highway speeds.

I pulled the codes using a jumper and the check engin light and followed the instructions in the chilton manual.

Key on Engin Off
Current codes-
111
111 All good

Stored codes-
117 - ECT sensor circuit grounded or below mim. voltage or over
254 degrees
21 - ECT out of self test range
72 - Insuffient MAF/MAP change during dynamic test

The run test said everything was ok.

So I replace the ECT Sensor and the MAP sensor. Still have the check engin light. So I tested the sensors, everything checked out OK. Drove untill the light came on pulled over took the voltage reading off the ECT, which was only reading around .6 volts or 194 deg (according to the chart). So I checked the wiring, even under the plenum since I had since I had to remove it to replace the leaky valve cover gasket. The wiring was in great shape. In desperation I looked up the engin schematic and found a common wire that went to both sensors and checked all the components that were on that circut. Still nothing.

I haven't been an auto mechanic since 1992, and I have never had to diagnose a problem without the handy snap-on scan tool. In the previous posts, someone said that it will always flash the code twice and there is an seperation flash before the stored codes. If this is the case the codes should have been 172 (twice) which is the lean code. Since it sets the code at highway speeds that would be about the time the EGR would open.

Did I just stumble on the answer?? Sometimes it helps to talk things out!

Any input would be great.

 

I was getting an intermittent check engine light on the highway in my 89 E-150 302, but it was setting code 33 in continuous memory. I tested the egr system and it was fine. However, after I tested it, no more light! Only thing I can figure is that when I applied and released vacuum to the valve several times, it cleaned the egr valve position sensor and restored proper indication. Maybe, maybe not. Who knows... Hope this helps.

 

Did you make sure you cleared your continuous codes after you did your work? You need to disconnect the jumper before the test is over and before you turn off the ignition.

What about KOER (running) codes?

When you are doing your codes, there are definite differences in the speed and spacing of the flashes Plus, you will only have 2 or 3 digit codes, not both.

 

Thanks for the input.

The KOER test gave me the 111 code twice (System pass).

I noticed the first flash was farther apart than the others, but did even think it could be a divider flash. And since there couldn't be more than 3 numbers in a code, I assumed the frist code was 117 and just paired up the last four numbers. I guess this proves that assumptions are the mother of all screw ups.

On a side note.

Before winter I had overheating problem at around 3000 rpms, but no codes were present. After determining the clutch fan was weak I replaced it, along with the O2 sencor since there was some engin ping when it started to get hot (a classic sign of a lean condiction) Then the weather started to cool down, so that problem went away.

That issue (which I forgot about) just came back today, with one twist. As the temp increased to a certain point the check engin light came on and until the temp came down (which would only happen when I backed off the throttle). So tomorrow I am going to block off the EGR valve, and if that does the trick. When I removed the intake, I visually checked the EGR, it was clean and seemed to opperate normaly. So that would leave me to suspect the EGR vacuum regulator. I have already checked vacuum leaks. The injectors don't seem to be the problem since the engin pulls strong (in 3rd gear) to over 5000 rpms, so the fuel should be there to run at 3000 rpm down the highway.

I will keep you posted just incase someone else runs into this problem. And if anything you can learn from my mistakes.

 

I just went through the exact same thing with my 91'. After a month of chasing it and spending all kinds of money on sensors, I gave up and took it in. A $100 dollar fuel injection cleaning later (I found out gas added injector cleaner just doesn't do it) my truck was fixed! I hope this helps.

 

F-150 Sport
Your continuous codes are 172 & 542. They have nothing to do with the EGR. You're running lean, and something tripped the inertia switch at some time. Clear the codes, drive it a day or so, and pull them again.

 

Thanks for your replys Steve83 and okla_stampede.

The only code I have now is the 172 a lean condiction. I only blocked off the EGR to see if that was pulling in too much air and leaning out the fuel mixture. I am fairly sure that the injectors just aren't flowing enough fuel. I am going to pull the plugs again to see if I can isolate a cylinder, if not I'm just going to have the injectors flushed like okla_stampede sugested.

The fuel filter has already been replaced, unfortunaly I forgot to bleed of the pressure before I unhooked the hose. I hate being covered with gas. I guess it is fairly odvous that my diagnostic skill are a little rusty.

Thanks to everyone for there input.

 

Spelling skills, too...

 

That hurts!

Looks like I won't be entering any spelling bee's any time soon.

I really miss spell check

 

JK I was scarred as a child by a mother who was a STICKLER for proper spelling and grammar, so I try REALLY hard not to inflict it on others, but I just couldn't pass up that little jab. No hard feelings?

 

Now I just need to get my truck fixed.

 

no hard feelings.

I have never been good at spelling. Thats why I don't write for a living

 

I was pulling a code 172 also!

Trust me CLEAN YOUR INJECTORS

Or you can change the IAC,TPS,ECT,IACT,EGR,MAP,Plugs,Wires,Rotor,Cap and Fuel Filter. Then give up and take it to Ford and get a $100 fuel injection cleaning and tell yourself all the way home, well at least now I have all these good spare parts in case one ever does go out!

 

Was going to call today and make an appointment, but didn't get it done. It is going in as soon as they can schedule it.

Steve83, check my spelling!

 

Good call Sport!

Don't forget to clean or replace your IAC, those things do seem to get a little nasty.