Check Engine light...on.....off.....on.....off??
 

My Check Engine light came on for the first time yesterday. It stayed on for a couple of trips then went off and stayed off lastnight while I was on a 120 mile round trip. It came back on this afternoon. I am new to the Ford truck scene and do not know all the little perks of a Ford yet. Is there any common problems that the Ford truck line has that I am not aware of that would cause this Check Engine light to come on and go off periodically? The truck has the 4.2 V-6, 5 speed with 114,000 miles on it. Please, any advice will be greatly appreciated.
Thanks

Here's an example of a problem that is much more common on your truck than we'd like:

www.leakingfords.com

The CEL could be coming on for quite a few reasons. You can have the code retreived from the computer at just about any chain auto parts store. If you come back with the code(s), we can do some trouble shooting. An intermittent CEL is usually associated with a misfire. The code will tell you which cylinder.

How's your coolant level been?

I took my truck to Auto Zone this morning, he checked the computer in the truck and told me it was the EGR valve. He told me to take it off and clean it with a brush and blow it out a little. What do ya think? Was he right?

Could be right.... Would be able to help with the exact code that you found. Some codes are for EGR. try to find out what specific code you have.

You can remove the EGR valve and try to clean it with Brakeleen, but I don't think that is the problem. It is more likely the DPFE sesnor (EGR Transducer) , the sensor that openes and closes the valve, that has failed.

The Ford DPFE sensors fail quite frequently. If cleaning doesn't help and it comes down to replacing parts, I'd replace the DPFE before I replaced the EGR valve.

https://www.f150online.com/galleries...9-75-29022.gif

I took the EGR valve off and cleaned it and the check engine light is still on. The guy at Auto Zone said just to brush it out and then blow it. That is what I did, I didn't use any type of cleaner on it. Where is that DPFE sensor located?

It's #4, in the illustration. The rectangular thing, with 2 hoses coming out of the bottom.

The EGR valve is operated by vacuum. That hose that runs off the top goes to the vacuum solenoid. You can take the EGR valve off and apply vacumm pressure with a pump or your mouth to make sure the diaphragm does move.

Also: Whenever you replace a part to resolve a Check Engine Light, you need to disconnect the negative lead on the battery for a few minutes to clear the computer's memory. That will turn the light off and if the problem is still there, the light will return within 3 warm up cycles.

Does the DPFE sensor supply vacuum to the EGR? The hose that goes to the top of my EGR has a little bit of vacuum on it, but not a lot. It just feels like it is gurgling a little when you put your finger on the hose while it is running. I did not disconnect the battery, but I will try it and see if it works.

DFPE doesn't supply vacuum to anything. It is an electronic sensor that helps decide when the EGR valve should be open. The EGR valve, if I am remembering right, shouldn't have vacuum at idle. There are some tests you can do if you have a digital multi-meter and a vacuum pump. Check out this site:

http://www.cybrrpartspro.com/Manual%...delLookup.html

It links you to repair manuals online.

Good luck

Rob

There should be little to no vac at idle at the EGR valve.

Your EGR valve is prolly fine it is most likely the exhaust line are partially clogged with carbon.

EGR valves rarely go bad it is usually the DPFE and/or clogged lines leading to and from the EGR valve.

And as noted above do not forget to reset the puter. (Only disconnect the neg cable!)

Is there anyway to clean the lines out if they are a little dirty with carbon buildup. I have tried to clean the EGR, and I reset the computer but the check engine light came back on the first time I drove it. Any other ideas on how to fix my problem??

AjRagno
 

Could you post the ilustration for the AC system?

I got a 97 Expy 5.4?