My 95 with a 4.9 really never ran smooth since I bought it and occsaionally would act like it had a miss which I thought might be the plugs or wires but when changing the oil tonight I decided to plug the vacumn hose to the EGR and the idle smoothed out and runs alot better,it now has the CEL on but will put up with that since it runs better now. The question I have is what controls the vacumn to the EGR since I doubt it has a ported vacumn switch like on the non computer controlled vehicles.

 

You probably need to just pull the intake manifold and seal down a new gasket set. It's notorious for eating manifold gaskets and rough idles come about. Your egr would just offset a vacuum leak in the manifold gaskets. You'll know if the manifold just lifts off, perty much.

 

I did some checking and the vacumn line is getting constant vacumn to the EGR and I dont think they are supposed to get vacumn at idle,its not much vacumn but probably enough to open the valve slightly so its probably the solenoid and will clean the EGR too.

 

Your question regarding what controls the EGR vac is a good one. I have never traced out or reviewed the schematic for the vac circuit on my 96 with the I6.

Have you checked your manifold vac? Hope it is around 20" Hg. If not start checking for bad vac hoses and replace as necessary.

Since the truck runs better with the EGR vac plugged this suggests to me that you might have a vac leak at the EGR diaphragm. One thing to try is to put a different hose on the EGR and attempt to pull a vac. If you can then the diaphragm is ok. One other thing you could try is to put a T in the EGR vac line and hook up a vac gage. Drive it with the gage in there you will find when the EGR is supposed to actuate.

Hmm, this sound interesting. Since I am off all week I think I will try this myself, just for my own info.

Merry Christmas

 

I think it was opening when it was not supposed to causing a rough idle and act like it was missing,I am thinking about putting a plate between the EGR and TB so the sensor thinks it still working and will not turn on the CEL. At the cheaper parts stores a EGR,sensor and solenoid are around 150 dollares which i dont want to spend on it right now and might look in to used parts.

 

go to www.easyautodiagnostics.com for egr dpfe diagnostics of ford 1995 f150. More complicated, not easy to explain. Then go back to Bing and search for
"1995 egr diagnostics for f150 4.9 " click on 6 steps at _easyautodiagnostics.com and it should open up to egr tests components of system. Believe by dot commen first you get the cookies.

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