my '90 3.0vze has had a hesitation latley even after new oxygen sencer and plugs wires/rotor/cap/air filter/ and gas filter, i even tried some seafoam in it but it still did it. so today i replaced the pvc valve and also found an egr filter that was dirty as hell, and thought i would post it in case some of you may not know of it, but its inside the round valve right above the powersteering pump. it has "P, Q, R" printed on it pull the cap off it and check the filter mine was so dirty i threw it away and made a new one out of the old ladies scotch bright pad. truck runs alot better now.

 

You are supposed to be able to clean it by blowing out the dust. I cleaned mine recently while troubleshooting my Code 71. I used throttle body cleaning spray. Worked great - idle got better but the code didn't go away. I just replaced the EGR valve and the code is still there so I'm not done yet...

May I suggest that you clean your throttle body thoroughly with the aforementioned spray? It does wonders for how the truck runs.

 

must be slightly stupid right now but i cant seem to picture where this filter is. Does someone have a pic of this filter? granted i removed my egr a few months ago but it still would be good to know.

 

i cleaned out the inside with spray and a pick but the filter fell apart when i pulled up on it it was so dirty it was stuck in there with all that hard gunk. and the filter is right above the powersteering pump look at that valve with 3 hoses coming out of it, on is an the drivers side and the other 2 hoses are on the pasenger side. and it has letters like R, P, Q on top just pull and twist on that cap with the letters on it. it may take aliitle force and clean away.

 

I borrowed somebody else's image so lets see if it works:



look between the yellow intake and the power steering pump reservoir

 

BTW guys - I'm going to try the 10k resistor trick on the EGR temp sensor wiring. Seems that once the engine reaches a certain temp it uses that pyrometer sticking out of the EGR to ensure that the exhaust temps are at a certain level. I already replaced the EGR valve (my old one tested good once I had it out, DOH!) and all my vacuum lines are good so that thing has to be the culprit. I can say that the truck runs much better now with the new EGR -the old one had a lot of carbon but the valve itself moved smoothly.

 

Codes don't "go away" unless you disconnect the battery for atleast 15 seconds.

 

on my truck all i have to do is pull the efi relay to clear codes right???

 

right

 

Battery was disconnected each time. Code was gone until the engine got up to temp after a good drive. As a caveat my clock went out this last time I reset the code.

 

My 89's was so clogged it was like a solid piece of felt in there. I just cut up a wix filter material and replaced it. It passed emissions and it ran a bit better too.