i followed the following procedure :
You can check the egr valve for proper operation by starting the engine, letting it warm up. Pull the vacuum line to the egr valve, and hook up a hand vacuum pump going to the valve and apply vacuum. If the egr is working properly, it will open up, and stall the engine, or at least cause the idle to drop. The egr is working at this point. Hook the vacuum line back up. back probe the gray wire on the egr solenoid connector and ground the wire to a good ground. If the solenoid valve works, it will do the same as the vacuum test. This test assures that the solenoid is functioning. if any component fails the test, replace it.
MY RESULTS:
i put 20in" of vacume to the egr and the engine did not die or even drop idle the slightest amount. so is it telling me i should replace the egr valve? the reason i am testing this is because i get a variable high idle sometimes it idles normal(900) in park and others it will idle higher(2000+) sometimes it will drop down to normal, but its so random that i cant figure it out.

 

Hey whats up this sounds just like my buddys IROC. This strange idle problem stumped me for a while. This sounds dumb but one of his throttle blades came loose and was out of adjustment just enough for the throttle to stick ever once in while. For the EGR pull the plenum, I know it sucks and grab the inside area of the EGR valve and pull up. This will open the EGR valve (what you were trying to do with a vaccum pump) sometimes carbon builds up and they get stuck semi open, fully open ect... open and close that piece manually until it moves freely then put the vaccum pump on it and see if the motor reacts. Just some ideas, good luck I need anouther drink

 

if im going to pull the plenum to do that i might as well change the egr valve for a new one right. i didnt even bother to ground the wire on the solinoid because the erg valve has no reaction to the manual way, so i would have to test that after i replace the valve. i dont get any check engine codes from it, so do you guys think i should just replace the egr valve, or could it be something else? as for the throttle blades, those are fine, i had it off the car and checked it out.

 

HI QUICKSTYLE, I just replaced one on my car sat. but am not going to complaine because it has 196k on it and its the factory one, just a tip check and see if you can find one first before you pull everything apart, I had a hard time finding one even at the dealers around here in georgia and they make several ones so see if they have them in stock also make sure you have a crows foot for that last bolt in the egr "ITS A BEEOTCH" if you dont. I ran a code scan on mine because of the check engine light. GOOD LUCK.......

 

i checked autozone out already, they can get one from their warehouse next day for $65. but im starting to think its another problem now. i was reading other posts, and came across one that says the VSS vehicle speed sensor effects the ecm and how the car runs including the egr operation. and my speedometer does not work, so im thinking maybe that has something to do with it, what do you guys think?

 

HI if your not pulling any codes you may be correct, but if you do need the egr you also need new plenum gaskets, and like I said the first one it showed for my car was wrong and had to scramble to find the right one. good luck and hope its a simple fix.

 

From my personal experiance, I had no codes and the idle wasnt right at all, Just on a limb, I replaced it and BAM works perfect (except for start up thats a different problem though) It wasnt hard to change at all I dont know why everyone makes such a big deal about taking off your plenum, Leave the runners just remove the plenum and while you are at it check to see if you might have a cold start injector problem like I did and didnt realize. Also might be a good time to change the Temp sensor. underneath the plenum. I replaced the sensor but not the 9th injhector Soon enough I will do that. I wish you luck.

 

As the test stated, if the EGR is "bleeding" at idle, it should hurt idle. I don't see that increasing the idle speed. Perhaps making it "bounce" as the ECM tries to compensate, if the valve will move, but I'd suspect that not to be the case if the problem isn't fairly consistent.

VSS is tied into idle. (and EGR) Fix it, or at least make sure the ECM is seeing actual vehicle speed.

 

You cannot check all egr valves simply by pulling a vacuum at idle and expecting the engine to die. There are 2 types of egr valves. Positive and negative backpressure valves. I'm reasonably certain both types were used on TPI. A positive BP valve will not hold vacuum unless sufficent exhast backpressure is present like at cruise rpms. Your egr valve may or may not have failed but unless you know for certain which type valve you have that test is not valid. I can't really see the relationship between VSS and
idle...Care to elaborate?

 

VSS article

Poster says its random, does that section pertain to your problem QuickStyle?

 

Okay I understand that on decel however I took from the orignal
post (900 in PARK) that the vehicle was not moving. Do you have cruise and does it work? If so and it does then the VSS is okay..
I think your suggestion that the ecm is trying to compesate for something else is probably accurate.

 

now that i have read that vss article, it explained just about everything wrong with my car, cooling fans come on and off whenever they want, egr is messed up, idle speed is messed up, and my fuel mileage is not that great. i think i will find out what is wrong with my VSS before i start getting into anything else, because it needs to be fixed anyway because it is tied in with the ecm in so many ways that keep it from running at peek level. and who knows, it might cure all the other problems.

 

are you saying you know then me cuz im a shadetree mechanic?

 

That holds true for my 88' applying vacuum won't make it stall, unless the rpm is at least 2k.