Egr system, What a pain in the rear!

[commutercar]

I just can't seem to get this right. i been troubleshooting the egr system on my car(1994geo prizm with 1.6) When i bought this car it had a engine check light on. the prior owner took it to the dealership and they said it was the egr temperature sensor. by the way the egr temperature sensor are on the car that were california emission vehicles from 1993-94 if i'm correct. so as soon as i bought it i took it to smog. got labeled a gross poluter which i found funny. i went home with my new but used car and i tested the temp sensor myself and at 100 c the reading was 14 ohms which is within spec. so i went back to the smog shop with my check light reseted. this time i ran and passed the 25mph test. but failed the 15mph. at this point i thought that the egr valve was the problem so i replaced it with another I bought a used one which i cleaned out and vacum tested to make sure the vacumm would open and close. but i still am getting the check light. As a last resort i have replace the egr vaccum switching valve because it read 44ohm which was within spec but i felt it was too close that it could be a problem. I also had a chat with a toyota part department worker and he said that a lot of the repair shops replace this part before all else, if this part doesn't do the trick they normally just replace the egr and call it a day. but sadly i am still getting the check light. i know that its not the ecm. my gas mileage is pretty poor. about 250 a tank with a manual. i know the egr is the problem. anyhow does anyone have any experience or suggestions in what i should do? the only thing left would be the vaccum modulater. but i highly doubt thats the problem. Any advice would be most greatful.

[94_Rolla_Guy]

if i were you id check the vaccum system make sure its all ok it sounds like you have the tools and the know how, there may be a vaccum thermo switch around the thermostat if so give that a check, sorry not totally familiar with califonia engines

[foodaa]

What codes are you getting with the check engine light on?

[commutercar]

the code i am getting is 71. I wish i had the newer car so that the codes would of been a bit more specific. i did vaccum test and everything is fine. I think i might have to buy a brand new egr and toss the used one i picked up even though its good. the last time i went to the smog i had high nox. everything else was in working order. the other thing is that this car passed smog last year sept no prob from the paperwork i recieved from the previous owner.

I know this is a bit out of the subject but does anyone know a good brand of gear oil i can use for my manual transmission. i did a fluid change a week ago. THANKS to 94_Rolla_Guy( great info in the bolt size and location). the gear oil i used was bought at the toyota dealership. they were selling a crc brand weight 80w/90 i asked if this is what they used on all their cars that come in. aparently they do. so i changed it out, and now shifting feels bad( very crunchy and notchy) in the morning untill the car is driven for 10 mins. after 10min the gear just side right in and out. I'm thinkin that the oil is maybe the i should get a thicker oil since once its up to temp everything is find. anyone know any pros and cons to putting thicker gear oil in this tranny.

thanks in advance for the help.

[foodaa]

Maybe the egr temp sensor is bad? Did you test it if its working?

[speedyts49]

Have you got this problem fixed? I have a similar situation and was hoping for some help through your experience.

[toyo_tech02]

replace the temp sensor, even though they test bad... alot of the time the problem will be intermittant