About a week or so ago, my SES light went off with 32, as I was coming off the highway. Haven't drove much at all, and it's been in-city driving, and no light has come back on, but my mileage has been absolutely terrible... it took me a quarter tank of gas to go roughly four miles.

I just managed to get a vacuum tester today... now, my test methods may be wrong, as sifting through all the threads about it(and the Chilton ain't much better), so please correct me if I'm wrong...

Hooked the tester to the EGR itself with the engine off and added vacuum...the diaphragm held no problem and released just fine when I let the vacuum out. I then placed the tester between the EGR and the solenoid and let the engine get to 190F-200F and then looked at the tester--no vacuum. I revved the engine up to about 3500rpm and it topped off at 2in Hg(Chilton says it should hit 5in Hg). I had my friend hold the engine at 2k and then I continued the service steps in the Chilton manual, so I removed the vacum tester, but the diaphragm stayed closed(down). I put it back on, and the diaphram stayed still; engine speed never changed. We also tried this while in idle, just for good measure.

The next step is to check engine vacuum pressure, which is why I'm here: where do I test this from? I saw someone say at the brake booster or something like that, but I didn't see anything I could hook up to(I'll blame my lack of car guru-ness). One thing I did do was while I was tracing hoses from the EGR, I hit the two on the throttle body...while the engine was running, I unhooked them and the engine stalled entirely, so appreantly everything seems to be fine at that point.

Any help, y'all?

 

Here's what you check.

unhook the vacuum line from teh EGR valve itself and hook the guage on the end of that line, then rev the motor several times. You should get a vacuum signal, it won't be huge, but it should move the needle.

If nothing happens, then you have to check the vacuum source to the solenoid. hook the EGR line back to the EGR and find the line that goes from the engine to the solenoid. disconnect it at the solenoid, not the engine. Check to see if you have a signal here the same way. I forget if it's a manifold signal or not, if it's manifold you'll have a signal all the time, if it's ported, then you'll have a signal when you rev it.

here you should have a signal for sure.

If you have a signal from the engine and at the egr, then you have to check the signal at the EGR sensor, it's the little black box right next to the solenoid. if you have a signal there, then the sensor is bad and the solenoid assembly has to be replaced.

If there's a feed to the EGR solenoid, but nothing to the EGR valve itself, the solenoid needs replacment. Otherwise, it's a hose problem.

 

Thanks 2point8boy, you answered my question too. I'll be trying that this weekend.

I'm still getting crappy mileage and wonder if I created a leak somewhere when I swapped engines.

 

Did all the detective work and concluded that the sensor is bad. Looked around at every parts store around and they all want to sell me the sensor AND the solenoid together, cheapest being $95.94. Is it really necessary to have both of these together when I replace the sensor, cause as far as I can tell, the solenoid is fine.

I did go and hit up a couple junk yards today, but all of the thirdgens already had their engines ripped.

 

too bad you dont live close. I have a sensor that you could have... that is, if my mechanic hasnt thrown it away yet!

 

Well, I ain't goin nowhere for several days(I work where my buddy does), so I got time for shipping. How much you want for it, if it's still around?

 

Well I got a faint signal at the EGR, so I guess everything is working fine. I'll get some hose I guess and try replacing it all.

 

if you have a signal at the EGR then the vacuum sensor is toast and replacing the lines won't fix your light problem. YOu'll have to get a new solenoid/sensor assembly to fix it.