Twisted

I just pulled off a couple of my vacuum lines--one going into the EGR valve, and another going into some sort of cannister--and it seems that no vacuum is present in the lines. I also threw a vacuum guage on the EGR vacuum line, and got a zero reading (although, maybe my guage can't detect signals that small). Am I correct in assuming that vacuum pressure at these lines should be high during idle? I then wrapped my lips around the vacuum port on the EGR valve (with the valve removed from the intake manifold), and sucked a little, to get an idea of what kind of vacuum is necessary to open the EGR valve. It doesn't seem like anywhere near that amount of suction is created by the EGR valve vacuum line. What could create such a condition? Thanks.

Tims 88GT

they only have vaccum at certin times. why are you checking it? idle problem or something?

marx91

^^^^^^^^^ yeah it changes when the car is under load

Tims 88GT

yep

Twisted

Thanks for the replies, folks. I'm checking the vacuum because I am trying to rule out all possible causes of a lumpy idle. The EGR system is my focus for this week. At any rate, I did notice some electrical wires going into some of the vacuum line junction points, which would confirm the notion that vacuum is only present at times chosen by the computer. I am just confused because I thought idle would be one of those times when the EGR is functioning. Hmm.

Tims 88GT

what does the car idle at?

Twisted

Somewhere between 750 and 850 I would guess.

Tims 88GT

well thats not bad, is it ruff? or does it have a miss?

Twisted

It feels slightly rough sometimes, to the point where it feels like the car is rocking a bit. I mean it sort of feels like a miss when sitting in the car, but doesn't sound like one when I get down near the tailpipes--it sounds more like a mild lope. Hell--for a brief moment, I entertained the idea that some previous owner had stabbed in a mild cam at one time. But it's hard to imagine that since most other parts are stock. I'm at a loss.

Tims 88GT

it could have a cam, i camed a stock motor and it improved it. have u done a tune up?