idle problem. Vacuum? MAP sensor? Brake Booster?

[great white]

Gotcha - I defer to GW, he's the guru

Guru?

Nah, just a guy with a couple books handy....

 

[jdyates]

Sorry for the late reply, guys. I recently tried capping off the EGR Solenoid (save for the "vent" nipple), and the EGR port on the throttle body, and there was no change. Good, since EGRs are expensive to replace. Haha.

And yes, I unplugged the brake booster line and held my thumb on it, and there was no change in idle. Therefore, I have reduced it to one of two things.

1. Fuel. My pump is putting out a steady 11psi. No problems there. Had my mom blip the throttle a few times with the gauge hooked up and it kept up pressure, didn't change in the slightest. Fuel filter is brand new, and old one had a little gunk in it, but i could blow through it no prob. FPR is my next guess, maybe I have it set too low from the last time I played with it. Entire throttle body is basically brand new, injectors work great (they came out of an H1 with only 50,000 original miles).

Also, one of my injector wires got pinched and is exposing bare wire, in theory I'm thinking injector #2 is getting bad connection and possibly not opening fully or firing correctly. They both have a nice, even spray though. No dribbling.

or 2. MAP sensor itself. All vacuum lines are good, and I have sprayed carb cleaner EVERYWHERE, no change in idle.

 

[jdyates]

Guru?

Nah, just a guy with a couple books handy....

Sometimes that's all that's needed.

 

[gmcyukondriver]

Have you tried putting an actual mechanical vacuum gauge on it?

I would give that a try. I think you could just 'T' it into the vacuum line for the MAP sensor (so it's still plugged in for comparison). Then, plug in your diagnostic tool and compare the readouts. If the mechanical gauge has a different vacuum reading than what the snap-on unit reads, then it's your sensor. If not, then it's a vacuum leak.

Just thought this would be a good way to know for sure if your MAP sensor is bad.

 

[jdyates]

Have you tried putting an actual mechanical vacuum gauge on it?

I would give that a try. I think you could just 'T' it into the vacuum line for the MAP sensor (so it's still plugged in for comparison). Then, plug in your diagnostic tool and compare the readouts. If the mechanical gauge has a different vacuum reading than what the snap-on unit reads, then it's your sensor. If not, then it's a vacuum leak.

Just thought this would be a good way to know for sure if your MAP sensor is bad.

Unfortunately I don't have one handy, but I read this:

"0 in. Hg ...... 4.7 Volts.
5 in. Hg ...... 3.9 Volts.
10 in. Hg .... 3.0 Volts.
20 in. Hg .... 1.1 Volts.

Stock engines usually idle between 1.3 and 1.6 Vdc."

And looking at my data from the scanner (previous page), something is wrong. Hooking up the mechanical gauge will tell me. As soon as I find one, I'll try it out.