idle problem. Vacuum? MAP sensor? Brake Booster?

[Enginebuilder]

Disconnect the brake booster vacuum hose and plug it with your thumb while the engine is idling. If the idle cleans up, voila- brake booster failed.

 

[jdyates]

Have you checked IAC or TPS? Both of those can mess with idle.

TPS is new, IAC is a known working one off an H1.

 

[jdyates]

Disconnect the brake booster vacuum hose and plug it with your thumb while the engine is idling. If the idle cleans up, voila- brake booster failed.

Ill definitely try that. Is it logical that the booster only partially failed? I read that when its bad, the pedal gets really hard. Thats not the case in mine. The pedal is actually really spongy until the VERY end of pedal travel that it gets stiffer.

 

[Yeti_Owner]

Yes, it's possible. Pull the hose off the booster, stick a socket extension in the end of the vacuum hose, see how it runs.

 

[bow61509]

I'm going to say that injector you mentioned on Facebook could be part of your problem

Sent from my static android

 

[1997chevydriver]

You said map was reading 7inHG that is low. Try replacing map sensor with a different one and read it again

 

[Yeti_Owner]

You said map was reading 7inHG that is low. Try replacing map sensor with a different one and read it again

Actually that's pretty good considering sea level is 30inHG. Subtract roughly 1 inch per 1000 feet of altitude. Unless my math is wrong, that means it's pulling about 23inHG at idle. That is, assuming, that the Snapon is showing the absolute pressure, not the differential (IE 7inHG difference between ambient air pressure and what's in the manifold, which, if that is the case, is some seriously weak vacuum at idle, which means, conversely, he has a nasty vacuum leak.

What will be telling, is what the MAP sensor reads when it's not running.

 

[jdyates]

You said map was reading 7inHG that is low. Try replacing map sensor with a different one and read it again

The vacuum gets lower as the engine spins up doesn't it? It was at 975rpm when i took the readings, my idle is usually about 400-500.

 

[jdyates]

I'm going to say that injector you mentioned on Facebook could be part of your problem

Sent from my static android

Gonna work on getting that fixed today. Lol.

 

[Yeti_Owner]

The vacuum gets lower as the engine spins up doesn't it? It was at 975rpm when i took the readings, my idle is usually about 400-500.

Not all the time. Lots of factors. Engine temp, mixture, compression, throttle blade % open, load, etc all affect vacuum. Check the difference between low and warm. I swear you've got a vacuum leak, if you're idling warm at 975rpm, lol.