ok, so my ls motor has a pulsating idle..... no honda or acura owner isnt familiar with that or hasnt heard of it....sooooo me and an experienced mechanic friend changed the throttle body gasket, cleaned the fast idle valve, put a new thermostat, cleaned that other idle sensor on the intake manifold... checked all my vacuum lines and i still get this freaking pulsating idle!!!!!! the oddest part is that when i pump the brakes it makes the idle do its thing even more and when the car is at a dead stop is only when it will try to idle normally... we are thinking i might have a tiny tiny leak in my head gasket??? aside from that we are f-in stumped.... anyone got any ideas? seems anything is possible at this point....

 

 

LMK when you find out cuz I just bought a 95 GSR and it does the same damn thing. I even went so far as to block off the fast idle valve and it still does it. But only when warm. My air/fuel gauge goes rich/lean when the idle bumps, so I'm thinking the coolant temp sensor is reading wrong possibly or the 02 sensor is bad.

 

does yours do it when u pump the brakes?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by saikouEF8 &raquo;</TD></TR><TR><TD CLASS="quote">does yours do it when u pump the brakes?</TD></TR></TABLE>

Pumping the brakes fast will always make the idle go up to it's maximum, then fall back down and start pulsating. Then it should even itself out when you stop. It just cause you are making it demand so much vaccum.

Check you PCV. If it's cracked even a bit it will make your idle jump. Happened to my brother Si swap, he cracked his pcv when he rushed to put it on. Then he stole mine, didn't tell me and I drove around for 2 weeks on a pulsating idle with no PCV valve, the bastard.

 

hmm.. pull off the vac line from the brake booster and plug it see if that fixes it, might have a bad check valve or booster.