Originally Posted by Krazy613

I thought I had same problem. My b20v would stick 1600-2200 sometimes and other times it would surge 1800 and drop and 1600 and drop. 6 months later cleaning my sk2 throttle body and intake I seen there's a screw in the plate that was missing. Started the car(of coarse stuck at 16-1800 I put my finger on the screw hole and bam 750 idle . I actually just swapped in a b18c5 and that screw came out and banged my valve but I got it out . So check but stock has rivits and if a screw thred loc it.

Originally Posted by 95gsr@530

That screw you're talking about, is it the idle air adjustment screw? on the front of the throttle body, if you're looking down the throttle body into the manifold it's to the left and somewhat below it? My screw was missing the plastic cover that was supposed to go over it, but I don't think that there is vacuum leak there. Thanks for the advice and i'm going to go thoroughly inspect my throttle body right now

Originally Posted by wunfstgsr

Sounds like the IACV might need to be cleaned or your iat sensor is going bad.

Originally Posted by 95gsr@530

I cleaned the IACV and no help. But I will definitely look into cleaning the IAT because that is very easy to do. I still need to do a smoke test, it was mentioned in one of the comments and I totally forgot to try it. even though my vacuum reading is nearly perfect, it jumps up and down with the rpm. when rpm increases the vacuum also increases. When i'm in a really cold start up it will hold 3 grand for about two minutes, way before operating temperature, so it may be vacuum related, who knows. I'm gonna keep digging and I really appreciate all the advice

Originally Posted by wunfstgsr

The engine is suposed to run rich at a high idle on cold start ups thats normal. 3k is a bit high but as long as it starts to drop idle as it warms up then thats fine. Also indicates the IACV is operating correct.

Your saying when the engine gets to op temp it starts to fluctuate?

Could also be a old map sensor o ring. or map sensor going out but usually you will get a check engine light if any of those sensors fail. Most common is a vac leak but if this just came out of no where then i would start checking those things i mentioned.

I remember i long time ago i had this weird fluctuating idle and i believe i would disconnect the IAT sensor and plug it back in and start it up it would go away but it only did it a few times.



I reset the ecu several times during my attempts to solve the problem but no change. I looked past the throttle plate and found black liquid thin slimy residue all through out the inside of the throttle body and it seems to continue all throughout the manifold. I'm thinking now that this residue has blocked the orifice for the map sensor. When I shine a flashlight down the open throttle body I see no light coming out through the small orifice which feeds the map with vacuum. This concerned me. I'm also concerned with the source of the gunk. I'm thinking either my charcoal canister is flooded/or over delivering fuel to the intake manifold. Or, and hopefully not, there is a leak in my throttle body and somehow the coolant ran through it to warm it up is leaking into the throttle body/manifold. When I pulled the IAT sensor this slimy residue covered it also. Do you know of any good tests for charcoal canister's proper operation? i'm about to check mitchell1 right now. thanks for your help.

And yes during very cold start up the rpm will hold 3 thousand (a bit excessive even for cold start up) and prior to reaching operating temperate the rpm fluctuates. Quite substantially too. 1-3 g's is a big annoying rev making my car a huge embarrassment to drive




Also try resetting the ecu.