I recently bought a built b20v and it's having some what idle problems.cold starts while idling I would push in the clutch and the rpms would jump and couple hundred.once warmed up sometimes coming to a stop when I put it in neutral it would then idle jump 1-2k till I put it in gear again.

 

fast idle control valve, find it and give it a few turns clock wise looks like this
other then that check for vacuum leaks and make sure your coolant is full on your radiator & overflow & bleed the valve if you can to release air from the coolant lines. this is the fast idle control valve tighten it all the way and then turn it counter clockwise 1 full turn this fixed my exact same issue you're having. I warn it's a pain to reach with a flathead screwdriver but i almost guarantee this will fix your issue

 

the car at has an aftermarket manifold I can't find it

 

I sort of figured your b20v throttle body doesn't have the FITV on it.

Idle surging is quite prominent with air in the cooling system, so the advise to repurge your cooling system is a good one.

As well as your IACV may need to be cleaned or have a bad connection to the ECU.

The last common area that causes idle surging is a vacuum leak.

 

yes bled the coolant..took radiator cap off and let it run for a min right..??also did. Clean the iacv.ill check connections to ecu.

 

O.o

Ummmm, no.

I'm not sure if the b20v has the same bleeder screw the 92-95 does or if it's more like the 96-00 series.

The difference between the two is very minor. Either way, you run the car for MUCH longer than a minute. Can take up to 45 minutes idling with the heater temperature selector on max heat during cold winter days.

It's also advisable to have the nose of the vehicle raised a little. Do not try to bleed the coolant with the nose of the car pointed downhill on a decline.

I believe you can find the coolant bleeding procedure in the FAQ sticky at the top of this forum.

 

I can't find the bleeder either

 

Also would get a cel when driving but once I turn it off and would turn it back on it goes away.i checked to see if any codes. Came up and Nothing.last owner had it tuned on hondata..was wondering if it. Could be from the tune?

 

You are now in an area I am not familiar with.

You might ask this question in the engine management forum as it's where the experienced tuners are. They would likely know more about the possibilities of a tuned car, good and bad.

 

ok should I get that cel checked out is that what your saying??it wont show a code when I try to pin it

 

I'm saying, talking to a tuner, they should be able to answer if a bad tune can cause idle surging.

But first, I would bleed your cooling system properly.

 

ok I'll post it up..where would I check for the bleeder on a b20

 

I would just check the ends of the top coolant hose. If you see a bleeder screw in any of the housings, then you bleed that first with cap off until no bubbles flow and then follow the rest.

If you don't see a bleeder screw then you don't need to worry about it and do the full process.

 

You should def invest in a FSM for your motor. It will help a lot.

 

fsm??sorry what is that

 

Factory Service Manual also known as the Helm's Manual.

Can usually be purchased from helminc.com

 

they have that for b20 vtec

 

More or less, you have to get 2 FSM's one for the B20 block, then another for the B16 vtec head. Between the two you get full specifications. From that you can compile the modifications to those specifications, such as what timing belt works with your franken motor.

And then, depending on what chassis you have thrown he motor in, you might have to get a 3rd FSM for the chassis.

 

tried bleeding coolant..when I run the car with the rad cap off coolant just slowly pours out.also have my distributor all the way towards the radiator.i looked up some info and it said that can affect idle also.and I also have a code 43 that sometimes pops up if I drive the car when it's not fully warmed up.i can turn it off and on again and it never comes up again until it's cold again

 

In your other thread, "How to bleed radiator" people posted the bleeder funnel kit.

And you are still trying to do it with just taking the cap off? That is one reason coolant overflows out the cap.

Now if you use the funnel and it ends up filling that to overflow, definitely something wrong.

 

Resolve the cooling system / overheating problem.

Set the timing with a light and LEAVE IT. If you can't get spark timing to spec with the distributor near the center of its range, the timing belt is likely out of time.

THEN consider any idle problems.

 

what if I use the funnel and the coolant just stays there doesn't flush?

 

I believe I don't have a bleeder valve on the b20v

 

Your avatar is appropriate.

Are you ever going to actually do any of these things or just sit there asking "what if?"

 

yes reason I'm trying to bleed coolant is to rid of my idle issue.not over heating coolant seems to be good now