91 integra...help with reving up and down at idle...

[brian_bolcao]

hey i have a 91 integra gsr and i just rebuilt my b18 a1....i have a problem....the car runs great but when its cold or under normal running temperature it idles up and down till it warms up...then its fine....or when im driving and i go to stop it will rev up and down once then idle fine after i push in the clutch........what could be the cause of this? vaccuum leak? could the timing have anything to do with this?bad idle air control valve if it has one? any help would be appreciated.. nobody else seems to know

[Randy]

Well if you just rebuilt your engine i'm going to guess that all your fluids are topped up.First thing you want to check is your coolant level.If the coolant is low it may cause your engine to run like you explained.

If your coolant level is ok then I would guess it's going to be your fast idle valve.It's possible it's stuck open and letting too much air through which will cause your idle to go up and down.

Hopefully this helps you....I can only guess from where i'm sitting.;)

Randy

[Jack FFR1846]

Let us know what you find as the solution. I have this issue with a JDM VTEC B16 Integra that I just bought, but sort of the opposite. It idles fine when first started but when warmed up just a bit hunts up and down for the idle. The previous owner said that it never did that until it sat for a while and he changed the battery right before I came to look at it.

I've also had this happen with my D15A3 87 CRX-Si at times when cold like you state, but only occationally....usually at the start of the season (April) when it's been sitting all winter.

Come to think of it, the issue was also there in a 94 VTEC USDM GSR engine'd Civic I bought last year. Only there when cold. I guess this is very common. I sort of ignore the problem because I'm using all this stuff as Roadcourse track cars so the car pretty much is wide open or braking into corners.

jack

[4re308]

Could definately also be a vacuum leak.

[brian_bolcao]

thanks......ill try the fast idle valve.....i checked all over for vaccuum leaks and found none and also my coolant level is fine.....so i probably could just take it off and clean it out can i? or do i have to buy a new one? thanks for the help i really appreciate it......ill post if that was the problem.

[Randy]

If it is the fast idle valve it's more then likely shot.It can't really be plugged up so cleaning it probably won't help.

Just for reference a new one will be around $80-$90(canadian)

[brian_bolcao]

its the origional one....same as before i rebuilt the engine.

[brian_bolcao]

ive ifgured it out guys.

The function of the IACV a.k.a. Idle Air Control Valve is to adjust the idle based upon the amount of air entering the engine, then the computer reacts to this information by adjusting the cars rpm.

Reasons why you should take it apart and clean it:
-High idle after your car warms up
-Lumpy idle
-Roaming idle
-Hunting idle
-Fluctuating idle

Tools Needed:
Ratchet
12mm Socket
Pliers
Brake Cleaner or Simple Green
Paper Towels
A cooled down engine for at least 2 hours

1) Now you got to locate where the IACV is, pop your hood and it’s located directly behind the intake manifold. It’s actually connected to it. Remove your intake and strut tower bar. (If applicable)





2) Place a couple of rags underneath to catch the coolant spill. Loosen the two hoses running to the IACV with your pliers by squeezing the two clips and moving them away from the end, circled in yellow. DO NOT cut the hoses as they are the exact length and you will have to buy new ones if you do.

3) After doing that remove the harness connected to the IACV on the driver side, circle in blue.

4) Then to finally remove it from the intake manifold, remove the two 12mm bolts, circled in red.



Now that the IACV is removed from the intake manifold make sure that you do not lose the rubber gasket as you need this so that it does not leak after you re-install the IACV.

5) Take your brake cleaner or simple green and start to clean up the inside of the IACV by spray inside the two holes. Continue to do this until no more dirty fluid comes out. Should take anywhere from 5 minutes to 15 minutes. This depending on how old and dirty your IACV is. The gasket can be seen in this picture as well.



6) Once you’re done cleaning out the IACV let it air dry. I let it air out for 20 minutes while I did other maintenance on the car.

Now your ready to re-install it back on the car so follow the steps backwards from 5 – 2



Good Luck


--------------------------------------------------------------------------------

"Spooning Leads to Forking"

[4re308]

SWEET!! You found it! That is awesome, good job!

[brian_bolcao]

yeah it helped for a while......lol but now it does it all the time.....i think the sensor has gone bad or something...im just going to get a new fast idle valve.....only $74.68 at the honda dealership. lol it was worth the try...lol

[brian_bolcao]

ok new problem......it may not be the aic valve.... it only does it when i have less that a half a tank. any more than a half a tank and it doesn't do it.

[nsxtcy21]

If the IACV doesnt work.. try a different set of injectors, change the fuel filter, and inspect/replace the fuel pump.. and also do a compression check just in case.