Motor:
98 B18B

Car:
98 GSR Shell

Ever since I completed this swap I have had idle problems. Basically, upon initial startup the car idles great ~ 1200 RPM, and as the car warms up, the idle slowly comes down until the car reaches full temp. Once the car is full temp, the idle is around 750RPM, but then it starts dropping randomly to almost 300 RPM. It continues to slowly roam between 300 and 750 but usually wont stall. And these symptoms continue the entire time the car is warm for the most part. However, the car sometimes runs great, and the RPM falls to exactly 750 with to dip down at all. So this intermittent problem is very hard to diagnose.


What I have tried (none of which worked...obvisously)
-swapped out IACV with another used one
-changed out throttle positioning sensor, and set it to proper range(voltage)
-Replaced EVAP control canister vent shut valve with brand new
-Checked timing



Have to CEL, and no stored codes.....Any thoughts or ideas?

 

hi m8 i have a civic eg 1.5 vtec-e and i have the same promblem i have tryed all of the above that you have mentioned and also tryed abit more have you cheeked ur o2 sensor im puzzeld to with what it is any help would be good

 

Have not checked 02 sensors, but not throwing a code

 

have you tried bypassing the FITV & screwing it back in? not sure if theyll cause your symptoms but its worth a shot

 

correct me if I'm wrong but I don't think I have a FITV - the ECU controls the higher idle upon startup

 

yes on most/all honda's the ecu controls the idle through the idle air control valve (IAC) but the FITV is there to just warm up the throttle body when its cold.

notice the coolant line right below the throttle body, if yours looks just like the one if the pic then you havea FITV
http://farm1.static.flickr.com/143/3...ab7988de_o.jpg

heres the link to the FITV fix
https://honda-tech.com/forums/showth...highlight=fitv

if you dont have a FITV, try a can of brake clean and try spraying down vaccum hoses, intake manifold gasket & throttle body gasket to check for leaks. if the idle changes at where you spray it, you found your leak

 

yeah I don't have a FITV. I will try the spray test and see if i get any results, otherwise I am leaning towards a new cap and rotor

 

i could be wrong but if the cap and rotor were weak you would have problems other than just at idle

 

I would personally try this. Checking for vacuum leaks never hurt. Also was the IACV you purchased clean? I had the some problem and did EVERYTHING you can think of to try to find the problem and never did, i think it had to do with the wiring somewhere, But GL.