Specs: B18a Block, B20b Head, OBDO, heavy wire/brake line tuck, civic 1/2 rad, slim fan hooked up to turn on with the key.

OK, I am finally about ready to unlease the beast on the road, I have 1 problem I am tring to fix.

Once I let the car warm for about 5 minutes, and the car reaches its normal opertating tempature (right below the half point), the car starts to surge really bad (idle goes up, down, up, down by itself).

The thing I did notice after letting the car run for about 5 minutes is that the bottom radiator hose is still pretty cold compared to the top radiator hose.

MY THOUGHTS: Air trapped in cooling system somewhere, thermostat, or something else.

Does anyone have any insight to this problem, I hope to have this resolved by the weekend so I can get the car in for inspection. If anyone has any suggestions PM me, I am working on this tonight.

 

Reported for relocation.

 

Thanks for moving it the thread!

 

well.. for the bottom hose being cooler than the top.. thats normal. its suppose to be cooler. but make sure you burp the system. any cel codes? if not just start checking to make sure everything is plugged up right and wired right. maybe clean the ivac.

 

No CEL's, I am pretty sure everything is wired correctly. I think I will clean the IACV. Is there any other coolant bleeders besides the one on the heads waterneck?

 

nope......check the plug on ur throttle bodie for the ICV and tighten it up ....sometimes they vibrate loose

 

If it idle surges after warm up, there is a chance it is the IACV. If that doesnt work, it is probably a vacuum leak. I don't think it's the FITV because that really only regulates idle when the car is cold. How is idle on start up?

 

It idles like it should (a little high when first starts, then drops down to where it should be), it only happens once it is at average temp (right below the 1/2 mark). I will check out the IACV tonight. Luckly I have an extra FITV and IACV somewhere, just got to dig it up.

Thanks for the input, I will keep you posted.

 

If it doesn't work, I'll show you a way to check for a vacuum leak.

 

i have the same problem, im not to good with abreviations tho, wut r the FITV & IAVC? wut be used to clean m?

 

Im gonna say that your problem is for sure the IAC. Slap a new one on there and reset the ecu and you should be good.

 

just wondering if you have found a solution to this yet? because I have the same problem in a 96 civic and cannot find the problem. no vacuum leak, and only surging when warm. did the iacv fix the problem?