I'm experiencing idling issues for the past one year that driving my evo is no longer a pleasure.

I've certainly search through the forum to look for solutions but there seem to be too many possibilities. My problem started after I changed my spurned bearings, cams and injectors. My car will go pig rich and lean on closed loop after I go into Neutral. It works better after I forced it to run in open loop. Currently, it only goes rich and no longer lean.

The strange thing is my idling is stable during startup. It only started to act strange after I go into Neutral after driving. At times, it went down to 500rpm before recovering to around 1k rpm. Unlike others that encountered continuous unstable idling, mine becomes stable after a minute or so at idle.

I am on HKS BOV (VTA type) which works perfectly fine before fitting the cams and injectors. Among the things I've tried:

1. cleaned MAF
2. replaced plugs
3. cleaned Throttle body
4. Boost leak test

Anyone can offer any solutions or basing on the problems, offer any advice?

 

Sounds like the problem I was having a while ago that also took me forever to fix.

Do you have an aftermarket fuel pump? What are your injector settings? How do your fuel trims look? Do you have a fuel pressure gauge?

 

I'm on a Walbro 255, a SARD fuel pressure regulator and a Defi Fuel Pressure Meter. It used to idle at 29PSI but I adjusted it to 25PSI to see if it helps. Now, it doesnt seem to increase no matter how I adjust the fuel pressure regulator. I only know it works as my AFR goes lean or rich when I drive, depending on my adjustment. On idle, it refuses to budge and stays at 25PSI.

I'm running a FIC1050 and the scalings are slightly above those in the threads here. Low and Mid Fuel trims seem fine during warm up idling but goes crazy once I go into Neutral after a drive.

From what I've read, people who has faulty IAC usually encountered stalling issues or difficulties keeping the car alive after cranking. Any idea what are the symptoms if the problem lies with the injector? My car seems to be pulling fine but does a lazy injector pulls equally fine?

 

Check IAC?

 

Idle fuel pressure is supposed to be 42 with the vacuum hose plugged. Adjust it to that and it should get better, it did in my case.

 

Roger!

Will check on that and update on status again!

Thanks!

 

This is the same exact issue I am having...urrrgggghhhh!

 

Why are you venting to AIR when running a MAF setup? Recirculate, set your fuel pressure correctly (42-43psi with vaccuum hose disconnected from regulator),scale your injectors, drive a few days and tune as necessary.

 

Hi,

Do you think you can advise what disadvantages for running VTA with MAF setup?

Thanks!

 

You are venting air that was measured by the MAF and that the engine is expecting to receive. Since that air isn't there, you end up running rich and having issues not unlike those you're having.

 

I think I have an HKS BOV adapter for recirculating it back into the intake lying around if you want it. You should definitely not be running VTA with a MAF sensor. This is most likely your problem. Switch to speed density or recirculate the valve.

 

this depends how much vacuum the motor is pulling,

Set the FPR to 43.5psi with the VAC Line off then it should be correct

when i did this if my vacuum is like 15-17 its like 38-39psi, but idling with cams and 10vac its more like 40-41psi

 

What Raptord said...

 

I havent encountered this problem before on similar setup.

To report back, I've set the FPR to 43.5 with vacuum off but it doesnt help..

 

You've also recirculated the BOV?