Idle hunting, pretty annoying.
 

Hey guys, this isn't really a problem but it gets on my nerves because I've been attempting something every month. No dice.


On a cold start up, the idle surges.( setting the desired idle to 1500-1300rpms till warm up cures the surge, anything lower it idle surges)


Whats going on is, when I coast to a stop in N the rpms go from 1000-1300 once I come to a complete stop then the rpms sit at the desired idle. This is with the car fully warm.


It seems like a vacuum leak, thing is I do blt's all the time. If leaks are found, I fix them. Plus the egr is blocked off.

Other steps I've taken,

- TPS reads 12.15% at idle, 100% at wot

-I've tested my iac, tests out fine but I still put in a spare iac(same result)

-Throttle body has new seals, first time replacing the seals by accident I cleaned off all the Mitsu goop. Thinking this might be the cause, I got a rebuilt throttle body that had sealant on the plate( no change)

- New BISS and oring. Adjusted the idle through evoscan, disconnected battery for 10 minutes.( this helps for a couple days and then the idle hunt returns)

- Turned to a reputable evo tuner, he sent me his iac settings and where to adjust BISS. Also looked over my tune (again adjusting the idle through evoscan works for a couple of days then the idle hunt returns)

- I've tried different iac settings with no luck.


So the bottom line is, seems like there is a vacuum leak but there isn't any. Adjusting the idle bandaids the idle hunt for a few days then decides to return.

Restarting car or disconnecting battery also seems to bandaid issue but thats about it.


It's become frustrating because my car idled perfectly before I put it in storage last year and this was with horrible throttle body seals and boost leaks.


I know this is a long post, I tried to fit everything in at once.


If you guys have any recommendations throw them at me, maybe I'm overlooking.

Thanks!

Have any pics? How about the nipples over the throttle body?

I have the same issue except mine idles low. Drives me nuts. Going to do some more trouble shooting this weekend.

Pics of what? Nipples over throttlebody are capped off.


Yeah it's gotten annoying.

Have you replaced your throttle body seals? If you have a tactrix cable and evoscan you may just need to adjust your BISS. Then resetting your battery.

I have a Works Throttle body so aftermarket one. I have scanned and settings look good. I am going to try another set of plugs to see if that helps. at this point I am at a loss as well

Once I had this problem. It turned out I was low on compression on cyl 3. Had to rebuild the engine.

Well, you need to adjust your BISS to whatever you want your idle to be. Not necessarily what it says in a manual on a shelf somewhere, that's why it's a Base Idle Set Screw.

Also, it just does it while it's really cold and quits afer like 5-10 min of driving? Do you have bigger injectors? Have you converted to any of the Tephra roms?

If you answered yes to most of those, then you need to pull up and adjust your IPW adder table because your injectors are dumping in too much fuel when the car is cold.

I also highly suggest googleing "merlin's evo tuning guide" and downloading it. It's a really good read and shows all of those little tips and tricks along the way. I managed to get a smooth lopey idle out of RC1200's on 91 oct and hks 280 cams by reading it.

I can't count how many times I've adjusted the BISS. I've adjusted it to my desired idle on full warm up then picked up another method to adjust biss according to idle steps in ecuflash tables.

This helps for a few days then the idle hunting starts all over. I can drive for 2 hours and it won't make a difference. Sometimes If I shut off car and restart it'll be fine.

My setup hasn't changed, before I deleted the egr the idle was fine.

I may just have to get used to this and live with it.

any update on this?