4AGZE Idle Issue

[ozhummer]

OK - I've just converted my AW11 4AGZE back to standard and I'm having a PITA idle issue.

If I start the car it revs quite high initially to about 2K, then drops and stalls. All within a few seconds.

If I caress the throttle, I can stabilise it, but it hunts up and down quite abruptly - not like the coolant-not-purged hunt, this one is aggressive and I know the coolant has been purged ok.


These are the things I have tried

Completely different TB - with pre set TPS and different idle control valve
Changed the ECU
Change the O2 sensor
Changed the AFM
Changed the exhaust
Checked and replaced all the vac lines
put in new plugs
changed the ig coil

Nothing here makes any difference ..

Temp is steady on 190F

Any advice would be appreciated ....

[fixeruperer]

got the abv connected still ? all the blue/brown solenoids working and plumbed correctly ?

[ozhummer]

Yep - all the vac hoses appear to be correct ...

One more thing - I do have slightly larger cams (256 deg Kelford) they are not aggressive by any means and I really don't think they would cause this issue, but I have mentioned anyway...

Surely some one has had this type of issue before ... and fixed it ????

[fixeruperer]

id be looking at the different tb and idle control valve. the icv might not even be working.


usually a 4agze with idle problems like the one you have is associated with installing a front mount cooler with longer pipes.

but seeing as you dont have a fmic and different tb and icv, could point to that.

[ozhummer]

Ive changed the tb including tps and icv completely without success. . What are the odds of having 2 faulty icv's? Can they be bought new?

[fixeruperer]

oh i thought you meant, a different tb from another model car.

if its all stock. ecu and all. read the codes out.

[dumbass]

A lot of 4agzes have idle issues when u put them in rear wheel drive form like in a ae86
And this is due to vac hoses and stuff being Mixtec around
I've worked on these issues many years ago and some I could not get 100 percent
But yours is standard form so maybe u have problem with hoses

Also I doubt the idle motor will have enough opening on fuly open to get to 2000rpm
So maybe your accelerator is sticky or the linkages or return screws

Anyway I recon u have air leak that's making it goto 2000 rpm
Try blocking air that feeds the idle motor and see if revs stay low

[worldwalker]

I had a few idle problems which turned out to be the ECU but nothing as bad as you've described. Mine were all temp sensing related. I just replaced the ECU with the correct model number, which changed every year.