Thread: 3.9 base idle

has the throttle cable go any slack. Have seen when the IAC valve fails people adjust the cable up to get it to idle.
also check for air leaks

IAC good, cable has a little slack. idles around 900rpm in neutral, but hunts up and down from around 500 to 600rpm in drive or reverse. almost stalls when put into gear, then hunts again. idle surges up about every two seconds, then down again?

By far the most common problem is an air leak.
IAC mounting plate tight?
All vacuum hoses no leaks or cracks including the one to the Fuel pressure regulator.
Tried blocking off the vacuum booster?
Checked that the T piece in the crankcase ventilation is the correct one with a little hole to the plenum.?
Regards Philip A

Having problems with my 3.5 D1.and the manual not much help.it just a test replace deal.gone from 250 km per tank to 450+km.

replaced a few sencors and set timing.it has a english distributor-afm.
i havnt changed the fuel temp sencor or fuel filter yet.Ive imported a few bits recently.

now the car runs better when im driving.
BUT it trys to hold 1500rpm this is common with other types of emission engines,butto drive at 40-50 kmh i have to select [auto] 2 or 3 and ride brakes.i dont think this is normal.

selecting neutral when the engine is warm the rpm comes down in steps in 30 seconds then sits at the corect idle.cold running is no issue.
select drive when warm it hunts.i was thinking it might be a speed sencor issue-thinking it might be moving when stationary or slow moving??

I adjusted the AFM and base idle with TPS disconected other wise it runs crap.

the step motor is a little sad.previous owners had put lots of home made gasket and sealer on the valve adaptor and adjusted the base idle out so the aac motor did not work.