Stumbles on light throttle when cold

Have tried a search couldn't find anything. I've got no idea what might be the prob, fire me some clues.
Car starts fine but when it's cold and I apply some light throttle to get going it just stumbles. Heavier throttle helps but isn't much better. By the time I've gone 500m seems to be warm enough for it to stop.

 

CTS pins clean and connector ok? Tps adjustment may be out or tps failure.

 

I've had this problem for over 6 mnths now. It's started intermittantly and now it's every time.
I've tried a replacement TPS, no change.

 

It may be that the throttle bodies are out of sinc. Start to open the throttle off their seat and check that they both open simultaneously.

Cheers,
Dave.

 

I will check them but this problem has developed over time and progressivly become worse, therefore I doubt the TB will be the prob.

 

Check resistance between the

air regulator pins (looking for 70-80 Ohms Ω) and also as Dzr suggested, CTS and/or wiring faulty. Can check CTS with resistance check again, looking for

o 2.1-2.9 kOhm Ω at 20C (68F)
o 0.68-1.0 kOhm Ω at 50C (122F)
o 0.30-0.33 kOhm Ω at 80C (176F)

NOTE: Clean all the male and female terminals before testing both units as dirty/corroded terminals may result in a false resistance reading. Retension the terminals after cleaning them.

 

What and where are air regulator pins?

 

Air reg is centre/rear of plenum - check hoses for vac/air leaks.

 

CTS resistance and connection fine.

A/F values strange though. Jumping from position to position rather than moving smoothly like a rev dial. ie. value of 89, then 109, then somthing else. At idle it sits rock solid at 109.

Also light throttle both O2s hit zero for a few seconds. Once the car reaches about 35C the stubling is gone.

TP did stick at .6 at one point, then a few pokes of the throttle and it returned to 0.42-0.44.

 

Don't know if it could be related but is there any point in having AIV's if the EGR pipe is not connected to the exhaust. Ie headers installed EGR pipe sealed off?

 

Do you mean the two plugs on the IACV? One is vertical and one horizontal? Or is there another plug there somewhere on the actual air regulator. Rear of engine

 

In that photo you can see the plug under the clamp on the "S" hose that connects to the balance tube.

Check clean your throttles aswell, then reset the tps to the correct voltage.

 

Throttles have been cleaned not long ago, I will re-adjust the TPS, it's not far out though. Data scan only reads to .02 accuracy.

 

The A/F values are correct and that's normal. It's just informing you that the self learn is removing 11% fuel and adding 9% in the above-mentioned cases from the base programmed levels.
These values are of no use however until the car reaches 69 degrees and the exhaust is hot enough to make the o2 sensors work.

Until the ECU allows the car to enter close loop operation, it will be guessing mixtures based on the programming it has (against RPM, TPS AFM). There is cold engine enrichment programmed into the ECU, but maybe in your case it needs a tweak.
I'd be guessing it's probably running a little lean, but not something you'd be able to confirm without a wide band AFR gauge.

 

typical of iridiums mate ! get some platinums or coppers

 

The plugs are only about 20000k's old, or less, thats young for iridiums.
Just took the car out and no stumbling at all????

 

Try coppers and see what happens. $12 a set, it's worht a shot.