Pajero stalling on slow down

[Gaurav]

My Pajero (1999, 3.5L DOHC 6G74, SWB) started stalling when i slow down. It doesn't happen when i start the car and go, but after 10-15 mins of driving with or without AC it stalls as soon as i slow down and about to stop. There is no hesitation like it stalling due to bad or choked fuel supply or something, full throttle runs very well like before and again it starts almost instantly w/o any hesitation or hiccup.

It stalls every time when car slows down like in speed of under 10km. It cuts without fight, judder, or hesitation. Silently motor dies and battery and A/T icon appears then I realize its off.

This symptom is not there when car is cold from overnight and in first 10-15 minutes it behaves just fine and after that it start showing this behavior of stalling. Also when it stalls, it restart just fine with little touch of throttle, w/o throttle it doesn't even start.

Checked HT leads and Coils look good. Spark plugs changed couple of months back (3000 kms) and checked the spark plug again, it looks good. Cleaned the throttle body with spray, but it still same.

Any guesses on what I need to look into??? Thanks in advance.

[yusuf]

I hope car is well serviced and you have clean air filter. You can start from first cleaning the idle control valve just below the air filter neck and see if it helps. My second guess it could be coolant temperature sensor is giving wrong reading to ECU, as you mentioned that it misbehave when fully hot. That raise quite a suspicion here. As coolant temperature tell the ECU to how much adjust the air flow through air flow meter sensor and if any of two reading is bad then it will fluctuate the idle. Btw, just for record your 6G74 engine ideal idle should be 800-900 rpm at cold start and when fully warmed it should be around 900 - 1000 rpm. Hope this help.

[Gaurav]

Thanks Yusuf for your help. Well i adjusted a throttle controller from engine bay and its not stalling anymore. Looks good with slightly higher rev almost touching 1k rpm with AC, still monitoring it and see if i can find the real culprit or not.

[Gaurav]

Finally got the time to see mechanic and he opened the ICV and indeed it has black soot in it and he cleaned that thoroughly and fixed it back. He also cleaned the throttle body again and remove the throttle nut-bolt additional race that i have adjusted and car was fine and not stalling. After all this cleanup and standard race setting car was idling at 800 rpm without AC and at 950 rpm with AC, when i move to D (drive) it drops to almost 750 rpm without any shakes or vibrations.

Drove the car for 20-30 kms as a test and out of happiness and finally after an hour of joy, car again stalled same way like before. Jumped out adjusted that throttle nut-bolt again to increase rpm to stay closer to 950 rpm and its fine again. Any more ideas guys, what should be next to troubleshoot and look into?

Thanks in advance.

[jamesdias]

Any further update, Gaurav. I might need your help.