QuestionThe vehicle is a 1998 4Runner (V6, SR5, Automatic, 117k miles)...About 13 months ago I had one occurance of this vehicle stalling, which happened while moving at idle speed in heavy traffic. Until three days ago, nothing of the kind had happened since then. In that instance (three days ago), I was stopped in traffic, noticed the engine running a bit rough, and shortly thereafter it stalled. The engine was able to restart without any hesitation. It happened again yesterday, once again while stopped and idling. The tach showed about 600 RPMs, and I was definitely able to notice a change in the pattern of engine vibrations (more, and rougher than normal). After stalling, I put it into neutral, started it back up, and was on my way. Sadly, I don't know what the normal RPM reading has been over the last 7 years, so I don't know if the 600 is good or not. However, the engine characteristics while at low speeds do seem odd. The oil in this vehicle was changed at a Toyota dealership five days ago, with no maintenance work between that and an oil change approximately 4500 miles previously. What is the most likely source of this problem?
AnswerIdle problems on this engine are mostly caused by the idle speed control valve which is located underneath on the throttle body, I'm assuming there is not a check engine light on, is this correct, if not let me know.
I recommend removing the throttle body and removing the ISC valve from it and the thoroughly cleaning both with a throttle body cleaner, literally scrubbing it to remove any carbon deposits from inside the throttle bore and the plate and also the ISC valve, doing this will solve the problem.
