X300 Stalling on Idle
 

Our 1996 3.2 litre X300 likes to stall on idle. In the past we have
noticed it stall on the odd occasion, but it has been terrible of
late.

Some days it will be fine, and then others it will stall every time
we stop for traffic lights etc. It starts up OK post stall, and is
fine until the next lights. This can become extremely tedious after
the tenth stall!

Any suggestions would be most welcome.

Need more information. Do you have check engine lights? Is it a sudden death (electrical) or does it just sort of peter out?

There are no check engine lights and the CAN OBDII thing doesn't report anything.

I guess it's relatively sudden. It's hard to tell sometimes because the car idles so quietly. Sometimes I don't even notice until I look at the dash.

Cleaning the throttle body has been known to cure some peculiar ills on these cars. That's where I'd start.

Cheers
DD

hey doug, i have a similar problem with my 96 XJ6. my car has rough idling, loss of horsepower, bad steering sometimes, initially the check engine light came on and it was the EGR valve. I replaced it and after a week the same thing happened. since then i have had the throttle body cleaned, using BG 44K fuel system cleaner, and the problem is still there. the technician then recommended me to replace all ignition coils. what do you suggest? Thanks.

by the way, the technician told me that one of the cylinder may have carbon deposit and caused misfires in idle, or it could be ignition coils.

Could be the Air flow Meter ?.
I had similar problems recently and cured it by fitting a new meter.

Stepper motor
 

I have a 3.2 1996 X300 executive that has been suffering with exactly the same stalling problem. It stalled once a few months back and then gradually got worse until it would stall every time I took my foot off the throttle. It was also iding roughly, didn't want to start soemtimes when it was very cold -5 or so. I had cleaned the throttle body, changed the spark plugs, checked the coils and replaced one that had some hairline cracks. I had a theory for a while that if I started it up and then switched it off for 30 seconds and switched it on again the stalling problem ceased etc etc. Anyway, it got really bad the other day so I sat down and resolved to sort it out by researching the internet once and for all. To cut a long story a little shorted than I have already made it I bought a new stepper motor - part no. JLM12185 at a cost of £64.34, though by the time it gets to you with vat and postage it's £84.36. It bolts to the throttle body and regulates the idle speed and is sometimes referred to as the idle speed valve or sensor.

I put it on the car this morning and it has made a miraculous difference. The engine feels smoother, no stalling, no lumpy idle. It feels as if I have just had an expensive service done on the car and all the coil packs have been replaced - which is a job I was on the brink of doing.

I hope this helps anyone with the same problem - don't change your fuel filter, coil packs, throttle body, air flow meter, ECU earths or anything else - if your car is fine but it keeps stalling sometimes more than others and runs roughly sometimes more than others, invest £84.36 in a new stepper motor before you buy 6 new coil packs, not the other way round.

That's interesting thanks for your input normally when a similar things happen I normally don't mention a part called stepper motor ,honestly I have never heard of anything like that lol

Most of you hit it already and I was gonna recommend cleaning the throttle, slightly opening the mechanical throttle blade setting(small allen head socket on the top of the TB) and replacing the IDLE AIR CONTROL SOLENOID< (IACS) this is responsible for control the idle speed for decel(keep from stalling from sudden closure) AC, power steering electrical load etc,..
The issue is that as the TB gets deposits it closes and seal the normal mechanical opeing between the throttle blade and throttle bore. AND since intake oil laden air also goes past the IACS, it too gets plugged up and worn out trying to operate the pintle when dirty....SOOO you get stalling cause the mechanical blade clearance is gone, and the stepper pintle is getting plugged and slow.....Be VERY carefull taking out the stepper motor screws, they have lock tight on them and break off easily. I would buy a new 1 and replace it cause it comes with new screws rather than trying to take it off and clean it....All this is really just maintenance IMO that should be done every 60k, fuel injection system, tb cleaning, etc...on that engine there no tb gasket and it is easy to remove and clean with a toothbrush and carb cleaner, this also allows you to spray and clean the IACS port and pintle. same thing applies to all TB's etc the removal part. Also always clean the TB on a warm(operating temp) engine, otherwise youll have a very hard time restarting with carb cleaner in the intake, if you removed the TB it doesnt matter....