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stepper motor
Posted: Fri Jul 09, 2010 6:56 pm
by danny
Hi all im running a 3.9 efi in a landrover discovery,when i start the engine it is hunting for revs i.e it goes to 1500 then down to almost a stall then back up to 800 down to 300 and eventually settles on 750,i've asked a few people and they seem to think it may be the stepper motor,does anyone know the part number i have part number 73312a but the orientation of the plug is wrong any help/advice greatly appreciated,danny.
Posted: Sun Jul 11, 2010 4:18 pm
by HazelR
Hi, I've got that engine in a Range Rover and the part for mine is ETC6660 there's also a similar part ER5199 for post 95.
Mine was also hunting and stalling at junctions until I changed the Stepper motor. A short term fix is to remove it and thoroughly clean the valve end with duck-oil and brake cleaner, also clean the seat area and the pipes leading to it.
Posted: Sun Jul 11, 2010 6:52 pm
by bobtail84
I've got a stepper motor from a 3.9 RRC that was working fine when I removed the engine. Take a picture of the plug end and post it up then I will see if it is the same or I can cut the other end off of the loom and you can solder it on. But I'm pretty sure the're the same.
Jeff
Posted: Mon Jul 12, 2010 3:46 pm
by katanaman
before you go replacing parts check you dont have an air leak.
Posted: Tue Jul 13, 2010 2:36 am
by 92rrrandall
When you turn the motor off, the stepper motor opens up by 200 steps. This causes the start up RPM to be 1500, then it settles down to the programmed idle speed.
Most idle problems are caused by incorrect base idle speed. The stepper motor should only have to add 50 to 100 rpms to the base idle speed.
Most likely you have a vacuum leak(check with vacuum gage) or incorrect base idle speed(check with timing light).
Randall