Rough idle issue when cold
Thread Starter
Senior Member
Joined: Aug 2003
Posts: 350
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From: Dallas, TX
2001 BMW M3 vert
Rough idle issue when cold
94 E320 coupe 80k on it
When car is cold, the idle is very rough-bounces down around 5-600 rpm and acts like it wants to die. It's an annoyance at stop lights and know it can't be good for the car. The rough idle stops after the car has been driven for 10 or so miles.
Help is appreciated!
When car is cold, the idle is very rough-bounces down around 5-600 rpm and acts like it wants to die. It's an annoyance at stop lights and know it can't be good for the car. The rough idle stops after the car has been driven for 10 or so miles.
Help is appreciated!
MBWorld Fanatic!
Joined: Dec 2006
Posts: 1,042
Likes: 1
From: Bellevue, NE
1995 E320 SE, 162,000 Miles (Sold) 2007 CLK350 Cabriolet 2014 ML550
I would say either the temp sensor is defective and not telling the computer that the engine is cold, or the throttle actuator assembly is bad. The throttle actuator can be very pricey ($1,200) but I found a company on e-bay that rebuilds them for around $400. If the rpms also drop noticeably when the A/C compressor engages I would say it almost has to be the actuator assembly. The wiring to the actuator deteriorates like the engine harness and it disables the throttle servo inside the actuator.
http://motors.search.ebay.com/search...e=search&fgtp=
http://cgi.ebay.com/ebaymotors/Merce...QQcmdZViewItem
http://motors.search.ebay.com/search...e=search&fgtp=
http://cgi.ebay.com/ebaymotors/Merce...QQcmdZViewItem
MBWorld Fanatic!
Joined: Dec 2006
Posts: 1,042
Likes: 1
From: Bellevue, NE
1995 E320 SE, 162,000 Miles (Sold) 2007 CLK350 Cabriolet 2014 ML550
On the front of the engine, next to the thermostat housing. There are 2 of them; one has 4 wires, one has 1 wire, I think. Do a search on this forum for more info. I'm not sure which one does what. They control the temp gauge, cooling fan, and input to the computer. You might try disconnecting them individually and see what happens. I would think that one of them would cause a check engine light or rough engine running when it's disconnected. If I get time I'll go out to the garage and mess with mine and see what happens.
