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Barn Car Club President
 
Join Date: Oct 2017
Location: New Jersey
Posts: 3
'84 318i High Idle

Hi All. New to the forum -- old car.

When she starts up in the AM, the idle will hover around 1200 RPM and won't kick down as it should. Once the car warms up, the idle will usually calm down to around 750. I recall the car did this last winter -- the colder the outside temp, the higher the RPM -- but things went back to normal once the weather warmed up.

Any Ideas?

Jay
Old 10-01-2017, 03:35 PM
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Dmitry at Pelican Parts's Avatar
 
Join Date: Aug 2016
Location: Los Angeles, CA
Posts: 2,618
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Hello and welcome to the forum Jay - I'm attaching a link to a DIY tech article on the E30 platform to help you troubleshoot the idle issue. Please let us know if you have any questions!

BMW E30 3-Series Idle Speed Troubleshooting (1983-1991) | Pelican Parts DIY Maintenance Article
Old 10-03-2017, 12:17 PM
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Barn Car Club President
 
Join Date: Oct 2017
Location: New Jersey
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I went through all of the vacuum lines. Everything looks sound. I've found that spraying carb cleaner on all suspect areas while the car is running is the best way to find a vacuum leak - the engine speed will change when a leak is found. I sprayed everything, but nothing found. Out of frustration, I started disconnecting sensors to see if anything happened. Sure enough, when I disconnected the pale yellow coolant sensor located on the top coolant outlet, the engine speed immediately dipped to almost stalling, and then leveled out to around 500 RPM's.

I installed a new sensor yesterday afternoon - car was still a little warm. After the install, the car idled as it should -- so I think the problem is solved. Get in the car this morning -- cold start -- back to 1200 RPM's and holding. I guess I could leave the sensor disconnected and try to increase the idle, but I'd rather have the car working as it should.

So the sensor was not the problem, but surely it appears to be related in some way. And this certainly appears to be electrical in nature... frustrating.
Old 10-16-2017, 08:56 AM
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Barn Car Club President
 
Join Date: Oct 2017
Location: New Jersey
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A quick report / observation. Got down into the 40's last night. Took the car out for a 10 mile trip. Idle RPM's were steadily approaching 2,000. Seems the cooler it gets, the faster the engine idles... Coolant appears to be up to proper operating temp. FWIW, thermostat, water pump, & radiator are less than 2 years old. Is there an outside air temp sensor on these engines?
Old 10-18-2017, 06:23 AM
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