Question on BMW 3-Series E30 /BMW/techarticles/JF Tech/BMW_E30_3_Series_Idle_speed_troubleshooting

1989 325i m20. Suddenly had a problem with my car idling high and then having the idle bounce. Occurs whether cold or warm. When I start the car it immediately goes to 1500RPM and then starts to bounce to 1800RPM. Also exhaust smells "rich". I reviewed your article on the topic as well as used Bentley's and some other forums. To date I have done the following and still have the problem.

1. Changed my vacuum hoses and no leaks the boot is also in perfect condition and checked for leaks and none found. I did not do a smoke test which I understand is more sensitive.
2. I replaced my ICV last year and cleaned it anyway and seems to be working fine the piston freely moves, hums at startup and clicks, but looks like its closing less than 1/2 way. I checked the resistance as well got the appropriate readings 40 ohms and 20 ohms.
3. Checked the throttle switch for continuity and seems to be fine.
4. Checked the 02 sensor and heater relay and again everything checks out.
5. I checked the Blue Temp sensor but I was not confident with my readings. I was referring to an online article checking resistance between pin 24 and 45 at the ECU both cold and hot but not getting readings anywhere close to those they suggested. I could not confirm these pins in Bentleys. I replaced it and still have the problem.




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This post was auto-generated based upon a question asked on our tech article page here: BMW E30 3-Series Idle Speed Troubleshooting (1983-1991) | Pelican Parts DIY Maintenance Article

[Nick at Pelican Parts]

The idle control valve ECU may be faulty. Very common.

- Nick