M3 issues - Need help [Archive] - Bimmerfest - BMW Forums

: M3 issues - Need help

06-17-2008, 04:42 AM
I have a few issues and hope you guys and galls can help.

I have got a 1995 M3 3.0 Euro

1 - My temp gauge intermittently will show that the engine temp is just out of the blue even after a long run. It will be fine (bang in the middle) then it will drop quickly to just above the blue. The oil temp stays perfect at all times. I then boot it and the temp goes up. Sticking t-stat maybe? She never goes above the middle and the oil temp never goes above middle either (i have an oil temp gauge in my instrument cluster - standard)

Sometimes it is perfect for 300-400 miles and sometimes it plays up

2 - I have got a really bad idle. Is there a DIY to clean the ICV (if it has one)?

3 - When i accelerate hard below 3k revs, the car is dead as a doornail, but the second it hits 3k, it is like all the power kicks in at once and the world goes blurry (http://m3forum.net/m3forum/images/smilies/smile.gif). Is this normal?

4 - I have got the carsoft program and cables on my laptop. It works perfectly on our other BMW's (we have a few) but when i plug it into the port in the engine bay of my M3, it just says that all the modules are not responding. Could the port be faulty?

06-17-2008, 07:14 PM
Sounds like you have some problems with the temp sensor. If you have never changed the radiator, t-stat housing and hoses, now would be a good time to do so.

The idle can be caused by vacuum leaks or bad injectors, or even coil packs. I sent you a PM.

06-18-2008, 12:48 PM
You have two temp sensors on this car. Both are close to the front of the engine on the intake side and you are describing symptoms of failing sensors. One is for the gage and the other for the DME. They are cheap and fairly easy to replace so I would just replace them both. On a car of your vintage it is likely that this is the problem. By the way I have never seen a code for the coolant sensor on the OBDI for a 95 when I replaced them on other cars.

DME senses the wrong condition and car responds accordingly and the other is the gage in the car. Here in the US they were maybe 12 bucks each.

06-19-2008, 02:49 PM
Thanks mate, will get them changed

06-20-2008, 10:51 AM
NO power down low and then power up high sounds like the VANOS isn't working. There is a test for it, but you have to take some of the top off the motor.

07-03-2008, 02:49 AM
I checked this buddy but the Vanos was working

Was convinced it was the vanos solenoid but it is not that...doh

07-03-2008, 07:24 AM
Like the e30, coolant temp sensors play a role in how much fuel is injected into the cylinders on start-up as well as a failing sensor causing irratic idle due to the fact that it has an invalid reading from the coolant temperature to report to the DME. The DME Coolant Temperature Sensor play a role here but since theyre cheap, replace both coolant temp sensors as stated above. Irratic idle can be caused by this sensor but you should also check your Idle Control Valve and all other vacuum lines for wear and tear.

If your Coolant temp sensors are NOT at fault and you still have that irratic coolant needle, you need to replace your thermostat because its starting to fail. BMW thermostats were designed to fail in the OPEN position as to not overheat the engine itself, rather keep it under optimal operating temperature. When replacing the thermostat, that would definately be a good time to replace your waterpump, check coolant hoses, and replace any if needed.

No power under acceleration until 3k could be as simple as cleaning your MAF sensor, checking your vacuum lines, and making sure everything is in good order. When was the last tune up? Have you checked your spark plugs for proper igniting of the mixture in the cylinders?

09-21-2008, 01:06 PM
so it was the o2 sensor?
did you try unplugging it? was the idle bad then?