Author Topic: Are DME failures common in the E30 M42's? (Read 4549 times)

Cobra Jet · « **on:** April 17, 2008, 09:22:14 AM »

Just curious, as some folks seem to jump to the conclusion in some older threads on here (on bfc, r3v, etc) that replacing the DME is the "answer" to all idle/stalling/driving issues...

Is the DME in the M42 E30's prone to some sort of premature failure and if so, why? What is the most common cause of a DME becoming inoperable? Can the DME's be repaired and if so, is there any online tech for doing such a repair to them?

Is there any way to determine a true DME failure, rather than just assuming it's bad?

Also, do all M42's use a "175" DME?

r0ckrat · « **Reply #1 on:** April 17, 2008, 10:50:29 AM »

There are DME failures in E30's in general due to age and vibration - sometimes the solder joints crack, and need to be re-flowed by someone good at small electronics.

However - most issues are not the fault of the DME. Idle issues can be caused by:

vacuum hose leaks
intake hose leaks
MAF Sensor issues
coil failures
bad plug wires
bad plugs
intake manifold gasket leaks
O2 Sensor failure

And probably more...

colin86325 · « **Reply #2 on:** April 17, 2008, 10:12:38 PM »

If a weather seal goes bad, under some rare circumstances water can damage the DME.

Everything about the 318iS in this capacity is similar to the other E30s (325, M3)

***Thought flash--replace the "elephant trunk" hose on the passenger side of the firewall. If this thing is clogged, you will get rainwater where it doesn't belong!

Cobra Jet · « **Reply #3 on:** April 18, 2008, 09:34:13 AM »

Quote from: colin86325;47385

***Thought flash--replace the "elephant trunk" hose on the passenger side of the firewall. If this thing is clogged, you will get rainwater where it doesn't belong!

colin - where is this hose located and what procedure is needed to replace it (or clean out that area)? Do you have a pic or diagram of the part/area?

Frank Gallegos · « **Reply #4 on:** April 18, 2008, 11:44:20 AM »

Cobra Jet,

check out the bottom of this link to get an idea of where to locate your elphant trunk.
And read the addition for a nice method in drying your interior.

http://e30.bmwdiy.info/passenger-water-leak/index.html

Hope this helps.

Frank

Cobra Jet · « **Reply #5 on:** April 18, 2008, 01:22:02 PM »

Quote from: The Brown Bomber;47457

Cobra Jet,

check out the bottom of this link to get an idea of where to locate your elphant trunk.
And read the addition for a nice method in drying your interior.

http://e30.bmwdiy.info/passenger-water-leak/index.html

Hope this helps.

Frank

Frank - thx! I saw that piece hanging off the firewall when we were reinstalling the M42 into my 318ic... now I'll give it a thorough inspection to make sure it's not clogged...