1998 z3 roadster starting problems

M

_Mqx_

Newbie
Australian Zeds
Joined
Sep 21, 2025
Points
3
Location
Brisbane, Australia
Model of Z
Z3
Hi team

Bought a 1998 z3 with the 1.9L m44 engine here in Brisbane a few weeks ago, fuel pump was totally dead.

Replaced the following today:

- new fuel pump
- new fuel filter
- new spark plugs
- replaced fuel pump relay with known good working one but not new.

I have tested spark to all cylinders as well as injector pulse to all cylinders. Working as expected.

Here's the weird part. The car runs great with 3/4 ignition coils plugged in. With the 4th one plugged in, the car will not run.

We have 12v to fuel pump and relay but I am confused on what could cause this. I may try a new battery but otherwise out of ideas.

Thanks all.
 
Welcome aboard.
 
It may be useful to check if any vacuum / air intake hoses are split / pitted / worn through?
 
Welcome to the forum from over the ditch in New Zealand.

As the problem occurs when you plug the last coil to the spark plug, it looks like a failed coil pack, Replace the coil pack.

The 4 in 1 M44 coil pack can be very expensive. See if a junk yard has one to try.

The alternative, if you are DIY handy, is to convert the engine to coil over plugs. See attached file.
 

Attachments

Hi and welcome from me in Scotland :welcome:.

Yes would have to agree my first thought was the coil pack.
Stephen.
 
had a bit more of a look at it now.

i think we are getting a weak spark, from what i can see it should be blue? certainly not that, small yellow spark. I didn't think of this originally but that would make sense.

From what i have read i need to test the CPS and plug wire ohms. have not replaced either of those.
 
You must log in or register to reply here.
Back
Top