Testing Ignition Control Unit - PeachParts Mercedes-Benz Forum

graftdesign · #1 10-31-2006, 05:46 PM

I have a problem with my engine not starting and originaly thought it was a fuel delivery issue. The fuel pumps, relays work.
I am also getting spark.

I sprayed starting fluid in the intake and was hoping it would start... at least for a moment but got nothing. Could this be the EZL module? Would I still get spark if it was bad? I'm trying to diagnose if its a fuel or ignition problem so I dont go on a expensive part buying mission. I have always had success with starting fluid provided it had spark so this has me a bit stumped.

You help would be appreciated.

graftdesign · #2 10-31-2006, 05:47 PM

Almost forgot. It's a 1990 560 sel with 142k.

cjlipps · #3 10-31-2006, 05:56 PM

Graftdesign. I have what might be a similar problem with a 1989 300E. I have started a thread on it "300E intermittent start/run problem". (I don't know how to post a link to a thread yet) No solution yet but it might help us to watch each other's threads.
Chuck.

graftdesign · #4 10-31-2006, 06:52 PM

Thanks Chuck. I'll check your posts.

Good luck!

jhodg5ck · #5 10-31-2006, 07:07 PM

Try bringing 12v to the positive terminal on the coil and see if she'll start.

Could be a wonky ignition switch.

Jonathan

graftdesign · #6 11-01-2006, 08:05 AM

Thanks Jonathan:

Craziest thing happened. I went to turn her over last night after charging the battery all day and she fired right up! This is after two weeks of not starting. It may just have been fouled up plugs or something simple like that. I've been giving her multiple doses of starting fluid, gas, etc over the course of two weeks and may have fouled the plugs up too much... who knows.

I'm going to keep your coil suggestion in mind nest time I have a starting issue but my first course of business is going to be changing all of the plugs (I was told they were new when I bought the car in April) and gap them at .42 and see if the problem continues. I the coil was bad I probably wouldnt be able to start the car correct?

I can probably safely assume the EZL is ok...

Ferdman · #7 11-01-2006, 06:10 PM

If the ignition control module fails the engine will not start. I've been through that scenario with a 1991 300CE. A spark plug gap of .042" seems extreme. Are you certain that's the correct figure?

graftdesign · #8 11-01-2006, 07:14 PM

Thanks Fred.

Regarding the spark plug gap, the MB 560 engines apparantly run better with the wider gap of .42. From what I understand you get a smoother idle and a larger spark for a bit more power. This info is from some seasoned mechanics on another Benz site that I trust.

Thanks for the info on the ingintion control unit. I wasnt looking forward to spending a few grand on a new one!

greg

jhodg5ck · #9 11-01-2006, 08:17 PM

Yes, .042 is the ideal for the V8's. They really do like the wider gap.

Had one come in w/ the gap around .02..idled like crap.. Opened everyone up and it made quite the difference.

Jonathan

graftdesign · #10 11-02-2006, 01:52 PM

thanks for the update Jonathan. I think you were the one suggesting the .42 gap on the "other" site.

jhodg5ck · #11 11-02-2006, 10:59 PM

Could have been;-)

Jonathan