M-100 Message Board
M-100 Message Board
Home | Profile | Register | Active Topics | Members | Search | FAQ
Username:
Password:
Save Password
Forgot your Password?

 All Forums
 M-100 Message Forum
 General Discussions
 need help with my d-jet 3.5 stuck 1100km from home
 New Topic  Reply to Topic
 Printer Friendly
Next Page
Author Previous Topic Topic Next Topic
Page: of 2

S class

South Africa
933 Posts

Posted - 12/29/2014 :  17:12:18  Show Profile  Reply with Quote
Please help, I'm 1100km from home with my W116 350SE. Its a 1974 euro spec D-jet.

The first part of the 1100km journey went well, can ran excellent. It then started to develop a stumble/surge behavior, almost a misfire, but not quite.

In 800km it didn't really get any worse. The symptoms are surging/stumbling at part-throttle. Full throttle seems good.

Prior to setting off, the following has been recently done :
- new plugs, cap, rotor, ignition leads (all genuine Bosch)
- new points
- set valve clearances
- changed all fluids
- checked MPS for holding vacuum
- did electrical checks on all the d-jet sensors and injectors.

possibilities I've considered :
a) fuel starvation eg bad filter. I will be trying to get another filter tomorrow, but I'm not over-hopeful, as the correct full-load behavior and good acceleration seem to dismiss this possibility

b) I did check the points gap, and although it was a bit tight, I opened it up, and no real change occured.

c) condenser?

d) problems with the throttle position sensor?

e) I fiddled with the MPS, making t leaner, which did help a bit. I think possibly because after leaning it a bit, I had to push the throttle deeper. I am leaning towards an ignition issue, not fuel, because the loss of performance was accompanied by a modest increase in fuel consumption.

Any suggestions would be appreciated, as I am facing the 1100km return trip next week, through pretty remote countryside with no assistance.

I have with me :
- multimeter tester
- good selection of tools
- timing light
- fuel pressure gauge
- spare djet 'computer'



116.036
116.036
116.024
116.028
126.037



paul-NL

Netherlands
4176 Posts

Posted - 12/29/2014 :  17:19:00  Show Profile  Reply with Quote

might be a leaking coldstartvalve ....
Go to Top of Page

S class

South Africa
933 Posts

Posted - 12/29/2014 :  17:27:37  Show Profile  Reply with Quote
Interesting thought Paul. I can easily block off the fuel suply to the CSV to experiment.



116.036
116.036
116.024
116.028
126.037



Go to Top of Page

karra

Finland
849 Posts

Posted - 12/30/2014 :  03:42:59  Show Profile  Reply with Quote
I asked my buddy who is very good with the D-Jetronics. He said possible faults could be:

broken ignition cable or coil lead (even they are new)
distributor vacuum box
ignition amplifier (?)

Good luck and hope you get home safely!


Kari Pykäläinen

1971 6.3 #5581
1980 6.9 #7201
1981 380 SL
1987 560 SEC
1996 C180 A
1998 ML 320
1995 Tahoe 350cid
1980 Stingray SV175 boat
http://suomi.mercedes-benz-clubs.com/
Go to Top of Page

Ron B

Australia
11508 Posts

Posted - 12/30/2014 :  04:44:43  Show Profile  Visit Ron B's Homepage  Reply with Quote
Pull the distributor, check the condition of the trigger points. Get some spray on points cleaner and wash Any oil off them but do not try and adjust them. Check the connections to the trigger points. I have often found dry solder joints on them.
With Your pressure gauge you can hook into the cold start valve line? you need 28 PSi ,constant. A blocked filter can be sorted by fitting a filter from a 1980's GM car .
Heat reflecting off a hot road will also make a pump run slow. Again a later model Kjet pump will work fine if you can find one close.

Check the rubber line to the manifold pressure sensor . Again I have lost count of the failed lines I have found on those.

quote:
12-14-2004, 11:49 PM #8
Tom Hanson
MBCA Member

What the heck, try to stuff a MB 6.9 liter V8 in it. What a machine that would be..
__________________
Tom Hanson
Orange County Section
Go to Top of Page

S class

South Africa
933 Posts

Posted - 12/30/2014 :  13:54:17  Show Profile  Reply with Quote
Thanks guys. Ron, I don't think heat is the issue. Monday was very hot, but today I drove the car in cold rainy conditions and it was the same.

I wasn't able to get a new filter despite considerable effort. I will do the pressure check and if that is all good, I think I can then assume the filter is not the culprit.

My plan for tomorrow is :
a) check fuel pressure and simple things like the MPS vac line
b) swap to other D-jet computer, since its an easy thing to try
c) pull out and inspect injector trigger points.

Thanks.



116.036
116.036
116.024
116.028
126.037



Go to Top of Page

S class

South Africa
933 Posts

Posted - 12/30/2014 :  13:56:27  Show Profile  Reply with Quote
Kari,

To me the sypmtoms do not indicate a problem on the HT side of the ignition. I really hope its not the ignition amplifier though, because then I'm in trouble.



116.036
116.036
116.024
116.028
126.037



Go to Top of Page

karra

Finland
849 Posts

Posted - 12/30/2014 :  14:25:39  Show Profile  Reply with Quote
OK Ryan, I was just a messenger here . Have you had a look at dark, so without any light if there are any loose sparks jumping around the engine?

Ron perhaps knows Timo somehow; he gave me the advice. He is a friend of Dr Q's.

Kari Pykäläinen

1971 6.3 #5581
1980 6.9 #7201
1981 380 SL
1987 560 SEC
1996 C180 A
1998 ML 320
1995 Tahoe 350cid
1980 Stingray SV175 boat
http://suomi.mercedes-benz-clubs.com/
Go to Top of Page

mtrei

USA
3722 Posts

Posted - 12/30/2014 :  14:41:47  Show Profile  Visit mtrei's Homepage  Reply with Quote
Blocked air filter?

Sometimes it's the stupid obvious stuff.
Go to Top of Page

Ron B

Australia
11508 Posts

Posted - 12/31/2014 :  05:52:57  Show Profile  Visit Ron B's Homepage  Reply with Quote
The Mercedes world is a very small one... Happy new year !!

quote:
12-14-2004, 11:49 PM #8
Tom Hanson
MBCA Member

What the heck, try to stuff a MB 6.9 liter V8 in it. What a machine that would be..
__________________
Tom Hanson
Orange County Section
Go to Top of Page

paul-NL

Netherlands
4176 Posts

Posted - 12/31/2014 :  08:18:29  Show Profile  Reply with Quote
Ryan,

"a modest increase of fuel consumption" as you wrote, can only be because an false and to rich fuelmixture ....

1. leaking CSV
2. blocked returnline (pressure over 2 bar)

All the other "hints" imho are doomed to fail ......
Go to Top of Page

S class

South Africa
933 Posts

Posted - 12/31/2014 :  13:55:03  Show Profile  Reply with Quote
Paul, I agree with you, but there are other possibilities. IMHO ignition misfiring results also in less efficient operation, and therefore increwsed fuel consumption.

Today I checked the MPS vac line and it looks good. I swapped in the other D-jet computer, and it made no improvement. Tomorrow I will check the trigger points.



116.036
116.036
116.024
116.028
126.037



Go to Top of Page

paul-NL

Netherlands
4176 Posts

Posted - 12/31/2014 :  14:36:12  Show Profile  Reply with Quote

Triggerpoints are also not the possible cause; in that case it would not run in higher RPM's neighter good ...
Go to Top of Page

S class

South Africa
933 Posts

Posted - 12/31/2014 :  15:45:22  Show Profile  Reply with Quote
Paul, I'm thinking about what you say, and it does make some sense. The reality is that on Friday I will be undertaking the second leg of the journey, being 950km. Much of that distance is in locations far from help, so I would like to try and at least identify the problem before then so I can make a better decision on whether to risk the trip.

Therefore tomorrow I will do some pressure measurements, confirm of the ignition timing is stable, and check the injection trigger points.



116.036
116.036
116.024
116.028
126.037



Go to Top of Page

S class

South Africa
933 Posts

Posted - 12/31/2014 :  15:46:38  Show Profile  Reply with Quote
performance is equally afected at low and high speeds. But performance is much better at full throttle than at part-throttle coast conditions.



116.036
116.036
116.024
116.028
126.037



Go to Top of Page

paul-NL

Netherlands
4176 Posts

Posted - 12/31/2014 :  15:53:04  Show Profile  Reply with Quote

when the CSV is " constant " leaking it has MUCH more effect on idle then on high rpm's, because the " percentage " of extra fuel is more on low rpm's and is less the more throttle / higher rpm's you have ....
Go to Top of Page
Page: of 2 Previous Topic Topic Next Topic  
Next Page
 New Topic  Reply to Topic
 Printer Friendly
Jump To:
M-100 Message Board © 2002-2015 International M-100 Group, Inc. Go To Top Of Page
This page was generated in 0.21 seconds. Powered By: Snitz Forums 2000 Version 3.4.06