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Old 04-15-2003, 11:15 PM
Registered User
Join Date: Jun 2001
Posts: 259
Let's play "Name that problem!"

Good grief
-rough idle continues
-drives fine at normal cruising speed
-fast takeoff or geardown going up a hill, shakes rattles and rolls and looses power-feels like something is slipping.
-slowly accelerated past 70 with no loss of power, when I went from 40 to 70 simulating passing, it shuddered and rattled, bogged but eventually caught up.
-thought it was tranny related but now it seems motor related with no tranny noise and smooth shifts.
-recently had the fuel accumulator off, seemed ok-didn't quite know how to check. .
-retightened all fittings, will drive tomorrow.

I'm thinking it's got to either be a fuel filter, pump or bad acuumulator or? Vacuum related? Can't be timing, it's automatic adjusting.


J. Boggs
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Old 04-16-2003, 12:21 AM
Registered User
Join Date: Mar 2003
Posts: 16
Name that Problem

Hello Boggs. These are just my guesses in order.
1. Plugged fuel filter. Replace
2. Weak fuel pump. Replace
3. Weak secondary wiring in Coil; thus, weak(lower voltage) and/or erratic spark when under load. By chance does the car try to spit back thru throttle valve? Replace coil.
4. Low voltage to Coil & ECU's. Replace voltage regulator brushes.
The above are all relatively inexpensive. Best O' Luck!
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Old 04-16-2003, 07:49 AM
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Join Date: Jun 2001
Posts: 259
Thanks a bunch.

Thanks for the great detail.

Not sure what you mean about spitting back through the throttle valve but except for the standard constant weeping at the EHA, I see no fuel anywhere else.

A few days back I ran the car in the dark to see if the wires were sparking and I could make out very faint spark off of the main coil to dist cap wire-verrrrry faint thought-that tell you anythhing?

Can I test the coil, ECU (what is that?) and the low voltage brushes with a standard meter? Any help with the test procedures would be welcomed.


J. Boggs
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Old 04-16-2003, 08:13 AM
Registered User
Join Date: Sep 2002
Location: Newcastle upon Tyne, UK
Posts: 215
Sounds like weak mixture. Too much air or not enough fuel.

Rogue has done the obvious 'not enough fuel', now look for too much air.

- leak in vaccuum system as you suggest
- leak or split in air hoses etc.
Cheers, Neil
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Old 04-16-2003, 09:53 PM
Registered User
Join Date: Mar 2003
Posts: 16
Name That Mistune

Hello JBoggs. By spitting back, I was referring to erratic timing -- kinda like the old Chevy spitting back thru the carberator when the timing was off. Many times when the secondary coil windings have a small open, the coil will discharge erratically; thus, sending a pulse down a plug wire causing a cylinder to fire at an inopportune time and cough or spit back thru the intake if the valve is open. doesn't sound like you've had that problem. While the Haynes manual is relatively useless, the section on ignition diagnosis is very applicable. Use a volt/ohm meter & perform the indicated tests for the coil & ign. control. Another option(suggested) is hook engine up to a scope & observe test patterns & total coil output. From your reference to very weak color voltage from coil wire, that to me indicates low coil voltage. Before you condemn the coil, make sure that the coil is getting sufficient voltage. A coil receiving low voltage cannot provide max voltage to the plugs. If so equipped, make sure the coil over pressure(read high heat) pop-up has not popped up. And as Neil suggested, check your vacuum lines for leaks. Finally, all suggestions assume that you have maintained the car in good operating condition. I'm sure you have but I had to say it. If budget allows, go to a service center for a written diagnostic; otherwise, get your vot/ohm meter. On my 190E the diagnostic connector is on the inner fender panel.
Personally, I still suspect a dirty fuel filter or faulty fuel pump/relay. My 2 cents.
Keep us posted :-)
P. S. Almost forgot, voltage regulator. On my 190E the voltage regulator brushes are housed in the rear of the alternator. I have not worked on your model(read cannot afford, wish I could), check your manual. The brushes and/or brush holder are easily replaced. I actually bought a decent alternator off of ebay & carry it as a spare, complete with new voltage reg. If the voltage reg ever fails, you Will be stranded as The Benz is dead! Easy insurance other than the belts a B*tch :-(

Last edited by Rogue; 04-16-2003 at 10:05 PM.
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Old 04-17-2003, 09:55 PM
Senior Member
Join Date: Sep 2002
Location: New Jersey, U.S.A.
Posts: 2,398
Cap, rotor, suppressors/wires. Passing from 40-70 MPH and hill climbing put a high load on the ignition system!.
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