Lose of Power 560 SEL - Page 3 - PeachParts Mercedes-Benz Forum

waylifeshouldbe · #31 12-13-2003, 08:33 AM

Hi Moedip and all - Thanks for the hint. I looked up hall effect and got nothing in AllData. Can you tell me where it is exactly? Does Mercedes call it something different? After cleaning up the wires and all it appeared quite evident that a new set is in order. Although chaffed in areas I don't have a strong feeling that wires are the cause - just ready to replace. After cleaning up some ground points, my "hard-to-start" issue seems to have been fixed. The car did the same old "lose-of-power/hesitation" last night. Not the coil/cap/ or rotor.

#32 12-13-2003, 05:27 PM

I had a similar problem with my 420 SEL some years ago, and it was driving me crazy. It turned out to be a loose nut holding a ground wire. Sometimes it would vibrate loose and the car would loose power because of loss of electicity. Of course when it was just idling, there wouldn't be any vibration to make the ground loose contact.
If you haven't found the problem, you might let the car idle and shake the all the wires (except the sparkplug wires) and see if you can replicate the problem.

Good luck

cc260E · #33 12-14-2003, 06:45 AM

Quote:

Originally posted by swyoung
[B]I had a similar problem with my 420 SEL some years ago, and it was driving me crazy. It turned out to be a loose nut holding a ground wire. ]

Could you tell me which bolt it was?

#34 12-14-2003, 12:51 PM

This was some years ago, but I believe it was on the intake manifold or very close proximity to it. The key in finding it was shaking the harness in the dark and looking for a spark.

I hope that helps.

Good luck

waylifeshouldbe · #35 12-16-2003, 04:14 PM

the answer to my intermittant "stumble". Man when this car runs right it sure is a pleasure. Ran great all day Monday. Tuesday first half of the day no problem and then 10 minutes after turning car off when out to run an errand and in the first 5 miles the tach indicated erratic behavior illustrating the car's "rumbling/misfiring". This time it did not stall out - I only had to keep constant pressure on the accelerator and "drove through it" till it smoothed out (20 seconds). I picked up a set of new wires. Will install tonight. Have checked all wiring that is otherwise easy to check. Also sprayed all connections with electrical cleaner with no change. Will keep all informed. I'm starting to lean towards a fuel delivery problem. may have to purchase an hour of Mercedes diagnosis time.

mhingram · #36 12-16-2003, 04:34 PM

did you every pull and resolder the fuel pump relay? This is a tough one.

pentoman · #37 12-17-2003, 06:34 AM

I feel strongly this is not a fuel pump relay issue but if you're lost...

Anyway hope you get it sorted soon!

Make sure you get the exact correct set of wires, not some 'one-type-fits-all' rubbish!

Rusty

waylifeshouldbe · #38 12-17-2003, 07:24 AM

I know this is a bit early but I feel compelled to keep those that have expressed an interest - which I surely appreciate and have benefited greatly from.....I replace the wires yesterday. The wires are made for the 560 SEL and fit very nicely. They are constructed of "silicon over silicon" and carry a brand name of "STI". The old wires when put next to the new certainly showed their age - chaffed, not very malable, etc. After installing I took car out for a 20 minutes test. I swear the car never ran better - great response and smooth power delivery. Could it be my imagination? Possibly. This problem has a way of not showing itself for a few days. We'll see. To answer in regards to the fuel pump relay: I visually inspected and could not find any indication of solder joint breakage. It looked very much intact and complete. So far I have inspected the fuel pump relay, cleaned all (many) electrical contacts, inspected/cleaned grounds, replaced coil-plugs-cap-rotor and finally wires. If car continues running as great as it did last night and this morning (3-5 days) I would have to conclude it was the wires. Do any of you believe faulty wires would exhibit the symptoms I've described? Keeping you informed - wish me luck!

#39 12-17-2003, 09:25 AM

Could have been a break inside one of the wires. To find out - hook up an ohmeter across each wire - one at a time of course - and measure the resistance. Then with the ohmeter firmly connected to each end of the wire - flex every inch of the wire while observing the resistance - then push and pull along the entire length of the wire -if it shoots up at one point on a wire - you have found the problem. The reason I suggest this is that if you find the cause eg wire with internal problem - then if you ever have the same symptoms again - you will have a troubleshooting proceedure to use - as will every one else who has followed this thread. Replacing a bad wire is curing the problem - finding out what failed is good troubleshooting practise.
Morris
PS - Have a Blessed Christmas.

mhingram · #40 12-17-2003, 10:09 AM

Woody, It sure would be nice if it is the wires. The issue sure does act like a bad connection somewhere in the ignition system. I think however, we will have to look outside of the ignition as the only things left are the rpm sensor and the ezl.

m

waylifeshouldbe · #41 12-18-2003, 11:09 PM

I am now pretty confident that after three days following the installation of new wires - my intermittent misfiring/erratic rpm issue is history. Thank you very much all for chimeing in and offerring your well thought-out coments and guidance. I have learned a bit more than otherwise for the experience and now look forward to tackling more pleasing improvements to my 88 560 sel. Happy Holidays to all!

mhingram · #42 12-19-2003, 08:40 AM

great news woody.
m

#43 12-19-2003, 09:11 AM

Woody please check the wires with ohmeter as I suggested - if the faulty one shows up - tell us what you did to get it to act up - it would be a great help to all if we had a troubleshooting technique to find a bad wire - if what happened to you happens to one of us - it would save us the grief you went through and changing the wires or other components on spec instead of troubleshooting. and changing only what is needed. Congratulations on getting it fixed and Merry Christmas!!!
Morris

waylifeshouldbe · #44 12-20-2003, 08:56 AM

I'll bring the old wires to work Sunday night and run a test. I'll post what I find. Car still running great. Now I need to decide whether I should take on ball joint replacement or call my mechanic - after that air cells - but thats for another thread

Merry Christmas

waylifeshouldbe · #45 12-24-2003, 11:08 AM

The # 4 and #5 wires had significant detrioration of the insulation to the point where when one bent them the metal shielding would show. There was also a dull-whitish color to all but the #4 and # 3 wires at the cap end. The #4 and #3 were of a copper color. The car has operated wonderfully since changing to new.