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ignition leads

Started by nathan, 03 November 2006, 08:21 AM

nathan

hi all,
considering its been quiet on the board, i feel compelled to post.
after a recent episode of some serious shuddery take off at low revs in my 6.9, the mechanic replaced a 'cap' in the leads between the distributor and spark plugs.  i thought it remedied the problem but alas, the odd shake came back today in similar situations (although 95% cured!)...i discussed it with him and asked if new leads would cure the problem which he thought was best...are these 6.9 leads unique (supposedly the 450 leads with 5 ohm resistance are not great) or are there any modern improvements i should be aware of? 
best regards
nathan
1979 116 6.9 #6436
2018 213 e63
2011 212 e63
2011 463 g55
2007 211 e500 wagen
1995 124 e320 cabriolet
1983 460 300gd
1981 123 280te

alabbasi

I would stick with the correct leads for the car even though they are a little expensive
With best regards

Al
Dallas, TX USA.

oscar

It'd be interesting to see if you could borrow a new set to test if that made a difference.  After my learning curve with d-jet a few months ago, everything I read and was told about troubleshooting FI said to rule out ignition first.  I ended up buying Bosch leads to replace the decrepid missmatch of wires I had on the car, which showed no improvement IMO.  In the end, 2 FI components were the cause of misfiring and shuddery performance.  After fixing/replacing those parts, out of interest I replaced the new wires with the old and again noticed no difference. 

It left me sceptical somewhat about the "need good wires" argument, in a way similar on thoughts discussed about the right engine oil.  After all, most of my car's life has been lubed with the cheapest crappiest no name brand oil before I took ownership and despite the need for new valve guides, compression is between 160-170psi on all cylinders and the engine runs smooth even after >380,000km.

However, partly due to hype, word of mouth, testemonials, good science, and the general belief in - "you get what you pay for", - I use Penrite oil, have my Bosch leads on and wish I forked out extra $ for Beru's.  In the end, using OEM is your best bet for reliability before suspecting another component.

FWIW, before I bought the Bosch leads I converted the right hand bank to modern silicone ones ages ago and found the insulation material around the dizzy's studs went white.   Although the engine ran fine I stopped experimenting after that and got 2nd hand Beru's.
1973 350SE, my first & fave

oscar

Quote from: styria on 03 November 2006, 12:53 PM
BTW, what were the two FI components that actually caused all your problems ? Trigger points and MAS ? Would be interested to know.

Yes, trigger points (repaired) and MPS (replaced). 

Nathan's running issues on take off reminded me of mine, but I got no clues on how k-jet let alone 6.9 specific things could cause it.

BTW re leads; MBSpares puts up a good argument for the affirmative from experience.  Towards the bottom of the newsletter after the concours info and under ignition leads.  They even gave our forum a plug, thanks JG. http://www.mbspares.com.au/default.asp?d=201137&p=17935
1973 350SE, my first & fave

jjccp

I just changed out my plugs, rotor, cap and wires on the 6.9 and it made a huge difference. Sometimes you have to eliminate certain items before you can find the bad component. Did the fuel filter too. Then I cut open the old filter and found it to be very clean.

BTW, I used the Bosch wires from Autozone for US $102.99. Although not identical to the original set, they work fine. The part number is 09029 and you can order them online and get free shipping.

Jim


1977 280 SE
1978 San Juan 23
1979 6.9 #6846