S-Class (W126) 1979-1991: 300 SE, 300 SEL, 380 SE, 380 SEL, 420 SEL, 500 SEL, 560 SEL, 360 SEC, 500 SEC, 580 SEC, 300 SD TURBODIESEL, 300 SDL TURBO, 350 SD TURBO, 350 SDL TURBO

1988 500/560 SEL injection problems

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Old Oct 5, 2006 | 07:24 AM
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1988 500/560 SEL injection problems

Hi all,
I now have a replacement ignition module for my 500 sel, it was obtained from a 1988 560 sel and was interchangable luckiy for me.
The car now starts and runs well but has a fuel injection problem with hunting and over fueling until it is up to normal tempreture.

I have two problems im trying to find out more about!
1/ The engine has a version of CIS E (Bosch KE jetronic 3?) that im not that familiar with but from what i understand it should have an O2 sensor that is used to fine tune the cis via a fuel regulator on the meetering head. The engine starts well but has a rough runnng problem and surging with black rich mixture eminating from the exhaust during warm up. I have looked around the whole exhaust system and i cant find the O2 sensor. I dont have a cat fitted and the exhaust has two very new looking pipes running from the headers down to the rear muffler boxes. It is possible someone has removed the O2 sensor by mistake? i cant see a plug for it if it was fitted, where should i be looking if it is sopposed to have one?

2/ Does anyone have a vacuum tube and piping diagram for the 500/560 sel engine? My fuel pressure regulator has a hose off it that i think should go to an atmosphereic vent connection somewhere. i also have the remains of a plastic pipe coming from the lower throttle body that i have temporarily connected to the small hose fitting on the engine breather, and there is a red/black pipe that seems to run accross the engine from a solinoid valve behind the left headlight and then down to a clear pipe towards the transmission tunnel on top of the bellhousing?

Any files or other information greatly appretiated
Mike
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