W116032 450 SE USA Benzin in Öl

Hi Volker,

After quite a long time I am sending the update on w116 - we were quite busy with other stuff.
When all measurements were done we decided to check the valve clearances and timing again. Valve covers dismantled – found extremely loosened/stretched timing chain. So everything needed to be replaced – all tooth wheels, guide rails, rollers. Once all was replaced, the valve clearances and camshaft timing were set up, following with CO measurement. CO dropped to 6-7%, but it’s still high while the adjustment knob on the ECU is at the minimum. When rotating with the knob the CO value goes up, so it means that the system reacts properly. But we observed one phenomenon: when accelerating – increasing revvs CO value constantly rises, which means there is still too much fuel.

Test drive confirmed that the petrol is not collecting in the oil as previously. The consumption is still high (see CO value) – around 17 ltr per 100km out of the city (extra-urban cycle). Another phenomenon – driving style doesn’t have the influence on consumption, it is same when driving fast on highway (meaning fast – 150 km/h) or driving slowly countryside 90km/h. City consumption (urban cycle) is still around 25 ltrs. Compare to the previous state the consumption dropped for 2-3 ltrs.

So far it was done:

- Replacement of all injectors for brand new ones (Bosch)
- Fuel pressure adjustment, measured during test drives – constant 2 Bars (pressure regulator and diaphragm damper replaced 3 years ago for brand new OEM, fuel pump changed for another D-jet in very good condition with low mileage)
- All temp sensors measured (resistance ass per tables) – all are ok (these were also replaced 3 years ago for brand new OEM)
- Vacuum hoses and proper connection check
- Throttle valve switch cleaned, adjusted
- MPS sensor replaced for remanufactured one (coming from American supplier Germanstar), part number matches ECU part number (checked with you previously)
- All air hoses on intake manifold check (new installed 3 years ago - orig.MB)
- Check and clean impulse trigger
- Ignition Timing adjustment
- Drive test with oscilloscope connected – impulse signal varies continuously with the load from 2 to 10 msec
- wiring harness check (remanufactured 3 years ago) – we found one mistake, 2 injectors were wrongly connected/swapped. It was also visible on graphs from oscilloscope.
- Supplementary air valve remanufactured by Volker
- Engine compression test done – values ok.
- Timing chain, wheels & rails renewal
- Valve clearance adjustment

After all these jobs we reached CO value drop from 12-14 to 6-7%, but the mixture is still too rich. There was one job done on ECU 3 years ago – reportedly some old resistors and capacitors were replaced. Based on the above and your observations and advices in your D-Jet guide we assume following – during the ECU repair components with different specifications were used thus ECU is not regulating as it should be.

Volker, as you really helped us with AAV, would it be possible to send you also the ECU and MPS sensor for check? Please let us know (or PM). Thanks a lot.

Regards,

Petr&Petr

Hello Volker, any contamination was traded oil and filter.
BR. Petr

Hi Volker, yes, the car is eating our brains..Petr tore already all his hair, being completely bald now...but we are not giving up this journey Oil, oil filter changed properly.

PM sent.

Rgds,Petr

Hi Volker, my apologies not referring the succes...thnx so much again for tuning/setting the sensor. Everything installed back, emissions like almost new car . I did not have a chance to test it for longer period, consumption dropped for sure, but once that white nasty substance is off the roads and winter over I will continue, need to check emissions again.
Rgds, Petr

Hi Petr,

you are welcome and thanks for updating us!

Hi Volker,
did you check the ECU, too?

Norbert