# CIS-E low power poor mileage



## ps2cho (Apr 16, 2009)

Hi guys,

I have a 1987 Mercedes 260E and I seem to be getting nowhere on our forums so I am here looking for a fresh perspective.

My MB uses the KE-Jetronic and I am experiencing very poor power and my fuel economy has dropped dramatically. I used to average about 20-22mpg on my daily journeys. I now get 13-13mpg average, along with the loss in power.

Ignition system is brand new, plugs rotor cap etc, New EHA, New Injectors, Cleaned fuel distib, no vacuum leaks.

Mixture is functioning correctly. I adjusted to 50% and it fluctuates. After changing injectors it went outside boundaries and went into open-loop, but after a quick adjustment it came back within control realms and is in closed-loop again.

Control pressure is to spec. 5.1 + 5.5bar

O2 sensor is fluctuating from 0.1v-0.9v when connected to ECU. When disconnected it reads 0.8v which indicates very rich....makes sense...

Any ideas on what the heck could be going on?

Thanks!


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## ziddey (Apr 16, 2006)

How old is the oxygen sensor?

When you changed the injectors, did you check that the spray pattern of each was the same before installing back into the head/manifold?

The engine coolant temp sensor is also used in fueling, but if you are going into closed loop, I wouldn't spend the money here yet.

You were having these problems before you refreshed the ignition system? Imagining timing didn't skip anywhere?

Does the exhaust smell noticeably rich? When making mixture adjustments, which way have you been going? Enrichening?

Sounds like the oxygen sensor might be out, but usually you can see abnormal behavior when watching the DPR (EHA?).

You can try unplugging the o2 sensor, and enleaning the mixture a step at a time and going for a drive. If driveability ever improves, you're getting closer to proper mixture.


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## ps2cho (Apr 16, 2009)

Wanted to update....

I think I figured out the issue. I was swapping the distributor and noticed the gas was brown and dirty. I looked closer and saw what seems to be some sort of sediment 

Rust in the fuel tank or a split fuel filter (even though its only 10k mi old) ....which would mean the distributors micron filter is probably blocked.

CIS Flow Tech rebuild I think.


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