Hi all,

I have an 84 280 Se w126 Euro model with the pre-computer K-Jet system.

Recently I had a problem with a bad fuel pump relay which I replaced and now the car doesn't stall as it used to (scary at times).

However, I have a persistent mixture/cold start problem that seems to be getting worse.

When I first had the car, I replaced the thermostat, thermotime switch and egr valve, setup the valve clearances, changed and gapped new plugs (BERU) good cap and rotor arm, no tracking and clean. I would have a cold start problem, it would fire up instantly but the rpms would die off and eventually she'd stall. Applying throttle exagerated the problem. After a couple of attempts she'd idel at about 1000 rpm and slow down to about 800 when she reached 85 degrees.

The idle when hot wasn't silky smooth but no major wobbles or shakes.

Recently I was tearing down the road at about 80 mph and when she came to a rest, I noticed the idle was really lumpy and that the mixture seemed really rich. I have tried adjusting the mixture with a C/O meter but cannot get her to idle normally at all, and at the moment she's running lean under load as the only way I can egt even close to a correct C/O reading is by completely closing the idle adjust valve, and leaning her back to get her to idle below 1000 at idle hot.

I don't think this is a vaccum leak problem as it is an over-rich mixture rather than too lean. Could this problem be:

1. Bad warm-up regulator

2. bad fuel pressure regulator

3. faulty air flow meter

4. Cold start valve stuck open (removing the harness when hot running seems to make no difference at all)

5. Some kind of relay breaking down

6. None of the above?

Any of you experienced K-Jetters out there who have come across this before, I welcome any suggestions.

BTW, I put a new coil on her, no change.

Thanks,

Alex

Yes is the answer, but that is all of an answer you need til you learn how to adjust mixture. Mixture is adjusted by adjusting fuel not air. One adjusts air to achieved desired engine speed.

Mixture is adjusted with the allen screw between the fuel distributer and the airplate.

__________________
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

Thanks for your reply.

I know how to adjust the mixture and understand the principles of gasoline/sir mix and their effects. As I said b4, the problem just suddenly arose, I hadn't touched the mixture prior to this problem occuring. I cannot adjust the problem away, I either end up too lean or way overrich under load.

Thanks,

Alex

Thanks for the input.

After a couple of hours investigation I raised the front of the car on ramps and found the offending leak. It was at some kind of valve assembly which cannot be seen from under the hood. A loose pipe at the assembly which seemed to bypass the throttle plenum and throttle butterfly.

I think it is some kind of anti stall device?

Cheers,

Alex