My 1992 300E performance was not good after sitting for several months. In the Washington area I'm in it is impossible to find non ethanol fuel. I know the CIS system does not tolerate the alcohol very well as it will absorb water. I put in a bottle of Techron and took a trip and engine is much better. I normally use Techron but wonder if there is a better additive such as SeaFoam.

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Handyjay

The best additive you can get is conveniently attached to your right ankle. Use that foot to push down on the accelerator pedal. These cars like to run and run much better because of it.

My idea of a good drive is to pick someplace an hour away, mixed interstate, back roads etc then get there, enjoy a snack or something and drive back home.

Jayare

Sent from my XT1710-02 using Tapatalk

Old gas makes some cars run like crap. I went abroad for a couple months a few years back and left my Honda in the garage for 60 days or so with a full tank of "fresh" fuel. Whatever the circumstances were, that car did very poorly on that tank of fuel. Hard to start, extremely rough running, and shockingly poor fuel economy. Fresh gas cleared it right up.

My SL sits a lot (also K-jet) and I found that adding Sta-Bil additive to the fuel really seems to help keep the gas from turning to green goo.

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Current stable:
1995 E320 157K (Nancy)
1983 500SL 125K (SLoL)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Gone and wanting to forget:
1985 524TD 167K (TotalDumpster™) [Definitely NOT a Benz]

I add "Star Tron Enzyme Fuel Treatment" in my 1990 420SEL. Dont know if it helps or not but I add 2 oz every tankful - religiously.

Thanks for the info. Still trying to find out what the proper procedure is for reseting or rebooting the ECU. Lots of info out there on newer models but not for 1992 CIS.

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Handyjay

None. The KE jet mixture control seeks to maintain stochiometric conditions so that the catalytic convertor(s) produce minimum pollutants. A new O2 sensor can help, as can insuring that the duty cycle (on/off ratio) brackets 50%.

Frank, by "None" are you saying there is not a proper procedure to reboot the ECU? I replaced the O2 sensor last year along with the OVR. The car accelerates well now, and cold start idle is about 1000rpm until put in gear and then stumbles around 500rpm until warm up. Cleaned the aux air valve but no change. The car has 52,000 miles. Plugs, wires cap rotor all new. Temperature sending unit new. How would one determine the duty cycle?
Any thoughts? Thanks for your input.

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Handyjay

Best stuff I ever used was redline fuel additive. It’s like $10 for the bottle but was the only additive I have ever used that made a difference. I still use it to this day

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Eugene

10 E63 AMG
93 300te 4matic
07 BMW X3
14 Ford F-150 Fx2

This is the stuff

https://amzn.to/2yvFfUl

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Eugene

10 E63 AMG
93 300te 4matic
07 BMW X3
14 Ford F-150 Fx2

The "ECU", in Bosch terminology, is called a Lambda Controller. It operates the Electro-Hydraulic Actuator (EHA) on the Fuel Distributor (FD) to adjust the fuel/air ratio. The only other output signal is to the relay that switches the air injection pump on & off. Inputs are O2 sensor, engine speed, coolant temp, air temp (some models), baro pressure, air flow sensor position, WOT & idle throttle position, and vehicle speed.
The "programming", such as it is, is fixed, and is non-adaptive. What you see is what you get, installed by Bosch, with no provision for field boot-up or re-boot. It either works, or does not.

On the later units, such as yours, the duty cycle can be determined by the use of the Bosch tester specific to the KE system.

Frank, many thanks for sharing your expertise. I will look into a Bosch tester. My sense is the FD was the problem with setting and ethanol fuel. We will see. Thanks again.

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Handyjay

Pop in half a bottle of RED-X to full tank .

My problem of poor acceleration and low idle fixed. Installed a new EHA valve. Corrected low idle and terrible acceleration. Runs like new.

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Handyjay