My 1988 230E W124 has almost 400,000 kilometers on it. The engine block has been refurbished once and is still in good condition. However, the KE-Jetronic (CIS-E) FI system is no longer in good health.

I examined the cost of rebuilding it and discovered that it is quite expensive, as it has many components, such as fuel regulators, fuel pumps, injectors, distribution unit, fuel pump relay, ECU, and so on.


I've decided to discontinue the use of the CIS-E system. And in my area, LPG is far less expensive than gasoline. I'm thinking about removing the CIS-E and converting the engine to run entirely on LPG.

This necessitates the removal of all gasoline injection components (parts listed above) and the addition of the fuel tank, with the LPG tank installed in lieu of the fuel tank. LPG injectors will be installed in place of fuel injectors.

Has anyone tried it before? Is it worthwhile?

I have no plan to sell this car because it'll be my forever car.

It is not that easy.

In the last 40+ years I have driven 4 Mercedes, W114 280, W126 280S, W126 300SE and now W210 280. In total over 2000,000 km.

• If you want a system with LPG injectors you need a sequential fuel injection system.
• The LPG system get the timing signal (when to open and how long) from the petrol injectors.
• The K-Jetronic is not a sequential system so that won’t work, you can only use as older type vacuum controlled LPG system or a system that is designed for the K-Jetronic.
• An other problem is that LPG only works if the engine temperature is above 40°C , it takes a lot of head to evaporate LPG, under 40°C the evaporator freezes. For that reason there are no cars with only LPG, only Bi-fuel, you have to start with petrol and switch to LPG when the engine is warm.
• The valve seats need to be replaced with harder seats, LPG does not lubricate the seats and they get hotter.
• A good LPG system is not cheap, certainly a lot more than the repairing a K-Jetronic.

Rob

Circa 1970 when I was a grad student at the U. of Wisconsin Engine Research Center we prepared two cars of the "Clean Air Car Race" sponsored by MIT.

One was a Opel GT that we converted to propane using a carburetor and catalytic converter common to warehouse forklifts. We also designed and built a mechanical EGR system to control NOx because we had to meet the then proposed 1975 exhaust emission standards.

The conversion wasn't too hard. I'm not familiar with "propane injection" or know if such a system exists today, but if propane carburetors are still around I'm sure one could be adapted to the manifold.

However from a practical standpoint you can probably buy a decent relatively low mileage 124 or 201 on bringatrailer.com for less than any propane conversion will cost.

Duke