In my quest to get more power from my '90 M103 I think I have found one limiting factor. I would like to add a vortech supercharger to the engine. It seems that engines that use a mass airflow system to calculate the fuel metering are easy to modify. If you add more air they add more fuel within the limits of the injectors. I am not sure which system is on my truck, Bosch LH maybe. How does this system work? Does it use a speed density system with a computer map, reading the various sensors, throttle position, temp, rpm etc. to determine fueling from a programmed set of variables? I would guess that this type would be very difficult to program for more airflow. I know my 944T uses a vane (barn door) type sensor to measure incoming air. I do not see this on my M103. Any clarification of the workings of this system and any know ways to alter it would be appreciated.

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90 300GE 5sp
95 740iL
86 944 Turbo

Looks like I may have K-Jetronic, a mechanical continuous injection system. I have to check the owners manual to be sure. I can't seem to find the info on the truck itself anywhere.

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90 300GE 5sp
95 740iL
86 944 Turbo

Your 103 motor uses KE 3.1 and has a airflow door very similar to the 944 except it controls a hydraulic system rather than an electronic control.

The system should do well measuring the extra air you will pump. If you need more enrichment a auxiliary control of the EHA should be able to give all that is necessary.

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Steve Brotherton
Owner 24 bay BSC
Bosch Master, ASE master L1
26 years MB technician

So the door opening actuates the size of the oriffice in the fuel disributer via hydralic fluid? Once airflow has maxed out the size of the opening in the dist. how does an EHA supply more fuel. By the way could you define EHA for me? I know that I could monitor the mixture via a sensor in the exhaust. Would this EHA have any sort of variable control to fine tune the mixture?

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90 M-B 300GE 5sp
01 Volvo V70 T5
86 Porsche 944 Turbo

The EHA (electro-hydraulic actuator) provides all the mapped enrichment for the system, from starting enrichment to cold running enrichment, acceleration and closed loop operation it is all done at the EHA.

I seriously doubt that you can blow enough air into that motor to bottom the airplate but normally this would be accomodated by running the system at a higher pressure.

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Steve Brotherton
Owner 24 bay BSC
Bosch Master, ASE master L1
26 years MB technician