EFI vs CIS - Page 2 - PeachParts Mercedes-Benz Forum

GGR · #16 10-12-2009, 08:20 PM

D-Jet systems can be reliable even 40 years later. I just did 10.000 miles last summer around the US with a W111 Coupe equipped witha Djet 3.5. My only issue with the system has been the non original fuel pump relay that didn't like the heat of the desert. Problem sorted out on the spot by bypassing the relay with a bit of wire. The problem is the price of some elements when they go wrong: MAP sensors and trigger points are a scandal.

I am currently working on a euro 5.0 M117 that will go in that same car. I am replacing the Kjet system by Megasquirt. In this respect Djet elements come handy, starting with a 4.5 Djet intake manifold that I have grafted to the engine. It was designed for EFI from the beginning, so no strange air routing through the ruins of the Kjet system. Throttle body and intake ports diameter are the same as on the CIS system (later M117 engines went for bigger diameters though). D-jet injectors and rails are a straight fit and plenty available around. I will also be re-using the Djet fuel pump and air & water temp sensors. There were some clearance issues with the 4.5 plenum that were sorted out with a bit of grinding. But nothing compared with the work and cost involved with the fabrication of fuel rails as I have seen in other posts. In a few words, I keep the reliable and readily available D-jet stuff and I ditch out the problematic ones like the trigger points and MAP sensors as well as the "computer". Granted the look of the Djet style air cleaner is not as nice as the Kjet ones. But with the older style valve covers it will look stock in my W111 Coupe. Below are some pictures:

babymog · #17 10-12-2009, 11:09 PM

There was a really sweet Shadow Can-Am car at the Elkhart Lake vintage races last year with the entire fuel-injection system hidden under the intake horns etc. to look stock, really nice job. Your photos remind me of that car, looks like a fun project.

400Eric · #18 10-15-2009, 02:36 AM

Quote:

Originally Posted by tjts1

So did LH and Motronic with better fuel economy, lower emissions and more power. Mercedes was being lazy with its 90s Kjet cars. The late CIS cars with both electronic and mechanical injection components are diabolical to diagnose and maintain. All EFI cars have 1 fuel pump and 1 pressure regulator. Thats the extent of the mechanical side. The electronic components either work or they don't work. They are not subject to mechanical wear and adjustment. Fuel injectors, sensors, FPRs and pumps are all standardized and interchangeable with cars from a dozen different manufacturers that also used Bosch as a supplier. I've seen plenty of nice Benzes go to the JY in California because they failed emissions and from a Kjet fault. People generally prefer what they're familiar with but selling cars in 1993 with mechanical fuel injection is pathetic. Bosch EFI technology had gone through many generations and was very mature by the mid 80s. The 16 valve 190e could have been a truly great car with EFI, on par with the E30 M3. There is no excuse.

X2! And I should know. I have a 88 300E and a 89 300E as well as a 93 400E. While I love my M-103s, it is true that MB had no business holding on to that system as long as they did. Squirting fuel at a closed intake valve 75% of the time is not the recipe for good emissions, fuel economy, or performance! My LH equipped 93 400E offers up the same fuel economy according to Car & Driver's tests and my own tests, and better fuel economy according to the EPA despite having 98 more horsepower, 107 more ft. pounds of torque, and more than 25% greater displacement. Yes, there are other factors at play here but as far as I'm concerned, it's all win and no lose for the LH when compared to CIS! Anybody disagrees with me can buy my 2 M-103 cars so you can love them even more than I do!
Regards, Eric

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