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1969 280se (the diplomat) -- 1986 190e 2.3 16 (cosworth) -- 1985 300TD (panzer wagon) -- 2004 E55
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38 Posts
*bump*

Hello all! I've been enamored with the thought of MS in general - mainly for MB->MB engine swaps (M117 in a w123 for instance)

Anyway! I just picked up a 1973 280SE 4.5 (http://i.imgur.com/a5iQJwz.jpg) - and would like to start by MS'ing the fuel at least, and then a complete replacement.

I'm waiting on an alternator and a fuel pump relay (I got her to fire up on 1st inspection with some gas, battery spare relay from my 1969 280SE 2.8)

I see there are broken image links of the ordeal of MS swap early in thread - wondering if there is a pseudo-complete write-up, images, howto and fuel maps and the like for a 73 4.5. It seems I would need

*whatever recommended injectors of a Ford? of all things
*a Throttle Positioning Sensor, as the current one's signal/setup will not work
* O2 or wideband sensor
* Wire up the MS to these existing/new connections

Anything else? I can use the existing rails and whatnot correct?

What realistically else is involved, custom fabrication for simply taking a 4.5 to this level.

It may or may not need it currently, but as to wake to motor up, and not have any ecu/d-jet gremlins or replacement part cost/hunting. (not to mention a method to view/tune the system in real time)

Just seeing the ancient ECU near the headlights makes me nervous. (vs. say the MFI in the 1969 280SE or the W123 300TD for that matter) I already have the CIS in the cosworth to bang my head against :) (I'd think about doing the 16v, but its an all original puppy)


In the future, I'd like to put a 560 in my new 'red pig'. I figure if I start with MS on the existing 4.5, I would have considerably more 'tribal knowledge' and confidence with the implementation.

Thanks again! I've picked up a lot of information here and there, I just need a little push :)

Cheers!
 

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1966 MB 200; Porsche 914 (6); Porsche 914 (Chev 350); 36 ford
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420 Posts
Just my 2 cents,

All you need to get ms to work is:

1. Load sensor, usually a map.
2. Tach signal
3. Intake air temp sensor
4. Coolant temp sensor. ( just needed for warmup)

Everything else just adds refinement. Ms will still fire without the o2, you just will not be able to tune. Having said that, a wide band O2 is a must. ( I am on my third ms install. One is using the above 4 sensors and a wb O2.)

You will still, of course, need to wire the inj, plum the fuel, etc.

Hope that helps.

-- brett
 

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1969 280se (the diplomat) -- 1986 190e 2.3 16 (cosworth) -- 1985 300TD (panzer wagon) -- 2004 E55
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38 Posts
Thank you Brett! Very much helpful.

Can anyone chime in and/or advise on the following? (again just a stock W108 73 4.5)

1. Load sensor, usually a map.

What should I use for a load sensor, perhaps a map? What works best for this motor?

2. Tach signal

Is there an existing connection -- and can it be used? If not what should I get?

3. Intake air temp sensor

Is there an existing working connection for this? If not, what sensor should I plumb into the air filer box?

4. Coolant temp sensor. ( just needed for warmup)

I assume the existing one works fine here

5. Wideband 02

I assume get said sensor (which one) and plumb it somewhere in the exhaust under the front seats about

6. Injectors

I see people using various Ford pieces - I just need to know what exactly I need to get

7. Beer

How much beer is recommenced, and what brand should I get? :)

Thanks again all!
 

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1966 MB 200; Porsche 914 (6); Porsche 914 (Chev 350); 36 ford
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420 Posts
Start with Belgium beer. Golded Drak or Duval. :)

1. MS comes with MAP built in. You just need a vaccum siganl below the throttle body.

2. If you are just doing fuel, you can come off the disty, or if you are using an MSD, off the MSD tach output, which is what I used.

3. GM style IAT. GM Open Element IAT Sensor with Pigtail DIYAutoTune.com I put mine in the intake track and pointing down, so if came loose no parts would get sucked into engine. See my thread on the W110 project.

4. Can't help with that... If you want to use GM style, you will need an adapter. If you use the stock CLT, you will need to calibrate it, which is easy to do.

5. On the W110, I used the existing bung. On my 914, I welded into one of the headers the bung, about 18 inches downstream. (The install kit will have the desired distance in the instructions.)

6. Take a picture of the existing injector connector, more than likely you can use if its electronic, otherwise you may need to adapt. You can get injector pigtails for most common injectors from diyautotune.com. For my 914, I got adapters from a firm in canada. (The 911 motor had the early style CIS injection, and are mechanical injectors.)

-- brett
 

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85 500SL
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8 Posts
Welcome LotusJeff.

My 1980 K-Jetronic had many goodies to meet new EPA standards including a warmup enrichment vacuum circuit, Lambda feedback enrichment circuit as well as vacuum advance and retard of ignition. Megasquirt has been great in eleminating all of these vacuum based potential problem areas. All of that junk is gone now and the motor is truely computer controlled. My car will actually drive smoothly with a bad power door vacuum solenoid. The new fuel plumbing consists of 8 injectors, two fuel rails, a fuel pressure regulator and some fuel line. I swear that with the old K-jetronic system if I sneazed in the cabin it would cause the engine to stumble:)

I have been driving my Mercedes for a couple of months now and I am still amazed that it starts EXACTLY the same every time I turn the key. Hot or cold it doesn't mater. I figure it is starting at about 3/4 of a second of cranking. Just minimally longer than it takes my 2003 Maxima to start but always exactly at the same amount of cranking.

She has been idleing better and more stable than she has since I owned her. This last weekend I changed my settings from 2 injections per cycle to 4 injections per cycle and she is even more rock steady at idle.

Acceleration is silky smooth without any flat spots. The throttle response is instantanious compared to the K-Jetronic. When you look at what has to take place when accelerating with k-jetronic it make a lot of sense.
1) Push on accelerator and open the throttle body.
2) A vacuum is created causing more air to enter the intake.
3) More air rushes in over the CIS measuring plate causing it to lower.
4) The fuel distributor opens to allow more fuel into the intake.
All of these take time and the mass of the measuring plate creates momentum. Add these up they make a big lag in throttle response. Add on top of this the imprecise nature of a mechanical control system. With megasquirt the properly metered fuel is injected near simutaniously with the opening of the throttle body and the arival of air in the intake.

The simplicity of the Megasquirt fuel circuit is so basic that diagnostics are almost eliminated once your car is tuned. I must admit that one of megasquirts down sides is that it does promote tinkering. Even though my engine runs so much smoother that with K-Jetronic it is hard not to try to get that last little bit of fine tuning. When I can sit in the air conditioned (Theoritically) cabin and make tuning adjustments with a couple clicks of the touchpad it is hard to resist.

I have talked little about the computerized ignition advance of MegaSquirt but this in itself is a major improvement over the vacuum based advance.

The process of installation has been such an education that I feel I have a much better understanding of how the fuel system is supposed to work and how to make changes and what I can expect the outcome to be.
Is it possible for you to share the results to us?, I am done with my lumpy idle on my 85 model. Thank you !
 

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'72 250C, '74 280C, '85 500SEL, '81 300CD.
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1,041 Posts
If anyone is interested in 36-1 trigger wheels for the M117 and M116 for converting to ignition control I have them. $20 delivered by USPS. These mount on the balancer pulley so you don't need to pull the harmonic balancer from the crank. Two styles, no difference in readings, I had them made different just to check.

2625800


2625801
 
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