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Mercedes W114 250 Coupe - help!

(for obvious reasons the current injectors can't be used as they work on the pulse system that D jet uses).

I am slightly puzzled by that remark Charles as don't both D jetronic and Megasquirt use individually or paired or tripled!! pulsed injectors on a common rail unlike the later CIS [ continuous injection]K Jet cars making any conversion easier? [ that's assuming the old injectors work or can be reconditioned of course ?]

see this treatise on the V12 Jaguar engine.
The injectors are simply precision solenoid operated valves which are opened for a brief period once per engine cycle, when they introduce a fine conical spray of fuel into the inlet ports, just upstream of the inlet valves. The amount of fuel injected is determined solely by the injector opening time (injector pulse width) under the control of an Electronic Control Unit (ECU). In most D Jetronic applications the injectors were divided into two alternate firing groups but there were instances of 8 cylinder applications where 4 groups were used. Each injector group is fired once per cycle, timed so that one injector fires during the induction stroke whilst the other(s) must fire progressively earlier in the cycle of their respective cylinders. Obviously some cylinders would be better timed than others but to the disappointment of many purists it didn't really seem to matter very much. That being so, if the firing points of the two groups were reversed there was a definite loss of drive quality. In this respect it is true that 'a little bit of richness can cover a multitude of sins' and really the D Jetronic firing arrangement would certainly not be good enough for modern engines operating with stoichiometric mixtures, but it was much better than carburettors.
http://www.jagweb.com/aj6eng/djetronic.html
 
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The chap who did my SM explained it and I have forgotten, but no, it is a different system for opening and shutting the injectors and they are very much less efficient in pattern than modern ones.
 
/8 Forum
TECH TALK------ THREAD= MEGASQUIRTING THE M110
Good pictorial thread :thumb:but no relevant multi injection info because the guy uses a Holley TBI throttle body injection conversion to replace a previous carburettor conversion.:doh: Still worth a look tho.
 
A little further investigation on the injector issue shows that the development how they were located in the head /manifold was changing pretty rapidly around that time as experience was gained. Early injectors appear to have been modified with the addition of plastic caps to protect the rubber seals for one?
artikel_peter_bild_nachher_850px.jpg

picture from
D-Jetronic Part 2 - a book with seven seals!
the definitive text on D JETRONIC would appear to be
Schulung: Bosch

of which I have as yet failed to locate a free copy online.;)

The blurb does list quite few vehicles which used this system

BMW E3, E9
Citroen DS 21, DS 23, SM
Lancia 2000
Mercedes-Benz 107, 108, 109, 111, 114, 116, /8
Opel Admiral, Commodore, Diplomat
Porsche 912
Renault Alpine A110, Alpine A310, 17
Saab 99
Volvo 140, 160, 1800
VW 411, 412, 1600
VW-Porsche 914
 
For those whose education required the use of visual aids! :p this recent episode of Wheeler Dealers on a PORSCHE 914 shows you what can go wrong with these early fuel injectors. at 17 and 24 minutes in.
[YOUTUBE]3uwgeu881s8[/YOUTUBE]
 
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A quick question. I'm researching the requirements for the Megasquirt conversion, and injector choice is sticking out. I've hunted around but as yet can find no information on the size of the current injectors and therefore what modern replacements to look for.

I can't tell what exact injectors to use but I'd initially choose something like Bosch injectors from any 2.2-2.8. six cylinder i.e., BMW M20/M50/M52 etc, (using BMW 2.5 M20 throttle body is popular choice too). Get adaptors machined up to fit the inlet manifold (common on the Likes of M102 16V's & M103's) for the new injectors along with a new universal fuel rail, cut & drilled to suit with a couple of connections for feed, return on both ends and a FPR, then decide where's best to bolt the rail to the inlet manifold, ideally using original injector location bolt holes. http://trigger-wheels.com/store/contents/en-uk/d51.html

P.s. Also join the Megasquirt site for info & advice. MSefi.com MegaSquirt Forum ? Index page
 
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if only the injector seals were the principal issue with D Jet - but I do need new O rings anyway! What is remarkable is how much the technology changed within a very short space of time, what was a rarity in the late sixties was almost totally ubiquitous 10 years later.

The SM specialist who did my Megasquirt was busy doing two Citroen DS at the same time, and when I popped back in the summer he had a BMW E9 he was doing the same to. If it weren't for the distance (which does make logistics complicated and a bit more expensive) and my thought that there is enough info on the Megasquirt system for a straight six (the map on the Maserati irregular fire V6 is pretty unique and not many people have tuned one!), I'd pop it over to Renard to do.

John - you have the analysis spot on, I'm keen to find a relatively standard injector that doesn't cost a lot new (and can be easily find).
 
I'm keen to find a relatively standard injector that doesn't cost a lot new (and can be easily find).

No need to buy new, especially as you've plenty or other items that need attending to with this project. Just get six suitable & commonly used Bosch injectors that suit the Megasquirt system and your engine, sent them off for testing & cleaning. You'll pick up a set of used injectors for a tenner each and twelve quid each for testing & cleaning - see eBay for both.
 
Just a quick calculation. I reckon you should have a suitable fuel rail - drilled, bungs fitted, connections on both ends and a FRP plus serviced 2nd hand injectors, machined injector manifold adaptors & seals all in @ £400.
 
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Just a quick calculation. I reckon you should have a suitable fuel rail - drilled, bungs fitted, connections on both ends and a FRP plus serviced 2nd hand injectors, machined injector manifold adaptors & seals all in @ £400.

I'd been pricing in new injectors, which obviously makes it much more expensive.
The next cost saving is putting the Megasquirt stuff together as opposed to ready made - I have a friend who is exceptionally capable with electronics who would do it for a pint or two for fun.

The next largest expense are the sensors and the loom - I think they are best bought new!
 
Interesting videos, the throttle bodied ones sound great (my little BMW 02 with throttle bodies was just a symphony on the move), the 2.6 sounding not at all great.

Here's one of the Citroen SM (Renard's not mine) being tuned and tested.

[YOUTUBE]pXgamY5Lfkw[/YOUTUBE]
 
Today was the grand move. After 20 years sitting in Tony's garage the car was surprisingly easy to get out - that Mercedes turning circle helping immensely. The only difficult bit was getting it up onto the trailer but with two ratchet straps that was fine, if slow. Tony2 and Laurence did most of the work while I flapped around, but it could not have been easier, even the model railway was left undisturbed.

Despite appearances the body is entirely free of rot, everything absolutely fine. All the bushes and springs have been replaced too.

The joker in the pack was my BMW which is completely dead, fuel pump clearly packed up. Getting that out the way was the real pain.

Tony2 and Laurence doing all the work

w114home2_zps1f0563b2.jpg


Happy in its new home.

w114home_zps64e2c427.jpg
 
Ooh, a lovely discovery. Vacuum pipes galore in the back and going forward to the engine.

w114vacpipe_zps20e737dd.jpg
 
Seats starting to look more civilised with a scrub with that well know detailing fluid for Vinyl - Tesco's Value All Purpose Cleaner

w114seat_zps7cc9b8fb.jpg


Instrument binnacle and steering wheel also look just a bit better

w114console_zps8eb74c73.jpg


Now the really big surprise of the day - it's a five speed! Ummm....

w114gearknob_zps3e6b985d.jpg
 
From the 73 Autocar review article Articles
The 280CE [ 250CE pro-rata?? ] comes as standard with a 4 speed manual box, but the test model came with the optional automatic unit(4speeds with fluid coupling]
There is the further option of a manual 5 speed box


Indications would be its a GETRAG G76/27-5 BOX shift levers on the sidecover rather than the earlier ZF box fitted to the Pagoda W113 cars
Mercedes-Benz Teilekatalog (Ersatzteile online)
 
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4 Speed ratios on 280C

I: 3.90; II: 2.30; III: 1.41; IV: 1.0

5 speed ratios on 280C

I: 3.96; II: 2.34; III: 1.43; IV: 1.0; V: 0.87

5th is basically an overdrive then - which is a very nice thing to have. It makes the manual doubly rare too.

An intriguing quandary now beckons...
 

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