Mercedes W114 250 Coupe - help!

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Its perhaps a sobering thought that Mercedes themselves only briefly toyed with sequential injection Jetronic-D on these early cars before adopting the CIS [ continuous injection system] Jetronic -K on their later models- perhaps because they acted more like carburettors??? Leaving that troubling thought aside it could be a myriad of things that might go wrong as the car warms up over time. While its easy to blame the megasquirt [ the computer] - these things rarely go wrong as electronic components are pretty reliable-- what goes wrong are its inputs or alternatively certain "constants" that vary- an example might be fuel pressure- which might drop if say a vacuum was to develop in the tank? Its likely to be a problem with a primary input signal however which might be timing related- both for ignition and injection? While you have chosen to employ a large timing wheel on the flywheel Charles most megasquirt conversions seem to use a smaller timing wheel on the front crank pulley- could this be a clearance problem as the engine heats up? The other alternative might be to employ distributor timing like the old D jetronic using one of these new electronic distributors?
Just a few random thoughts nothing concrete!
 
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Engine is running perfectly Graeme, it is entirely devoid of mechanical issues. All the sensors have been checked and record perfectly. The timing has been checked etc. It is the inputs in the ECU that need sorting.

The problem is entirely down to the tuning - it is finding a tuner who will map it to get the best combination of performance and economy. No conventional tuner has shown any willingness (quite the reverse - their business model is based on selling OMEX and being told how to set it all up by the latter) to do any optimisation as it requires them to understand the set up (Northampton Motorsports were a classic example -they set it up completely incorrectly while pocketing £90 an hour plus VAT). Meanwhile MS tuners are thin on the ground and much given to declaiming the performance of conventional tuners.

I'm not going to go over old ground again.
 
Another thought vis a vis hot running problems- could that elegant /neat metal fuel rail be a little too close to the engine for comfort? The orginal injection piping was a bit of a dog's breakfast cosmetically speaking but had flexibility and a lot of surrounding airflow round the pipework---- Could you be getting a fuel vapour lock/ or airleaks in the fuel rail ???
 
Problems all sorted - there was an exhaust blow between manifold and downpipe that got worse with temperature. Some repair welding and a much better retaining bracket resolved the issue.

I am not going to tempt fate by saying there are no other faults but at present the thing standing between me getting full use of the car is the map, being fuelling, timing and correct installation settings. For that I need a competent tuner who understands programming MS, or to change to an ECU that more people are capable of programming. Which is why I said MS is a tuning dead end. There are too few people prepared to do it and those that have said they can have so far, without exception, been flakes of the first order.

It will be resolved, but on current timing this classic car year has been entirely lost to me.
 
Well progress of sorts Charles. :thumb:It must be highly frustrating after all your efforts to get the car running correctly over its entire operating range. :wallbash: You are probably paying the penalty of being the first to Megasquirt the M114.980 2.5 engine, so no previous maps for guidance.:confused: Closest will be the 2.8 M130 I would guess? but the only 6 cylinder engines of that era to be "squirted" would appear to be the twin cam M110.:(
 
Would one of those clear spark plugs help with mixture settings, so you can see what is going on in the combustion chamber air/fuelwise across the rev range...?

Is there nobody at MS themselves that is willing to lend a hand...?

Maybe get a hold of one of these guys or somebody equivalent in Australia, lots more experience than the UK I'd say and if they were full of it they wouldn't be round long doing this sort of stuff in this part of the world.

https://www.megasquirtnz.co.nz/
 
The wideband lambda sensor is what ensures the correct mixtures.

Being programming, which can be done anywhere, that is a very helpful suggestion. The real problem remains that the only way to get the best results is to tune on a rolling road, which I'd quite like to be a little to home closer than NZ!
 
Of course.

I am surprised MS hasn't gotten in behind you and sorted the problem.

Can you flip the situation and say "this system doesn't work", to be replied with a "yes it does", setting you up for the "show me then" line.
If they can't make it work it's money back with an invoice for your time and efforts to date.

Hard ball time Charles...No...?
 
MS aren't in any meaningful sense a company - it's an open source tuning chip that depends entirely on external tuners. It's another reason why I have come to think of it as a tuning dead end - when the chips (sorry) are down there is no external support. It's one of the reasons I think that rolling road specialists aren't able to support it - they get no support themselves.

Anyway, when I'm back from my outings today I'll register on the NZ forum as I've yet to find a single tuner here in a position to offer meaningful help.
 
Ah, I hadn't understood the MS situation.

Well is it a matter of linking up with as many MS people as possible globally - somebody somewhere has the information/knowledge you are looking for, it is just a matter of finding that person...
 
WDB124066 said:
somebody somewhere has the information/knowledge you are looking for, it is just a matter of finding that person...
Click to expand...

Unless nobody has done/encountered it before, that is.

MS is definitely the Maplin home electronics end of ECU - I see plenty of reports of spurious and unexplained behaviour and less than perfect consistency that people are willing to write off because it's dirt cheap. A repeat offender is that the ECU seems to lose everything and have to be reloaded with the map again.

A Motec/Syvecs/AEM/Emerald/Haltech is several times more expensive. That buys you a more consistent hardware build, better backup and better support with the tuners.
 
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My experience with the SM may have served to deceive but it was rock solid. Much of it is down to who builds it.

Tuner support is the criticism that chimes with me completely. Having said which, on my BMW 02 with an Omex ECU the results from different tuners were, putting it as delicately as possible, rubbish to OK. Most retail tuning is focussed on a very small range of engines with an awful lot of experience in making those work.
 
Quite amazingly someone on the Alpina Register forum has just had Megasquirt 2 fitted to his Alpina C2 (a 2.7 litre E30) which was mapped at a rolling road some 20 miles away. But to add to that - just after he posted the details of the tuner, the guy I mentioned in post 2640, who has not been in touch for 2 1/2 months, emailed to ask how I'd like to proceed. I think it might be with someone local, but inevitably that requires him to be keen to do it.
 
Ah, off to see Charlie. I'm sure he'll be able to set things right. :thumb:
 
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