Mercedes W114 250 Coupe - help!

[brucemillar]

Charles

Can you find a "period" counter - SMITHS or the like? I know they can be expensive but a bit of fettling and a discreet pod mount in an air vent? could leave you with that OEM look. The other option would be just go all out "I Have A Rev Counter" and stick a big STACK gauge in there, not attempting to blend it.

 

[grober]

Bluetooth adapters are available but may have baud rate restrictions.
Megasquirt Support Forum (MSEXTRA) ? $7 bluetooth WORKING on MS1! (View topic)

 

[Charles Morgan]

I suspect with time I'll be able to judge revs by engine sound, but at the moment it's entirely unfamiliar and without a helper in the passenger seat monitoring the laptop it is all guesswork.

One bit of entirely un-electronic tuning was achieved. I think the firewall moved a few mm back with all the welding, so adding soundproofing, foam mat and carpet (thicker in total than original) meant the throttle pedal was prevented from making full travel. Remove the foam around the throttle lever and lo, full TPS opening.

The real issue now is the fuelling (the VE table effectively supplements the AFR) and ignition timing. Lots of work still to be done.

 

[Charles Morgan]

Good progress and not so good regress.

Updated the VE Table and it is producing wonderful acceleration at higher throttle openings. The engine is now singing at these revs.

Lower down there is a massive flat spot which I suspect is ignition timing related. Having only me to drive the car is making the task of finding out where close to impossible.

I'm almost certain that the throttle adjuster (it is minimising lower throttle opening and concentrating it in the last bits of travel) is making this effect far far worse than it needs to be.

Idling has got much less efficient and it is cutting out each time I slow down. The AFR meter is showing 14.7 at 0% throttle - yet the y axis on my AFR table is starting at 30% throttle and I can't adjust the figures lower down (when you want idle to be just a touch richer).

The electronic fan is not coming on despite having programmed it.

Minor but very frustrating things to sort on my own.

 

[grober]

Charles have you checked for an error between actual and commanded ignition events with a timing light?
https://www.diyautotune.com/support/tech/other/base-timing/

 

[Charles Morgan]

Yes. That was done on the rolling road session for idle and low load.

 

[Charles Morgan]

Prevailed upon my very computer literate brother in law to join me for a drive and data gathering session tomorrow. At least now I can get a handle on at what point in the rev and TPS position the flat spot is occurring.

 

[C43AMG]

Good luck Charles.

 

[Charles Morgan]

Progress, again of sorts. Coasting to idle it no longer cuts out (a very simple tweak to the fuelling at low revs and 0% TPS).

BIL was able to see where the flatting (hesitation and misfiring) was occurring (gear dependent) so we adjusted the fuelling at the worst levels and that made no difference, so it's definitely timing related.

However, I am going to change the throttle bar modulator for the 1:1 one - there is such a cliff edge at wider throttle openings it makes the tuning much more difficult as a tiny change in pedal movement can effect a 40% change in throttle opening when the gearing effect is removed.

My instinct it is not advanced enough timing (plus some continued over-fuelling coking the plugs), so I am trying to persuade young Billy from Project shop to come and do some live mapping as he has done it very successfully on several cars for which he has set up the mappable 123 electronic dizzies - the Daimler Dart V8 123 available has been set up by him and the factory have used his timings.

Then when I can drive the thing proper distances without issue, a real refining session on the rolling road.

Whether I can get this done in time for Benz on the Green is currently not clear.

 

[trapperjohn]

Good Luck Charles lets hope Billy can work his magic for you and Brunnhilde.

 

[grober]

72 280SE M130 MFI - Need Help timing this beast... - PeachParts Mercedes ShopForum

 

[Charles Morgan]

My timing isn't far off that, but my fuelling most certainly is different to the M130 in original form (and the M114 for that matter), so a lot more work required.

As it was Drive it Day yesterday I took Tony, the neighbour who gave me the car almost two and a half years ago, out for a short run. The roughness got worse with the length of time out, almost as though with the engine warming up it was misfiring a bit. The point of course being that here I am, a history graduate, trying to optimise an engine with a fuel injection system that wasn't developed for it, so missing the numerous engineers and a large budget, I must expect it to take some time. Tony enjoyed going out in the car, and we checked one plug afterwards and it wasn't particularly black so the fuelling (except at start up) is a lot lot better.

 

[grober]

Only non ignition thing I can think of might be engine valve clearances which would close up on warm up. We always forget about these in the pre-hydraulic tappet engines. Can't remember the engine rebuild details now sorry.
http://s272261875.websitehome.co.uk/gal251981502/pdf/M180_rebuild_guide.pdf
wouldn't take the above as gospel either

 

[grober]

An explanation taken from another site.
You need to keep your valves adjusted in the specified range. Within that range, looser valve adjustments promote smoother idle, more stable idle at lower idling rpm, and increased performance in the midrange. Tighter valves promote higher rpm power but also increase wear. And the power difference is not going to be greatly noticeable.
There is an irrefutable advantage to running the valves at the loose end of adjustment, but it's not performance. Gains in reliability, longevity, and ease of maintenance are produced from running the valves at the loose end. This is because valves adjusted tighter wear faster and go out of adjustment quicker than valves that are adjusted looser. Having the valves at the looser end of specification will make it more likely that the valves will still be within spec at their next adjustment, contributing to ease of maintenance and slower engine wear- but ALWAYS stay within the specified adjustment range.

which seems to chime with Charles running symptoms- valve clearances too tight?

 

[Charles Morgan]

Interesting possibility, I'm also looking at the possibility that the estimated injector dwell time is wrong, which would not help.

 

[grober]

I'm assuming Charles your valve clearance adjustment is something similar to this rocker arm and adjustable height ball pin pedestal?

Taken from this thread
https://www.sl113.org/forums/index.php?topic=18743.0
I notice the M114.980 EPC lists two shims for the rocker arm[A1140550001]-----------

A1300530453 =3.5mm
and
A1300530553=2.5mm
presumably to compensate for rocker arm wear and achieve the correct clearance-- altho the article refers to a M130 engine where the correct valve clearance cannot be adjusted due to valves with shorter stems I think .
Just something else to ponder

 

[Charles Morgan]

Update - Brunnhilde is up at Project Shop trying to improve the running. Another compression test (the first was done by starter motor before we fitted the engine) which showed excellent compression, and a leakdown test which showed it to be very good. Next step to start playing around with timing and see where we get to.

 

[Charles Morgan]

Progress at Project Shop in my absence - John Weller is cracking on with all the ignition and fuel mapping. It is reportedly coming on very well.

 

[Charles Morgan]

Ignition barrel transplant in progress, Puff the Magic Wagon again alongside, and the East German alternative to a W114 outside.

 

[Charles Morgan]

The saga of finding a tuner who can make Megasquirt work continues. I approached one who was recommended, long 45 minute phone call on how he could sort out the mess etc and then two months has passed since providing him with the info requested and guess what, nothing.

Try another, 4 days since email and nothing. I have come to the conclusion that Megasquirt is the biggest dead end in tuning, my positive experience with the Citroen SM entirely down to a single individual who didn't give up. I'll write up my experience in more detail, but suffice it to say, the car is going nowhere until I can get it running properly and my experience of doing that to date is highly mixed.