3.2 starting issues

[Dieselman]

I'd be tempted to open up the ECU and meter back to the output chip(s). There may only be one supplying all the injectors or there may be six.

Once you have the IC number it's just a case of buying it/them and a quick blast with the soldering iron.
The output devices will be cheap as they are simple switching devices.

5v fed from the main Lsi will switch the internal transistor on to short the injector return line to Gnd.

Given this issue I might be tempted to install a fuse on the 12v feed to the injectors.

 

[television]

I'd be tempted to open up the ECU and meter back to the output chip(s). There may only be one supplying all the injectors or there may be six.

Once you have the IC number it's just a case of buying it/them and a quick blast with the soldering iron.
The output devices will be cheap as they are simple switching devices.

5v fed from the main Lsi will switch the internal transistor on to short the injector return line to Gnd.

Given this issue I might be tempted to install a fuse on the 12v feed to the injectors.

There must be 6 output devices as the switching to do it any other way would be horrendous and would be a problem within itself

 

[Dieselman]

Not necessarily six seperate devices.
I'm not sure whether the injectors operate individually or simultaniously anyway. There is no need for them to be completely seperate, just the dwell needs to change as more fuel is required.

With there being six individual return lines it would indicate that they are seperately switched, but this could be done by either commonly ganging up inside the Ecu or by a single six way output device.

My guess says a single output device covers all six injector returns. It is likely to be a simple digital switching device, no need for it to be controlling voltage and current, just on and off.

That would cost about £5 max and take about ten minutes to swap over even on a double sided board.

It would be interesting for Mark to open the case and trace it back anyway, just for info.

 

[Mark300SL]

ECU will be coming out this evening anyway - so I will open it up and see

At least this one isnt coded, so when I find a replacement it shouldn't be a major problem.
I'm certainly not against repairing the original and I have a desoldering station, but I will likely send it up to Scotland to the guy who does my Honda ECU's - he has a much greater undertanding than me and to be honest the quality of his repair work is in a totally different league to mine

For anyone wondering the ECU's dont come out of this car easily - its a major mission to remove the ally casing that sits where the battery used to be in a stock 190and there is no other way of getting the ECU's out. Fortunately Ben made a tool to remove the rear mounting bolts so that makes it a bit easier

 

[Mark300SL]

Not necessarily six seperate devices.
I'm not sure whether the injectors operate individually or simultaniously anyway.

Not sure about the device level, but HFM is most definately sequential FI and therefore should be individually switched. This also ties in with the 6 seperate injector earths

 

[Dieselman]

Not sure about the device level, but HFM is most definately sequential FI and therefore should be individually switched. This also ties in with the 6 seperate injector earths

Sounds logical, but I suspect there will only be one driver supplying all six signal lines.

If so it's dead easy to replace them. Snip off all the legs then desolder individually, suck out the holes and install and solder in the new device.

You would probably find stock at either Maplin, RS or Farnell as it's only 12v switching.

You will probably find the device just by sight as the top will be blown off or cracked due to the current of a dead short.
If not a quick continuity check back from the injector signal pins should soon provide the answer.

 

[television]

Mark, the info is sparse for the 140 in my current programs. I have more info under the 124

What was the engine number 104 ??? Please, I just want to see what I have on this

OK I found it 994

 

[jagmad]

Defective wiring loom

What you need is A2025406081

or MA124 546 09 80 GO40102 CABLE LOOM

Can anyone advise where I can purchase these repair cables.
Is it Merc dealer part number?