MSefi.com read only forum (Jan.15,2018)

Have MS II on a Mercedes 190E. EDIS ignition. Initially used Megatune and ran with v2.891 from March 2012 to the start of cold weather. Fuel economy became poor. Updated to v2.905 which then required TunerStudio. Had connection problems with Megatune but managed to fight through it. TunerStudio has become impossible to fight with. My laptop is a Dell Inspiron 600m, with XP, which has a real serial port. Looking at similar posts, the cable between the laptop and MS was the problem. I first tried a cable from Radioshack. Then a cable from Cablestogo which was described as shielded. I'm fearful of trying any more cables. I've done the foil covering with no better results.

When operating with the JimStim TS and MT both check out good, but on the car both MT and TS work poorly.

The behavior I am experienceing now with TS is a rythmic on-line ... off-line condition. Sometimes the gauges display something. Most of the time not. I can start my engine and get running, but preliminary tuning is impossible. I don't know what to do next.

Attached is an MSQ file. I don't have a datalog at this time. Thanks for any help that can be provided.

How does MS get its power from the car? And how is it grounded?

trakkies, Thanks for the reply. MS gets powered from the same circuit that the former mercedes ecm was powered by. I have the multiple grounds from MS to a place on the intake manifold. I don't remember how many but something like 6-8 ground wires from MS. WisAndy

Is that the same place as M-B grounded its ECU too also? Are you running the laptop off its internal battery or via a 12 volt converter? It's just that the serial port uses a pretty robust signal so I'd be looking for other causes.
In my workshop, the PC is some way from the bench and I feed the MS serial output to it using ordinary balanced microphone cable about 5 metres long.

trakkies, Thanks again for the reply. I used the existing ground on the M-B ecm harness. From what I recall, that ground connected to a screw on the intake manifold. The additional grounds that MS has are routed external to the M-B harness and connect at the same screw on the intake manifold. The grounds happen to be routed close to the injectors which were not there on the original fuel system.

The laptop is run off of its battery. I have also operated with the charger powering the laptop when the car is within reach of 120 volts. I have always had the laptop in the car. I have two cords: Radioshack 6ft long, Cablestogo 3ft long. Both give similar results. WisAndy

Don't fight through comms dropping problems, The trouble is that the data being read for runtime values is being corrupted as TS is reading runtime values. Too many errors TS stops.

If the corruption occurs to data being sent from TS to the controller, you risk corrupting your tune. You really just need to get a decent cable.

http://tunerstudio.com/index.php/faqs/7 ... nnectivity

LT401vette, Thanks for the reply. The cables I have were declared by the seller to be shielded. I see that DIYAutoTune has a cable for $5.50 plus shipping. Unless you know of a better cable I'll get that one. I'll let you know what happens. WisAndy

Are you using a USB to RS232 adapter? The USB side is far more often the problem as USB was not designed for a noisy environment. RS232 was designed in the primitive days of very noisy analog phone lines and far more resilient to outside noise. That is why it is still strongly used in the automotive and industrial environment.

LT401vette, Thanks again for the reply. I have a Dell laptop running XP with a real serial port. I'm not well versed on these things but I would expect that the cord should not be a problem. Please advise accordingly. WisAndy

Usually not, but that is not absolute...

A while back I started having drop outs, so I naturally switched to a different USB to serial adapter, it still did it. I grabbed a different regular serial cable and it was cured. I had been using that cable for a while without a problem before it started acting up, so I'm not sure if it got pinched or what. I still use it on the bench without problem, but it doesn't work in most running cars

However, the issue could also be elsewhere such as a loose solder or a problem with the serial port itself.

LT401vette, Thanks for the reply. I don't lnow where to go from here. I think I'll return to the Jimstim and reload (I think you guys call it) the firmware. Start from the beginning in case there is something corrupted. I will get a cord from DIYAutoTune which should be the best that can be obtained. I may be able to scare up a different computer (will take more time) to also prove that it is not a possible problem. WisAndy

I really wouldn't bother reloading the firmware.
What you describe can only be a bad connection. Chances are it is not the laptop. The cable is the problem in most cases.

LT401Vette, Thanks again. I'll pursue getting a cable from DIYAutoTune and see where that takes things. It will take some time for that to arrive. Thanks for your help. WisAndy

The actual connections via the serial cable are only a transmit and receive wire plus ground. You could make up your own cable using some decent co-ax cable and a couple of D9 connectors. A good audio co-ax with braided screen will be fine.
Connect pin 2 to pin2 and pin 3 to pin 3. The screens of the co-ax should both be connected to pin 5 at both ends

trakkies, Thanks for that idea. I have some audio cable left from putting the ignition on. The additional components should cost about the same as the DIYAutoTune cable plus shipping. The big issue is the reduced turn around time. Thanks again. WisAndy

If you already have a spare D9 cable, you could hack it apart and use just the actual connectors. If that then works, you can buy covers as a separate part. They fit over the connector/cable, so you wouldn't need to remake the connections.

trakkies, Thanks for the advice. I already bought some connectors at radioshack and used the audio cable I had on hand. The home made cable checks out with the jimstim. Will know how it works on the car later this morning. I'll let you know how it works. WisAndy

Best of luck - although it is a bit of a long shot. As I said the serial port signal is pretty robust, and you'd need some hairy RFI to interfere with it. Unlike USB.

LT401Vette, trakkies, With the home-made cord, on the first start up everything was ok. In my head I was doing a victory dance. Let the car warm up and shut it off. Restarted and the old behavior returned. An error message about the ini file appeared. I have had to re-establish that frequently. But the offline ... online repetition is still present. I forgot to bring my camera. I would like to take a video of what I am doing and what is happening. I can drive the car, but want to get the tune dialed in better. WisAndy

Examine the DB9 to PCB soldered joints under a powerful light with a magnifying glass. And those to the IC. Or simply re-solder the lot. Keep the iron on the DB9 connections for about a count of three after the solder has flowed, as there is rather more thermal mass than with other things. And can you log what is happening with TS? That might give a further clue.