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PostPosted: Sun Jan 08, 2017 3:13 pm 
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I've had my Volvo 850 for just over 16 years now, and it was converted to LPG a few weeks after buying it. Overall the LPG kit has been pretty reliable over the years, and I've put over 250k on the car running on LPG.

This year the car failed it's MOT on the emissions. It was presented running on gas, and was also tried (and failed!) on petrol due to a catalytic converter that's way past it's use by date. With the assistance of a very patient MOT tester, we managed to fiddle with the adjustment on the reducer to get it through on LPG. But it's obvious it's in need of a proper service and tune up.

So with this aim in mind, I'm now looking for the right kit to connect up to an ancient Tartarini TEC 97 ECU. I seem to remember the software being an old DOS program with a serial cable. I've found various versions of TEC97/99 software online, but finding the right cable and a laptop with a working serial port might be a little difficult.

The USB cables are much easier to find, and I wouldn't have to dig through the laptop graveyard in the loft. Does anyone know whether it would be possible to use a USB cable with this ECU and software combination, as that would be a much simpler proposition.

I'm guessing that I'm going to have to use something like DOSbox, and I've found a few pages in Polish and German that seem to suggest that this is possible. After installing DOSbox on a PC and running the TEC 97 software I downloaded, it comes up with a communication error (in Polish), which seems like a good start seeing as I don't have the cable to connect it up.

Has anyone any experience with configuring this to work, and any information on the cables needed to connect it up? I'm handy enough with a soldering iron, so should be able to make up an interface cable if a diagram is available.

If it's not possible to get the ECU talking to a PC, would a viable alternative be to replace the stepper motor between the reducer and the mixer with a manual valve and make the tuning adjustments to the reducer in an open loop configuration? Would the adjustments still be correct once the stepper motor is replaced and system running closed loop?


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PostPosted: Sun Jan 08, 2017 4:26 pm 
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Last point first, depending on how much random twiddling you did to the vaporiser to get it to pass the MoT. Unless the vaporiser is set correctly, using it in open loop will result in a mixture that is correct at idle or at open throttle but not at both.

Using a USB to serial adapter will work sometimes better than others. Adapters using the FTDI chipset are more reliable. Diagram for a suitable serial interface is here

Image

However, one thing to be aware of is going rich at idle is a sure sign that the vaporiser has reached retirement age and after 16 years, it's about 10 years overdue.....

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Last edited by Gilbertd on Sat Aug 19, 2017 4:19 pm, edited 1 time in total.

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PostPosted: Sun Jan 08, 2017 5:16 pm 
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Thanks for the reply, and the pin-out diagrams.

I was planning on installing a full service kit into the vaporiser, but didn't want to take it apart until I'd managed to talk to the ECU, as I'd be a bit stuck re-calibrating it afterwards. So when you say 'retirement age', do you mean completely retired, or is a rebuild OK to prolong it's life. It's a Tartarini G79SE. If it's in need of complete replacement, then I assume that there would be other 'time expired' components and I might be better off with a new more modern front end system.

The adjustment for the MOT was very small, it was just over the CO limit, so we adjusted the bias on the reducer the minimum amount so it just scraped through the test, only needed a few degrees movement on the adjuster. It's driving OK and still returning the normal mileage per tankfull, so I doubt it's that far out.

I have USB to Serial adaptors for electronics/microcontroller projects that output the serial signals at 5v levels, so I should be able to connect them direct to the ECU rather than shift them to the RS232 +/-12v levels, and then have to shift them back to 5v using the MAX232 circuit.

As it's not a hardware serial port, I suspect I will have to use DOSbox, does anyone have experience of this?


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PostPosted: Sun Jan 08, 2017 5:32 pm 
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There was a similar thread recently.

Agreed with Gilbert's above points.

As memory serves I have been able to connect to Tec97 with a wide range of (Tartarini pinout) USB interfaces using a laptop running XP that didn't have a serial port / win 7 32bit running Dosbox worked with a subset of those cables, win 10 running Dosbox a smaller subset.. seems to get worse as version of Windows becomes more recent. Of course, a laptop running an earlier version of windows, or especially DOS, with a proper serial port and cable should have no trouble at all.

Possible to go through a couple of stepper motors (in the flow adjuster valve) during the life of a reducer.

If it won't pass emissions on petrol either I'd be looking at the Lambda probe. Without checking I dunno if 850's use 0-1v probes, I suspect they do, in which case the LPG system will connect to the factory fitted probe signal. On even early V70s the factory (petrol) probe was wide-band, since single point LPG systems are not compatible with wide-band probes any vehicle with one converted to LPG using a closed loop LPG mixer system will have a 0-1v probe fitted as part of the LPG conversion that is additional to the vehicle's factory fitted probe.

Simon

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PostPosted: Sun Jan 08, 2017 5:36 pm 
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Our above posts crossed, not that it seems to have mattered :lol:

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PostPosted: Sun Jan 08, 2017 8:07 pm 
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This particular 850 has the 10v engine and Fenix (Siemens) petrol ECU, and uses the 5-0v Titania lambda sensors. The other 850 models (20v & turbos) use the 0-1v sensors. Most of the non turbo P1 V70s also have the same 10v engine/ECU/sensor combination. The petrol system is in fairly good working order, and I think the lambda sensor is OK but should be able to verity it's output using the TEC97 software.

I'd be interested to know about any possible incompatibilities with this type of sensor and a single point LPG system. I'm sure there were settings for Lambda type in the TEC97 software, so would have assumed it should work. Is it a situation of the settings are there, but it's not possible to get it working optimally? Would installing a 0-1v sensor alongside the OEM one be likely to improve things?

The stepper motor seems to be working OK. It's the earlier metal type and has been squirted with carb cleaner and WD40 every time I service the car. Last time I had the LPG side serviced I was told that if I carry on doing that it will 'go on forever', and the newer plastic bodied ones were rubbish.

I wonder if the cables not working on newer versions of windows has anything to do with the fake FTDI chip issue. The newer FDTI drivers block non-genuine USB-serial chips. The XP machine may have drivers that pre-date the blocking, and the Win10 machine will have the latest drivers that recognise (and block) more of the fake chips.

I'm hoping to get the software running under DOSbox on a Linux based laptop. But it'll probably be a good idea to install windows 2000 or XP on an old laptop just to make sure the cables and software are working first.


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PostPosted: Mon Jan 09, 2017 10:56 am 
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Dunno then mate, certainly on most V70's I've seen with none slave type LPG systems there's been an additional probe boss welded in the exhaust. I don't remember if Tec97 is compatible with a 5-0v probe, just ran the software in Dosbox but without an ECU connected you don't get as far as seeing any of the options. You'll know more than me about fake FTDI chips and windows driver issues, though I've never had windows refuse to recognise a USB/serial cable. Agreed the older stepper motor and metering units were more reliable than the newer plastic ones.

Simon

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PostPosted: Fri Feb 24, 2017 4:48 pm 
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Well, I found out what was causing the original problem that resulted in the MOT emissions failure. Over the past few weeks the engine has got harder to start and run on petrol, eventually misfiring so badly (on petrol) that it wouldn't start or idle. On gas it was running much better but still had a slightly rough idle and feeling like it had a little bit of a misfire. After driving it around solely on gas for a few weeks, I thought I'd better make the effort and figure out what was going on.

A few hours of diagnosis revealed that the injector emulator (AEB Pitagora) had given up. The signals to the petrol injectors were being attenuated by varying degrees when running on petrol, and No.2 petrol injector was still firing when running on gas. Opening up the plastic box, and it was clear that there's been a damp problem in there for quite a while, as the circuit board was badly corroded and some of the component legs had rotted through.

A quick call to Tinley Tech and a replacement arrived next day. The car now runs smoothly again, and a check by my friend at the MOT station shows that the emissions are well within the limits on both petrol and gas.

I still plan to wire up an interface cable, and maybe give the reducer an overhaul once I'm equipped to check the ECU settings, but for the moment it's nice to have found the original problem and have it running properly again.


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PostPosted: Mon Feb 27, 2017 3:25 pm 
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Nice one, yeh a broken Pitagora can definitely do that!
Simon

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PostPosted: Fri Aug 18, 2017 11:05 am 
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Well things are not going well again, and there's still a slight misfire running on both LPG and petrol. :(

Unplugging the wiring harness from the petrol injectors makes it run better on gas, removing the injector emulator harness and directly connecting the petrol injectors makes it run OK on petrol.

Looking at the TEC97 box and the pin for the blue wire (gas solenoid valves) is badly burned and blackened, though the solenoid valves are still working OK. I'm assuming that the injector emulator is also powered from this pin and is not coping as well with the poor connection as the solenoid valves are.

So what would be the best course of action?

The nylon connector housings on both the TEC97 ECU and the wiring harness around this pin are completely toasted with bits flaking off. So would need to replace them both.

New connectors and the tooling to fit them would set me back the best part of £50, and would be a fair amount of effort to remake all of those connections. If I can find one, a new wiring harness is likely to be a fair bit more expensive than the connectors alone, though it's offset by not needing to spend out on the tooling, but the effort to replace it would be similar.

Given that the reducer is likely to be in need of replacement (or at the very minimum a good service), and it's starting to look like the cost and effort involved is getting to the levels where considering a complete new front end might be a better choice.

Or do I just bodge it and snip the blue wire from the connector and splice it onto a wire soldered on the back of the ECUs circuit board?


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PostPosted: Fri Aug 18, 2017 3:34 pm 
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It will be the petrol injector emulation that is playing up... If it runs better on LPG with the petrol injector wiring disconnected from the emulator it will be because with the wiring connected at least some of the petrol injectors are still receiving power so still injecting a bit of petrol, pointing to a fault with the emulation. If it runs better on petrol with the emulator out of the system it will be because the emulator isn't properly connecting the petrol injectors to the petrol ECU, also pointing to the emulation.

The blue wire out of the Tec97 may be a bit toasted but if it flows enough power to open your solenoids it will almost certainly flow enough power (voltage on blue wire high enough) to switch a properly functioning emulator.

So, you may need a new emulator. If you intend to keep the Tec97 system you may wish to change the wiring to relieve the blue wire from having to carry the relatively heavy current - Have the blue wire switch a separate relay (so that the only current it has to carry is to switch the relay and perhaps the emulator), the relay will then switch the heavy current. You can solder a new blue wire to the Tec97 board if you think it's insulation so badly damaged already but it certainly won't get hot again if you do as I just described.

Simon

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PostPosted: Fri Aug 18, 2017 4:55 pm 
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The thing is, it is a new emulator. I replaced it earlier this year. I've also taken it off the car, and checked it on the bench with a 12v power supply and checked each of the injector connections with a multi-meter (both with 12v applied and without). It appears to work perfectly.

The misfire is fairly intermittent and I'm suspecting the burned connection is letting past enough voltage to switch to gas OK, but the connection may be slightly intermittent, and occasionally it'll break for too short a time for the solenoid valves to cut off the gas supply, but long enough to upset the emulator in some way.

I had thought about using an external relay for the solenoids, but it's an old system and it's lasted a good few years like this. I noticed it was a little burnt about 8 years ago when I had to replace the diode for the internal relay that switches the solenoids (it was leaky, and caused the system to switch back to petrol when it got hot). I had meant to replace the connector then, and maybe fit an external relay, but never got round to it. If I replace the connector and get another 8+ years from it, then that will be fine with me!

But all of this is just semi-educated guesswork on my part, so I'm essentially just replacing bits until it seems to work OK again. If this doesn't fix it, then I'll move on to the emulator/injector wiring harness, then maybe new petrol injectors. If it's still playing up after that, then who knows?

I'm getting to the stage where I'm wondering if its worth persevering on such an old system. All the frontend parts are 16 years old, so I'm assuming that all the solenoid valves and low pressure gas pipes should be replaced, the reducer should be replaced or at least given a full service kit, and if I've got to mess around with the ECU, emulator and wiring loom, then that's pretty much the whole lot done for!

So I'm asking myself if I'd be better off ripping it all out and starting again. Are there better lambda control systems for a single point/mixer? Or should I upgrade to a more modern injection system instead?


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PostPosted: Fri Aug 18, 2017 6:00 pm 
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It is possible for an intermittent break in supply from the blue wire to have some of the effects you mention because the solenoids are likely to shut off immediately with lack of power, though maybe only very briefly so not long enough to have much effect in itself on driveability; But the emulator might act on that brief lack of power by immediately switching on the petrol injectors, then, when power on the blue returns (so solenoids are flowing gas again), not immediately switching off petrol injectors... What I'm getting at is the fact that emulators usually have pots to allow setting of such delays during switching, of which I'm sure you're already well aware.

You seem to know the electronics aspects, so there's probably not much new I could tell you. At that age your system is indeed old and you might decide to replace the job lot. Worth checking out those petrol injectors like you say. Tec97s seem reliable, I still see plenty that are still working, even the stepper motors they use seem more reliable than most types and the reducers aren't bad at all. Newer differently branded equivalents to Tec97 are still technology from the same era with just about the same functionality set, just that you can buy different brand equivalents that are just as good cheaper and with better availability. Fix and replace bits to sort this system, fit a new different closed loop system or replace with a sequential system, your choice! I'd probably start by trying to find what's going wrong with existing components, particularly checking blue wire voltage and earth voltages during symptoms, and checking the new emulation is OK being wired in the same way as the old emulation.

I recently replaced a Tec97 on an old Mitsubishi V6 with an OMVL R90 and AEB175 setup, at first keeping the old emulator. The 'emulator' on this setup wasn't the usual Pitagora type, it was just a single channel jobby that shuts off power on the positive so if we were to replace it we might just replace it with a relay and a few resistors really. Sod's law that this emulator seemed to start playing up shortly afterwards, not cutting off the petrol injectors sometimes, not re-connecting the petrol injectors other times, so I fitted another 'proper' single channel emulator since lack of emulation does bring on the MIL light. Still the owner reckoned it wouldn't start sometimes and I've been through to his on several occassions when it wouldn't start... each time starting it on gas without problem even though he said he couldn't get it started even on gas. I suspect the petrol pump is on it's way out, sometimes running when the alternator is charging but not running when there's just 12v or less (less during cranking). But to him it seems I've introduced the problems with it starting/running on petrol... not very clued up and doesn't understand how the LPG could possibly effect running on petrol. But prior to my work on it the car had been stranded, engine cut out in deep water, the owner rescued it from it's probably rightful place at the scrappers by shelling out for some garage to get it running again with a different petrol ECU etc.

Simon

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PostPosted: Fri Aug 18, 2017 8:10 pm 
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Thanks Simon, that seems to reinforce my theory about the emulator. I'd forgotten that the emulator provides a delay between the LPG solenoids firing and the petrol injectors cutting off, so if there's still gas being provided the engine's going to go over rich for a short while and is likely to cause misfire like symptoms. There's no click from the solenoids when this happens, so I'm thinking that their residual magnetism means that if the break in power is short enough, they may not be affected at all.

I should really give the petrol injectors a once over, as if there's a problem with them, it won't matter what I do with the LPG kit. It seems to run OK on petrol, but there could be a leaky injector letting some petrol into the mix causing the misfire, without any involvement of the LPG side. Though I'm not confident of my abilities to test them properly. I have many years of experience designing and troubleshooting electronics, so I'm much more comfortable working on that side of things first and proving that it's not causing the problem, before I inevitably have get my hands dirty with the oily bits. ;)


I once had a car that I drove into a puddle that was a lot deeper than expected! Once it was all dried out it seemed to run OK again, but it was trouble from that point on. I ended up scrapping it and getting this Volvo instead. I hope your customer gains some understanding about the perils of dampening things that should be kept dry. ;)


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