Injector Module Upgrade - Sputtering with LPG

Hallo, I would write this in Deutsche, but the results would be hilarious. More important to get the idea across.

Yesterday I upgraded my VSI system from the Injector Simulator version A to version B. I had originally installed the VSI system flawlessly, and do know what I'm doing, but the version A started showing a Check Engine with open/shorted injector... its classic failure mode.

I used the solder-in wiring harness for the new IM (6 cyl), and was pretty careful with my work. It was unclear from the drawings what to do with the Injector Module's Ignition wire, so I left it not connected.

The car starts fine and runs great on petrol, and it even switches to LPG. But that's where the trouble begins. The engine slows and misses, going blurp-de-blub-blup-blurp and dies. It's as if I had the LPG injector plugs switched, but I do not. Also there's a loud rushing of air coming from the air intake venturi, only in LPG mode, which I find is coming from the air bypass caused by the motor opening wide. Connecting the IM's Ignition line has made no difference at all.

I am confident that my wiring is correct, as it runs fine on petrol and owing to the very invasive nature of this kit, I believe that it confirms my work.

Looking at the diagram, there is something that does not make sense:

The Injector Simulator is supposed to be active low, and so in petrol mode the ignition signal (a high) is supplied to the control (#26). What is supposed to happen is in petrol mode, the MOSFET is forward-biased, passing along the ECU's signal to the petrol injectors. However the MOSFET depicted is forward-biased with a low on the gate (arrow pointing toward gate). But low is supposed to be LPG mode. This error is disturbing.

Anyway, in LPG mode the MOSFET is shut off, so current from the ECU is shunted through the resistor and much reduced, so the petrol injectors do not operate. So what role do the vertical ECU lines play in the IM? Are these now active? Are these merely sense lines to tell the LPG computer what the car ECU thinks? Could I have switched two of these in my delirium?

In LPG mode the engine splutters and puts out black soot (incomplete combustion). My leading suspicions are that:
- The petrol injectors are not being turned off in LPG mode; or
- I switched two or more of the ECU lines;
- The LPG ECU needs a firmware upgrade for the version B IM.

It's implausible that I got my wiring wrong, as it runs so well on petrol.

I need to understand the differences between operation in petrol and LPG modes in detail, so I can try and ascertain why it works well in petrol, but poorly in LPG mode. Any input appreciated.

 

I haven't run Winduhs for some years (Debian), and the VSI software is Winduhs only. But I will try to install it in Wine and see whether it works, and check lambda and other parameters.

The wiring harness I have does have the connector at the IM, but all the rest is solder-in. I am guessing that lambda will be all over the place, as from millisecond to millisecond it seems to be starved for fuel, and then there is black soot.

So it seems the diagram is incorrect for the MOSFET. I was very careful with soldering in the wires one-by-one, but the writing on the old wires was smeared and very difficult to read, and by the time I got to the ECU sense lines I was exhausted and may have made a mistake. This will be difficult to confirm though, with the smeared writing and the lines all being yellow/white. I know that my injector wiring is correct, as it runs fine on petrol. It's the sense lines that I am suspicious of.

So it sounds like the IM's Ignition wire should indeed be connected to ignition? Is there a newer instruction document?

I am a bit concerned as the part numbers in my document do not match those on the IM. I actually got the IM over a year ago, and the wiring harness a month ago. Has there been more than one version of the version B IM?

Why is there an advantage to leaving the petrol injectors hot and only reducing the current? The install doc emphasizes this, but does not explain why it is good. It is quite a departure from the old way. Maybe it's because, rather than trying to simulate the injectors' presence to the car ECU with circuitry, the current that does flow is enough to satisfy the ECU that all's well and results in a simpler (and {cough} more reliable) IM?

 

I have now positively confirmed that all my sense lines (IM to ECU) are correct. Now confirming other connections.

Also I notice on the old diagram that ECU 50 was not connected and in the new it is.

 

Joy, joy.

I have found the problem. Amongst the last connexions I made the other day was the grounds. I now find that I had connected the IM GND and LPG ECU #54 to +BAT rather than -BAT. I had traced it to the car battery, but failed to check the marking (POS) and thought it was NEG. Yes the wire was red, but such was my state of exhaustion at that point.

So today I've corrected that, and the car runs perfectly now. No more Check Engine light, and a beautiful switch from that oily-smelly-shit-that-puts-out-alot-of-smoke, to LPG. I am running on moonbeams again! So nice to be gazzy, and burning a waste byproduct for motive fuel.

It's a miracle I didn't burn some electronika out, but then again it's pretty hard to burn out a MOSFET...

 

Hello Sixpack, the numbers on my IM are 091/71006 and A/40/07/0905. (maybe 9 May 07? or 40th week of 07? I got it shortly after that) Keep in mind that I bought my LPG ECU about 4 years ago, so it may be well-suited to the 091 part.

Wow, a self-made engine harness. Lots of opportunity for mistakes. Please consider buying an engine harness from a junkyard and just modifying that. The modification is less complex now, than it was with the version A IM. If you need an actual Prins harness I suggest checking with various importers. Portugal wanted E210, while Athens wanted E18! For the same IM harness! Of course you must be working in the country of the importer.

Presumably you know that for an 8 cylinder, you use two 4cyl IM's, and their Ground and Ignition wires are commoned together. The sense lines of the two IMs would be connected to bank 1 and bank 2 of four cylinders each, respectively.

What symptoms are you getting?

 

I suggest that the 180 is compatible with the 091. The connector is the same, and they almost certainly would have made the connector different if incompatible. I suggest that you not worry about this until proven otherwise.

No, interrupting the + injector line is not what you do with the 091 IM nor the 180. The + line is connected, as from the car factory, with either part#. The only petrol injector wire you interrupt is -. One wire from the IM goes on the injector side, and the other on the petrol ECU side. That is the only tampering you do with the engine wiring harness.

Then you must connect the IM sense lines to the respective yellow/white LPG lines.

OK, so it seems your custom engine harness is verified good? It runs well on petrol? And you have the IMs wired into it?

Yes, I have a brand-new IM harness which I just got a month ago from Prins, installed on my 091 IM, and it works great. The harness has an Ignition wire which is unaccounted for in the drawing, but I did connect it to Ignition and it made no difference in the operation. I suspect that it is not connected with the 091 module, but it is with the 180, so machs nichts.

However, I understood that your car is not operational, yet you've driven it on petrol? Did you mean that it is not operational on LPG? Have you tried it on LPG? If so, what was the result?

No, polarity of the IMs did not change; I merely connected it wrong, and that was the source of my problems. When I corrected it, mine works great now.

This is not clear. I don't understand what you are saying.

I agree with all of this except 3. I believe that 091 and 180 are interchangeable.

I do not understand why you think you have a problem? Is the car not running at all on LPG? It is running on petrol? Does it ever try to switch to LPG? If so, how does it behave?

 

My Deutsche would be laughable to you guys. Hey, I'm just tryin' to help the guy. V8gaser gave me the vitally important information I needed to make mine run, and I am just trying to 'pay it forward'.

Sixpack, yes I have that diagram too. But remember that the module on the right is not the version B IM. It is the old version A which originally came with the kit. That drawing is irrelevant to you. Please consider only the one I'd posted at the top hereto.

 

Right, there is one 091 part# for the rev A IM and another 091 part# for the rev B IM. And now there is a 180 part# for the rev B IM.

I do not know though, whether there is an interaction with the ECU related to part numbers. If your LPG ECU is a 180 maybe your IM must be a 180 as well. However it seems doubtful as the IM's connector would have been different, if the 091 and 180 parts were incompatible.