Thank erm heavens for that!
I have had another thought...
If you've been following my Resurrection thread in the last 1/2 hr or so I mention C0636 as (in my mind) the potential root of all my petrol idling/ mad metrics issues. Now Injector #1 is mentioned in the list of things fed from that connector. I wonder if this sudden LPG thing may be connected (sorry!) to that?!
It'd be almost too convenient!
If you've got dodgy connections there, it could explain all sorts of problems. However, the common supply for the injectors doesn't come from C0636, in fact, it doesn't come from the ECU at all. The pulse to injector 1, and all the other injectors, comes from C0636 but not the common power, it comes directly from fuse 37 via relay 19 (brown/orange wire). A feed goes to pin 8 of C0634 but it splits in the loom before it gets to the ECU and goes off to the injectors from there. You could easily pick up the ignition switched supply for the LPG from Pin 8 of C0634.
However, an admission that may explain why you are having problems. It was trying to use my generic OBD reader on Dina's sister's geriatric VW Golf and it wouldn't connect. Not having any contact cleaner handy, I gave the socket a squirt of carb cleaner instead. Still wouldn't connect and then found I couldn't unplug the reader as the carb cleaner had melted the plastic and welded the plug and socket together. Got it out with brute force and ignorance but took me ages to clean the plastic off the pins so my reader would work again. I wonder if someone has done the same with your ECU and the pins are covered in a thin layer of plastic?
If the connector is melted (don't care about ECU pins- it's going anyway) then I really am in a world of pain, or engine loom replacement, or connector replacement at least, but I'm going to cross more fingers and hope that isn't the case!
I can see a cry of "does anyone know a source for these connectors/ pins/ sockets whatever" going out, although I am talking to Chris offline about spare looms/ connectors.
Thanks for the info on the injector common supply. Will prove useful if the alternative is taking off that plenum upper again.
Once I've replaced the Molex on the LPG ECU, I might just temporarily splice in replacement permanent and switched power and ground direct to battery. Only a few minutes work. If then OK, working backwards I'll know which temporary splice to make permanent.
Replaced Molex today. Didn't get a chance to play LPG as was a bit busy reprogramming existing BECM, fitting new (original) ECU, TPS, checking continuity/ resistance of 20 or so key cables from one ECU connector to items that have been throwing up anomalies and cleaning all ECU connectors.
Car now runs smoothly on petrol with 0 faults reported. Not driven yet as have LPG loom stripped.
On the LPG thing, interestingly since doing the ECU change and all the other stuff, I now have a consistent Petrol light on Pet/ LPG switch!
Hopefully have some time to test LPG further tomorrow, or at least put it together enough that I can drive the car on petrol. Will probably hit the LPG switch when running at some stage to see what happens...
Maybe you had an iffy connection on the common supply to the petrol injectors? That would explain the LPG system getting offended and the popping and banging when running on petrol. If you had a high resistance in it anywhere, the LPG system would be seeing something less than 12V so wouldn't wake up and the petrol injectors wouldn't be getting a full supply.
Just noticed that the main forum "Oily Bits" and an unread thread link from George relating to his interior (!) brings you straight to this page, which is good if you're into my LPG ramblings, but not so good if you want to know about George!
EDIT- now has the right title, but will we ever find out about George's interior? I still have an Unread Post flag in Oily Bits- main forum page, but nothing unread
Gilbertd wrote:
Maybe you had an iffy connection on the common supply to the petrol injectors? That would explain the LPG system getting offended and the popping and banging when running on petrol. If you had a high resistance in it anywhere, the LPG system would be seeing something less than 12V so wouldn't wake up and the petrol injectors wouldn't be getting a full supply.
I reckon that's a good call.
Off subject slightly but it' remains an unwritten rule of thumb for installers to avoid connecting LPG ECU's switched live or rpm detection wire to the front cylinder of any bank of cylinders. Not relevant to P38's though!
On ECU's such as Stag and maybe including AEB2568 B suffix the switched live simply throws an internal relay, may be solid state in other ECUs. Main power for ECU outputs (injectors and solenoids) always comes through the fused main battery connection, wouldn't want to draw potential peak of maybe 10 additional amps from the petrol injector live as that could cause problems for some vehicles.
Good that the switch stays lit now, if all other wiring was OK but brown rpm wire was broken would expect the switch to light only momentarily when switched live was 12v.
Measuring voltage between chassis and an earth point can give insight into the condition of the ECU, sometimes voltage here increases when the vehicle is running on gas (when it is powering injectors and solenoids), any such voltage can throw off readings such as pressure / temperatures and can lead to more problematic connection with the laptop.
Sometimes the first sign of ECU trouble is difficulty connecting. Connection can mprove more difficult if the laptop is powered from the car (some earth loop type thing going on?). In some cases ECU's only work properly when they are connected to a laptop, dodgy ECU might benefit from the power connection over the serial link. Again, earthing the ECU chassis can help.
Simon
I'll check out the chassis/ earth point Simon.
Laptop's powered by own battery so no earth loop thing going on there. The new Molex on the ECU should help connecting as, apart from broken pin the rest were cruddy.
I'm going back to v 4.6.1 on the software 'cos even with all the issues, that came closest to actually talking to the ECU.
Just got to throw on a replacement IACV, and front foglight, check some BECM setttings, then will play gas for a bit!
Well, by turning ignition on, managed to get a conversation going with ECU.
Achieved a config set up. Put in twin coils for ignition as that's what I've got, 8 cylinders etc and it saved a config file. Can't see that config when lappy's not connected though.
Progress...
Um- it seems to be able to run on gas!
Was running through last cap off coolant burp warm up/ cool down cycle and thought "wonder what happens if I press gas button and blip throttle?" Light changed to gas, sniffed exhaust and it was running on gas!
Test drive coming once I've tidied away loom...
Edit- no I'm not. Going to wait for it to cool. Final top up of coolant, then run it, switch it to gas again and leak test gas system before I drive it anywhere on gas!
Good news- only found 1 leak!
Bad news- now I've tidied up lpg loom and put it away it's stopped lighting up the switch again, hence no gas
Damn- back to the loom...
EDIT Of course it started working again when I was driving it home from workshop. Even switched to gas again and ran. Left my leak detector at workshop so didn't run it on gas for long, but...
Now we're getting somewhere! Congrats Mark.
Thanks Tony- not far yet, but moving!
One thing that's occurred to me re the leak I found, as I reflect on the day, was that it was at the input pipe to the reducer solenoid and I was running on and switched to petrol at the time. Surely if the lpg is switched out there should be no pressure in that line as the tank solenoid valve and reducer solenoid valve should be closed?
OK, it was only a few bubbles in the gas detector spray and easily solved by 1/8 turn on the fitting. Residual pressure in the line or do I now have to add checking the tank valve to my list?
There will always be some pressure in the lines, even on the vapour side right up to the input sides of the injectors, after changing back to petrol.
That's kind of what I thought. The feed pipe is a pressure vessel when both valves close at the same time.
I'm going to explore Simon's suggestion of lpg chassis grounds and alternative power feeds tomorrow. Want to give the car a bit of an extended road test so might venture out to fill the LPG tank as only have 1 contents light on and it'll make testing pretty difficult if I run out of gas.
So used to having my 135L tanks which only need the occasional garage visit that I have to remember that the capacity of this one is only 88L. Take away the ullage and that's probably more like 65-70L. One light is not a lot, even though the lights are as reliable as, well, something not reliable!
The pipe between the two solenoids will be full of liquid gas. Assuming 3m of 8mm pipe, that's 75ml of liquid. When Propane vaporises, each litre of liquid becomes 270 litres of vapour, that'll give you over 20 litres of vapour so a little bit of bubbling will go on for any awfully long time.
Orangebean wrote:
Just noticed that the main forum "Oily Bits" and an unread thread link from George relating to his interior (!) brings you straight to this page, which is good if you're into my LPG ramblings, but not so good if you want to know about George!
Yes I noticed that this morning. It looks like George posted in the dodgy pollen filters thread but his post hasn't appeared (or he deleted it) although the forum still thinks it's there so is showing an unread post. Quite why clicking the link to the post takes you to this thread I've no idea, unless it is taking us to the most recent post.
The "Unread Items" flag in Oily Bits on the forum page no longer goes away even when you've read the items as well. To clear it, you have to go into Oily Bits and click on the Mark as Read check box at top. George's Interior has definitely had some strange effects on the forum!
Orangebean wrote:
Want to give the car a bit of an extended road test so might venture out to fill the LPG tank as only have 1 contents light on and it'll make testing pretty difficult if I run out of gas.
Run it empty! (after repaired the pipe) Than you will know how far you can do on one led and you can test if it switches back to petrol automatically.