Omega Owners Forum
Omega Help Area => Omega General Help => Topic started by: JamesV6CDX on 21 July 2008, 19:57:02
-
I refer to my earlier post below, re. Danny's LPG.
There is now one main issue that is causing us a problem and I wondered if anyone can shed any light.
The issue is this - the LPG ECU is not interpreting the correct RPM signal. The software parameters are definately correct. As reported the wiring was shoddy so I re-made the connections thinking this would solve it.
Unfortunately this didn't fix it. At idle, the LPG ECU thinks it's about 2000rpm when in reality it's just over 500.
It's getting the signal from the bright green wire and it's definately the right one. I've also checked earths and ECU 12v feed is ok.
Any ideas on this one? It's now the only cause of any evils, we've pretty much fixed the rest, apart from a final tidy up!
A couple of times it behaved normally and I suspected very stronly it was a bad connection, but I've double and triple checked and the wiring for this seems consistent :-/
Any ideas gratefully received..
As you all know by now Danny has had nothing but trouble with his "Pro" Gas conversion, and has never been able to so much as use his LPG conversion since it was installed.
After months of the installers not getting anywhere I had a look at it for him today.
The findings as to why it wasn't running on gas are as follows:
1) Coolant feed to the reducer was non existant, only just a trickle. What they had done, is take the tiny coolant pipe from the Nearside of the throttle body, bodge a rusty old union on there to connect it to a larger pipe, and run it to the reducer. There was then a pipe from the reducer, going into another cobbled up home-made adaptor, and then joined back onto the top of the header tank. Completely inadeqete and the reason why it wasn't happy under load and at high revs. To overcome this, I've ripped out all of the bodge pipes and re-connected the throttle body coolant feeds. Popped the scuttle off and have taken a feed directly from the coolant bridge for the evaporator, which flows through it, and returns back to the HBV. This way the evaporator will get consistent coolant regardless of heater controls. The result was an instant difference, a red hot evaporator! It's also a million times more tidy than the installers job, with coolant hose wrapped around the air inlet trunking.
2) The LPG filter was fitted the wrong way around. You may not think this would make a difference but, once put right, the idle was a million times smoother and is no longer hunting around and lurching like it was before.
3) Appalling wiring throughout.
- The lambda wires had just been cut, and not terminated, so were free to short.
- The wiring for the gas temp sensor was dodgey, (reporting -70 degrees at one point!)
- The wiring to RPM signal was appalling
- Wiring to the battry and 0v - again really, really shoddy, looked like schoolboy work. Resulting in an intermittent supply to the LPG ECU.
- The injector splice cables are again a huge mess and all over the place
- The gas injectors themselves are just hanging loose
4) The wrong type of evaporator and injectors were configured on the software (Thankfully my Stag lead worked).
Having done some quick repairs on the above, apart from a minor switching issue I'm looking at, the car is now running really nicely on LPG :)
Other faults found, were:
5) Manifold nozzles have been drilled in situ - you can see the swarf everywhere!
6) The evaporator is very insecure and has been mounted via a bracket connected to the BRAKE MASTER CYLINDER!
7) Gas switch inside the car very poorly fitted.
8) Rusty old gas unions used to join coolant pipes
9) Bare wires all over the shop.
10) components routed near EGR valve, won't last long there!
11) Pollen filter had been removed to make way for the gas ECU
12) Gas ECU insecure and hanging off it's cables..
13) Only 6mm feed pipe used for vaporisor, it really needs 8mm on an engine with this capacity.
In short, it looks like an ameteur DIY job at best, it's nothing like professional standards.
In a few hours it's gone from being a shambles to something that works, so that's good progress really.
Unfortunately couldn't finish it all off due to the sheer volume of work, but we are confident that another days tinkering and it'll be 100%.
It needs a day to properly solder and heatwrap the connections, do some continuety testing on suspect parts of the LPG loom, connect up the lambda's to see what they're doing and get the mapping spot on, and generally tidy up the install - it should be good as new, then :y
Must say, I much prefer the Stag 300 kit I've used compared to the OMVL21 fitted in this application. The Software is very very limited compared to the stag one, and components are not as good, IMO.
Hopefully all's well that ends well, pleased you're happy Danny :y
-
There is an option in the software to change the strength of the rpm signal. Under the tab - "type of revolution signal" there are two options standard and weak, I'd try changing that.
-
There is an option in the software to change the strength of the rpm signal. Under the tab - "type of revolution signal" there are two options standard and weak, I'd try changing that.
Tried that :(
-
Daft idea .... but you say you've checked the colour of the signal feed... if the wiring was a bad as you say .. perhaps the colours are wrong ... have you check back "at source" that the "bright green" wire is connected to the correct terminal ??? sounds to me like you are getting a "summed" signal of all pots rather than just a single signal ??
(but remember I know nowt about electrics .. just trying some sort of logic !!! )
-
Only other thing I can think of but I don't know how relevant this will be to the 3.0 litre is the wiring which comes from the omegas ecu temp sensor could also be dodgy or not connected properly.
It's a spade connector down the back of the egr valve on a 2.0 litre but as said I don't have a clue where it would be on that engine. If it's loose it interferes with both the temp and rpm on the dash so may be a place to have a look if applicable.
-
Is there a setting for the number of cylinders somewhere?
Sounds like it's either configured for the wrong number of cylinders or it's configured to be fed from a coil pack (which might only fire once every 3 ignition events) but the tacho signal from the ECU is one pulse every ignition event.
No wonder it was running bad! Didn't even get the basics right. >:(
Kevin
-
Daft idea .... but you say you've checked the colour of the signal feed... if the wiring was a bad as you say .. perhaps the colours are wrong ... have you check back "at source" that the "bright green" wire is connected to the correct terminal ??? sounds to me like you are getting a "summed" signal of all pots rather than just a single signal ??
(but remember I know nowt about electrics .. just trying some sort of logic !!! )
No, I checked the ECU pin, it's definately the right wire.
I've configured the ECU for the right number of cylinders, and have tried every setting for the type of rpm signal - still the same, whatever is selected!
-
What type of system is it? Just wondering of there are any specs on t'internet.
Kevin
-
Crank sensor?
If RPM feed and 6 cylinder it should be fine.
So lets look at interferance, does it run next to the coil pack or a plug lead?
-
What type of system is it? Just wondering of there are any specs on t'internet.
Kevin
OMVL I think
-
On mine, it's configured for 4 cyl, single coil engine taking the green wire feed. It is a 4-pot, but maybe worth a shot? Mine reads just about bang on, and changeover rpm is right as far as I can see (with 100rpm or soof the tacho).
Seems strange that you're reading a factor of 4 out on a 6-pot..
You 100% sure its picking up the right wire/ECU pin? Sounds more like you've got a PWM feed. like for the ICV..
Edit - Ignore all the above - just re-read the replies!
Does sound like its picking up some fixed frequency like a PWM signal, though...do you have continuity from the LPG ECU to the petrol ECU for the RPM wire?
-
100% right wire... !
-
Is there a voltage threshold to select - like on the Stag 300? My money is on that being wrong, or wrong number of coils, etc. selected.
Kevin
-
Is there a voltage threshold to select - like on the Stag 300? My money is on that being wrong, or wrong number of coils, etc. selected.
Kevin
Thing is, I have tried every combination possible on the software. And, at one point it was working fine, and another it wasn't, with no change of parameters.. :-/
-
Back to dodgy wiring - try the continuity check, then wriggle any wires you can - I suspect it might have worked on the right settings -then it loses the decent signal and picks up whatever it can. If the impedance is high enough, so will the induced voltage be..
Please don't tell me you've spotted a blue block of death on the wiring...the one which calls itself Scottish...
-
Back to dodgy wiring - try the continuity check, then wriggle any wires you can - I suspect it might have worked on the right settings -then it loses the decent signal and picks up whatever it can. If the impedance is high enough, so will the induced voltage be..
Please don't tell me you've spotted a blue block of death on the wiring...the one which calls itself Scottish...
The wiring is disgusting, were way too many faults to fix in a day :(
-
Oh dear...I spent half a day and far too much heatshrink on mine.
I know its "chasing your tail", but worth dropping a new wire from ECU to ECU, cutting the old one free? PLease tell me if this is a grandmother and egg sucking suggestion...
My money is on the cr@ppy wiring...
-
Oh dear...I spent half a day and far too much heatshrink on mine.
I know its "chasing your tail", but worth dropping a new wire from ECU to ECU, cutting the old one free? PLease tell me if this is a grandmother and egg sucking suggestion...
My money is on the cr@ppy wiring...
I agree exactly with what you're saying.. unfortunately once we'd fixed the coolant issues and other bits, it was getting dark/late and I had broke my multimeter, so with no spare wire, we had to call it a day :(
-
I know the feeling -I feel the pain!
We all forget the silly things from time to time - hence the silly suggestions/memory joggers. Please don't think I was being sarcastic - I wasn't. I think it was you nudged me to to my daft mistake on mine (Manual valve on the tank :-[)
Is the wiring a "to be revisited"? Seems a crying shame to be so close, having come so far. Has to be said, excellent work to date!
-
I know the feeling -I feel the pain!
We all forget the silly things from time to time - hence the silly suggestions/memory joggers. Please don't think I was being sarcastic - I wasn't. I think it was you nudged me to to my daft mistake on mine (Manual valve on the tank :-[)
Is the wiring a "to be revisited"? Seems a crying shame to be so close, having come so far. Has to be said, excellent work to date!
Oh, the last points will be revisited!!
-
I agree exactly with what you're saying.. unfortunately once we'd fixed the coolant issues and other bits, it was getting dark/late and I had broke my multimeter, so with no spare wire, we had to call it a day :(
Remember it's not necessarily only the wire to the green tacho wire that's the potentially the problem. If the negative supply to the LPG system is bad, this will cause problems as the LPG injectors pull current, because it acts as a reference for all the signals from the rest of the car.
Kevin
-
Ah yes...especially if you have 3 or 6 1 ohm solenoids pulling at once...thats a lot of amps...and probably only a bit of 0.5mm (if that) cable to cope with it.
If some chipmunk has spliced it onto a bad/small gauge earth, then the volt drop will be very significant..
-
Remember it's not necessarily only the wire to the green tacho wire that's the potentially the problem. If the negative supply to the LPG system is bad, this will cause problems as the LPG injectors pull current, because it acts as a reference for all the signals from the rest of the car.
Kevin
I've also checked earths and ECU 12v feed is ok.
:'(
-
:-/
Does the RPM indication on the LPG ecu appear stable and does it follow th real engine RPM or is it jumping around and a bit unstable? Does pulling the wiring about affect it?
Kevin
-
I've also checked earths and ECU 12v feed is ok.
:'(
The 12V may well be solid - but the earth may require a better look..
-
Have a look at my post that you quoted - states the earths are OK :y
-
Where are the 0V's to (remember, a car does NOT have an earth!), is it close to where the petrol ECU picks its 0V from or miles away!
Also, where is the rpm signal connected to, right close to the ECU pin or miles down the loom?
The ideal would be to check the rpm signal integrity with a scope at the LPG ecu.
-
It might be worth screening the gas ecu if it's somewhere it could pick up interference. If it's a metal case check it's grounding out ok or add a separate earth.
-
:-/
Does the RPM indication on the LPG ecu appear stable and does it follow th real engine RPM or is it jumping around and a bit unstable? Does pulling the wiring about affect it?
Kevin
I think this is the key to whether it's a configuration issue or an electrical noise issue.
Kevin