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[TheBoy]

You'd be stunned how many engine ECUs incorrectly get replaced because the bloke down the pub (or a random internet site) said it has to be the ECU.

no I wouldn't.  i've replaced 3 perfectly good crank sensors on wrong advice

Advice you never followed. Hence it all ended up with a pantomime.


Yet you advise on this thread to replace an ECU on a pure guess.


My reason for being on this forum, despite not personally driving an Omega now, is to help others, and save them money. I fall back mostly on my own experience of what works and what doesn't (because sometimes I think I know better than the advice of those that really do know their onions), and have a high performance car designer in the family, and somebody working at a major car manufacturer who is the supplier interface.

I also spent an awful lot of time and money (several Łk) learning and getting all the diagnostic gear for the Omega, and have extensive experience in diagnosing Omegas for other businesses.


I privately chat to the clever peeps on here on complex issues, and we work through issues, normally not on Omegas, because the inbuilt diags (and the published diag flows)are fairly good, and there aren't many electrical faults we haven't already seen.


I work in IT, mainly Unix and Linux now (but am a bit of a tart, so can do most technologies, covering from when a packet hits our network, right through to when it leaves, be that transit, or application response), so the diagnostic logic isn't dissimilar.  Also working in IT, you clearly meet a lot of wasters who think they know stuff, but I do have a very highly tuned BS detector.

[omega2018]

BS, do you mean like 'contact cleaner dissolves metal'

BTW your advice on my problem WAS to change the crank sensor and I did. 3 times.  only difference was you insisted I go to a bricks and mortar dealer. I now know all my crank sensors work. none were from dealers.  One is genuine bosch and one genuine delphi.  sorry forgot delphi are shit, apparently.

funnily enough I have been in IT myself 25 years and also UNIX.  Yes you do meet a lot of people who know they are right and dismiss others experience or questioning your dogma . 

also owned an omega non stop since 1998 when i was given one new as my company car

[Doctor Gollum]

Meanwhile, back in the thread...

Berserkerboy, have you tried this yet?...

Pull all the spark plugs along with fuse 18.
Crank engine for 15 seconds.
Wait ten minutes.
Crank engine for 15 seconds.
Pour a tablespoon or two of oil down each plug hole.
Wait ten minutes.
Crank engine for ten seconds.
Fit new plugs and reconnect everything including the fuse.
Now try and start the car.

 

[berserkerboy]

I connected a lead to the battery positive terminal and jacked into the connector at the pump. Pump primed. Cranked engine and the car started beautifully and then switched into gas when temp reached. I stopped car and swopped over the 2 purple relays. Car started perfectly so that rules out the relays. Jacking across the large spades of the pump relay allows the car to start perfectly. However, there is only 5v coming to the small spades, and at times I have measured only 0.7v, so presumably not enough to close the relay and run the pump.

Anyone have any thoughts as to why this would be so?

[omega2018]

glad you didn't waste your time pouring oil into your cylinders

beware the relays can fail slowly and intermittently in my experience.  eg they may stop working when hot then start again when cooled down etc..., before they fail completely.

however it does look like your problem is the supply to the pump relay.  am i right you are getting 5v sometime 0.7v on the small relay spade sockets when the large relay spade sockets are shorted and the engine is running? very odd.  check the cables including earth and that you have the correct rated fuses in and they are not overheating. all fuses in engine bay and fuse 18 in cabin (fuel pump) I think .  you could always wire the relay small spades from an ignition live supply and earth so it is on full volts all the time the ignition is on (or just run ignition supply to the pump with suitably thick wire). not when on lpg.

can't help thinking your lpg may be involved but know nothing about lpg installs.  no doubt others will help on that.. presumably the lpg controller can switch off the fuel pump when it wants to (and maybe when it shouldn't).

[zirk]

glad you didn't waste your time pouring oil into your cylinders

beware the relays can fail slowly and intermittently in my experience.  eg they may stop working when hot then start again when cooled down etc..., before they fail completely.

however it does look like your problem is the supply to the pump relay.  am i right you are getting 5v sometime 0.7v on the small relay spade sockets when the large relay spade sockets are shorted and the engine is running? very odd.  check the cables including earth and that you have the correct rated fuses in and they are not overheating. all fuses in engine bay and fuse 18 in cabin (fuel pump) I think .  you could always wire the relay small spades from an ignition live supply and earth so it is on full volts all the time the ignition is on (or just run ignition supply to the pump with suitably thick wire). not when on lpg.

can't help thinking your lpg may be involved but know nothing about lpg installs.  no doubt others will help on that.. presumably the lpg controller can switch off the fuel pump when it wants to (and maybe when it shouldn't).

LPG doesn't interfere with the Petrol Pump, its running all the time even on LPG, idea being its primed and ready to go should the LPG run out or develop a fault and die.

Down side to that is a lot of peeps unknowingly let their petrol tank run low, normally because they have plenty of LPG on board, which in turn over heats the petrol pump and it burns out.

This scenario wouldn't happen on Petrol only cars as the the car would die with fuel starvation.

[TheBoy]

glad you didn't waste your time pouring oil into your cylinders

Or replacing the ECU


OP - check the earth connections on back of 2/4/6 bank, and you'll need to start looking at loom faults beyond that

[berserkerboy]

glad you didn't waste your time pouring oil into your cylinders

beware the relays can fail slowly and intermittently in my experience.  eg they may stop working when hot then start again when cooled down etc..., before they fail completely.

however it does look like your problem is the supply to the pump relay.  am i right you are getting 5v sometime 0.7v on the small relay spade sockets when the large relay spade sockets are shorted and the engine is running? very odd.  check the cables including earth and that you have the correct rated fuses in and they are not overheating. all fuses in engine bay and fuse 18 in cabin (fuel pump) I think .  you could always wire the relay small spades from an ignition live supply and earth so it is on full volts all the time the ignition is on (or just run ignition supply to the pump with suitably thick wire). not when on lpg.

can't help thinking your lpg may be involved but know nothing about lpg installs.  no doubt others will help on that.. presumably the lpg controller can switch off the fuel pump when it wants to (and maybe when it shouldn't).

Voltages are with the engine not running but ignition on. Relay removed and volt meter applied to spade socket and earth. My wife has sat in car and cranked car and the voltage remains the same.

[omega2018]

Ok so lpg doesn't switch off the fuel pump (i would have thought it might), presumably it does switch off the fuel injectors.

berserkerboy which of the two purple relays are we talking about here is it the one nearest the passenger wing or the one slightly nearer the engine? maybe your lpg is switching off the petrol injector relay when it shouldn't.

voltage with ignition on will be similar to with engine running but don't bother measuring voltage when cranking engine all bets are off then.

glad you didn't waste your time pouring oil into your cylinders

Or replacing the ECU

whats the error code for "need a tablespoon full of oil pouring into each cylinder" then ?  At least there is a persistent error code indicating possible ecu fault, also some oof experience:

I have seen a 3.2 and a 2.6 display similar problems to the ones described cured by a replacement ECU.

[cam.in.head]

so if you can start the car by powering the pump independantly and it stays running then you are saying that voltages at the now unplugged fuel pump relay are not what they should be.there should be 12v( or up to 14v due to engine running)at terminal 30.this then runs vis term 87 to the fuel pump.so if you bridged these it should run correctly on its own.you are saying that you are only getting a very low voltage to the relay supply coil.(term 85 & 86).if i recall correct one should be 12v ,fed from tother relay and other should be a ecu controlled switched negative .by checking you should be able to ascertain if its the 12v or neg thats not working correctly. then a case of tracing back down the cables for bad connection .process of trace and eliminate

[zirk]

I will ask again, does it start on forced LPG start?

[berserkerboy]

glad you didn't waste your time pouring oil into your cylinders

Or replacing the ECU


OP - check the earth connections on back of 2/4/6 bank, and you'll need to start looking at loom faults beyond that

The boy: I presume 2/4/6 bank is passenger side?  Do I need to remove the plenum?

Migmog: The relay is the one next to the passenger wing. I will start the car and check voltage on small spades with the car running on petrol.

Zirk: Regarding hard start on LPG. It has not been while cold, wheras before I was able to do so. The LPG/Petrol switch in the car has not been allowing the hard start. Ie green light would not go to solid green when I continually pushed the switchover button.

However, yesterday when I had warmed the engine for a while I disconnected the jack across the large spades and replaced the relay. The car would not start on petrol but I was able to hard start on gas.

[TheBoy]

On pure LPG, it will start better when ambient temps are warmer, or the engine is still warm. This is due to the fact you really want it to be gas when it gets injected.

Bear that in mind when considering if its easy or hard to force start on LPG

[zirk]

Most system will allow Forced LPG Start without having to start on petrol, if its a newer type they normally have a bubble push type switch. Try this, Ing. Key out, push / hold bubble switch in permanently, Ing, Key in and wait at least 5 seconds before cranking, keep cranking untill car fire on LPG, as TB it may be rough from cold and may take a few attempts (Ing off between each attempt). make sure whilst your doing all this that you haven't actually switched the LPG Off, ie, its in the right mode before you try, some systems in this mode the Green LED will light permanently after 5 seconds telling you Im now on LPG only mode.

[berserkerboy]

Most system will allow Forced LPG Start without having to start on petrol, if its a newer type they normally have a bubble push type switch. Try this, Ing. Key out, push / hold bubble switch in permanently, Ing, Key in and wait at least 5 seconds before cranking, keep cranking untill car fire on LPG, as TB it may be rough from cold and may take a few attempts (Ing off between each attempt). make sure whilst your doing all this that you haven't actually switched the LPG Off, ie, its in the right mode before you try, some systems in this mode the Green LED will light permanently after 5 seconds telling you Im now on LPG only mode.

When I am able to hard start the green light stays on permanently and I can hear a click at the tank, a few seconds more cranking and the car starts. As you say, a bit rough when from cold. Recently, the car will not go to solid green from cold. Just switches over to petrol. I'll try your above procedure.