URGENT: OMEX Help

[Eeyore]

Hi Guys,
Been having some stupid problems recently and I cant get to the bottom of them.

Either the fuel pump wont prime or it will prime and stay priming flooding the engine with fuel coming out of the throttlebodies.
The ECU has to be getting power as ive cleaned up the earth and taking power directly from the battery instead of ignition.

Ive checked continuity on the ecus power wires and on all the wires connected to the fuel pump relay. I have also replaced all the relays in case they were sticking.

The ecu gets its times for sparks, injection and cranking etc from the crank position sensor so my current thought is that the sensor is at fault.

See page 40 for a wiring diagram...
http://omextechnology.co.uk/600%20ECU%20...202v01.pdf

I am currently trying to connect the PC to the ECU to see if there is a Crank Position Sensor reading but cant get it to connect atm.

Open to literally any suggestions as I am going mad.

[Niall]

I've said it several times, get it off to omex. You have tried just about all you can. Sounds like it's had it.

[welshpug]

fuel pump priming cannot flood the engine, its a wiring problem pulling the signal side to earth or the ecu is pulling them to earth all the time

[powerandtorque]

It must be more than just the fuel pump priming - the fuel pump could run continuously, but without the injectors firing you wouldn't get any fuel into the cylinders.

Thus it sounds like the ECU is running the fuel pump and firing the injectors - these are two separate outputs/actions - the later of which clearly it shouldn't be doing with the engine not turning and thus no timing signal from the CPS.

Is it doing this reliably enough that you can easily test and diagnose the issue, or is it intermittent?

You really need to get the PC connected so that you can see the live data readout from the ECU and see what it's doing.

[Eeyore]

fuel pump priming cannot flood the engine, its a wiring problem pulling the signal side to earth or the ecu is pulling them to earth all the time

any ideas then? ive checked everything I can and everything seems fine! Like Niall says its all pointing towards the ecu being at fault.

To put some context into this...

Tuesday - Drove the car a mile before the engine flooded and started spewing out fuel. Got it running again and the same thing happened 800m later. Fixed again and drove 20 miles with no issues.

Friday - Drove no issues 40 miles.

Saturday - Drove no issues 100 miles. Refused to start and flooded.

Sunday - Eventually started, drove 60 miles, refused to start and flooded. Eventually started and did 40 miles fine.

Today - Refused to start. Checked all wiring and all seems to be fine. Will not start again.

[Eeyore]

As in the above post its done this a few times but now its beyond intermittant. I realise that the injectors and fuel pump must be working together to make this happen. Should have thought about that in the OP.

Its really getting to me. I missed going to London last week because of this and looks like its going to be a problem this week too D:

[Eeyore]

Connected to the ECU eventually but as soon as I went to start it it lost connection. I could see the crank sensor was putting out 177 so that's not faulty... Will check the ECU power supply to make sure its getting enough power when cranking.

[Eeyore]

Couldnt connect to the OMEX again. Checked the power. Was getting down to 11 so put the battery on charge. Was fully charged this morning. Really pissing me off now :'(

[Eeyore]

So after getting the battery off charge this morning and plugging it back in the car started first time! No idea whats going on. By the end of yesterday the battery was down to 12.1v which wasnt terrible as far as im aware. Perhaps the OMEX is super sensitive but ive read in other places it should operate correctly down to 6V.

Of course it could be coincidence that it works... I could well get a mile down the road and break down!

[jammapic]

Is the alternator on its way out?

[Toms306]

Check the gearbox earth and battery terminals are tight as well...maybe a bit of threadlock on them also.

[Ruan]

Check the gearbox earth and battery terminals are tight as well...maybe a bit of threadlock on them also.

You're joking me right...

Also sounds to me like you've got a short somewhere that's pulling the injector switch wires to ground or the injector drivers have gone bananas.

[Eeyore]

THREAD LOCK ALL THE THINGS!

Hi Sam,

I agree, this would imply there are two issues.

You said the fuel pump remains on when starting the car, does it continue to run when the starter is released and power to the ECU still on? Which cylinder(s) is filling with fuel?

Best Regards


Guy Higgs
Omex Technology

Hi,

It appears you are powering off the ECU when your ignition switch is in the cranking position, a common fault is the ECU has been connected to an auxiliary pin of the ignition switch which loses connection when cranking.

I still don’t know why the injectors and fuel pump are turning on altogether, this would suggest the ECU has three internal faults. Have you checked the wiring harness for faults?

Would you like me to test the ECU for you? If you do decide to send it to us please include a letter explaining why you have sent it, return address and contact details.

Best Regards


Guy Higgs
Omex Technology

Guy from OMEX has obviously been very helpful. Odd how its working now. I guess a poor battery connection could have reduced power to the ECU when cranking?

[Grant]

Despite the fact it is now working, check your harness with a fine-toothed comb and if that brings up nothing then get that ecu off to omex for testing!

[Niall]

The Omex will run properly down to 8v as the battery can drop that low under cranking.

After the testing you have told me you have done, I think your Ecu is goosed.

[Eeyore]

Will see how it gets on on the drive to Felixstowe tonight. I have been over the wiring. All seems well!

[Ruan]

If the fault is intermittent I'd go with wiring...

Injector drives don't tend to jam open intermittently.... Either they've gone to short or they work...

[Eeyore]

Just went out and started it up. Worked first time. Turned it on and off successfully another 3 times! D:

[Eeyore]

Broken again...

[jammapic]

Check the battery voltage now.

[Toms306]

This is possibly a stupid question, but can you still use the standard ECU just to get it running and see if it's the Omex at fault or is that not possible with the standard map?

[jammapic]

It will run on the standard ECU with the bodies on... just won't drive.

[Niall]

This is possibly a stupid question, but can you still use the standard ECU just to get it running and see if it's the Omex at fault or is that not possible with the standard map?

Issue is though you're not proving much then as you would have to remove the entire engine bay loom to go back to the standard one. If this problem isn't the ecu its self (I'm convinced it is) then i would put a pint on it being a loom issue.

Would say i could bring my ecu to you and bang your map on that quickly but...well I'm not sure if mine works correctly

[Toms306]

Ah, I didn't think about the loom plug being different, that's that out then lol.

These Omex's really seem reliable...

[Niall]

I bought mine because they had a rep for being the most reliable out of the lot! But then i don't know if mines at fault yet as i haven't done any more testing. Bloody hope it isn't though!

[Eeyore]

Just tested my loom. All connections from the omex plug to their relevant sensors and relays all have continuity. :/
looks increasingly like its time to send the ECU back to OMEX. Just a few more things i want to check.

[darrenjlobb]

Continuity means nothing.

Just because it allows enough current for a meter to say its good, dosnt mean it isnt broke / creates interferance / looses connection constantly with running vibrations..

[Grant]

Continuity means nothing.

Just because it allows enough current for a meter to say its good, dosnt mean it isnt broke / creates interferance / looses connection constantly with running vibrations..

This. Connect 12v and check for voltage whilst giving the loom a good bend around and wiggle. See if there are any inconsistencies.

As others have said, if that doesn't prove fruitful, it sounds like your ECU has sharted.

[Eeyore]

So today I have redone the entire loom. Its a lot tidier than it was before and managed to strip out a few more wires.

Car started up first time. Lots of smoke from the exhaust manifold as it was burning off all the fuel that had flooded the engine.

To check the previous problem i wiggled the power relay and the car continued to run...

I then wiggled the ECU and the car cut out.

Started it up again and fuel pump and injectors were stuck open.

Wiggled the ECU and started again and started no problems.

Wiggled the ECU a small amount and it started to stutter and then caught again.

So it does run... and i think ive narrowed the problem down to the ECU socket. The car runs completely normally when it does work so i really do think its the socket and not the ecu itself. More investigation tomorrow!

[welshpug]

who attached the ecu plug?