17 replies to this topic

[RooBoonix]

Hi guys and gals,

 

I have a weird problem that has arisen in my car which is a 1994 Cooper SPi. It happened all of a sudden after a little engine bay work. (Checked and adjusted valve clearances, and I was also fiddling with fuses in attempt to fix my hazards, which are fixed now)

 

Basically, the car starts and runs fine (like it did beforehand at least) however now, when I turn the key off the engine stays running. Everything else stops (radio, gauges etc...) but the engine stays running. I can rev it and it idles fine etc... I'm guessing it will die after a while due to the fuel pump not being on. To stop the engine I either have to stall it or I unplug a lead from the ignition coil.

 

I have tested the alternator (unplugged the connector in the middle with the 3 pins and also took the thick red wire off, so only ground was left on) and the problem was the same. I have checked the fuse which is fine and wiring seems fine. I get ~14v to ground from one side of the coil and ~12v to ground out of the other; ignition on or off it's the same as long as the engine is running, however the weird thing is (to me at least) is that when I unplug a lead from the coil and plug it back in I can't get any reading near that what so ever. It's very weird.

 

I have also checked the relay module (engine management relay) simply by taking the cover off and looking at the individual relays work. Upon turning the ignition to 2, 2 of the relays click on, then 1 clicks off and the other stays on. When the car is started, 3 of the relays are on. If I then turn the ignition off, the car is obviously running, there are still 3 relays connected until I pull the wire from the ignition coil where 2 turn off almost immediately, and the other a short while after.

 

I haven't checked the ignition switch yet, that's next on my list. (Any tips on testing the switch is appreciated, I think it's working fine but no harm in testing it)

 

Is there anything else to check? Could it be a grounding fault somewhere causing it?

 

If you need any more information then I am happy to do my best.

Thanks in advance,

Cameron.

 

ps: I know it's a long post but I wanted to provide as much information as possible.

Edited by RooBoonix, 02 May 2014 - 09:00 PM.

[Jakemorrismini]

Sounds like timing to me. If your timing is out then you car can continue to run after the car is switched off. I had this problem once, reset all the timing and it's fine now

[Carlos W]

Running on is where the car carries on for a few seconds after the ignition is turned off!

That isn't what's being described here.

[RooBoonix]

Sounds like timing to me. If your timing is out then you car can continue to run after the car is switched off. I had this problem once, reset all the timing and it's fine now

 

 

Running on is where the car carries on for a few seconds after the ignition is turned off!

That isn't what's being described here.

 

Hi mate,

 

Thanks for the suggestion, but like Carlos said my engine stays running until the fuel stops... Thanks for the suggestion though.

 

Cam.

[Captain Mainwaring]

Sounds like the ECU is getting an ignition backfeed from somewhere - take a look at the CD's and have a poke about, I recall that the fuel pump gets a run signal when the key is first switched on then turns off until there is a crank rotation signal.

 

I'm guessing it will rev when it is doing its "running on"?

[Captain Mainwaring]

Oya, don't go running the alternator with no bus load.

[RooBoonix]

Sounds like the ECU is getting an ignition backfeed from somewhere - take a look at the CD's and have a poke about, I recall that the fuel pump gets a run signal when the key is first switched on then turns off until there is a crank rotation signal.

 

I'm guessing it will rev when it is doing its "running on"?

 

Ok, what do you mean "CD's"? (sorry if it's obvious). My fuel pump comes on with the second click of the key and stays on.

 

Oya, don't go running the alternator with no bus load.

 

I only had the ground connected when I tested it. Was only for a few seconds anywho.

 

Cheers,

Cam.

[RooBoonix]

Hey guys,

Any other ideas? I'm stumped!

I'm fumbling with the multimeter around the ignition switch now and as it stands I get nothing (to ground) out of any of the terminals (except live ofc). On the second click of the key I get 12 v out of the white wire (ignition wire according to Haynes). Start the engine, the same. Turn the key off, engine stays running and I continue to get 12v out of the white wire to ground.

All the other accessories like my radio and the dials turn off. Once I pull the negative wire off the ignition coil, engine stops, and then the white wire goes dead.

Could it be something to do with the radio power wiring that's ran from the ignition wiring in the steering column? Could it be a ground fault of the steering column?

Once I get some wire (and some more time) I'm going to rewire the radio power to the proper fuses in the engine bay.

I can't find anything!
Thanks,
Cameron.

[Captain Mainwaring]

 

Sounds like the ECU is getting an ignition backfeed from somewhere - take a look at the CD's and have a poke about, I recall that the fuel pump gets a run signal when the key is first switched on then turns off until there is a crank rotation signal.

 

I'm guessing it will rev when it is doing its "running on"?

 

Ok, what do you mean "CD's"? (sorry if it's obvious). My fuel pump comes on with the second click of the key and stays on.

 

Oya, don't go running the alternator with no bus load.

 

I only had the ground connected when I tested it. Was only for a few seconds anywho.

 

Cheers,

Cam.

 

 

 

CD's = Circuit Diagrams

Confused - i'm not sure it matters how long you run the alternator without load for , you can kill it in a blink of an eye.

[Captain Mainwaring]

Hey guys,

Any other ideas? I'm stumped!

I'm fumbling with the multimeter around the ignition switch now and as it stands I get nothing (to ground) out of any of the terminals (except live ofc). On the second click of the key I get 12 v out of the white wire (ignition wire according to Haynes). Start the engine, the same. Turn the key off, engine stays running and I continue to get 12v out of the white wire to ground.

All the other accessories like my radio and the dials turn off. Once I pull the negative wire off the ignition coil, engine stops, and then the white wire goes dead.

Could it be something to do with the radio power wiring that's ran from the ignition wiring in the steering column? Could it be a ground fault of the steering column?

Once I get some wire (and some more time) I'm going to rewire the radio power to the proper fuses in the engine bay.

I can't find anything!
Thanks,
Cameron.

 

 

Could be the radio backfeeding to the ignition dependent circuit - I'd disconnect the supply to it if I was in your position.

[KernowCooper]

+1 on what Captain Mainwaring said the alternator spike voltage can be over 200v and thats the end, so be careful running with the alternator disconnected. When you switch off the ignition and the car continues to run have you pulled the connection apart to the ignition switch does the engine die then like its switched off?

 

If it dies then I's suspect contacts in the switch are faulty. You should not have 12v on the white wire out with the key off.

Edited by KernowCooper, 04 May 2014 - 12:51 AM.

[RooBoonix]

Hi,

Would quote you all but its more difficult on my phone.

Thanks for the advise, hopefully the alternator is fine. I'll have to test it. Think it is as I have been running the car yesterday and no problems.

I haven't tried unplugging the switch connector like you said, ill try it later on (im out for the day at brands hatch) hopefully that will be my problem.

Thanks again,
Cameron.

[RooBoonix]

 

Hey guys,

Any other ideas? I'm stumped!

I'm fumbling with the multimeter around the ignition switch now and as it stands I get nothing (to ground) out of any of the terminals (except live ofc). On the second click of the key I get 12 v out of the white wire (ignition wire according to Haynes). Start the engine, the same. Turn the key off, engine stays running and I continue to get 12v out of the white wire to ground.

All the other accessories like my radio and the dials turn off. Once I pull the negative wire off the ignition coil, engine stops, and then the white wire goes dead.

Could it be something to do with the radio power wiring that's ran from the ignition wiring in the steering column? Could it be a ground fault of the steering column?

Once I get some wire (and some more time) I'm going to rewire the radio power to the proper fuses in the engine bay.

I can't find anything!
Thanks,
Cameron.

 

 

Could be the radio backfeeding to the ignition dependent circuit - I'd disconnect the supply to it if I was in your position.

 

 

 

+1 on what Captain Mainwaring said the alternator spike voltage can be over 200v and thats the end, so be careful running with the alternator disconnected. When you switch off the ignition and the car continues to run have you pulled the connection apart to the ignition switch does the engine die then like its switched off?

 

If it dies then I's suspect contacts in the switch are faulty. You should not have 12v on the white wire out with the key off.

 

Hi,

 

Could only set one of you as the "answerer" but both of you helped me! Thanks for the help it's all fixed now.

 

I disconnected the radio wiring and another mystery wire that was connected to the aux wire and it started and turned off fine. Radio is now connected up in the engine bay fusebox (where it should have been done) and the mystery wire was a switched 12v feed to the fuel pump... I don't know why as the fuel pump runs works fine and it now actually turns off a few seconds after the ignition is on (like it should I believe, until the crankshaft turns?)

 

Anyway, it's working fine now. Thanks again for your help.

Cameron.

[FlyingScot]

You are correct about the fuel pump, ECU "switches it on" to prime via the relay pack and then shuts off waiting for the crank sensor to tell it the motor is turning.

FS

[RooBoonix]

You are correct about the fuel pump, ECU "switches it on" to prime via the relay pack and then shuts off waiting for the crank sensor to tell it the motor is turning.

FS

 

Cool thanks mate, thought I had read that somewhere.

 

Cam.