Running-on (and it's nothing to do with the fan )

[k80rum]

So I've replaced a U/S coolant sensor, reduced the fuel pressure slightly and fiddled with the MBPS value for the Emerald base map I'm using for my R500-spec Duratec.

 

It seems to idle pretty well and revs cleanly; this has all been a cursory check while parked in the garage this evening - I haven't let it run long enough to get up to temperature yet but I reckon it's driveable and am looking forward to the next step of pottering up and down the road

 

I did notice when I switched off the ignition though, that the engine runs on (and I mean really runs on..it must be powered by magic)

 

What could be causing this? I didn't have the laptop connected to see what the ECU was doing at the time. Would it seem to point to a rich mixture at idle which the highish compression is then dieseling?

 

I can't see how it can be an electrical thing; my injectors and coil are relay-driven by the ignition switch so I'm positive they would have been off. The fan wasn't running and the charging light for the alternator came on when the ignition was off. It must be a mixture/plug issue mustn't it?

 

 

 

Darren E

 

K80 RUM Website and Emerald maps library

 

Home of the long-term, supercharged Duratec project

[Ivaan]

Darren, Try disconnecting the thermo switch in the top of the rad. ( switch controls the fan ). Just pull off the connectors, and try running/turning off the engine. If it still over runs, it can't be anything to do with the fan!

 

Clive

[Mr Locust]

Back EMF from motors as Ivaan says. 'Character'. The heater blower and the radiator fan can both hold the ECU live for a few seconds after key off.

 

Ian

 

Green and Silver Roadsport 😬

[Willie.]

Darren,

 

Research under the term "Pre-Ignition".

 

I'd check you're definetly running the correct plugs as a first move. They're maybe getting a bit too hot and air leaking past butterflies with a hint of fuel is igniting. You don't want to melt a plug...and maybe a piston.

 

Willie

Edited to add that this is going on my old school way of thinking 😬

 

 

Edited by - Opposite Lock on 28 Jul 2009 22:44:11

[tbird]

isnt it a symptom of too lean a mixture not too rich,

 

used to be on my old ford anyway, only way to stop it was to stuff it in gear with brakes on, jolly embarrasing

[Sigmamark]

I have a K series with an Emerald and am usually out of the car and unlocking the front door, before my motor stops. I thought it was a case of TADTS

[Mickrick]

When I were a lad, and cars had distributors, and carbs. We used to call that pre-ignition.

Combination of lean mixture/too far advanced ignition timing. (Too advanced ignition timing also cuased "Pinking" under load. (Sounds a bit like a tin full of tacks when going up a hill, or putting your foot down in a high gear).

It'll run hot and eventually hole a piston.

IIRC.

[I.Mupferit]

But hold on, surely to run on for any length of time requires a continual input of fuel, so regardless of any pre-ignition (which I doubt it is incidentally) there must be a power source from somewhere triggering the injectors at least, and probably the coil pack/fuel pump.

 

If the fan isn't freewheeling and supplying a power source, then it must be coming from somewhere else. I would be checking the relay output actually is killed when you switch off the ignition.

 

With carburettors of old, there was always the possibility of fuel still being supplied for a while if the engine was pulling air in through the intake, and then 'dieselling' which often denoted the need for a good old fashioned de-coke (aah thems were the days 😬).

 

Injectors however, should cease to supply fuel as soon as the power is cut and if there is no fuel, then the engine can not possibly run - unless you have discovered the answer to the worlds future energy problems. In which case - respect is due!

 

Edited by - Brent Chiswick on 29 Jul 2009 08:40:19

[k80rum]

Cheers chaps. I think you've put your finger on it Brent, thanks for that - I couldn't understand how it kept running on injectors unless they leaked, which given they're new seemed unlikely.

 

I've been giving it some thought (as you do, to make work that bit more exciting..) and I think its the way I've powered the Emerald; it needs 2 power feeds and instead of taking them both from the ignition switch, one's from the ignition and ones from the battery master switch, following a complete rewire including a change to how the MFRU is used (I've gone Peter C's route and done away with the single 30a ECU fuse).

 

I'd bet the fact that one of the ECU power supplies is still live when I turn the ignition off, is enough to keep the coil and injectors operating. The fact that the fuel pump stops means the injectors are squirting fuel under the gradually decreasing pressure until the supply stops.

 

Don't think I'll be giving up the day job to become an electrician any time soon! I'll confirm the theory and report back..

 

Darren E

 

K80 RUM Website and Emerald maps library

 

Home of the long-term, supercharged Duratec project

[I.Mupferit]

Sounds like a distinct possibility I'd say.

 

 

[Tony Whitley]

I have a K series with an Emerald and am usually out of the car and unlocking the front door, before my motor stops. I thought it was a case of TADTS

Well my K series with an Emerald certainly doesn't. It didn't when it had a MEMS either.

[Sigmamark]

My Emerald unit is apparently still powered up (red light still on) when the ignition is off and is only isolated when the Master Switch is off, so I guess I have the same issue as k80rum. I didn't install it so I don't get the logic of the 2 power sources, but I can't pretend that it is stressing me much

[Normans_Ghost]

De-cokes.

 

When I was a lad (before god was born) a Harley St. doctor would bring his Bristol 411 in for its annual de-coke.

 

Jimmy would take the car around Green Park flat out in firts and second with huge amounts of black smoke and soot emmiting from the exhaust. I woudl then clean the head and engine very carfully.

 

That was a 12 hour job done - think of all that bonus.

 

 

By the wey the car had spent the year being driven from the doctors house in Marleybone High Street to his surgery in Harley St. Mostly with the choke out.

 

Brent, you're so right - those were the days.

 

^{Norman Verona, 1989 BDR 220bhp, Reg: B16BDR, Mem No 2166, the full story here}

You and your seven toThe French Blatting Company Limited

[Johnty Lyons]

My K on an emerald when hot runs on....... I can be out of car and unpacking the boot when it eventually stops.It's been like that for eons Never bothers me 😬 😬 😬

 

---

jj

MTM , N.I. L7C AR 🙆🏻

Membership No.3927.

240BHP 1900cc K Series 40th Anniversary

 

[k80rum]

I've enjoyed reading the nostalgic recounts from years gone by 😶‍🌫️ Those were the days!

 

Well, I can confirm that the split power supplies to the Emerald were indeed the problem. I've hooked pins 11 and 28 up to a known ignition signal and now the engine stops and starts on the button It's a relief because given the head's just been ported and the pistons I used were new, I'd kind of ruled out carbon deposits..

 

Sigmamark, if you want your engine to die when you turn the key, I think switching whichever pin is on the BMS to the ignition switch should have a similar result.

 

Now to surprise the neighbours by wheeling it out of the garage for the first time in ages and try to get the hang of the new gearbox/engine/clutch/throttle/indicators setup 😬

 

Darren E

 

K80 RUM Website and Emerald maps library

 

Home of the long-term, supercharged Duratec project

[Pete-B]

Am I dreaming this?

 

When I was a kid ( hundreds of years ago ) my next door neighbour had an old lorry I think it was Morris I know on the rad were printed the words - Backbone Of England - and this must have been in the fifties. Anyhow I used to go out and help him at weekends for a bit of pocket money and I remember him sometimes pulling up, switching off, and there being a bang, the lorry would then start to shake and blow smoke everwhere. One day I said to him "why does it do that", he told me " it's running backwards" in effect sucking air in through the exhaust - which was very short - and blowing out through the air filter.

 

Peter

[Bob_Rich]

Dont know 2 much about ECU units but I am guessing that at low revs ( tickover) they dont take much current unlike a coil and contact breaker that takes around 3 to 5A. If the engine is running the alternator may still provide a small amount of power even with the ignition off and could this keep the ignition going and the engine running at tickover type speeds? depends on the exact circuit wiring I guess.

 

one test if it does run on along time would be when the ignition is off and its running on switch on the head lamps to full and that should load the system down and kill the source of power and if engine stops then that might be the source of the problem.

 

just a thought best of luck

 

Bob

[I.Mupferit]

I think he has found the problem Bob and it was down to the way the ecu was wired which provided a live feed to the injectors and coil pack even after switching off the ignition.

 

 

[Sigmamark]

I know that the problem has been solved and following the comment from k80rum, I found that I could kill my engine immediately by switching the master switch off, but why are ther 2 live feeds to the Emerald and further, why do at least a couple of us have those live feeds provided from different sources?