Misfire K Series

[rj]

Was this a like for like swap?

As Andrew suggests you may want a resistor to switched +ve to make the alternator light go out

 

[Orange]

It is supposedly, I could not determine what make the original was. Any idea which wire and what resistor. I am a bit reluctant to start messing with the wiring loom. This is the reason I did not go for the WOSP alternator……

any ideas on hunting/ stalling?

[rj]

You may need to reset the ECU if it has corrected for wrong mixture due to wrong supply voltage.

I need to look into the wiring diagram to make sure I give you the correct colour. You could, as a test piggyback in the connector on the alternator. I'd use a 68ohms 5w resistor. Be careful that it may become hot like Andrew says

[rj]

Brown with a yellow tracer will be your friend. It's also to be found in the grey connector that joins main and engine loom (pin 11)

The other end of the resistor should go to a switched +ve

[Orange]

Many thanks for your help. I am not great with car electrics and do not understand what you are suggesting I do. Please could you explain more.

I did disconnect the battery to fit the new alternator - will that not have reset the ecu?

[rj]

No, resetting requires that your turn on ignition without starting, slowly depress the throttle (ca 5 sec) five times. I am unsure id you can then start the engine or need to turn off ignition before starting.

Will try to reword the resistor part later

[Jonathan Kay]

11 hours ago, Orange said:

New alternator is working and charging but the red light on the dash does not go off once started…..

Private Message sent.

Jonathan

[Orange]

To provide more info. New alternator is Fahren for eu3 rover engine so direct replacement.

Wires going to alternator are 2No small in D connector are yellow/red and yellow/ brown plus the larger red +ve wire that goes to the battery via the starter motor.

Charging is now normal and working but ignition light does not go out when car is started.

i have reset the ECU/ TPS (5 presses of accelerator etc) but tick over seems a bit lumpy (very slight) and randomly every few mins seems to do revs and try to catch itself sometimes it does and others it stalls. That said it has just run for about 10 mins and not dropped revs or stalled……

I think I have 2 problems the light which sounds like it needs a resistor adding somewhere in the circuit, and lumpy idle and occasional stalling.

I have an obd11 reader - anything I could be checking or looking for?

[rj]

I have no experience with the OBD11, so can't help there.

It looks like your led needs help from a resistor. This would be the brown wire with yellow tracer (probably the one you call yellow/brown).
Between this wire and +12v via ignition you need the said 68ohms /5watts resistor.

[anthonym]

"You can add a power resistor from the alternator wire to +12V "

could that be an old fashioned bulb fitted somewhere?

[rj]

Yes, certainly.

Between the brown/yellow wire and a switched +ve (+ from the ignition switch)

 

[Orange]

Does this go across the yellow/ red and yellow/ brown that goes to the alternator?

would it not just be cut into the correct wire?

I am probably being a bit thick but I still don’t understand where the resistor goes.

[rj]

Not cut into the wire. One end connects to the unbroken brown / yellow and one to a switched +ve which I on my own car found at the MFRU.

If you are on WhatsApp shall I happily try to talk you  through (I'm in Denmark, hence the suggestion of using WhatsApp)

 

[rj]

PS: I'll soon be off for the day as I have to start *very* early tomorrow. That is not because I've lost interest in helping you to sort the problem.

[Orange]

Hi RJ - just sent you a BM

 

[revilla]

10 hours ago, rj said:

No, resetting requires that your turn on ignition without starting, slowly depress the throttle (ca 5 sec) five times. I am unsure id you can then start the engine or need to turn off ignition before starting.

Will try to reword the resistor part later

That's not quite correct.

That process is just to teach the ECU to recognise the closed throttle voltage of the TPS. Unlike with an Emerald where you have to set the TPS to give a precise voltage,  these ECUs were for production cars where that's just too much faffing around! So the TPS just gives whatever voltage it gives and the ECU learns it.

It's often referred to as an "IACV Reset" and while it may help the ECU to idle correctly, it has nothing to do with the IACV.

Neither will it reset any fuelling adaptations for voltage-dependent injector dead time. You can clear those with my (free) MEMS3 Mapper but to be honest a good bit of mixed driving and it will readapt anyway. 

And yes, you do ideally need to turn off for a few seconds to force it to commit back to EEPROM.

[Orange]

Thanks Andrew - I think the rough running is getting better. I have cleaned the IACV and reset the TPS. I have just got back from a run and tickover is now better and it only tried to stall once but caught itself.

Edited August 7 by Orange

[rj]

 

31 minutes ago, revilla said:

That's not quite correct.

That process is just to teach the ECU to recognise the closed throttle voltage of the TPS. Unlike with an Emerald where you have to set the TPS to give a precise voltage,  these ECUs were for production cars where that's just too much faffing around! So the TPS just gives whatever voltage it gives and the ECU learns it.

It's often referred to as an "IACV Reset" and while it may help the ECU to idle correctly, it has nothing to do with the IACV.

Neither will it reset any fuelling adaptations for voltage-dependent injector dead time. You can clear those with my (free) MEMS3 Mapper but to be honest a good bit of mixed driving and it will readapt anyway. 

And yes, you do ideally need to turn off for a few seconds to force it to commit back to EEPROM.

A bit off topic, but Andrew have you ever seen an ECU where this EEPROM fails?
If so have I a local whom may need one of your ECUs as it acts if it forgets the TPS reference points.

[revilla]

I've seen MEMS 1.9 ECUs which have a particular failure mode that looks like it might be connected with a failure of the EEPROM, but it tends to be a total failure; the chip is reliable and you don't usually get bad cells, and if the whole chip was failing you would also lose the immobiliser pairing which would be rather obvious.

I think it's more likely to be a worn TPS or wiring fault. I have seen ECUs which seem to forget the closed throttle reference and periodically need a reset. I think the adaptive nature of the ECU means by design if it keeps seeing a voltage lower than the learned closed throttle voltage, it lowers the set point to match to allow for wear and tear. If the TPS closed voltage becomes unpredictable, the ECU can adapt to a voltage below the normal closed throttle voltage; it then sort of "forgets to manage the idle" as the closed throttle isn't recognised.

[rj]

Niether wiring nor TPS seem faulty, but it behaves exactly as you describe. Sourcing a new TPS is not easy as this is the hens teeth option as fitted on early 1.4s albeit a 1.6.

Edited August 7 by rj
spelling

[Orange]

Rough running/ misfire is now completely cured! It took me a while through process of elimination……It was a dirty MAP sensor.