Engine Running Question
Turbo Mini Forums

Hi

My mini has been to Slarks and there is a slight issue with the running of the engine.

Its gets to about 4000 revs and the revs just die and then pick back up again. It happens when revving harder from low down in 2nd gear.

It is running a megajolt ignition. Could this just be caused from the wrong map causing a misfire as it seems to misfire a fair bit?

Thanks

Jon

Coilpack, wasted spark, EDIS - what have you fitted ?

If coilpack, try fitting a 20 microfarad Ford capacitor on the coilpack bracket. This should be Tee'd into the 12v feed wire to the centre pin of the coilpack connector and helps to improve voltage stability. Without it fitted, there can be a tendancy to cause misfires/ECU resets.

Talking of which, if you do a datalog of your ECU you should be able to see the misfire or the ECU resetting. If so, do some TM research and seek further advice from there.

Richard.

Minivanless, but reluctantly happy living with the decision. There'll be another one day.
http://www.youtube.com/profile?user=minimadmotorman#p/u

Are you sure it's ignition related and not fuel?

Having spoken to Neil at Slark he has said it definately is not the fueling.

It is a coilpack from a Ford Fiesta but I am sure there is the EDIS module aswell.

I have checked the sparks and they are nice and strong.

Its very strange, it just dies bit then picks back up again straight away but obvioulsy this needs sorting before Neil can sort the megajolt map out.

Could the cutting out be a result of the misfire, could this be caused by the map on the megajolt as they have not looked at this yet?

Thanks

Jon

Hi

Tried again this morning and it seems to stop after the engine has warmed up.

Cut out and picked back up 3 times in the spaces of 10 seconds.

I took a datalog of the event with the megajolt, you can see the first time being marked by the dotted line on the left hand side of the picture.



Anyone have any ideas?

Thanks

Jon

Jon.

The reason I said try fitting the 20 microfarad capacitor is that your symptoms mirror an issue I had early with my van. Fitting the cap sorted me out.

The capacitor is fitted with the Ford coilpack by Ford for this very reason.

Does your trace say that the ECU is resetting or are you unable to qualify this ?

Personally, I dont think your map is causing the misfire. But others are far better to advise on that.

Does this happen when you hold a steady 2000 rpm on the throttle ? or just at idle ?

Richard.

Minivanless, but reluctantly happy living with the decision. There'll be another one day.
http://www.youtube.com/profile?user=minimadmotorman#p/u

Hi

It happens when I am accelerating normally around 3 - 4k revs.

Where would the capacitor go as if it is not too expensive I will fit one anyway as I guess the voltage can change. The megajolt unit did seem to reset a couple of times as the datalogging reset itself.

Where would the capacitor go in terms of the wiring. The coil pack has the three wires going to it, would i just put this inline on the 12volt red wire?

Thanks

Jon

Also can you post up a link to to the capacitor I would need to buy?

Thanks

Jon

Jon.

Not in-line but Tee'd into the 12v feed to the coilpack.

All will be clear when you see the attachment which is from www.ExtraEFi.co.uk under ECU 'reset'.

The 'suppressor' as it's properly referred to, is usually bolted to the bracket in the engine bay on all Ford cars fitted with a coilpack. Its a 5 min job to undo and it'll cost you about 50p (assuming you dont buy the coil as a spare .

Any scrappy should have a Ford in it with a coilpack on, so just unbolt the grey suppressor and take the connector and a suitable length of the single strand wire attached to it.

Its just a case of then teeing this in to your central 12v feed wire to the coilpack. The single strand joins the 12v which then goes to the connector. The suppressor is grounded out on the bracket as close to the coil as possible.

Any probs, just PM me again.

Richard.

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Minivanless, but reluctantly happy living with the decision. There'll be another one day.
http://www.youtube.com/profile?user=minimadmotorman#p/u

I had the same issuse when I first fitted the MJ it would die and the rev counter drop to 0..

It was interferance on the sensor line, I earthed the sheilding at both the sensor end and Edit end to ground and the issue never came back.

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

Hi

The wiring has now been completed, fitted the capacitor and also fitted a 2 core shielded cable which has a good earth from it for the pip/saw cable and on the way taking the mini back to Slarks it did it again.

Any more ideas?

Thanks

Jon

Jon.

Well, thats fault finding for you.

Some cheap or older 9 pin / RS232 cables can cause earthing issues at the ECU.

1. On the drive to Slarks when it happened again, did you have your ECU to laptop cable fitted when it happened ? or not. Worth disconnecting this and seeing if it still misfires. I say this as I've had to cut the connector on my own cable down so that it is only the nine brass pins that make contact with my ECU connector - the metal connector does not make contact with the ECU case at all.

2. Have you checked that your trigger angle is exactly correct and that your idle ignition map setting is exactly what you are seeing with a strobe light ?

Richard.

Minivanless, but reluctantly happy living with the decision. There'll be another one day.
http://www.youtube.com/profile?user=minimadmotorman#p/u

Hi

The ECU connector was not connected so it does it with it both connected and un-connected.

I am going to ring Slarks in the morning and ask him to check the trigger angle to set it correctly in the Megajolt.

Hopefully it will be a fueling / timing issue as when it cuts out is also misfires at the same time so this could possibly be the issue.

Could it be down to cam timing, as I set this and I am no expert so could this cause such issues?

Thanks

Jon

if all else checks out in the electrical department ok, then any misfires
"Under Boost" is usally cause by a lean mixture

Excellent - I am pretty sure the electrics are ok, with the exception of the trigger wheel timing which I will get checked so hopefully it is just down to a fueling issue.

Cheers

Jon

Slarks have been doing some testing and the is very little load reading coming from the TPS.

To get this right there should be 0v when the TPS is in rest position up to about 5 volts when it is at 100%, is this correct?

Neil has tested the output from the TPS which is showing 2.5 volts, is this suggesting a knackered TPS, and also possibly a wiring issue.

Can anyone explain which what voltage these three wires should be showing etc?

Thanks

Jon

A TPS is fed with 5V constant and ground on two of the three pins. So one will be a constant 5V and the other a constant 0V. The third pin "reads" the position so registers between 0 and 5V as the throttle is moved.

If you are getting a constant 2.5V it implies either the TPS is fooked or the wiring is wrong.

To determine which, you need to disconnect the TPS and use a DVM between all three connections in a logical sequence, ie, find the highest resistance between two connections which doesn't vary as it's moved (which should be the 0V and 5V connections), then see how the third relates to the other two when it is moved to see which is high and which is low.

Schrödinger's cat - so which one am I ???

OK -

As confirmed from Neil -

There is a 5 volt coming from the megajolt.

There is also a ground.

The problem is that the other wire is producing a constant 2.5 volt output coming out of the megajolt unit itself.

This is clearly wrong but can anyone suggest what has gone wrong?

Thanks

Jon

Is this a turbo?

If it is then why are you using a TPS version of Megajolt?

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

You shouldn't be trying to measure what comes "out" of the MJ.....

It works the other way around. The TPS is fed 0V and 5V at either end of the track that measures the position and provides a voltage anywhere inbetween proportional to its position on the third pin.

If the MJ is not connected (or the TPS device is dead) the MJ connections will be 0V, 5V and totally random on the third pin as it's a current sink, it doesn't produce the voltage, it measures it....

Put a DVM on the TPS with the MJ disconnected and see if you get what I described in the previous post.

EDIT - I know I've explained tha badly..., try again - the MJ provides to 0V and 5V but does not provide the signal from the 3rd pin, it is derived from the 0V and 5V depending on the position of the TPS and fed back to the MJ. If it's not being fed back because either the TPS or wiring is faulty, the signal voltage at the MJ can be totally random depending on the fault in TPS sender or wiring.

Edited by Rod S on 11th May, 2010.

Schrödinger's cat - so which one am I ???

I've just tested the TPS with the following results:

Measuring resistance, meter on the following pins:

A-B -> Resistance goes from Low to High
B-C -> High to Low

Based on that would you think the following pin outs...

A=5V
B=Signal return to MJ
C=0V

Cheers,

Edited by jonb_5 on 11th May, 2010.

I've just found this link which suggests that C is 5V.

http://www.fordfuelinjection.com/?p=30

Mine is the same as the middle one towards the bottom of the page where the pins are labelled.

Edited by jonb_5 on 11th May, 2010.

What plugs are you using?

Not sure what plugs they are but they were knew last time it was rolling roaded.

Jon

Edited by Rod S on 12th May, 2010.

Schrödinger's cat - so which one am I ???