[Mk2] [Turbo] Suspected ignition problem, dizzy and rotor??

Anything and everything to do with mechanical issues with your Mk2

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Bear87
Posts: 300
Joined: Wed Sep 28, 2016 10:05 pm
Location: Essex

Re: [Mk2] [Turbo] Suspected ignition problem, dizzy and rotor??

Post by Bear87 »

I had similar issues with mine got to the point where I had to change parts did coil, ignitor, ecu, dizzy, rotor arm, leads, plugs and after all that it was bad earth leads to the engine block oh and x3 dodgy genuine knock sensors. I'm an engineer by trade and had all the testing equipment I wish I didn't over look the easiest problems first!

Ignition has always been the weak point in these cars but often its the age related stuff that all cars get before component faliure
Pauln
Posts: 850
Joined: Mon May 08, 2006 10:15 pm
Location: Cardiff, South Wales

Re: [Mk2] [Turbo] Suspected ignition problem, dizzy and rotor??

Post by Pauln »

Sorry to hear that Ed, it did sound like everything was sorted.

Are you getting a full set of warning lights when you turn the ignition on, just wondered if it might be an immobilizer issue.

I assume there are no error codes stored.

Are the ignition leads OK and pushed fully home, king lead in particular?

It does sound almost like a connection has come loose, or water has got into the ignition system somewhere.

Paul
yokomomr4bx
Posts: 216
Joined: Sun Jan 20, 2013 3:06 pm
Location: Cardiff

Re: [Mk2] [Turbo] Suspected ignition problem, dizzy and rotor??

Post by yokomomr4bx »

Ok, so after having the entire ignition system out, I traced it quite quickly to a high primary coil resistance... I hope. Either that, or its been a wonderful coincidence that it's started every time since I fitted a new coil, decent NGK one this time. In my removal of components I also reminded myself that about 1/4 of the wires going into the ecu from the loom had been spliced into a piggyback when I got the car and I had hurriedly twisted and wrapped them to get me home...and that was over 3 years ago...and it's been on some seriously long tours in that time :whistle:

This year really is going to have to be the year that I work my way through properly fixing the number of bodges that I've forgotten even doing, though I don't fancy shaming myself by uploading photos of them to my build thread :-$
yokomomr4bx
Posts: 216
Joined: Sun Jan 20, 2013 3:06 pm
Location: Cardiff

Re: [Mk2] [Turbo] Suspected ignition problem, dizzy and rotor??

Post by yokomomr4bx »

Ok so a development for anyone who is still interested...

Definitely fixed the starting problem, starts a treat now. However, I'm still plagued by a bizarre cutting out and hesitation under light load on a long journey. I got hold of a TOYOBD1 diagnostic unit in an effort to monitor a few parameters, however all I'm really seeing is the result of the hesitation/fuel cut on the timing/mixture/inj duration, rather than the cause.

Few questions, how hot should the fuel pump resistor pack be getting in normal running? As an example mine is too hot to touch for more than a second after normal driving.

Are there any known issues as a result of a corroded/broken E02 earth pin, which as I understand is the earth for the injector drivers in the ECU?

Would a fuel pump on the way out be overheating the resistor pack?? I'm going in circles in my head with this one as I'm convinced its a fuelling issue. Nothing else is going to make an engine stop dead in its track when its fully up to temperature like fuel being suddenly taken away.

Any opinions or general thoughts would be much appreciated, really can't wait to get to the bottom of this one, fun as it is to have a bit of a puzzle ;)

EDIT: On a side note, the TOYOBD1 module informed me that under full boost (in my case 1.15bar) and around 6000ish rpm, I'm getting a calculated MPG of 1.64... ACE! ;)
Last edited by yokomomr4bx on Sun Feb 11, 2018 8:44 pm, edited 1 time in total.
Pauln
Posts: 850
Joined: Mon May 08, 2006 10:15 pm
Location: Cardiff, South Wales

Re: [Mk2] [Turbo] Suspected ignition problem, dizzy and rotor??

Post by Pauln »

My understanding is that the resistor pack is used to lower the voltage supplied to the fuel pump to reduce the fuel rate. So when maximum fueling is required the resistor pack is switched out of circuit by the fuel pump relay. The fuel pump relay never actually switches the pump off, just selects the full 12+ volts for high flow or I believe around 8v for lower flow rate.

Whilst I've never checked, I'm surprised that the coil pack is that hot after a run as I would have though it spent a fair amount of time out of circuit during "normal" driving. The rest position for the relay is via the coil pack, so I wonder if the relay isn't switching. It looks like pin 6 on the ECU goes to ground to switch the relay via in 1 on the relay, which then takes the coil pack out of use.

Certainly worth checking that EO2 has a good solid connection to earth, as I few people seem to have issues that have been traced back to that.

I also spent a lot of time pulling my hair out with my previous na, which had a habit of stalling when I pulled up at a junction if I didn't keep the revs up, and eventually it ended up stalling and refusing to restart until the car was left for half hour or so. In the end I took it to my mates garage and we found the ECU was switching the injectors off for no apparent reason. The ECU all looked clean inside, but when I replaced it bingo, no further issues.

Just a couple of thoughts. These sort of issues are always the hardest to track down.

Paul
paulharry
Posts: 72
Joined: Tue Sep 06, 2011 6:25 pm

Re: [Mk2] [Turbo] Suspected ignition problem, dizzy and rotor??

Post by paulharry »

Try a different engine wiring loom if some one can lend you one
yokomomr4bx
Posts: 216
Joined: Sun Jan 20, 2013 3:06 pm
Location: Cardiff

Re: [Mk2] [Turbo] Suspected ignition problem, dizzy and rotor??

Post by yokomomr4bx »

Hopefully the last update on this issue...

Reattached the EO2 earth (properly this time) and she's been fine for the past few weeks :D I have a few theories regarding the electrical reasoning for this happening, but will save them for a build thread update later in the year.

I was able to data-log 3 occasions, before I repaired EO2, in which the engine was under this fuel-cut/misfire condition. Even though ECU refresh rate is only 1.3s this was still quick enough to show the injector duty returning to idle, along with the IACV, when the TPS was at or around full 90 degrees and boost pressure was X kpa (I can't remember off the top of my head, but around 180 I think at the exact moment before idle conditions). I should also point out that I'm not running crazy boost, you would need to subtract 1 atmosphere from the kpa displayed to show the actual pressurised air charge...or something along those lines.

Overall I highly recommend getting hold of a TOYOBD live data-logger if you see one going cheap!

To satisfy my curiosity and to exclude the fuel pump, I also installed a fuel pressure gauge which nicely showed the resistor pack function during start up and also confirmed normal fuel pressure regulation during all driving conditions.

I'm not sure if showing the specific data acquired at the time of the issue would be of any use to anyone in the future?
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