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Ignition wiring 
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Looking like a GTM

Joined: Mon Aug 18, 2014 6:07 pm
Posts: 160
Location: Devon
GTM: Libra
Post Re: Ignition wiring
I had several issues with the K3 I had. The first was the engine loom breaking down, there were some really Toffee joints and kinks in the wires from the factory, I ended up pretty much retiring the whole thing, not as daunting as it sounds, all the bits are available and Trigger Wheels do wire packs. You get to bin all the ‘extra’ wires you don’t need and replace the various fixes and bodges inflicted on the loom over the years.

Then the crank position sensor gave up, leaving me cranking with no spark, the failure was intermittent before finally packing up, which took some finding.


Mon Apr 15, 2019 9:37 pm
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Joined: Wed Aug 11, 2010 9:27 am
Posts: 421
Location: Sheffield
GTM: Libra
Post Re: Ignition wiring
Does your engine block have a good path to earth? Should be a wire going from rear face of block into the loom run that crosses the rear of the engine.

There should be no continuity between any coloured (not black) loom wire and any earth point.

On my car a fat black cable runs from battery -ve to starter. Batt -ve is also connected to the metal bracket (via a single bolt) of the fuse holder at front left under bonnet - all earths are taken from this point including one that goes to the engine bay and feeds the ECU with all it's earthing needs.

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2000 GTM Libra 1.8VVC 145BHP


Tue Apr 16, 2019 11:44 am
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Joined: Thu Nov 22, 2007 10:31 am
Posts: 96
Post Re: Ignition wiring
The engine has a good path to earth. Long black cable from the -ve terminal to the gearbox. I also have a bolt earth point under the bonnet, but my earthing at the rear of the vehicle (6 black earth wires / rings) for the ECU etc. connects to a plate which is bolted to the gearbox. All of these have been scrubbed free of oxide and show <0.01 ohm resistance.

Sidewinder, did you mean your +ve cable runs to the starter and not -ve? My understanding is that the red cable from battery +ve and a 12v switch run to the starter and it is earthed off to the engine through the bolts / fixings?..

I'll need to investigate more about this earthing on white ignition when it stops raining. Fully expecting to find a burned out mess somewhere in the wiring loom (sods law it will be in the middle of the tunnel under the gear change and hard to get to!).

Tempting to rewire the whole vehicle as there are so many oxidised connections, cuts and splices (and concerning insulation tape bodge repairs on the loom) from previous tinkerers I'm surprised there hasn't been a fire...


Wed Apr 17, 2019 2:02 pm
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Joined: Thu Nov 22, 2007 10:31 am
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Post Re: Ignition wiring
The plot thickens.

Traced the earthing to the fusebox. Opened it up and can see light corrosion inside. I know there has been water in the cabin before and the dash has been open for ages, so it does make some sense.

Open to suggestions what to do next. Buy a like for like fuse box off Ebay and cross fingers, or I could stop reinventing and rewire the vehicle using an mgf loom or make one myself.

Does the mgf loom fit down the tunnel?


Wed Apr 17, 2019 6:58 pm
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Joined: Sat Feb 14, 2009 6:06 pm
Posts: 365
Post Re: Ignition wiring
I don't know about an MGF loom fitting in the tunnel but I would imagine that would be the best start.

The Libra uses a Metro loom with various GTM sub looms and lots of extended wires that go all over the place. Plus of course the modifications to add the VVC engine.

I would use an MGF/TF loom from the correct mems car and just strip out the stuff not required. I did the same thing in my Thruxton build using an MX5 engine, ecu, box, steering column and loom. Plugged it in and it fired straight up.


Thu Apr 18, 2019 10:56 am
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Joined: Wed Aug 11, 2010 9:27 am
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Location: Sheffield
GTM: Libra
Post Re: Ignition wiring
Sorry, the batt -ve goes to a bolt on the gearbox behind the starter. Battery +ve goes to starter solenoid attached to starter motor.

Only the GTM loom goes thru the tunnel to the rear IIRC.

Sounds like you need to unplug and remove the fuse box to clean it up or get a new one, there are some decent looking ones on ebay.

Have you checked lights, horn, indicators other electrics etc to see if they behave, if not might indicate fusebox damaged.

Checked (bleeped) fuses including main ones under bonnet?

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2000 GTM Libra 1.8VVC 145BHP


Thu Apr 18, 2019 11:06 am
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Joined: Thu Nov 22, 2007 10:31 am
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Post Re: Ignition wiring
I managed to pick up a fuse box for 15 so I'll try that and go from there. All the fuses are good and I checked the relays out too.

Back up plan then is a new loom, bite the bullet. Thanks for your help and advice everyone.


Thu Apr 18, 2019 7:30 pm
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Joined: Sun Oct 19, 2014 10:10 pm
Posts: 793
Location: Bristol
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Post Re: Ignition wiring
tonygerrard(1049) wrote:
bite the bullet.

Probably better if you use a proper crimping tool - you'll chip your teeth! :roll:


Thu Apr 18, 2019 8:12 pm
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Joined: Thu Jan 23, 2014 10:26 pm
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GTM: Libra
Post Re: Ignition wiring
The resistance value you see on the white wire doesn't sound silly. There will be components with capacitance & resistance which will give a non zero reading.

You can slave 12v onto the coils & injectors to eliminate those concerns.

It sounds to me that the ecu isn't recognising engine rotation.

Check continuity of the crank sensor wiring between sensor & ecu.
Check the sensor has continuity & isn't physically damaged, ideally swap out if poss.

As I mentioned before the K used several different crank trigger patterns across the different versions & derivatives. If you don't have the flywheel which matches the pattern the ecu is expecting to see then it will never synchronise & enable sparks & fuel. VVC certainky different to the others.

The Emerald ecu has the capability of doing immo based around the 5as if you really want it but probably not worth the bother these days! People tend to keep the 5as for central door locking - I know the 10as does interior light control & various other bits. Not sure tge 5as does all that though.

Stew

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StewB

'09 Libra K20
'69 TVR Vixen V8
'86 Capri 2.8i S

Ex Libra V6


Fri May 03, 2019 8:05 pm
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Joined: Thu Nov 22, 2007 10:31 am
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Post Re: Ignition wiring
Thanks again for the comments.

Fusebox didnt help so back to the timing. I've purchased cam and crank sensors and will check the wiring between the ECU and connectors again to be sure.

Tested them both outside the car and they generate voltage when metal is moved infront of the magnet so they're probably ok, but at this stage - worth it I think.


Sun May 05, 2019 10:14 pm
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Location: Sheffield
GTM: Libra
Post Re: Ignition wiring
Pretty sure I read somewhere that there is more than one crank sensor with different sensor gaps too.

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Sun May 05, 2019 10:18 pm
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Post Re: Ignition wiring
Another couple of thoughts based on a conversation I was having about someone elses starting issues on a completely different car...

Have you checked for a spark by taking a spark plug out of the head and plugging it into the HT lead and cranking with the outside earthed? If you are then at least you know the coil packs and HT leads are working, whether that spark is at the right time is another matter. If no spark then likely causes are: 1) immobiliser, 2) coil packs, 3) sensors (crank 1st then cam), 4) wrong sensor pick up pattern on flywheel, 5) relay pack.

If you have a decent spark, do you have fuel? Does the pump spin up? If you take the flow pipe off the header rail does it squirt out?

If you are getting fuel, how old is the fuel? is it contaminated?

My friend's problem turned out to be the latter. The car hadn't run for over a year and the petrol had gone off and some water had got in the tank from standing. After draining the tank and replacing the inline filter he was back in business.


Mon May 06, 2019 10:32 am
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Joined: Thu Nov 22, 2007 10:31 am
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Post Re: Ignition wiring
I have checked for spark and there is nothing. No pulse from ECU by the looks of it. Plugs are new as are the ht leads and relay pack. I've done my best to test the coil. Petrol is new, only a few new gallons in the tank though. Petrol flows when filter is removed and I think I can smell a faint petrol smell in the cylinders when a plug is removed - doesnt seen like quite as much as there should be though, not that I have a reference.

Immobiliser should not be an issue now the ECU has a built in code generator. Crank and cam sensors are on the way but as I said in previous post i suspect they did work.

There may be issues with type. These are the links for the ones I got from Ebay:

https://rover.ebay.com/rover/0/0/0?mpre ... 1946722774

https://rover.ebay.com/rover/0/0/0?mpre ... 1893598427

My engine is a mems 2j 1.8vvc 143 bhp version. The Ebay parts selector said these were compatible.

In another post I looked at the belt and vvc timing and I think they are now ok but how do I begin the investigation into flywheel timing / pattern?


Mon May 06, 2019 9:21 pm
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Location: Bristol
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Post Re: Ignition wiring
tonygerrard(1049) wrote:
how do I begin the investigation into flywheel timing / pattern?

The first question is did it ever run with the engine/flywheel combination currently in it? If it has run and nothing has changed then it can't be the flywheel. If it never got as far as running following an engine swap then I'd say it is a good possibility. The flywheel needs to be the correct one for the ECU. The guy I bought my Spyder from learnt this the hard way. He fitted a 1.6 mems 3 from a TF but as he chose to use the original R65 gearbox (the car was originally built with a 1.4/R65) he used the flywheel from the 1.4. It didn't run as the hole pattern for the crank sensor pick ups was all wrong. If your engine has its original flywheel and ECU then it should work so could be the sensor itself. The gap between the sensor and flywheel is another thing that can impact on it working. The gap range is quite crucial and some sensors dont fit so well so the gap is too large or too small.


Mon May 06, 2019 9:52 pm
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Post Re: Ignition wiring
Just looked back at the start of this thread. Changing from a 1.1 Metro engine to a 1.8VVC. So, are you using the Metro R65 gearbox or did that get changed to a PG1? If you are using the metro gearbox then the original VVC flywheel must have been changed as AFAIK the standard VVC one won't fit. I suspect there are a few flywheel/clutch assemblies that will allow them to physically couple but probably only one that will have the correct pulse pattern. I'm sure Dudley would have known that though.

I suspect the only way to check for sure is to separate the engine from the gearbox and check the code stamped on the flywheel. That will probably need the clutch removing too to get to the markings.

First, have you got a PG1 or R65 'box. If its a PG1 I can't see any reason why the VVC flywheel wouldn't have been left on so should be correct. If you have an R65 then this might be the issue.


Mon May 06, 2019 10:02 pm
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