Distributor????

[motul1974]

I'm a bit (a lot) confused.

My chimaera died whilst idilling yesterday and then simply failed to start. It turned over well. Fuel pump did it's stuff, but just simply failed to catch.
The AA were called out where the very helpful AA nan said I had no power out of the amplifier. It was going in, but he couldn't detect anything going to the disi. I was annoyed as I has just fitted a new lucas one as I'd been told my car dropping on revs and cutting out was most certainly caused my the amplifier. Anyway cut a long story short, we switched the new one for the old one, same issue, but then he put a live from the coil directly to the disi (not sure where exactly ) and hey presto it started on the button
I managed to drive home where he had kindly followed me to to ensure I got back alright, and so I took the opportunity to ask him what the rough the issue was?
He explained the it was most likely the dissi that was at fault. He pointed out the dropping of revs occasionally whilst idilling and said that I needed part of the dissi replaced inside. I'm sure he mentioned something like a Holden switch....or least it was something very like that. It led below the rota arm.....im totally lost!

Does this sound like something anyone has come across before??

Or maybe there might be another suggestion as to my problem.


Any help would be great.


Adrian

[KKson]

It may have said hall effect pickup? Which is the sensor inside the dissy. I had an issue last year with my 350i - started fine but then as it got warmer a misfire kicked in that just got worse and worse. I replaced just about everything but the misfire came back. Eventually tracked it down to three components, all breaking down when hot - hall effect pickup, HT leads and coil, even though all three items were new.

Top tip was to run the engine at night, in the dark, and look out for any stray HT sparks - on mine the top of the coil and a length of the king lead were lit up like a Christmas tree.

It's easy enough with a wiring diagram to trace the power to the ignition amp in order to double check that the wiring and connections are all okay. Ignition amps do die due to the under body heat so if there's power to the unit - it might be dead? Worth checking the cheaper and easy parts before assuming it's the actual dissy itself.

[motul1974]

Thats great. Hall effect sounds very much like what he said to me. He did say it's a replaceable item, but i was under the impression the dissi was non-maintenance other than car and arm?
That all sounds great advice though. I'll check it out one evening.

Adrian

[Jurgen Schmidt]

My Griff is currently at Str8six with a similar issue

Infrequently, the revs will drop whilst stationary, in neutral and idling, and would eventually stall.

She'd restart fine, but the revs would oscillate quite noticeably

She wouldn't need to be warm to exhibit these symptoms

Hoping for some good news soon...

[blitzracing]

Its not a hall type set up, but a simple magnetic trigger with a coil of wire. There is a permanent magnet around the pickup "head" and when the 8 lobe rotor spins near it, it creates a small voltage in the coil. This is then amplified by the Ignition Amp that allows it to switch the coil- its ultra simple. There is not much to go wrong with the sensor- its just a coil of wire,but it has been known for the wires to break where it connects to then amp, but no amount of connecting wires to the coil would fix this fault. If the breakdown man jumped from the battery- or alternator to the coil to get it going, its more likely the feed to the coil is missing. I dont know how the TVR imobilser works but it might interrupt this feed. Ive done a bit about fault finding the trigger head here:

http://www.g33.co.uk/ignition_system.htm

[motul1974]

Is if funny that it turned over stringly, but refused to catch. Then by him appearing to jump if off what I thought was the coil to dissi (sounds like I could be wrong) it started up on the button, only to occasionally drop in revs to almost stalling point but then pick up again...not all the time, just maybe an occasion or two every minute or so.

[Sardonicus]

What Blitz said it's a constant energy system like Ford/Motorcraft and the likes of Honda etc used it the 80's

[Oldred_V8S]

blitzracing said:

Its not a hall type set up, but a simple magnetic trigger with a coil of wire. There is a permanent magnet around the pickup "head" and when the 8 lobe rotor spins near it, it creates a small voltage in the coil. This is then amplified by the Ignition Amp that allows it to switch the coil- its ultra simple. There is not much to go wrong with the sensor- its just a coil of wire,but it has been known for the wires to break where it connects to then amp, but no amount of connecting wires to the coil would fix this fault. If the breakdown man jumped from the battery- or alternator to the coil to get it going, its more likely the feed to the coil is missing. I dont know how the TVR imobilser works but it might interrupt this feed. Ive done a bit about fault finding the trigger head here:

http://www.g33.co.uk/ignition_system.htm

Mark

What is the trigger head off and where can I get a spare?
Many thanks
Paul

[blitzracing]

I dont know if the trigger head is available as a spare part at all- its easy enough to do a test on the coil, you just remove the ignition amp and put a test meter across the two connectors and measure the resistance. If its open circuit its knackered- I dont know off the top of my head how many ohms it should be, but Ill find out a value for you. In terms of getting it fixed, I see Powersparks do a complete dizzy for not lot including the Amp.

http://www.ebay.co.uk/itm/TVR-V8-Electronic-Distri...

Note this is the dizzy used on the preserp engine, I dont know if the serpentine engine uses a different one?

Edited by blitzracing on Thursday 19th May 16:27

[blitzracing]

Its 3k ohms.

[Oldred_V8S]

blitzracing said:

Its 3k ohms.

Thanks Mark.

[Andav469]

Distributer doctor will refurb your existing distributer for a reasonable cost

http://www.distributordoctor.com

Edited by Andav469 on Friday 20th May 09:22

[motul1974]

Thanks for all the guidance. I've one of technicians look at it tomorrow for me, so I'll hopefully post an outcome to my issue.

[motul1974]

BACK TO SQUARE ONE!

Techs looked at here and gave it an all clear. All connections good. All earths good....it ran like a beauty for them.

How is your car getting on Jurgen???


Adrian

[blitzracing]

If you do have trigger issues, and you can get the engine to misfire check the rev counter as this will behave erratically when trigger pulses are dropped.

[motul1974]

Thanks, but it doesn't miss- fire, only ever drops in revs to the extent of cutting out and I seem to get the occasional slight hesitation.

[blitzracing]

The idle control is a finely balanced system- its programmed to expect the engine RPM to drop at a fixed rate when it alters the stepper position. If anything alters the rate of RPM change then the system effectively overshoots, so the RPM can drop too far. Typically air leaks, unstable mixtures or misfires will cause the RPM to be unstable.

[Jurgen Schmidt]

motul1974 said:

BACK TO SQUARE ONE!

Techs looked at here and gave it an all clear. All connections good. All earths good....it ran like a beauty for them.

How is your car getting on Jurgen???


Adrian

No news yet I'm afraid