End of my tether! 86 S3 N/A

[jonwat]

2 hours ago, Steve4012 said:

I say this because there is a second wire that should be attached to the alternator to 'excite it' into charging fully from the off. Mine had come off and the alternator wasn't charging enough until I revved beyond 3k revs or so and these extra revs then it kicked into action and it charged normally.

My Europa Special did exactly this but in all the years I owned it I never knew why 😃

[Big Vern]

On 01/04/2021 at 14:13, jonwat said:

So, I can't think of anything that would cause those symptoms & then go away except a lack of fuel or air flowing into the carbs. What about the air intake, is it all clear & complete? I'm thinking of a problem Sparky had with a GT3, I know yours isn't  a turbo but it's worth checking. Failing that I'd suggest getting it on a rolling road where you can properly investigate while the problem is occurring. 🥺

John, i had a look at the air intake including all the pipework on top of the right tank. I temporarily took away the pipework and attached a pipe direct from the 'Ear' to the airbox. The problem still persisted although i prefer the way it is now. To think the air intake normally comes from the boot seems a little weird anyway.

 

 

On 01/04/2021 at 16:54, Steve4012 said:

Hi Brett. 

This maybe completely irrelevant but as you're struggling I thought I'd mention it. Is the voltmeter charge showing as low on the gauge when at the start of your journey? I say this because there is a second wire that should be attached to the alternator to 'excite it' into charging fully from the off. Mine had come off and the alternator wasn't charging enough until I revved beyond 3k revs or so and these extra revs then it kicked into action and it charged normally. I though it was temperature related as well but it was because I don't rev it hard from cold so it only solved itself when I revved higher after it had warmed up. Could this be some kind of low power problem (or surge)? Seems strange that your car runs worse with the correctly gapped plugs so could be related. Maybe it's lacking the juice to jump a spark .9mm across the plugs and it helps it at .7mm.

Cheers, Steve. 

Thanks Steve, i did check this and all wires are attached. I will take the airbox off though to double check, and while im there i will take another look at the dizzy and rotor etc......

I shall report back


Cheers guys

[jonwat]

16 hours ago, Big Vern said:

John, i had a look at the air intake including all the pipework on top of the right tank. I temporarily took away the pipework and attached a pipe direct from the 'Ear' to the airbox. The problem still persisted although i prefer the way it is now. To think the air intake normally comes from the boot seems a little weird anyway.

Known as the ram Air conversion worth at least one extra horse power 😃

[omegaman]

Have you checked the connections/wiring to the distributor ? have you swapped out the ignition amplifier module?

 

What does the Tacho do when it runs rough?

Edited April 5, 2021 by omegaman

[Big Vern]

19 hours ago, omegaman said:

Have you checked the connections/wiring to the distributor ? have you swapped out the ignition amplifier module?

 

What does the Tacho do when it runs rough?

I have checked the wires to the distributor, and they seem fine, i.e no breaks, and the plug part to the coil box is fine also . The tacho does drop when it does run rough. The other day it sat on the driveway and the stalled when it started to run rough about 10/15 mins after starting.....

[omegaman]

Did you swap out the ignition amplifier ? does you car have a ballast resistor ? sure you've got the correct coil ? If the Tacho is moving around in an odd manner when its running rough then it will be an ignition problem.......wiring, coil or ignition amplifier......or a combination. 

Edited April 6, 2021 by omegaman

[Bob Silk]

I had a rough running problem with my 82 S3 N/A a few years ago and went through everything time and again - all ignition and intake components. Ultrasonic clean of the carbs, etc. and got nowhere.

When I finally lost patience with it I did what I should have done in the beginning - sent it to Max 500. Independent Lotus specialist in Guildford; sorted!

Bob

[andydclements]

Given the erratic nature of the tacho during these episodes, it does seem to limit it to ignition problems. This is challenging though as there's no obvious component that would be fine cold, fail when starts to get warm, then return to an OK state when hot.  I think you're going to have to look for the type of improbable situation that @910Esprit called out (March 24th). On previous cars I've had things like rotor arms that short out when hot, cables to/from hall sensor that have cracks in metal and fail when the plastic coating gets too flexible when hot, along with fairly normal component failure in the ignition amplifier and coil, but I don't think any of those fit this, yours is probably going to be a case of get it to the point (sitting on the drive) where it falters and then diagnose methodically (check for spark at various stages of HT and LT system).

[Escape]

9 hours ago, Bob Silk said:

I had a rough running problem with my 82 S3 N/A a few years ago and went through everything time and again - all ignition and intake components. Ultrasonic clean of the carbs, etc. and got nowhere.

When I finally lost patience with it I did what I should have done in the beginning - sent it to Max 500. Independent Lotus specialist in Guildford; sorted!

Bob

Do you know what the exact problem and fix was?

[Big Vern]

On 05/04/2021 at 21:22, omegaman said:

have you swapped out the ignition amplifier module?

No i haven't.  I dont have a spare and they are quite expensive. I will look at finding maybe a second hand one to see if it helps.

 

15 hours ago, Escape said:

Do you know what the exact problem and fix was?

I'd also like to know!! It could be the answer to all my problems......

[Escape]

 

On 06/04/2021 at 18:10, omegaman said:

Did you swap out the ignition amplifier ?

8 hours ago, Big Vern said:

No i haven't.  I dont have a spare and they are quite expensive. I will look at finding maybe a second hand one to see if it helps.

Ask around here, surely there will be someone close by who will let you try a known good one. 😉

[omegaman]

Is it built into the distributor or mounted in a box externally  on the S3? like this 

 

 

[910Esprit]

If its an AB14 box, this is what is inside:  https://www.ebay.co.uk/itm/Ignition-Igniter-Control-Module-4-Pin-1875990-Fit-for-GM-Buick-Cadillac-Chevry/193540662875?hash=item2d0fec265b:g:WpAAAOSwl9RZ~C0b

( along with a zener diode I recall)

 

[omegaman]

36 minutes ago, 910Esprit said:

If its an AB14 box, this is what is inside:  https://www.ebay.co.uk/itm/Ignition-Igniter-Control-Module-4-Pin-1875990-Fit-for-GM-Buick-Cadillac-Chevry/193540662875?hash=item2d0fec265b:g:WpAAAOSwl9RZ~C0b

( along with a zener diode I recall)

 

Yeah they hide those in boxes on the jags as well 👍🏻

[Big Vern]

On 08/04/2021 at 08:05, omegaman said:

Is it built into the distributor or mounted in a box externally  on the S3? like this 

 

 

Yes i ts in the box attached to the boot with the coil. I did take it apart to check the internals and no broken wires. I also replaced the heat sink paste as there was hardly any of the original stuff left.

[Chillidoggy]

Just wondering, have you fitted a new ignition amplifier box?

My Chevy had the same ignitor module, and I know they can start to break down on occasion, usually due to heat.

[Big Vern]

29 minutes ago, Chillidoggy said:

Just wondering, have you fitted a new ignition amplifier box?

My Chevy had the same ignitor module, and I know they can start to break down on occasion, usually due to heat.

Do you mean the one in the pic above?

[Chillidoggy]

14 minutes ago, Big Vern said:

Do you mean the one in the pic above?

Indeed I do. 

[Big Vern]

1 hour ago, Chillidoggy said:

Indeed I do. 

Hi Ian, as i mentioned above, i Haven't mainly due to the fact they are so expensive for new ones just to test it, i will look around for a 2nd hand one

[910Esprit]

Brett - My link above shows the actual GM igniter thats inside the Lucas AB14 box - they're cheap and readily available.    Think I could find a spare if you get stuck

 

Edited April 9, 2021 by 910Esprit

[Chillidoggy]

33 minutes ago, Big Vern said:

Hi Ian, as i mentioned above, i Haven't mainly due to the fact they are so expensive for new ones just to test it, i will look around for a 2nd hand one

I don't know how much they are, and I don't know much about the S3 ignition circuit, but as a solid-state piece of electronics, it has to be worth a  try. Maybe see if anyone has a good, used spare they are willing to let you try. Only then can you rule it out as the cause.

[greentengu]

For additional reference, see above posts by 910Esprit, omegaman, and Chillidoggy. This just expands slightly on their input. 

If you search for GM 1875990 there are sources which have internal ignition amplifier / igniter / modules (not the full silver casing with other interior wiring), but from the pic below (from a Jaguar ignition module AB14) I wonder if there are a huge multitude of part numbers for the AB14 internals (?). In other words, an AB14 for a Jaguar might have a different internal PN than one for a Skoda, Lotus, or Chevy. 
 

In the US, Jegs.com, Summit Racing, and others carry numerous brands of these (including ones with labels/stickers attached to them from Pertronix for their various “Ignitor” parts; these come with a California CARB E/O number).

I found cross-references to this and a four-pin module at SKV Germany 🇩🇪 “Ignition System Switch Unit — Heavy Duty”. Via eBay UK.
 

I lifted this pic from a Brian Felts on the Jaguar Forums.com, which clearly shows the interior of the aforementioned Lucas AB14 module shown above. It clearly has “GM” emblazoned on its black plastic cover. Oddly, although the Jaguar thread is for the Lucas AB14, the part number stamped on the GM part is different from the ones I could find.

[semi42]

Not sure if you can with an s3 but I did swap out a duff lumenition system with a pertronix dizzy , was a cheap(ish) fix

[semi42]

Wasn’t pertronix, was an accuspark / powerspark  lucas 45 replacement

[Andyww]

If its a suspected ignition problem why not buy a set of 4 neon spark plug cap indicators and leave them fitted. Then you will have an instant indication of whether the problem is loss of spark and whether on all or some plugs.

I believe they started fitting some of the emissions stuff on UK engines before the HC such as the temperature controlled vacuum advance on the distributor.

The engine has the longer HC inlet manifold and HC style cam covers or did they fit those to all the LC NA engines?