End of my tether! 86 S3 N/A

[Big Vern]

Hi folks, apologies for the delay in responding, i've been (to the best of my abilities!) fault finding all week to see if can make use of all these great suggestions to solve my problem. First of all i took the carbs off and gave them a good clean and blast through. All seemed ok. I also checked the float heights which were correct. I did find one o ring that wasn't there on one of the idle mixture screws which has since been replaced. I also contacted Eurocarb regarding the tiny filters above the float needles as although they were there, they are tiny and were a bit crushed. On their website they were discontinued. They advised they were only used by Lotus as there wasn't a Banjo filter. On mine there is a banjo filter so although ive kept them ive removed the very tiny ones. All back together and back on the car with new gaskets etc and new O rings also on the spaces between the inlet manifold and carbs and set to the correct gap. I also balanced them using my Carbtune too. New Petrol also. One thing i did notice was the fuel pipe coming going into the carb was cable tied to the water pipe. Now i did read somewhere else about fuel evaporation if the fuel lines are near anything too hot so i unclipped it so its no longer attached to the pipe. Took it out for a spin..... and it still kangarooed after approx 15/20 minutes once it was up to temp. I think i'm ruling out fuel now as the problem so looked at the electrical side of things....

Again, the plugs, leads, coil, dizzy cap and rotor have all recently been replaced (prior to that it still kangarooed anyway). As a few of you have mentioned the Ignition Amplifier. The one i currently had, i replaced the 'hardly any' heatsink paste with some new gunk, but still it made no difference. I did notice the black amplifier metal box did get very hot but i guess that was the paste spreading the heat (the coil wasn't even warm). So i bought a new module for £10 which took a few days to come from China. It looked exactly the same but when i put it in the car ran on pretty much half power, so i had another look and after much perusing i found one from the uk on Ebay for £18. It has since arrived and will be swapped over probably tomorrow  for me to try. I will report back with an update then. Someone also mentioned unplugging the rev limiter but this also made no difference either. My only other option after this is the Distributor. This bit scares me a bit as i dont want to muck up the timing if i have to remove it. I cant see any breaks in the wires from the pick up either and i have wiggled them a bit when its stumbling at idle and it makes no difference.

So i'll check the ignition module replacement next and report back. Just wanted to give you an update

Regards all

Brett 

(Steve, i did check the wires on the alternator are attached as they should be and the voltage is ok)
(Andy, i also bought some neon sprak plug testers and put them on... no obvious sparking issues while the stumbling happened)

[Chillidoggy]

Are the AB14 modules specific to the car?

[Big Vern]

34 minutes ago, Chillidoggy said:

Are the AB14 modules specific to the car?

Its really hard to say as they all have different numbers on them, other than buying a complete unit for £200 odd from SJ, its a case of trial and error i think. I used the ref GM 1875990 that Scott mentioned as a guide.

[910Esprit]

I am not aware of different versions 'electronically' However there are 2 & 3 wire versions, but these can still be interchanged with some simple config changes.  Also the trigger connecting plugs seem manufacturer specific.  The trigger tails are polarity sensitive as the waveform that triggers the amp is asymetrical.   

What coil are you using?   You need the correct version such as a DLB198 with a low primary resistance.

 

[Big Vern]

39 minutes ago, 910Esprit said:

I am not aware of different versions 'electronically' However there are 2 & 3 wire versions, but these can still be interchanged with some simple config changes.  Also the trigger connecting plugs seem manufacturer specific.  The trigger tails are polarity sensitive as the waveform that triggers the amp is asymetrical.   

What coil are you using?   You need the correct version such as a DLB198 with a low primary resistance.

 

Hi yes it is a DLB198 form SJ's. Ive also got a spare from PNM

[jonwat]

Brett, any progress yet?

[Big Vern]

11 hours ago, jonwat said:

Brett, any progress yet?

Hi John, so far ive only been out once due to this crappy weather. It got up to temperature and didn't stumble. I'm not holding my breath just yet as being intermittent it hasn't always happened every time. I will however get oput again as soon as i can for a longer ride and more often. Constant testing is the key (good excuse to get out and about lol). I shall report back.....

[jonwat]

2 hours ago, Big Vern said:

Hi John, so far ive only been out once due to this crappy weather. It got up to temperature and didn't stumble. 

So, this is with a new/different ignition module fitted?

[Big Vern]

Yes thats correct John, just the module from the AB14 swapped to a new one.

[Big Vern]

So i went out for a spin today....maybe 40 mins of driving with no problems! Still early days but i think the ignition amplifier may have sorted it!

Makes such a nice change and the sun was shining too... Things are looking up
 

[jonwat]

2 hours ago, Big Vern said:

t i think the ignition amplifier may have sorted it!

Great news, I told you from the start it sounded like a fuelling problem. 

[Big Vern]

4 minutes ago, jonwat said:

Great news, I told you from the start it sounded like a fuelling problem. 

lol....lets not tempt fate John. All help is good help!

[Christian43]

Fingers crossed you have sorted it. It was similar on mine and the garage failed to diagnose it, I just changed the AB14 as I could not think of what else would fail so repeatedly after a set amount of time. I guess its the electronic components inside the unit failing under heat soak.  

[greentengu]

Wonderful news! 😇 
 

Just for confirmation, is the GM part 1875990 hopefully correct? (Trying not to jinx anything!)
 

Or did the Module take a different version of the bajillion part numbers? 😳

Fingers crossed x2! 
 

Cheers,

Scott

[Big Vern]

3 hours ago, greentengu said:

Wonderful news! 😇 
 

Just for confirmation, is the GM part 1875990 hopefully correct? (Trying not to jinx anything!)
 

Or did the Module take a different version of the bajillion part numbers? 😳

Fingers crossed x2! 
 

Cheers,

Scott

Cheers Scott, yes this is the one i bought which in the description does mention the GM part number above  

https://www.ebay.co.uk/itm/Ignition-Module-fits-RENAULT-R5-403-40J-1-4-84-to-89-C2J782-CI-7701021955-New/333852780890?epid=1754280237&hash=item4dbb2d295a:g:xMUAAOSwt4Nf-n0f

Happy Days! (so far)

[greentengu]

Wow! Keeping my fingers crossed! 😁

 

Cheers, 

Scott

[Big Vern]

Damn it!!!!

You guessed it.... it's back.

luckily i was on a fairly straight bit of road and i think i've worked out WHEN it does it.... Driving at a low speed of 30 in 4th gear so almost like its ticking along. This seems to be the time when i can feel its about to happen, i.e a slight hesitation then followed by the kangarooing again. Again it is only when the engine is warm. I think possibly the only way is a rolling road now.......

Grrrrrr, close but no cigar!

[Chillidoggy]

14 minutes ago, Big Vern said:

Damn it!!!!

You guessed it.... it's back.

luckily i was on a fairly straight bit of road and i think i've worked out WHEN it does it.... Driving at a low speed of 30 in 4th gear so almost like its ticking along. This seems to be the time when i can feel its about to happen, i.e a slight hesitation then followed by the kangarooing again. Again it is only when the engine is warm. I think possibly the only way is a rolling road now.......

Grrrrrr, close but no cigar!

 

Oh dear!

Did you fit a new AB14 or a used one?

[Big Vern]

Yes a brand new one....

[Andyww]

If its doing it at low speed when engine hot it could be a fuel vaporisation issue.

Is all the ducting correct which keeps the airflow through the engine bay, via the front and back sides of the ears and intake air from the outside? Any fuel pipes closer to exhaust than they should be? You have not got the cooling air through the louvres as on the Turbo so engine bay temp could be high.

If it does it when running slowly after a period of high speed running that would make this more likely as a cause.

[slewthy]

Reading with interest as I too have a 1986 NA. Sounds like same configuration. No diverter valves. No vacuum to the dizzy. Etc.

I can't add anything to the above fantastic technical discussion but I could check stuff on mine and would equally be happy to do temporary swaps of expensive components to prevent unnecessary purchases. And so on. Mine isn't the smoothest runner so I may check some of this stuff myself but I certainly don't have the same issue as here.

Re engine bay temp, I added a bilge fan to the passive air outflow that goes to the rear left ear. It's temp controlled and set to only come on when in prolonged static traffic. Reasonably simple mod and not visible.

Si

[jonwat]

2 hours ago, Big Vern said:

I think possibly the only way is a rolling road now.......

Hopefully it will be reproducible on a rolling road, but it's getting to sound like it's your only option left 

[Steve V8]

On 08/05/2021 at 13:28, Christian43 said:

I guess its the electronic components inside the unit failing under heat soak.  

Hi Brett, in my experience with the AB14 in Jags, they either work or they fail completely (no spark), and as far as heat soak goes on the early V12 jags the AB14 is situated between the heads so a much hotter spot than the Esprit, I'd be looking elsewhere. 

 

[Steve V8]

I think I'd bite the bullet and invest in a new dizzy. 

[Christian43]

On 29/05/2021 at 18:28, Steve V8 said:

Hi Brett, in my experience with the AB14 in Jags, they either work or they fail completely (no spark), and as far as heat soak goes on the early V12 jags the AB14 is situated between the heads so a much hotter spot than the Esprit, I'd be looking elsewhere. 

 

my AB14 most likely failed with heat soak (or something similar) to the components. I took my Esprit to the garage as it kept failing after 2mins 42sec of driving. The garage could not find a problem (despite changing every component on the car but the AB14) but I ended up changing the AB14 myself and it sorted the problem immediately and the car has been running well for a couple of years since then so pretty happy. I guess it could have been a vibration related problem but it really did seem to be related to the amount of time I drove the car for.