Technical Fires on 3 cylinders, but only if plug lead 3 is removed...?

[pinkpunto]

Tipo been messing around since Sat pm when I had to drive through torrential rain and deep puddles.

Cleaned leads, WD40'd them, opend dist cap, dried out etc.

Only just wants to start if all 4 leads are connected, sounds like it's firing on 2 at best, won't idle at all. Took off plug lead 4, still the same. Took off plug lead 3, and it's much happier, fires on all three, and idles OK. Put plug lead 3 back on and it goes horribly again.

I've checked several times that all leads are on the correct plugs.

Any ideas? :bang:

 

[custard]

sounds like a duff ht lead on 3

 

[pinkpunto]

But if the lead is duff, why does it screw up the firing of the other 3 cylinders?

 

[custard]

more likely cylidner 3 is firing rough and causing the roughness.its really trial and error.
swap lead three with one of the other leads to see if the prob moves to another cylinder

 

[Hellcat]

How old are your leads? The recent heavy rain uncovered some problems with my leads breaking down. Replaced them all and its much much much happier!

 

[Trancendental]

Its £20 for 4 new Sparks and 4 new leads.

Why not just replace em if you havn't done already?

Nothing to lose cause you are are going to have to replace them eventually and at least this way you'll know exactly how long you've had them AND if it doesn't fix the problem then at least you know whats not causing the problem.

Might want to replace the Distributor Cap at £5-£10 as well from HalFrauds.

Then if it still doesn't work... erm.... GARAGE! Dun Dum Daaaahhhhhhh!

 

[pinkpunto]

True enough, but they are almost new anyway - seller gave me the receipt for them - they've been on about 4 months and done 500miles...

 

[custard]

you can get faulty new lead.as i said its a process of elimination.swap the leads over 1st then plugs to see if it changes cylinders

 

[pinkpunto]

I've excluded the lead to cylinder 3, and the plug in that cylinder, by swapping around and getting the same results.

It's only if I connect plug 3 to the dizzy that it goes lumpy and stalls. With plug three disconnected, it'll idle on the other three quite happily. :bang: :bang:

 

[custard]

right if its not the lead or plug you need to work your way back. is it twin coil packs?if so swap them over and see if the problem moves cylinders.

 

[pinkpunto]

Sorry -we've reached the end of my automotive engineering skill/knowledge. Twin coil pack - how would I know if I have one fitted? Where is it, and what does it look like?

 

[custard]

its where the HT leads plug into on the end of the block.if you can take a pic or one of the tipo guys will know

 

[Trancendental]

its where the HT leads plug into on the end of the block.if you can take a pic or one of the tipo guys will know

I think the Tipo guys (I'm one of them ) refer to this/these as:

The Distributor Cap and The Distributor.

The Cap is the Black/White or Creamy coloured thing the Leads plug into, The Cap covers the Distributor. The cap has 4 pins in there if I remember correctly. The Distributor has the Rotary Arm that touches the pins.

If you say its only when you disconnect the HT Lead from the Cap then your problem could be the Cap.

You can also "Time" a Tipo by adjusting the Distributor, you do this by rotating it. Make sure you mark its current position with Tip-Ex or something before fiddling with it otherwise you could make things worse.


BUT AS Custard Said if you didn't do it correctly maybe, Use HT Lead 1 and SWAP it for HT Lead 3 if the problem remains then obviously its not the lead but as you said if it works when not plugged into the Distributor Cap then Change the Cap OR clean all the Cap connectors and try again.

 

[pinkpunto]

Traced this - by fitting a new dizzy cap, which solves the problem. Inspected the inside of the old one, and there are cracks from plug 3's connection, tracing round to the next one, prob 1. The damp has got into the crack, and transmitting some of the spark to another cylinder, hence the rough running when plug lead 3 was connected.

The dry summer kept it away until a wet day allowed moisture into the cracks, and so start the problem.

 

[Hellcat]

Good to hear that its happy again.

 

[pinkpunto]

When I had the plugs off to eliminate them, I noticed that they were quite black/sooty. Can I adjust the mixture richness, or was it just (and more likely) that they were gungy because of my continued attempts to start it, meaning that it never got up to temperature?

I'll give it a decent run and then re-inspect.

 

[Trancendental]

If your Tipo has a Fuel Efficeny Meter like mine and others on the dash check where the Needle stays at Idle once the Engine is warm.

If your mixture is nice then the needle should not be above the 1st quater. if it idles at half or more then it needs adjusting.

There is a Screw on the Carb to do this.

Looking from the front, the screw is located on the right hand side towards the bottom but closer to you. Kind of behind the Idle Adjustment screw.

This should ONLY be fiddled with when then engine is warm (been running for about 20 minutes) and after you set the Idle Speed correctly so that if there is a manual coke, the coke should be ALL the way in and the Idle speed should be between 900 - 1200 rpm. Adjusting the Mixture may cause the Idle speed to change but the idea is to maitain the rpm and have the fuel efficiency meter needle low (furthest away from the red)

If you dont have this meter then you need an emmisions machine or go to a garage and ask them to do it.

And by Dizzy Cap do you mean also Distributor Cap?

 

[Hellcat]

Does your tipo have a VAE cylinder too? Mine was seized with oily crap which meant the tickover was all over even if the bypass screw was adjusted. Got the VAE cleaned out with carb cleaner but still need the throttle pot setting up..

P.S. In your post above can you use Pepsi or does it have to be Coke?

Edit. Just realised you are talking about fuel mix adjustment rather than idle adjustment

 

[Trancendental]

Does your tipo have a VAE cylinder too? Mine was seized with oily crap which meant the tickover was all over even if the bypass screw was adjusted. Got the VAE cleaned out with carb cleaner but still need the throttle pot setting up..

What's a VAE?

P.S. In your post above can you use Pepsi or does it have to be Coke?

I know I wrote coke instead of Choke but its usually written Coke ain't it?

 

[Bunny]

What's a VAE?

http://www.btinternet.com/~andy.brinkman/idlevalve.htm