Running On 3 Cylinders....AAARRRRRRGGGHHH

[Lordbenny]

Took my Westfield (2.0 Zetec, 45mm Dellortos)for a spin yesterday, all was going fine, warmed the car up properly then once warm it went down to running on 3 cylinder but ONLY UNDER 3500 RPM.

Got the car home and checked everything, the HT leads are brand new, the plugs are under 500 miles old. Cylinder/plug 4 wasnt firing, the plug was sooted up but dry. I did a spark plug test and there was a spark. I checked the coil pack by swapping cylinder 1 and 4 and there was no change which suggested to me that its not the coil.

Im about to do a compression test which has been suggested to me. Any other theories? Could it still be the coil pack?

[cptsideways]

Blocked injector

[Evoluzione]

Lordbenny said:

( 45mm Dellortos)

cptsideways said:

Blocked injector

[Evoluzione]

Lordbenny said:

Took my Westfield (2.0 Zetec, 45mm Dellortos)for a spin yesterday, all was going fine, warmed the car up properly then once warm it went down to running on 3 cylinder but ONLY UNDER 3500 RPM.

Got the car home and checked everything, the HT leads are brand new, the plugs are under 500 miles old. Cylinder/plug 4 wasnt firing, the plug was sooted up but dry. I did a spark plug test and there was a spark. I checked the coil pack by swapping cylinder 1 and 4 and there was no change which suggested to me that its not the coil.

Im about to do a compression test which has been suggested to me. Any other theories? Could it still be the coil pack?

Sounds like a blocked (idle?) jet in your carbs maybe, you have spark and no fuel.

[Locknut]

I agree that a compression test might be useful so get that done.

I'm not sure that an idle-jet would effect an engine at up to 3500RPM but it could be something in the carb, how many carbs are fitted?

[stevieturbo]

Could be a main jet or something blocked.

[NTEL]

Assuming you have 2 twin carbs (1 barrel per cylinder) just clean all the jets, emulsion tubes, airs........and it should be ok. I do my delorto 48s after every race meeting, only takes 10 mins per carb.

[cptsideways]

Evoluzione said:

Lordbenny said:

( 45mm Dellortos)

cptsideways said:

Blocked injector

[Lordbenny]

I've looked at the jets and blown them all through, I'll try again now!

They're twin 45's by the way.

It's got to be fueling hasn't it?

[Lordbenny]

NTEL said:

Assuming you have 2 twin carbs (1 barrel per cylinder) just clean all the jets, emulsion tubes, airs........and it should be ok. I do my delorto 48s after every race meeting, only takes 10 mins per carb.

Where would I fing emulsion tubes and....airs(what are they)?

Sorry, I know like I soiunded like I knew what I was talking about but Im a bit lost now!

Just an update....it seems that it's running on about half a cylinder!!! the header is getting hot but its not running properly.

[Steve_D]

I would still suspect the coil pack.
The coil pack is not 4 coils it's 2 so swaping 1 & 4 is still the same coil.

Steve

[neiljohnson]

Did you do a compression test? Sounds loke it could be a valve not seating properly a compression test would show this

[Lordbenny]

Steve_D said:

I would still suspect the coil pack.
The coil pack is not 4 coils it's 2 so swaping 1 & 4 is still the same coil.

Steve

Ok, I didnt know that! I just took someones advice!

I might just buy a coil pack then.

As far as the compression test is concerned, its a bit of specialist kit. Waitng on a mechanic/mate to bring a tester round to my place.

Can someone explain what a 'weak spark' is. I've got a spark so surely thats enough to ignite the fuel......or is it?

Edited by Lordbenny on Tuesday 23 April 07:27

[Chromed]

A weak spark is just that, not a nice juicy strong spark . As the previous posts have said the main probable reasons , you have to try each one, starting with the coil , electrical problems , then fuel etc. good luck .

[HustleRussell]

If it's absolutely fine above 3,500RPM you can probably forget about the compression test and forget about internal engine damage. This is a spark or fuelling problem (Most likely spark I reckon!)

[Lordbenny]

I've been offered a Mk3 XR2 coil as a replacement. The XR2 engine is a 1:8 Zetec. Will this be suitable, it looks very similar apart from two of the coil 'posts' are taller than the other two.

[Steve_D]

Lordbenny said:

I've been offered a Mk3 XR2 coil as a replacement. The XR2 engine is a 1:8 Zetec. Will this be suitable, it looks very similar apart from two of the coil 'posts' are taller than the other two.

Don't know but you may find the spark lead terminals are different on the coil so your leads may not fit.

Steve

[NTEL]

Lordbenny said:

NTEL said:

Assuming you have 2 twin carbs (1 barrel per cylinder) just clean all the jets, emulsion tubes, airs........and it should be ok. I do my delorto 48s after every race meeting, only takes 10 mins per carb.

Where would I fing emulsion tubes and....airs(what are they)?

Sorry, I know like I soiunded like I knew what I was talking about but Im a bit lost now!

Just an update....it seems that it's running on about half a cylinder!!! the header is getting hot but its not running properly.

Whether the Carbs are the problem or not, you may find this link helpful. http://www.dellorto.co.uk/merchandise/products.asp...

All the diagrams, parts, layouts, configurations are all there I have DRLA carbs which are probably a different config to yours?

[Lordbenny]

Fitted brand new Motorcraft coil today.....problem UN-resolved!

Took it for a spin round the block, same issue....up till 3000rpm the car is running on 3 cylinders above that its ok. When on 3 cylinders its banging and popping from the exhaust and carbs.

[neiljohnson]

HustleRussell said:

If it's absolutely fine above 3,500RPM you can probably forget about the compression test and forget about internal engine damage. This is a spark or fuelling problem (Most likely spark I reckon!)

Incorrect I'm afraid a bad valve seat can cause this