Rough running Sigma 125

[huwp]

About 15 minutes after start-up on a run the car started to cough and splutter while on a constant throttle.

 

It then worsened to the extent that I thought the car would stop altogether. We limped home although under acceleration the car seemed ok, only to struggle again on a constant throttle. The car struggles to hold an idle.

 

After 10 minutes to cool down I took it out again. At first seemed ok the the problem progressively returned.

 

I cannot see anything obvious but then again I am not a grease monkey. I did notice though that the cat is very very hot indeed. The car is undriveable.

 

Diagnosis? Car is on an '07 Sigma 125 having done 6500 miles.

 

Lambda? Cat? Something else?

 

 

 

Huw

[Doug phillips]

I would guess that if the Cat is getting very hot, you may be over fulling that car so there could be a problem with the injectors or something. Sorry not my strong point, somebody will be along soon with a better answer .

 

Su77on Se7ener

 

[huwp]

Doug - thanks.

 

Four leads(?) emerge to the rear from under the engine cover and connect with a Bosch box. Each lead has a boot on the end which mates with the box. The inside of 3 of these rubber boots seem to be fine and the copper(?) connectors look clean. The inside of the no.3 boot is fouled and generally looks knackered (I said I was no grease monkey).

 

Are these the "ignition coils"? If so, and if one is knackered, is that the problem or a symptom of the problem?

 

Anyone?

 

H

 

 

 

Huw

[The Pikey]

I'd guess at a knacked plug as I had the same problem on my Sigma.

 

Jason

 

 

[huwp]

Would a knackered plug result in the fouling of the boot to the no.3 lead and the coil itself?

 

 

Huw

[juleslid]

Had that problem on mine last summer, once engine was warm it only ran properly at full throttle. Cat Mids replaced the fuel MAP sensor (I think it was!) - basically the engine was running fully rich all the time. You'll have the same problem if your exhaust is black and you're emptying the tank in less than 100 miles.

Good luck!

[weeman]

I had a similar problem with mine some time back, I found (by pure fluke) a broken conductor in one of the three wires that lead to the TPS. Might be worth a try 🤔

 

_________________________

Be Lucky!!

 

Martin

(Solent Se7ens) M7

[huwp]

Thanks all.

 

As one lead and the coil looks knackered I will replace them. I'll also check the plugs.

 

Two further questions if I may:-

 

What does the TPS look like? The picture on the CC parts site is not complete.

 

Also re the HT Leads or what ever they are called - does anyone know the part number? CC don't stock these and have advised that I approach Ford direct. I am away from my car at present and would like to call in by the dealership on the way home. I presume I will need to buy all four leads in some sort of pack.

 

 

 

Huw