Technical Another misfiring 55S

[Station Master]

I've been looking at the threads and guides trying to sus this one out - the car in question is a '95 1.1 55S. It's running rough and has just about enough power to make progress downhill with the wind behind it.

I've checked the plugs and all appear OK with exception of slight discolouration on external ceramic of No4. Checked resistances of coils against Haynes values and found both LT resistances to be higher than expected (0.2 ohms), one reading 0.4 ohms, the other 7 ohms.

After reading the forum guide I tried starting the car with each coil disconnected. Would not start at all with either coil, so reconnected both, started up, then disconnected each in turn with the engine running (and thick rubber gloves!). As soon as either coil was disconnected, the engine died.

Anyone got any ideas where I should look next?

 

[bredsticz]

I'd suggest doing a compression test to make sure the engine it self is t good condition. Also your coils may be going!

 

[rallycinq]

Don't disconnect the coils while running, disconnect and replace each spark plug lead in turn, noting which, if any, made no difference to the poor running.

I guess the management light is on.

Cheers

SPD

 

[Station Master]

No management light on. I'll scrounge a compression tester and try the plug leads in the meantime. Thanks.

 

[Station Master]

Is there an idiots guide to compession test available? I've found one for a Mk1 Cortina (!), but some expected figures for the 55S Punto 1.1 would be handy.

 

[Station Master]

OK, I should have looked in the haynes before posting!

 

[Station Master]

Compression test showed 160 on 1 & 2 and 20 on 3 & 4. Head now off and sure enough there's a big hole in the gasket beween the cylinders.

 

[reddy4bed]

For future reference, 1 & 4 also 2 & 3 plugs run in series with each coil, so disconnecting any one will also disconnect its partner.

 

[nedge2k]

Compression test showed 160 on 1 & 2 and 20 on 3 & 4. Head now off and sure enough there's a big hole in the gasket beween the cylinders.

out of interest, did you not have any mayonnaise under the water cap to indicate the gasket had gone?

 

[rallycinq]

out of interest, did you not have any mayonnaise under the water cap to indicate the gasket had gone?

Unlikely, as the gasket had gone between cylinders, not between a water way and an oil way.

Head gaskets can 'go' in so many interesting and different ways!

Cheers

SPD

 

[rallycinq]

Compression test showed 160 on 1 & 2 and 20 on 3 & 4. Head now off and sure enough there's a big hole in the gasket beween the cylinders.

The spark plug test would have found that too.

Cheers

SPD