Technical Help! Still firing on two cylinders!!

[ecumadness]

Hi All. I have read all the posts on here regarding firing on two cylinders and none seem to be the same problem as mine! Whilst driving at roughly 40mph, the engine made this tapping noise and lost most of the power. After getting it home and having a mechanic check it out, it is not firing on cylinders 1 and 2. This would suggest that its not the ht coils as 3 and 4 are fed by the two coils, i have tried unplugging each one seperately and the car will not run. he ecu light is not on, which suggest its not the ecu. I have been also told there is no fuel from the injectors, although isn't very rare for two injectors to pack up just like that?? I have a multimeter and will test the ohms of the injectors to see what the reading is, i think it should be about 16 ohms??

Any advice on the matter would be very much appreicated, this problem is so frustrating!

The car is a 1.2 2000 model 8v with about 70k on the clock.

Thank you.:bang:

 

[Ziggy122]

Have You actually tested the Coil Packs?
Via T14086 thread?

And You sure that the leads are also NOT at fault?

Ziggy

 

[luke15000]

Hi there, i have exactly the same problem on my 2001 1.2 16v elx... it has been like it for 2 months now and trying to find the problem is annoying... its not the coil ht leads or plugs... everything was pointing towards ecu... changed that (EXPENSIVE!!!!) and it still is misfiring but sounds better... done a compression test on cylinders 2 and 3... and there is no compression in them would this suggest head gasket? Thamks

 

[rallycinq]

Hi there, i have exactly the same problem on my 2001 1.2 16v elx... it has been like it for 2 months now and trying to find the problem is annoying... its not the coil ht leads or plugs... everything was pointing towards ecu... changed that (EXPENSIVE!!!!) and it still is misfiring but sounds better... done a compression test on cylinders 2 and 3... and there is no compression in them would this suggest head gasket? Thamks

Yup, break between 2 and 3 leading to lumpy idle.

You should have found that with the coils and lead test!

Cheers

SPD

 

[ecumadness]

Hi. The mechanic couldn't find a fault, doesn't mean he didn't miss it i suppose. Is there a simple test i could do to make sure they are working?

I have done the ht check as using the other thread, but if the mechanics right and its not firing on 1 and 2 then surely the hts have to be working??

I will have another go tommorow and check the injectors.

 

[Azzam]

maybe it could be your timing sensor on the crankshaft? i have a friend that had a 8v punto and it was running on 3 cylinders, found out that the timing sensor had packed in.

 

[ecumadness]

Thanks! Thats great, i will give it a try, the only other thing i can think of was i drove through quite a lot of water that day, which is still bugging me.

Colin

 

[thefallenangel]

checked the spark plugs? Checked the gap as it was what done my punto over when i changed the belt and had closed the gap on 2 plugs completely.

 

[reddy4bed]

Going on your original post, you heard a tapping noise, therefore its mechanical.
Looking at further post you say No's 1 and 2 dont fire, so it cant be coils and unlikely to be 2 injector drivers gone down.
More likely that the compression has gone between 1 and 2.
Could be that the ecu has detected 1 and 2 are not firing by reading the oxy sensor, and stopped delivering fuel there.
Check compressions.
Tony.

 

[ecumadness]

I think today i will remove the ht coils and check with a meter, so i know they are working probably, not what i have been told!

 

[T14086]

to check the coils correctly they need to be 'working' which you obviously cant do without a oscilliscope. A resistance check will show a onbvious fault but not if the coil is breaking down under load.

coil 1 fires 1 and 4 and coil 2 fires 2 and 3...are you sure the leads all in correct place? Did you actually cjheck for negative trigger at coils as per guide?

 

[ecumadness]

Hi, i havn't actually checked the negative trigger myself, only what the mechanic done. As wasn't present at the time, i was just going to check them, sounds like theres a bit more to it than i thought!

I'm thinking maybe join the rac so that they can run diagnostics on it to ensure i get to the bottom of this, although i'm not sure they have the neccesary checking equipment?

 

[T14086]

RAC wont stick out their necks and tell you it needs a £350 ECU.....might sell you a battery though!

 

[tinytim]

agree; check compression

 

[ecumadness]

Hi All. Have now replaced the ht leads and spark plugs. Seems to rev more freely but still running rough although it seems its now running on four cylinders. When you rev it you still get the knocking noise at the top of the engine, which still seems weird for an ignition problem? Anyway as a last resort have unplugged the battery as this might reset the ecu?

Forgive the newbie me but i think it has beaten me.

 

[T14086]

When you rev it you still get the knocking noise at the top of the engine

what knocking noise

 

[DaveMcT]

A pair of used coils and new plugs will prove the ignition system.

Top end knock? Take off the rocker cover and make sure all the valves are opening

A compression check is quick and easy also make sure the coolant is ok - head gasket.

 

[ecumadness]

what knocking noise

Seems to knock at higher revs, i'm not sure why.:bang:

 

[DaveMcT]

If you check the things suggested you might find out why.

 

[ecumadness]

Hi. All the valves are opening, had the rocker off yesterday. As for the coils i will try the local scrappy. I have tried all the thing i have the equipment for, as for a compression test i don't have the equipment. Thanks