Hi there

I have a bit of a problem. I recently got the car back on the road after it was SORN for 3 years and it has been running sweet as a nut.

So I changed the coolant today after a slight leak and so I could fit a new jubilee clip to the top of the radiator. I bled the coolant quite a bit to try and get all of the air out. Then started the engine and it was just running very rough, as though it was misfiring. The engine management light is also on.

I disconnected one of the coil packs and it runs the same. If I disconnect the other the car doesn't start. I have therefore tested this failing one with a multimeter and there seems to be a current coming through, although one of the pins much less that the other. I followed the guide in the Punto section.

It has been a while since the plugs were changed, at least a year. It just seems weird that this has happened immediately after having the car on axle stands and changing the coolant. Could there just be a problem with moisture? Btw I went for a longish run this morning and everything was fine.

So, I take it the ecu is ok? Does this mean a problem with the coil pack? Any advice is much appreciated

EDIT: Forgot to mention, it's an 8v 1.2 mk2 (2000).

By the fact you did the Test for coil pack - unplugging it Didnt make it better or worse
Then that looks like you're in right area

So the 2 sparks that are off the "affected" CP, i'd be checking cables and plugs for a GOOD spark -

Change Plugs as you said as it's not been done, and see if that helps

If you've got the Fiat ECU scan software - defo get the fault codes read, as this will give you a reason why the EML light is on

Ziggy

There is a known fault with some ECUs where the coil trigger signal goes AWOL for one pair of plug leads. the same cylinders will missfire with a new coil pack.

But the coils/leads/plugs should be ruled out before going OTT with ECU faults.

Dont run the engine with 2 & 3 or 1 & 4 leads removed. The ECU should cope, but with no plugs to fire the coil can throw a nasty power spike at the ECU. Only ever remove one plug cap at a time.

Ok, I tried swapping over the coil packs today to try and diagnose a failed one. Even though I have done this, the same 2 cylinders aren't firing, which leads me to believe the packs are ok.

Does this mean my ecu is shot? Or could it just be a daft fuse somewhere?

Have You Definatly Checked that the Spark Plugs are giving a Clean Spark GOOD spark?

As Its either a Spark/HT Lead Problem
OR looking at a dreaded ECU problem

Ziggy

I have replaced the plugs today before I changed the coil packs but this hasn't made a difference. I will check there is a spark from my HT leads tonight. If no then I guess change them (have some here) if not again then time for a new ecu!!

I've just re read THIS guide again and when I tested for the pulse from the 2 pin connector, one of the pins had the constant 12v signal. The other was showing something 0.* v, but because I was using an LCD multimeter I'm not sure if this was a pulse.

Given the above, that the coil packs are ok, and that there are 2 cylinders not firing, I think it has to be the ECU. I've seen THIS ECU rebuilding service on eBay. Does anyone have any experience with this?

Thought I'd give you an update.

I got the company in my previous post to refurb my ECU, and got some new coil packs in case it was those that blew the ECU in the first place. It's done the trick anyway, thanks for your help!