Fiat Punto Firing on 2 Cylinders (Ecu?)

[dannyboy2005]

This is the situation.

I drove 60 miles down the motorway to my dads works to change the engine over because i had a worn out cam shaft on my engine.

I drove down with no problems at all, and used only £5 worth of fuel so clearly no problems.

We took the engine out swapped the components over from my original engine, sensors, leads, plugs etc.

Fitted the 2nd hand engine which i knew was a good engine as i herd it running before. It was from the same year, same model and even same colour car.

Fitted the second engine, connected all the sensors and timed it up correctly with a new belt and tensioner. Doubled checked everything and started the car. It started on the button and ran for a good few seconds without a problem.

I turned the engine off, checked the engine level oil, restarted the engine and ran ok for a few seconds. Then it developed a slight mis-fire and ran quite un-even.

Turned the engine off, doubled checked the timing which was spot on. The tension on the belt felt the same as before.

We ran it again, it started fine though it had a mis-fire. The longer it ran, the worse it became. No matter what we did to the engine we couldn't eliminate the problem.

It started to puff out white smoke quite badly. So we suspected it had a internal mechanical fault. With that it started getting more and more juddery and cut out on us (After being running for around 1 hour, whilst trying to eliminate faults)

With that we fitted my original engine (Which we knew would work as i drove down using it) using my original components. The engine started fine then developed a mis-fire and again gradually got worse the longer it ran. It then conked out on us (just like the engine i put in earlier)

We don't know why this is happening. All the plugs are fine, new HT leads and coil pack is fine too. The alternator belt is nice and tight with a new alternator and we again checked all sensors.

Can someone tell us what we're doing wrong?

Thanks

P.s. The fiat engines are "non-interference" meaning its impossible for the valves to become damaged if the timing is out.

[Lewis1600]

I did have the same problem it was running on 3 not 4.. ended up needing a set of Plugs which were about £10... Ive had Auto Sparky and a Mechainc look at it both said Plugs...

Have you checked the compression in the cylinders??

[dannyboy2005]

I did have the same problem it was running on 3 not 4.. ended up needing a set of Plugs which were about £10... Ive had Auto Sparky and a Mechainc look at it both said Plugs...

Have you checked the compression in the cylinders??

The sparks are absolutely fine, all sparking and gaps set correctly to 0.9mm

There is nothing wrong with the mechanical side. Like i said. This is MY original engine that i put back in and less then 48 hours before i was driving with it. So can't be compression.

Funny thing is, its the EXACT same problem with my doner engine too, hence the reason (ECU) is in the title in case it may be that?

[ryanmt]

Which two is it running on? if its wasted spark its quite possible it can be one of the coil drivers in the ecu.

[dannyboy2005]

Which two is it running on? if its wasted spark its quite possible it can be one of the coil drivers in the ecu.

We don't know. My guess is 3 & 5, but thats a guess.

How would i know if it was a ECU problem. Would wiring up to a diagnostics computer be able to reset the codes?

I hate Fiats :wall:

[ryanmt]

if its 3 and 4 its not the ecu. If it was the ecu it would be 1+3 or 2+4

[dannyboy2005]

do you know how to check what pistons are firing? Like i say, removing the HT leads from the spark plug makes no difference to the engine what so ever.

[Tom5190]

removing the HT leads should make a difference, if i dusnt make a difference when u un-plug one then generally its that cylinder missing, surely you cant of unpluged them all and got no difference on any?

p.s my first guess would be coilpack as im sure there a wasted spark rnt they? are u using the same pack on each engine? also if you get it plugged in and pull up live data you should be able to see which cylinder is missing, check the fuel side of it jsut for daftness (although it dosent sound like its that) and are you using the same ECU to run both engine's? what year is it?

[dannyboy2005]

removing the HT leads should make a difference, if i dusnt make a difference when u un-plug one then generally its that cylinder missing, surely you cant of unpluged them all and got no difference on any?

p.s my first guess would be coilpack as im sure there a wasted spark rnt they? are u using the same pack on each engine? also if you get it plugged in and pull up live data you should be able to see which cylinder is missing, check the fuel side of it jsut for daftness (although it dosent sound like its that) and are you using the same ECU to run both engine's? what year is it?

Right.

The HT leads + Coil pack are FINE. We removed one lead from the spark at the time and saw it sparking. Plugged it back in the took another one out. Doing this made NO difference to the running of the engine.

I've not hooked it up to a laptop, as i wouldn't know what i'm doing. I'm using the exact same ECU that i drove down with (I'm also reverted back to my original engine tat i drove down with, so now everything is original).

The car is a S reg, '97 iirc?

I got a hunch its a spiked ECU. This can be caused by a faulty coil pack or incorrect spark and damages the ECU :geek: (Shit Idea)

If it was tat, would a unlocked ECU (from same model and year) be able to over come the problem? Or hooking it up to a diagnostics machine be able to reset the ECu so it was like new?

[ryanmt]

depending on the ecu you can usually just replace the blown coil driver.

[dannyboy2005]

depending on the ecu you can usually just replace the blown coil driver.

The Fiat Punto Forum (Which are giving alot of helpful posts to me) are suggesting that my ECU is very hard, if not, near on impossible to fry (Gave them the number on the ECU)

A few members suspect

Fault TDC Sensor (Althoguh i'm using my original)
Faulty HT leads (All are sparking
Faulty Coil pack (Which works to produce the sparks)
More recent one: Faulty/ damaged SPI

[saxo-parts]

is yours the type with two coil packs on the end of the head? i've had trouble with these on customers cars in the past.

[dannyboy2005]

is yours the type with two coil packs on the end of the head? i've had trouble with these on customers cars in the past.

Yes, thats right

At first when i took the coil pack off, i thought it was connected to the cam shaft, turns out its got nothing to do with the cam shaft :geek:

Are these a common problem then?

Although, like i say. Its sparking and its my existing coil pack i used on the car to drive down less then 48 hours before.