Hi,

My mothers 2001 8v 1.2 Fiat Punto is running on 2 cylinders.

I've changed spark plugs, coils, HT leads and the ECU (self programmable from eBay), but the problem still remains.

It has thrown unrelated error codes: P0115 and P0120.

Does anyone have any idea about what could be wrong? Is the most likely thing a bad connection?

running on 2 cylinders is almost always bad engine ecu

did errors came back after you cleared them?

flisko said:

running on 2 cylinders is almost always bad engine ecu

did errors came back after you cleared them?

Click to expand...

No, the error codes didn't reappear after I erased them.
But as mentioned I just fitted a new ECU and the problem is exactly the same. I wonder what else could be wrong?

I had the exact same problem [front coil was suspect], sometimes she was on 4 sometimes on 2.
I took the air cleaner off, put a separate earth from the ECU body across to the negative terminal on the battery, no bloody difference!
I started to fiddle about with the feed wires from the top of the coils that disappear into the loom, for some reason she ran on four & the more I fiddled I could actually make her run on 2 or 4. Buy, steal or borrow a tin of 'contact cleaner' spray brake cleaner will do, & give the tiny connections on both coil feed plugs a good dowse & hopefully that may do it.
Or........send the ECU back saying it doesn't work. I had one from 'amscarsp' & was very pleased.

Hope the above helps.

Po115 = ect malfunctiok
Po120 = throttle position

If the ect is messing up, this will most certainly mess up fuel mixture and could cause a misfire....

Another case of - blame the ecu but probably needed an ect to start with...

Ziggy

The timing belt had skipped 1 "gear tooth". It has now been fixed, but the engine is still running very badly. It constantly runs bad, but I'm unsure whether or not it actually fires on all cylinders.

I tried to reset the ECU by repping 5k 2 sec, stopping, repping 5k again etc. The result was a big blow/bang coming from the engine. I stopped and the engine continued to run unevenly.
Ziggy122 does this still sound like the ECT?

MK2lover said:

The timing belt had skipped 1 "gear tooth". It has now been fixed, but the engine is still running very badly. It constantly runs bad, but I'm unsure whether or not it actually fires on all cylinders.

I tried to reset the ECU by repping 5k 2 sec, stopping, repping 5k again etc. The result was a big blow/bang coming from the engine. I stopped and the engine continued to run unevenly.
Ziggy122 does this still sound like the ECT?

Click to expand...

Why did the belt jump? Gone slack? Auto adjuster sloppy?

A ect thats stuck at negative 40 for example will be seriously rich
The more fuel means more chance of it dropping into the hot exhaust and causing a "backfire" hate that word...

Anyway - see why the car is missing
Its gonna be mechanical or electrical
Id blame the ecu last.... as there harder to diagnose correctly

Live data read outs are good way to see what car see's

Ziggy

Ziggy122 said:

Why did the belt jump? Gone slack? Auto adjuster sloppy?

A ect thats stuck at negative 40 for example will be seriously rich
The more fuel means more chance of it dropping into the hot exhaust and causing a "backfire" hate that word...

Anyway - see why the car is missing
Its gonna be mechanical or electrical
Id blame the ecu last.... as there harder to diagnose correctly

Live data read outs are good way to see what car see's

Ziggy

Click to expand...

Don't know why it jumped. It was nice and tight. Might have been installed that why by a mechanic when the belt was changed 2 months ago.

Will measure the ECT's resistance...

MK2lover said:

Don't know why it jumped. It was nice and tight. Might have been installed that why by a mechanic when the belt was changed 2 months ago.

Will measure the ECT's resistance...

Click to expand...

Here is the full ODB readings when idling (Outside temp 4 C):









Not sure what most of these should be for a Punto, but ECT sensor seems fine?

A compression test would be a good starter for ten then a vacuum test then go on to electrical testings

Compression test showed no compression on 2 cylinders. Turned out to be a broken head gasket. Head gasket had been changed 2 months ago. Now running perfect again

MK2lover said:

Compression test showed no compression on 2 cylinders. Turned out to be a broken head gasket. Head gasket had been changed 2 months ago. Now running perfect again

Click to expand...

who changed head gasket? was head skimmed?

Hi Guys,
I have a similar (and all too common?) problem. She runs on 1 & 4 only. I have tried changing the ht leads and coil pack. Checked the low voltage connections to the packs (my voltmeter shows 6 volts?). I am reluctant to condemn the cylinder head just yet. I have the OBD Auto Doctor software on my computer and wondered if getting the multi pin connector for the car would pinpoint the fault Anyone tried that route?
Cheers

Panman3 said:

Hi Guys,
I have a similar (and all too common?) problem. She runs on 1 & 4 only. I have tried changing the ht leads and coil pack. Checked the low voltage connections to the packs (my voltmeter shows 6 volts?). I am reluctant to condemn the cylinder head just yet. I have the OBD Auto Doctor software on my computer and wondered if getting the multi pin connector for the car would pinpoint the fault Anyone tried that route?
Cheers

Click to expand...

spark plugs or engine ecu
errors?

Hi flisko,not spark plugs - tried swapping them around

No oil in water or vice versa so unlikely to be head gasket?

Only way to really tell if HG is causing an issue is a compression test.
One of my previous cars (Which wasn't a Fiat) had an HG issue, oil and water were clear, BUT the Engine started eating thru coolant at a rather impressive rate....which ultimately cost a lot to fix.

My hg didnt mix but was pumping coolant full of air all the tims
Before it finally blew and allowed the mayo mix

Compression test is only way to be fair sure whats going on

Ziggy