Technical engine warning light flashes when going at high speed, p0302 misfire code

[dragonfly]

Hi,


I just bought a 2002 Punto 1.2 dynamic, with 40k on the clock and limited history, on the whole it's been great, and got me across the country and back last month.


One problem I have though, which the seller did tell me about was that the engine warning light flashes when pushing the car hard, typically above 70mph. The light continues to flash for 10 to 30 seconds, then goes out.


The drivers manual says to slow down when this happens (which I do), as it could mean the catalyser is being damaged, and to take it to your fiat approved dealer.


This light doesn't seem to be causing me any problems that I can tell, just limiting the speed I can go at so it doesn't come on. It was only a £500 purchase so I'm not keen on taking it to the main dealer and paying for big part replacements.


I've checked the codes, and there is p0302 code which says cylinder 2 misfire.


I've searched on this forum, and there seems to be several things that come up that could cause this:


spark plugs, ht leads, coils, wheel phase. Are these things that are simple to replace DIY?


Looking at what service receipts there are, I can see the spark plugs and cambelt were replaced not too long ago.


Any advice welcome

 

[Eklipze3k]

Spark plugs are an easy change, and something I would do immediately after buying a used car along with oil and filters. Is yours the 8v or 16v as I have the 1.4 16v and it doesn't have HT leads so you might not need to replace those.

For what it's worth, mine also cost £500 and was showing occasional engine failure and oil pressure warnings. Follow a change of all of the above (plus thermostat and coolant sensor as it wasn't heating up properly) it's running perfectly.

If you change the plugs and you still have the same issue, then we can look at coils.

 

[jazz452]

Im thinking coils would show misfires on 2 cylinders, hoping for plug or lead if u have them

 

[dragonfly]

Thanks, so I've just done the following test:


1. Added some redex to the fuel
2. Cleared the p0302 code
3. Took it for a gentle drive, so the warning light wouldn't flash.
4. Checked the codes, no p0302.
5. Took it for an Italian tune, flooring it on a dual carriageway, got up to 90. The light did flash a few times during this, but never for long (not as long as I've seen it sometimes), and easing off or continuing to floor it appeared to make no difference as to how soon it stopped flashing.
6. Checked for p0302 code, I was expecting it after the flashing warning light -but nothing at all!
7. Went for a brief but hard drive and wasn't able to get the warning light flashing again.

I wonder if my deliberately driving it gently to avoid the flashing warning light was actually making it worse?

Also, looking at what history there is, I can see the spark plugs were changed in 2008, and I've only done 25k since then. The owners manual says change the plugs every 40k.

Whatever the reason, it seems the flashing warning light doesn't leave the p0302 code - it must be something else.

 

[jazz452]

Thought it was 20,000 could be wrong. Think a plug change would be in order.

 

[Eklipze3k]

I tend to change them every year regardless.

 

[flisko]

plugs every 30k

 

[Ziggy122]

Throw a set of plugs and leads at it

I'd be curious though - often under heavy load and speed is when it MIGHT be possibly timing been just a tooth out

the 8'vs are happy to still run like it though

Ziggy