Technical Punto Misifiring

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Technical Punto Misifiring

Joined
Jan 29, 2014
Messages
42
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Location
Derby
Hey Guys,

Hoping you can help.

Got a Punto mk2 1.2 8v.

Really hard to describe the problem, but its bad.

Basically say if I'm pulling off and i raise my clutch and apply gas at the same time, the revs will drop from around 1000RPM (idling) to about 500rpm..

To get it going i have to put my clutch to the floor and gently press the gas, and then ram it after its past 1500 RPM. When driving its fine, its just when it gets to pulling out..

It happens more when its warm as appose to cold, however it does happen now and then when its cold.

ECU isn't showing any faults :( - Used MultiECUScan

Replaced:

Coils Packs
Spark Plugs
HT Leads

And no luck at all.


Please Please Please if anyone can help me find the problem I will be externally grateful.
 
Last edited:
Hi Ziggy,

Thanks for your reply. (y)

It started about a month ago, but it was no where near as bad as it is now.

I went on holiday and therefore it was standing for a couple of weeks.

Took it out and now this is what it does.

No work was carried out on it before it started to do it, i just got in one day and it started to happen.

It isn't my brakes because its the revs that drop ridiculously.

It feels like Petrol starvation...

Ive come to 3 possible causes,

Fuel Pump?
Water in Fuel tank? Wynn dry fuel may sort this? or redex?
New ECU - as it dosent show any Error codes.


Cheers,

Jayden
 
Are you even getting a Strong spark to each cylinder?

I know you've overhauled, but if there is no spark to 2 cylinders
an idle speed will quickly drop

Sometimes the ECU doesn't know its failed = No codes

Check that fuel is getting to the fuel rail as well - beaware tho its under pressure

Ziggy
 
To check for a strong spark
replace the HT lead and i tend to use a known good plug

Simply insert plug into HT lead and hold near the cam cover (as this is an earth)
As somebody cranks the engine for you - it'll start to spark and hit the cam cover

You should be getting a nice consistant blue spark cracking, you should see the spark easily jump as you move it off the cam cover and away
if it fails to jump after about 2.5cm, its okay, but thats a rule of thumb i use
If its a yellow'y and weak spark, its not good, and probably isn't able to ignite the fuel air mixture quick enough to get a better engine running

The ECU will try to compensate for it - but it can only go so far

ziggy
 
Thanks a lot piggy.

Will check tonight.

If its a yellowy spark what could it be?

Cheers.

Jayden

piggy...................................

yellow spark = weak coil or resistance somewhere
But i suspect you'll get a nice blue strong spark

Sometimes plug give a yellow spark that can still jump = okay :)
Most of mine have been blue/white

ziggy
 
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