Hi guys, I am new here. My other half's got this punto I am stuck with it.
I try to be short on a long story. Since we bought the car I knew she is missing a little bit, than I tought I'll sort her out after (she had new MOT). Started with common things : Plugs (bosch 0.9mm gap) leads, coils,ECU. The ECU was from ebay but I still sent the original to ecutest but it came back with no faults.Than I moved on vacuum leaks... replaced intake manifold,and trottle body gasket. Didn't fix it. Double checked timing, but it is right. Had injectors out ultrasonic cleaned them and "tested" they do open and spray, also added injector cleaner to the fuel. It' driving me nuts now, could you please advise something what else it could be? I would really appreciate it. My only concern is that the spark seems to be weak to me, when I jump it to the earth like 10mm it is really thin and it turns orange instead of blue. In my experience you should get a strong blue arc within 10-15mm. Does it make sence? I might be wrong... As the MOT coming up soon I took her for preMOT but she failed staight away on emission.
Anyway thank you for any suggestion.
Kind Regards Attila.

Temp bang on middle? any codes

Compression test
It may br a mechanical misfire vs an electrical misfire

Also
Whats the temperature like?
Also have you scoped the lambda sensors? It may be an overfuel due to a duff sensir causing the issue

Ziggy

Thank you guys for the quick reply I've done compression test too
1 14 bar
2 14.5 bar
3 12.5
4 12 bar
I think it is okay,she's got a tiny battery. I tried to take a peak when the guy did the emissions on the preMOT the HC was around 100-120, the CO was around 0.46 ...
Yes the temperature is right in the middle.(new thermostat) The only fault code I am getting is P0300(random misfire...)but it takes a week to set the engine light on.
The next thing is going to be the lambda sensor, I tought about trying another battery, and evap vale sticking??? I would rather think she's running lean cos
the mpg is 47-55, and can't see over fueling on the plugs even the old ones look like "new". Thank you very much

Atis012 said:

Thank you guys for the quick reply I've done compression test too
1 14 bar
2 14.5 bar
3 12.5
4 12 bar
I think it is okay,she's got a tiny battery. I tried to take a peak when the guy did the emissions on the preMOT the HC was around 100-120, the CO was around 0.46 ...
Yes the temperature is right in the middle.(new thermostat) The only fault code I am getting is P0300(random misfire...)but it takes a week to set the engine light on.
The next thing is going to be the lambda sensor, I tought about trying another battery, and evap vale sticking??? I would rather think she's running lean cos
the mpg is 47-55, and can't see over fueling on the plugs even the old ones look like "new". Thank you very much

Click to expand...

i work in PSI
14.5 = 210
14.0 = 203
12.5 = 181
12.0 = 174

So those figures i'd be suspecting a possible HG issue here
Notice cyl 1 and 2 are good
But 3 and 4 are starting to drop?

There is a good 10% difference between them (10% of 210 = 21psi)
210-21 =189psi

Might be worth while either having a Sniff test done of the coolant
OR
doing a leak down test - to see if there is an issue that way

I wouldnt be throwing parts onto it yet - i'd be wanted to make its a correct diagnosis first

Ziggy

Right, now I am completly stuck. Changed lamda sensor yesterday no changes :bang: Did another comression test, just to make sure it is the HG before I take the head off. I made sure she was well warmed up, and started from cylinder nr. 4 this time :
4 15 bar = 217psi
3 14.5 bar = 210psi
2 14 bar = 203psi
1 14.5 bar = 210psi

Atis012 said:

Right, now I am completly stuck. Changed lamda sensor yesterday no changes :bang: Did another comression test, just to make sure it is the HG before I take the head off. I made sure she was well warmed up, and started from cylinder nr. 4 this time :
4 15 bar = 217psi
3 14.5 bar = 210psi
2 14 bar = 203psi
1 14.5 bar = 210psi

Click to expand...

That setup would indicate a good healthy engine though

Maybe a 3rd compression test and we might get a good average

Ziggy

hi my daughters punto had the same prob and it turned out to be a burnt valve but i wouldnt go taking the head off until you have checked the coils ,i see you have done the leads etc hope this helps. ps if you dont know how to check them there pretty cheap from eurocarparts and you only need to buy one to check it out.

Hi I have the same engine in my 2001 Doblo 1.2 petrol engine my misfire happens about 2/3 times in about 3 mins got no idea it's not bad doesn't stall just irritating going to start with plugs go on too ht leads then to coils hopefully be the plugs only notice when on idel mines got 78000 miles on the clock was thinking of changing timing belt and water pump as just got it with no history I know I know but was cheap but body on it is fantastic so am I going down the right road or should I stop any advice would be very happy to receive thanks

timing belt stuff wont fix your misfire, are there any lights on?
plugged it to computer to check for errors?

Hi guys again Still not fixed... but done timing 3rd time and it turned out it was almost 2 teeth out ... do NOT bother with google pictures abouth crank shaft mark... Go for DTC on 1 and 4 see flywheel mark by the little hole on gearbox bellhouse...And also gates timing belts has white marks on, and they should mach up with the marks on your cam and crank sprokets...
Anyway checked fuel pressure and it is 3.8 bar=55psi ??????????WHAT??????
Isn't is too high?
Anyone knows what it should be ? Thank you guys for all your replys.

it shows 3.5bar in autodata, i think you got normal pressure

3.8bar = 55psi
3.5bar = 50.7psi

5psi aint gonna be much different
Take in the fact of different component wear - inacurancy of any tool/guage

I wouldnt worry

ziggy

It is beginning to sound like burnt out valve as someone said.

do another compression test on a cold engine

Heating up might conceal an issue

Done a cylinder leak down test on cold engine. I only got on number 4 about 8-9% loss, nothing on the others.
BUT on all cylinder I can hear the air hissing back up at the oil cap especially on number 4 , Should I be hearing it ? If the rings or pistons worn why it doesn't burn oil?
I used 100 psi air pressure and had 1 mm restriction hole between the two gauges. Any idea guys? Thinking of get rid of the car

Atis012 said:

Done a cylinder leak down test on cold engine. I only got on number 4 about 8-9% loss, nothing on the others.
BUT on all cylinder I can hear the air hissing back up at the oil cap especially on number 4 , Should I be hearing it ? If the rings or pistons worn why it doesn't burn oil?
I used 100 psi air pressure and had 1 mm restriction hole between the two gauges. Any idea guys? Thinking of get rid of the car

Click to expand...

8/9% is very good actually....
The reason why you are hearing a Hiss out the oil cap is because of how the piston rings are made
There not a complete circle - there is about a 2-3mm gap between them when there fitted
have you wondered why you car has a Crank case breather too?
Because those tiny gaps DO ALLOW A SMALL AMOUNT of air to pass through
Without burning anything much in the form of oil
Its called Blow by - usually as the Combustion happens and as the piston goes flying back down - it creates some pressure

Ziggy

Hi everyone again I would need some help please, I still haven't found what is wrong with this punto. BUT I know what is happening now. I studied a bit more about diagnostic and understand short and long term fuel trim...
Long term fuel trim is about negative 40 , short term is all over the place, -35 to +5
I see now it is running rich and the computer trying to compensate by taking fuel away.
My question is what causing it?
Fuel pressure is 5psi higher to what it should be, injectors not leaking. Have 2 map sensor witch I tested they are both the same good.
There are IWP 095 injectors in it how would I know they the right ones.
Thank you for any help guys

Atis012 said:

Hi everyone again I would need some help please, I still haven't found what is wrong with this punto. BUT I know what is happening now. I studied a bit more about diagnostic and understand short and long term fuel trim...
Long term fuel trim is about negative 40 , short term is all over the place, -35 to +5
I see now it is running rich and the computer trying to compensate by taking fuel away.
My question is what causing it?
Fuel pressure is 5psi higher to what it should be, injectors not leaking. Have 2 map sensor witch I tested they are both the same good.
There are IWP 095 injectors in it how would I know they the right ones.
Thank you for any help guys

Click to expand...

So basically the ecu uas leaned out the mixture alot

What are the lambda sensors doing?
Is pre cat peaking and troughing and the post cat showing a faint weave?

Also is the engine temperature fairly close to outside temperature when left outside?

As lambdas and engine temp sensors pegging out and stuck can cause mega fueling issues which in turn can cause a misfire

Ziggy

Thank you very much Ziggy for the quick respond. I have already changed both lamdba sensors and the cat , the pre cat one is switching between 0.2 and 0.8 V ish and the post cat is aroung 0.7 0.8 V.
Engine temperature is same with outside temp. when left outside, even intake air temp. fairly close to ouside temp. on start up.
When fully warm, coolant sensor is reading 97 C .

Kind regards Ati