My punto has been running very rough over last month

I have changed plugs, leads, lambda sensor, and checked coil packs for a spark.

been pulling my hair out over last week trying to work out what the problem could be, if i could read a fault code it may help me, does anyone know how to doit on a punto (thats if it supports it)

kind regards, Richard

punto55sx said:

My punto has been running very rough over last month

I have changed plugs, leads, lambda sensor, and checked coil packs for a spark.

been pulling my hair out over last week trying to work out what the problem could be, if i could read a fault code it may help me, does anyone know how to doit on a punto (thats if it supports it)

kind regards, Richard

Click to expand...

it's probably a head gasket failure or something

you need fiat to read codes from a mk1 as it's a 3 pin thing

if you give a few more symptoms maybe we can help

when is it rough cold hot all te time

you say rough do you mean missfireing or just rough

does it happen at idle or reving

also was the lambda leads and plugs all from fiat

as after market often don't work well atall on fiats

specially as they have 8 amps running thou the coils

eat crap leads for breakfast

Thanks for getting back to me,

It is rough all the time and wont go above 50mph.

When the revs are high it doesnt seem to misfire.

The lamda sensor was a bosch from a scrap yard, taken from another 55sx 1.1.

The leads and plugs were fron unipart which are generally good.

How can i test the lamda to find out if its functioning correctly?

Also could it be a weak spark on the coil pack causing the problems?

Is there no way of reading from the 3pin plug on the punto?

Kind regards, Richard

littlepip17 said:

it's probably a head gasket failure or something
you need fiat to read codes fro
m a mk1 as it's a 3 pin thing

if you give a few more symptoms maybe we can help

when is it rough cold hot all te time

you say rough do you mean missfireing or just rough

does it happen at idle or reving

also was the lambda leads and plugs all from fiat

as after market often don't work well atall on fiats

specially as they have 8 amps running thou the coils

eat crap leads for breakfast

Click to expand...

punto55sx said:

Thanks for getting back to me,

It is rough all the time and wont go above 50mph.

When the revs are high it doesnt seem to misfire.

The lamda sensor was a bosch from a scrap yard, taken from another 55sx 1.1.

The leads and plugs were fron unipart which are generally good.

How can i test the lamda to find out if its functioning correctly?

Also could it be a weak spark on the coil pack causing the problems?

Is there no way of reading from the 3pin plug on the punto?

Kind regards, Richard

Click to expand...

i would definitely recommend you use fiat leads at least as they will last years if looked after

as for the fault you may have a blocked exhaust

if you split the join were the front pipe joins the centre pipe and see how it runs

weak spark these coils dont tend to go weak they will work or fail really

you can only read with fiat equipment i'm afraid

is your engine light on at the moment

if it is not on then there are no faults stored anyway

littlepip17 said:

you need fiat to read codes from a mk1 as it's a 3 pin thing

Click to expand...

littlepip17 said:

you can only read with fiat equipment i'm afraid

Click to expand...

Not 100% true and yes there is a way.

1. Switch on the ignition -the SD warning light should illuminate.

2. Use a jumper lead to bridge terminals A and B in the 3-pin SD connector (light blue/white and black).

3. The stepper motor will operate once so that the plunger will fully extend and then retract.

4. The codes are displayed on the SD warning light in the instrument panel. The flashmg of indicates the 2-digit fault codes as follows:
a) The two digits are indicated by two series of flashes.
b) The first series of flashes indicates the multiples of ten, while the second series 1 of flashes indicates the single units.
c) A single flash indicates fault codes in tens, while a flash followed in quick succession by a second flash indicates units.
d) A 3.2-second pause separates the transmission of each individual code.
e) Code number "12" is indicated by one single flash, followed by a 1.2-second pause, then two flashes in quick succession

5. Count the number of flashes in each series, and record each code as it is transmitted.

6. The first code transmitted is "12", which signified code initiation. Code 12 is repeated twice more for a total transmission of three times.

7. After transmitting code "12", the warning light will extinguish.

8. After a 3.2-second pause, the warning light will begin transmitting all stored fault codes. Each code is transmitted three times. with a pause for 3.2 seconds between each code.

9. If no fault codes are stored, the warning light will continually flash code "12".

10. Turn off the ignition and remove the jumper lead to end fault code retrieval.

A quick list of codes.
14 Coolant temperature sensor (CTS) or CTS circuit
15 Coolant temperature sensor (CTS) or CTS circuit
21 Throttle position sensor VPS) or TPS circuit
22 Throttle position sensor (TPS) or TPS circuit
23 Air temperature sensor (ATS) or ATS circuit
25 Air temperature sensor (ATS) or ATS circuit
33 Manifold absolute pressure (MAP) sensor signal or circuit
34 Manifold absolute pressure (MAP) sensor signal or clrcuit
42 Ignition circuit
51 Electronic control module (ECM)
52 Electronic control module (ECM)
55 Electronic control module (ECM)

thanks for your reply's, most helpful.

Just a little progress report:


I took it down to a local garage and they were unable to interface with the ecu using their equipment, doh

I had a feeling that the coil pack might have been the trouble so i bought a new one from wilco's for £36 and the car is now running alot better but still not 100% as not picking up speed too well.

I will try what FiatFXR said to read the codes and also split the exhaust.

Will post back my results asap.

Thanks for all your help, much appreciated.

kind regards, Richard

No luck with the code reading, shorting those wires didnt seem to do anything.

Which one is the SD light?

I turned the ignition so lights come on dash and shorted the wires but i couldnt see anything happening

unable to disconnect exhaust easily so i'll leave that one for now

Forgot to ention that the gasket on the downpipe had gone prior to the 'rough runnung' I put a new gasket on and thats where i started having troubles. Thats why i thought maybe i had disturbed the lambda sensor or something.

Smoke is coming from the backbox so i guess it means that there is no blockage?

cheers
Richard

punto55sx said:

Forgot to ention that the gasket on the downpipe had gone prior to the 'rough runnung' I put a new gasket on and thats where i started having troubles. Thats why i thought maybe i had disturbed the lambda sensor or something.

Smoke is coming from the backbox so i guess it means that there is no blockage?

cheers
Richard

Click to expand...

you could well have damaged the wires to the lambda sensor or the wires to it

the ecu may not necessarily pick up on a dodgy lambda so it could still be faulty even if you have no warning light

Hi i have a similar problem
where do i find the sd connector ?
and what stepper motor plunger moves?

The method described only works on certain management systems. Different Punto's had different systems and only some can be DIY'd. For example, my Sporting uses Weber-Marelli (I think) and can't be done.

The stepper motor is probably the one that operates the idle control valve on the throttle body. On the mk1 16V Sporting, the plug is beside the ECU - don't know about other models.

Your best bet is to go to Halfords and look amongst the Haynes manuals (the ones that cover welding, building your own sports car for only £250 etc) and find the diagnostic manual. Rip the cellophane off it and look up the chapter that covers Fiats.