General punto mk2b idle pulsing

[h0mel1fe]

I have a Punto Mk2b (2004) 1.2 8v, when cold pulses at idle, 800 rpm down to 600rpm (feels like only running on 3 cyl). When driving it car runs ok and behaves itself. When the car is upto temperature it idles fine. There are no warnging lights on the dash.

Thing already done:
spark plugs changed
Throttle body cleaned (but will do this again)
I changed the Timing belt recently by everything was ok after this (but thinking of checking timing marks again - for piece of mind)

Has anyone got any more thoughts? Thank you for your time and assistance.

 

[jmckee4]

I have a Punto Mk2b (2004) 1.2 8v, when cold pulses at idle, 800 rpm down to 600rpm (feels like only running on 3 cyl). When driving it car runs ok and behaves itself. When the car is upto temperature it idles fine. There are no warnging lights on the dash.

Thing already done:
spark plugs changed
Throttle body cleaned (but will do this again)
I changed the Timing belt recently by everything was ok after this (but thinking of checking timing marks again - for piece of mind)

Has anyone got any more thoughts? Thank you for your time and assistance.

Had this with mine. Cleaned throttle body and it fixed it.
You could try changing the HT leads

 

[h0mel1fe]

Since my last post. I have changed both Coils and it's slightly better.

Still pulsing at idle but not as bad (more stable 700- 750 rpm), i've cleaned the Throttle body again without success.

Has anyone else got any thoughts? thank you for your time and experiance.

 

[s and b]

you dont give mileage but if throttle body gunged up with oil its probably macduffed

 

[fingers99]

Best way to clean TB is in an ultrasonic bath.

But check that the rubber hose to the IAC (and the IAC connections) are intact. From memory, all 1.2 16v, Sei MPI and Mk2 Puntos use the same IAC.

 

[Jamie MK2]

All 8v punto's are prone to this 'hunting' idle
its just the joys of owning a Fiat

 

[fingers99]

All 8v punto's are prone to this 'hunting' idle
its just the joys of owning a Fiat

It's an issue. Can't speak for the Mk2 Punto manual, but the Sei Technical Manual defines it as a fault and suggests measures to correct it............

 

[Ziggy122]

All 8v punto's are prone to this 'hunting' idle
its just the joys of owning a Fiat

No there not
if there hunting - it means something is wrong

Fingers has said above - measure to rectify this issue

Ziggy

 

[h0mel1fe]

Dear All

Thanks for your thought and idea's.

The car is a 54 plate with 49K miles. the throttle body was clean before i cleaned it.

I have cleaned the throttle body again, and I have also purchase a S/H throttle body and the problem still persists.

Can you please clarify what the IAC connectors are? not heard this term before.

 

[RaulCarnahan]

Dear All

Thanks for your thought and idea's.

The car is a 54 plate with 49K miles. the throttle body was clean before i cleaned it.

I have cleaned the throttle body again, and I have also purchase a S/H throttle body and the problem still persists.

Can you please clarify what the IAC connectors are? not heard this term before.

Just a question, has anything been done with the ECU?

 

[fingers99]

IAC = Idle Air Control (there are other names for it). Essentially it control a stepper motor which determines how much air by-passes the throttle plate and thus controls the idle speed.

Can't be absolutely sure of the colours FIAT used on the Mk2 Punto, but if you find a connector with:

light blue/black
white/green
white/blue
grey/black

wires leading to it (4 in all), then that'll be it.

I'm 98% sure that it'll either be the throttle body (they need to be spotless, and ultra sound or carb cleaner is pretty much the only thing that'll do it), the IAC or the wiring (or any plumbing) to it

or, in maybe 2% of cases, a high tension "leak" from a spark lead.

 

[h0mel1fe]

Hi, no nothing has been done with the ECU by me. I can see that it was original progreammed back in 2004 with the multiscan software. The car did not have this problem when first purchased it started 2/3 weeks after.

 

[Ziggy122]

Remove the alternator belt and see if this stops it pulsing

mine had this weird and odd pulsing thing - not throttlebody related
But more an engine demand issue - made worse when i put electrical demand on

Turned out my alternator belt was slipping, the voltage changes meant the engine changing the fueling to make the idle higher and then lower so the alternator demand was stable "ish"

Ziggy