Technical Fiat Punto mk2/2b 1.2 8v (2004) - Rough idle, mostly on electric load

[Mike1alike]

I would add in this topic something that I've just discovered, as I've mentioned earlier that

The problem when rev goes under 600 RPM is the pressure being to high inside the cooling system.

It looks that the high pressure was just something extra that was adding up to the real problem and by fixing the pressure issue I've manage to make the engine not to rev down, but the problem was still there.
The adjustable tightener of accessories belt had the roller's movement limited by the deformed cover that was holding the roller in it's place. I think that was really causing the rev to drop down on idle.
And this days the same roller, moving even harder than before, added extra engine load and caused the engine to rev up on idle this time, to 2000RPM. The rev was done repeteadly up and imediatly down again and so on. The problem seems to be fixed now, after I've took that deformed cover off and placed a washer instead and the roller moves free now.

 

[Mike1alike]

Seeing my post above and by this time, figuring exactly what was the problem and having it fixed, here it is: that problem was caused by IACV malfunction and the fix was replacing it with a new IACV (Idle Air Control Valve). I've even started a topic here somewhere about it.

 

[lowaaa]

Seeing my post above and by this time, figuring exactly what was the problem and having it fixed, here it is: that problem was caused by IACV malfunction and the fix was replacing it with a new IACV (Idle Air Control Valve). I've even started a topic here somewhere about it.

Here is the link for anyone searching.

Technical - Engine revs at 2000 RPM on idle

RalphM Yes, it is. The throttle butterfly works good, the same does it's position sensor. judderbar This is what I suspect the most to be the cause of the problem, the cooling system. There was no presure inside, after the engine was running. Then I've put the new cap and for the first time...

www.fiatforum.com

@Mike1alike Where did you buy the replacement? I think I'm in need of doing the same :/

 

[Mike1alike]

I bought it on a local auto parts store.
I put a picture with the code, I hope it helps to find one nearby.
I will put this picture in that link you've added, too.

 

[PuntoGR]

what spark plugs do you have on there ?
copper, iridium ??? model number ? specs ?

 

[Mike1alike]

These are the plugs:
NGK 4983 DCPR7E-N-10 Standard Plug
Corrugated Ribs
Triple-Gasket Sealing Process
Copper Core Shell
Thread Size: 12mm
Thread Pitch: 1.25mm
Seat Type: Gasket
Resistor Value: 5K Ohm
Reach: 19mm (3/4")
Hex Size: 5/8" (16mm)
Terminal Type: Solid
Overall Height: ISO
Gap: .039" (1.0mm)
Center Electrode
Material: Nickel
Type: Standard
Size: 2.5mm
Projection: Projected
Ground Electrode
Material: Nickel
Type: Standard
Quantity: 1
Specifications
Warranty: 1 Year
Torque Specs: Cast Iron: 10.8-18 lb. ft. Aluminum: 10.8-14.5 lb. ft.
Brand: NGK
Heat Range: 7
Longevity: 30k Miles
Resistor: Yes

 

[Mike1alike]

Actually, I jumped with my answer there. I remembered that now I don't have those NGK plugs, I have the Denso equivalent. The NGK that I had before were almost done, pretty close to the maximum kms they are recommended to run, and someone, from his experience, recommended me Denso saying that he is happier with that brand than with NGK and he used both on many engines. Now, I can say that they both work pretty much the same, but I tend to prefer NGK. Next set will be NGK. Who knows, maybe even... ruthenium.

 

[MarkoRantala]

I was exactly same issue and exactly same car. I did same services, replaments and even more. Issue still continues. And my case problem was very easy to fix. 10 minutes, and that's it. First put some plug and gloc that tiny pipe which coming from airbox (even when I had Toyota corolla 1977, was same issue with tiny pipe and many other cars after that as well. I didn't imagine, that 2004 could be same prolem anymore. I was wrong). The pipe is totally useless. Even this can help a little. After that You can see butterfly has adjusment screw. Start loosening it 0,25 round at time. And test by starting and stopping engine between adjusmenting and give a throttle and monitor what happening. When it settles, You're done and You also can leave plug in the pipe. That helped for me. It is logical if butterfly is too open, it gets air too much (as well from tiny pipe aas well) and IAC cannot working properly. And You can test what happening if You tightening that adjusment screw, the issue getting worst as can be.