Technical reccuring problem

[JPeake94]

Whenever I start my car, it sits happily at 1000 RPM, but after say 15-30 seconds the revs keep dropping to 800 and back to 1000 then back to 800. However just it dropped to roughly 500 and the lights were dimming, any ideas anyone?


Thank you.

 

[flisko]

Whenever I start my car, it sits happily at 1000 RPM, but after say 15-30 seconds the revs keep dropping to 800 and back to 1000 then back to 800. However just it dropped to roughly 500 and the lights were dimming, any ideas anyone?


Thank you.

did u change anything recently on the car, could be alternator

 

[antipesto93]

Could also try giving the throttle body a clean?

 

[Ziggy122]

Check the throttle body is clean yes - give it a clean even

the punto does sometimes "hunt" 800 - 1000 rpm on cold startup is perfectly normal
Bobbing no, but i've seen quiet a few and never found a cure

The bobbing to 500 and lights going dim is because the alternator isn't been spun fast enough meaning its not generating enough electrical charge to keep things where they wanna be

You can always check the battery terminals - clamps and Eyelets to starter and alternator are also nice and clean and free from ""rot""

Some cables rot on the ends and there is nothing you can do about it except replace

ziggy

 

[JPeake94]

I haven't changed anything, I gathered after seeing the lights dim it was probably the alternator, once I get going its fine really, just when the car stands for abit. I'll try cleaning up a few things see how that goes if not I'll probably have to change the alternator.

 

[JPeake94]

Another thing I've read is poor fuel could be causing a build up on the throttle body. I've been using tesco's 95 only because it was the cheapest. But I have been told their petrol isn't very good that it builds up all kinds of **** inside the engine, so I'll clean it up and try a better a fuel see if that cures it.

 

[fingers99]

1. Clean the throttle body -- carb cleaner (sometimes cheap at pound shops Netto, etc.) or brake cleaner. Clean the outside first, then inside.
2. Don't replace the alternator willy nilly -- get a cheap multimeter, set it to 20v DC, take the voltage between the battery terminals
a. Engine off
b. Engine running, everything off
c. Engine running, as much electrical load as you can conjour up -- main beam, demister, etc.

Report back.
3. On the Mk2, no fuel passes near the throttle body, so fuel is not a possible cause.

Generally, provided a fuel meets british standards (and Tesco does) it'll be just fine.

 

[jammass]

mine is doing same thing and garage changed alternator to a 2nd hand one but tbh don't think he knows what to do with puntos as it is still bobbing and when put city steering on all went heavy and steering light came on don't think he has put the correct alternator on and if it is not at 20v what does he do?

Also when i turn everything electrical on it bobs worse what is the solution need help badly.

thank you and glad i found this forum. :worship:

Btw i have 05 active sport 1.2 8v.

 

[Ziggy122]

The alternator sense's load and adjusts automatically

The bobbing is because the altnerator is now straining the engine because the alternator has kicked up his electromagentic field to generate the required power

its now alot harder to turn that the engine wasn't expecting to happen, so you get a "bob" but once running again mine clears as well and i dont worry

Hell a few higher revs and it usually cures it

Ziggy

 

[jammass]

I think the alternator he used was not from the same model punto though i think he just took it from a general punto not an active sport also is it worth new battery and leads to alternator?

Is that what the post above is getting at when mentioning the 20v business when testing
a. Engine off
b. Engine running
c. Engine running with all electrical things turned on.

Should the battery testing stay at the set 20v?

Also another question how much would a back bumper for sport active in broom yellow cost as mine has crack in it and don't wanna claim on insurance. My car is nice lol I am making it sound like a shed but it is far from it apart from these two problems.

 

[atom0007]

no, 20V dc is the range to use on your multimeter, which will give you a reading (battery voltages etc are round the 13-14V mark)

If you set it too low, you'll be out of range, if too high, your reading will be less precise.

 

[Ziggy122]

Most punto alternators from the 1.1 era to the 1.2 8v in the mk2 and mk2b are pretty much the same i believe

Alot of 1.2 8v's out there
The 16v, diesels and HGT are different tho

Most are 14v 60A alternators
There are a few rarer 14v 70amp and 80amp versions

Ziggy

 

[jammass]

So could a new battery and leads be what is needed because throttle body and all other things are fine. Could that also be the reason why when i put city on to park it went heavy and light came on then when turned car off and on again all was okay. I am beginning to suspect new alternator is working and the problem is a new battery is needed as like you said when i turned car back on put heater, stereo, lights etc and bobbing started.

will get garage to test battery as since new alternator has been on solved lights dimming etc just the bobbing when cold issue. Mechanic says could be stepper motor.

 

[atom0007]

Check out the sticky on steering light. There's a thousand threads on here, the sticky distills it down to a large extent

 

[oldhammer]

Most punto alternators from the 1.1 era to the 1.2 8v in the mk2 and mk2b are pretty much the same i believe

Alot of 1.2 8v's out there
The 16v, diesels and HGT are different tho

Most are 14v 60A alternators
There are a few rarer 14v 70amp and 80amp versions

Ziggy

16v has same alternator as 8v,

aircon models have plastic sheild over pulley avoid these if none/aircon model,

 

[jammass]

Been out in my "bobbing" car today as waiting for garage to check it out Friday and noticed the longer the car is running the worse the bobbing gets and when in second gear going up hill there is a slight rattle at first change but other than that temp and running etc is fine any ideas any one as my mechanic is scratching his head.

Ahhhhh lol.

 

[flisko]

Most punto alternators from the 1.1 era to the 1.2 8v in the mk2 and mk2b are pretty much the same i believe

Alot of 1.2 8v's out there
The 16v, diesels and HGT are different tho

Most are 14v 60A alternators
There are a few rarer 14v 70amp and 80amp versions

Ziggy

i took whole alternator from a mk2b punto put it in a mk1 punto, and it had the bobbing revs rising and dropping and lights flickering as op is describing, after that i only took regulator with brushes from a mk2 alternator put them in a mk1 alternator (had worn out brushes) and lights stopped flickering

 

[oldhammer]

When was the last time this punto had new spark plugs/leads?


when cars start running like a donkey this is first thing ilook at before replacing
other things,

if not plugs /leads breaking down id then look at coils,

 

[jammass]

Discovered the bobbing or dropping revs problem think it is an air leak on the inlet manifold would that make sense?

 

[Brendan W]

Could be, only way to find out is fix the leak. Where do you think the leak is? Is the manifold loose? Does rocking the maniforld make it worse? If it's between the manifold and the head one of the little port seals could be damaged or missing. You would have to remove the manifold to check it out.