MentalMick said:

The following used to work on most of the earlier Fiat injection to reset the idle.
1. Run the car until hot and wait for the cooling fan to cut in once.
2. Disconnect the battery for a minimum if 10 minutes to reset the ECU.
3. Reconnect the battery.
4. Start the car and hold the revs at about 2000rpm until the cooling fans cuts in and out twice.
5. Now allow the engine to idle.

If there are no faulty sensors this should have now reset your base idle.
Hope this helps.
Mick

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Scott8105 said:

Fixed, and it was a quick fix too, the throttle cable was too tight, where it was dismantled and reassembled the adjustment was out, loosened the cable off and it's happy at 800rpm

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neopickaze said:

Hi All

I have a 98 MK1 60SX Punto, for the past few weeks it's been idleing very high, initially pulsing from between 1.5k to 2.0k before raising up to 3k and staying there until I give it some throttle, at which point it drops back to the pulsing before repeating the cycle.

It seems to happen at all temperatures, from starting cold to after a 100 mile run.

I've changed the map sensor and checked the hoses don't see any leaks, but it still does it.

Seen a few posts like this on the forums but very few people come back to say what has resolved it, just wondering if anyone has any advice what next to check and when the problem is solved I will be sure to come back to let everyone know.

Cheers

Dan

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majobusa said:

Sorry for the upload!, but I'm facing the same issue, and because of that my Punto is not passing the annual inspection (your MOT)

All started 3 year ago, car was stalling after revs going down. I changed the idle motor putting one from scrapyard. It went "better", not stalling but revving as described above. I changed At the begging it happened randomly but then got worse more often. In February I changed the lambda sensor and went a bit better, but still faulty. Now it's happening always at cold start and some times when warm (couldn't determine a reason) and I didn't pass the MOT because of high CO emissions. I guess both issues are related, the high idle and high CO emissions.

Last week I've changed the following, all of them brand new:
- throttle position sensor,
- intake air temperature sensor,
- idle motor,
- coolant temperature sensor,
- coolant,
- air filter, spark plugs,
- spark plugs cables,
- throttle body cleaned

After changing all, problem was still there. Then I decided to scan the car (I know, it should be first...) with IAWScan2 tool (thanks to the creators!!!) and there were two errors logged, Coil2 and Throttle position sensor, I don't know since when they were there... I cleared them and haven't appeared again. But the issue is still there.

I've gone today to MOT again, just to try my luck, and again declined. CO levels are high when revving. Idle was fine at around 1000 rpm, CO at idle 0,22%, but CO when revving 0,42% (it was 0,76% the first time) when it has to be below 0,30%. Lamba ratio looks good

before going to MOT I started the car and idle was between 1500 and 2000 rpm. When warm, coolant fan jumped, rev has gone down to 1000 rpm. I've driven with high revs all the time and driving feeling was good. As I said before, idle at MOT was fine, but not the CO emissions. But the funny thing is that when coming back to home more relaxed, rpm didn't went down when changing gears, staying at 200 rpm (at the end it's idle), but right after it disappeared and revs went down as normal and idle was ok when arrived.

I've read many places in this forum the potential cause can be a leak in the intake or exhaust. I couldn't find any leak in the intake, just a fissure in the exhaust manifold and last part of the exhaust (pictures attached). I would say the second is not affecting because it is after the lambda sensor. but what about the fissure in the exhaust manifold? do you that can affect? by exhausting more air or vacuuming more air?

IAWScan2 indicated 11,94v as battery voltage. 12,24v measured with multimeter, can this affect as well to the idle?

in addition, the throttle sensor indicates this, so variable, is it normal? The bigs up/down are when moved it manually (unable to post the full url, sorry)
youtu.be/Zkt_8IGN6hE




And here i am, still with many thing potentially causing this and not sure from where start. I would really appreciate any help on this. I love my Punto, 25 years at home, and this year I was planning to start regularity rallies with it, 25 years is the minimum in Spain, so i don't want send him to a scrapyard

cheers and sorry for the long post!

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blu73 said:

i concur, the cracks in the manifold are probably the main issue here. Could cause a funny idle that, and the lambda will be getting a false reading and therefore the fuelling will be off.

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majobusa said:

Back again. Fissures sealed. No leakage of smoke. But saddly MOT not passed. CO rev still high at 0,49 (should be <0,35). I've looking so hard for any other leakage in exhaust or intake but all seems to be fine.

In addition, revs are not going down as expected when shifting gears. No clue what can be as I'changed many parts already. Do you think it's related to high CO?

What else I can check? Due date to pass MOT is so close and I'm a bit worry

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