Technical Not flexible at low revs - the Cat or something else?

[ser907]

Hello everyone,

once again i want to ask about the problem i have with my Cinquecento ,899 SPI. This car is very "unflexible" in the low RPM range. In other words, one have to drive with, at least, 2000rpm. Previously i had a number of cars with the motor of this type, but all of them were just ok (Nevertheless, all of them has no catalisator). And the consumption was a bit better too...

So, currently i have no idea why it behaves like that. The motor have around 140.000km and show no errors by IAW-Scan. My questions to the community are below

1. How long the catalisator should live in the reality? How the motor should behave when the cat is nearly dead?

2. How long the valve compensators should live? I have some ticking sound when the motor is cold, but when it warmes up everything is normal.

3. The algorythm of the bypass-stepper is not clear to me. Why is tries to regulate something when the motor is not at idle? Could it be the case that the influence of the stepper at low RPM range is comparable with my gas pedal play?

 

[MrDerv]

Hello everyone,

once again i want to ask about the problem i have with my Cinquecento ,899 SPI. This car is very "unflexible" in the low RPM range. In other words, one have to drive with, at least, 2000rpm. Previously i had a number of cars with the motor of this type, but all of them were just ok (Nevertheless, all of them has no catalisator). And the consumption was a bit better too...

So, currently i have no idea why it behaves like that. The motor have around 140.000km and show no errors by IAW-Scan. My questions to the community are below

1. How long the catalisator should live in the reality? How the motor should behave when the cat is nearly dead?

2. How long the valve compensators should live? I have some ticking sound when the motor is cold, but when it warmes up everything is normal.

3. The algorythm of the bypass-stepper is not clear to me. Why is tries to regulate something when the motor is not at idle? Could it be the case that the influence of the stepper at low RPM range is comparable with my gas pedal play?

The idle stepper motor could probably do with a clean. Also worth taking the pipe off the MAP sensor and giving it a good blow through to ensure there is no fluid in there.

I had this similar problem when i had my first Cento SX.

 

[ser907]

MAP - sensor tube was checked, it is ok. MAP-sensor itself shows some pressure decrease when sucking. Should i do the exact check with the manometer? I agree that such a behavior could be caused by wrong ignition advance too...