Technical Punto mk2b, bad idle.

[Dimich]

Hello!
I immediately want to apologize for my English, since I do not know it, I use a translator.

I have a Fiat Punto mk2b 1.2 8v with this problem.
It starts well when cold, after about 20 seconds there are gaps, the tachometer needle oscillates a little.
After warming up and switching to an idle speed of 750 rpm, the engine vibrates with a small amplitude, but a fairly high frequency, as if it does not pulsate.
If you start it hot, the revolutions rise to 2000-2200 rpm and immediately fall to 750 rpm.
Replaced spark plugs and spark plug wires.
The resistance of the primary winding of the ignition coils is 0.5 Ohm, and the secondary is 6.6 kOhm.
There is a difference in the time of energy accumulation in the coils, the first is 3250 ms, and the second is 2670 mm.
When driving, sometimes there is a misfire after 2500-3000 revolutions.
Changed coils, nothing changed.
There are no errors in the ECU.
Please tell me what could be the problem?
I suspect the coil driver.

 

[George1982]

Hi!
As long as you have obd2 scanner,check your long trims not only at idle,but also at high load e.g at 2200 rpm.
Have you ever cleaned the throttle body, particularly the idle control valve?

 

[Dimich]

Привіт!

I don't know what "trimmers" are.
The throttle body was removed and cleaned with carburetor cleaner.

 

[jackwhoo]

Does the engine coolant temperature sensor signal drop to Very cold suddenly for no reason part way through alpha obd scan?

 

[Dimich]

The photo shows the temperature after parking, which is why it dropped.

 

[Dimich]

I don't like the different charging times of the coils.
What does it depend on besides the drivers in the ECU?

 

[jackwhoo]

Charge time affected by - Voltage supply to coils , clean connections , good wires .

 

[Dimich]

That is, if we exclude the malfunction of the conductors from the ECU to the coils, then only the malfunction of the ECU itself remains?
I ran the ECU test with the tester in diode test mode, the voltage drop on both channels has minimal difference.

 

[kik]

Resetting the self-adaptation parameters might help.

 

[Dimich]

I reset self-adaptation, nothing changed

 

[Dimich]

Today I disassembled and soldered the ECU.
The charging time of the coils has become almost the same, but the vibration of the motor is still present.
Maybe smaller, I haven't tried it at work, I'll go for a ride tomorrow.
What else should you pay attention to?
maybe this is normal for these engines?

 

[Dimich]

Hello.
Can someone tell me if this motor mount looks worn?
In my opinion, it is very compressed.
Perhaps because of this, engine vibration is transmitted to the body.
I have already replaced the lower and left ones with new ones.

 

[judderbar]

>>If you start it hot, the revolutions rise to 2000-2200 rpm and immediately fall to 750 rpm.

Thats not normal! have you checked for air leaks at the manifold?

 

[Dimich]

>>If you start it hot, the revolutions rise to 2000-2200 rpm and immediately fall to 750 rpm.

Thats not normal! have you checked for air leaks at the manifold?

There seems to be no air leak, I checked it as best I could.
By the way, after tightening the throttle cable, this defect disappeared, but it is not certain, it has not been driven yet.

Now I'm struggling with vibration on the body and steering wheel.
There is a suspicion of the right engine cushion.

 

[Dimich]

After all, the problem with high revolutions at the time of starting remained Maybe it is connected with a weak battery?
Even at the moment of start-up, the temperature arrow goes to the very top and the overheating indicator lights up and immediately settles into place.
They say this is a sign of a weak battery.

 

[judderbar]

After all, the problem with high revolutions at the time of starting remained Maybe it is connected with a weak battery?
Even at the moment of start-up, the temperature arrow goes to the very top and the overheating indicator lights up and immediately settles into place.
They say this is a sign of a weak battery.

I had very high revs when starting when I had not properly bleed the cooling system. So potentially your problem is caused by something to do with the temperature sensor. The car will start normally if you disconnect it, but the engine fan starts running.

 

[Dimich]

I had very high revs when starting when I had not properly bleed the cooling system. So potentially your problem is caused by something to do with the temperature sensor. The car will start normally if you disconnect it, but the engine fan starts running.

The revolutions rise literally for a second and immediately fall to normal.
The temperature is read correctly.
Unless the sensor fails at the time of start-up, and then becomes functional)

 

[judderbar]

The revolutions rise literally for a second and immediately fall to normal.
The temperature is read correctly.
Unless the sensor fails at the time of start-up, and then becomes functional)

>>Even at the moment of start-up, the temperature arrow goes to the very top and the overheating indicator lights up and immediately settles into place.

the sensor connector is a bit fiddly to unclip but why not do that to be sure it is not the sensor?

 

[Dimich]

Will have to try.
Today I looked under the hood, but I still haven't figured out how to get to the temperature sensor connector.