Technical Cinquecento Sporting hesitant at low revs

[frodovic]

Hello forum members:

I have a small Cinquecento Sporting with a problem.

When the car reaches the normal temperatura (when its cold it runs fine) and I do a stretch of road just barely pressing the gas pedal, when I try to give more gas to rev up the car from 2/2,5k RPM the car starts failing and doesnt rev up. If I lift the pedal completely and press it again it revs up smoothly and fine again.

This started after I changed my battery and I found out that the ECU may have reset. Someone on a forum said that there is a procedure to start the car after an ECU reset (it said it came in the Haynes manual but I dont find it there) but I cant seem to find it.

Also, after I halt the car, I hear from the side of the ECU a noise like a baloon desinflacting. Is that normal ? Could this be a problem with the MAP sensor ?

Thanks in advance for your help.

 

[fingers99]

You might check the blue coded temp sensor (on the inlet manifold). Should give something like:

0C 10000 ohm
10C 7000 ohm
20C 4000 ohm
30C 3000 ohm
40C 1800 ohm
50C 750 ohm
80C 330 ohm
90C 200 ohm

and so on.

You might check that the hose to the map sensor (especially the soft rubber ends) is intact, also the servo pipe and bung are airtight.

 

[frodovic]

Thanks for the quick reply

The temp sensor you are talking about measures the air temperature of the inlet manifold ? Is that it ? Can you point me to some diy guide on how to use the multimeter on this situation (sorry but complete noob here ).

Im going to take the hose to map sensor out and blow on it and suck to see if it has no leaks but Im not sure what you mean by "servo pipe and bung". Where are these located ?

Thanks again for the help. Very appreciated

 

[fingers99]

Measures the "engine temperature" (but actually the water temp). There's a seperate air temperature sensor in the throttle body.

Just set the multimeter to ohms, put the probes across the pins.

You can either do it "in car" -- get your assistant to call out the temperature on the guage or remove it and pop it into a pan of water on the stove (use a suitable thermometer to measure the temperature of the water.

Really, you're just looking for a rough correspondence of the values. Resistance must drop as the temperature rises.

 

[Pep0]

It measures coolant temperature note hose temp
remove cable from sensor
the sensor has two pins
set the multi meter to ohms
connect the multi meter probes to each pin
write down multi meter reading
reconnect cable run auto start at top again

 

[frodovic]

Ah Ok, it measures coolant temp, I know the sensor you are talking about, thanks a lot

About the servo you meant the brake servo rigth ? It migth be that too, now that Im thinking, the noise comes from the area where the servo is installed (behind the master brake pump rigth?) ...

 

[fingers99]

Yep. That's it, right behind the master cylinder.

 

[rallycinq]

If you have an air, or more likely vacuum leak, you will get strange running, thats for sure.

Cheers

D

 

[dr pinkie]

"ECU reset" is deffo in the Haynes manual :

Start car & run on tickover until the rad cooling fan cuts in /then out/then back in .
Disconnect battery .
Leave for a while....45 seconds?
Then re-connect , start , and run on tickover until fan cuts in again .
Should the engine stall during this - go back to the beginning .

The ECU is then (apparently) reset , although it may take a little while to re-learn its correct settings .

 

[frodovic]

I cant find it maybe because the one I have is in italian

Thanks a lot for describing the procedure.

Im going to take a look at the temp sensor and servo in the weekend and hopefully come back with some answers. This morning I made a simple test: I pressed the brake pedal with the engine off and it was already hard as a rock (Wasnt it supposed to take 3 or 4 pumps on the pedal until it reaches that state?) and when I started the engine the break pedal didnt give in. It stood hard as a rock until I had to first break with the car already running. When I break normally the pedal goes almost to the floor of the car and usually I have to pump the pedal twice so it breaks. My guesses go from a faulty servo to a problem with the master cylinder or both. Do you agree ?

Thanks a lot to you all

 

[fingers99]

I'd think servo, but if you find the lot in a scrap yard, pinch it all.

 

[frodovic]

I already bougth one for parts Hopefully its servo is OK ...

 

[frodovic]

Well,

Couldnt wait till the weekend so I tried the following:

- Disconected the servo hose from the inlet manifold.
- Covered the hole on the inlet manifold with a small cap.
- Went for a spin.

No luck. Still fails under the same circusntances ...

Next stop, the temp sensor. Maybe Thursday I'll have some time ...

 

[frodovic]

So, I connected the machine and ...

- Lots and lots of errors. If you can think of a malfunction this baby had it on its litlle log

- Cleared the errors and let it work on idle.

- Car acelerates by itself after a couple of minutes and a lambda sensor fail appears on screen. Deleted it.

- Went for a spin and reconected the machine. Lambda sensor error.

So, ordered the lambda sensor and will fit it upon arrival on Thursday. Cross your fingers for me

Cheers

 

[frodovic]

Still waiting for the lambda sensor.

This weekend I decided to visit a friend who has a multimeter and we tested the lambda.

It is giving poor mixture voltages when accelerating and very very rich voltages when I cut gas. Probably the Zirconium wore out and its taking samples from the wrong part of the sinusoid. :yuck:

After cutting gas it fails probably due to the mixture being too rich ...

 

[frodovic]

Problem SOLVED.

Faulty lambda sensor was the reason :slayer:

 

[frodovic]

After changing the lambda sensor and doing about 500 kms without any problems, the hesitantions and failings started again

The car in this 500 kms was its usual self. Responsive, nervous and even more economic.

Im running out of ideas ...

 

[fingers99]

White box lambda?

 

[frodovic]

The lambda was an original Fiat Ricambi part that came directly from Italy. I had to wait almost a month for it so that I had the original deal ...

Can this be a Kat problem ?? I notted a certain odd smell lately (kinda like burned paint or something) ...

Thanks for your help

 

[fingers99]

Cat will tend to smell if it's running rich. I wonder........ test the engine temperature sensor?

You'd expect an ECU light, but......