Hi forum, lately my bravo 1.4 12v 1996. have had som strange rev up when startet in the morning, the temperature is +5 degrees celtius. normaly it would rev up til 1500Rpm+/- 100 and slowly drop as the coolant would heat up. but lately it have been reving up to 3000 Rpm+/-500.

Any suggestions what could cause this ?

Bad IAC. ( Idle Air Control Valve).


(Just noticed the 1.4 has monopoint injection, so maybe no IAC on them...?)

Maybe dirty intake.
Use a bottle of injection cleaner in the fueltank, and use a spray bottle to clean the inlet, after taking of the aircleaner, follow instructions on bottles.

The 1.4 12valve is a very simple injection system its calculations are based on engine rpm and throttle angle. The fuel mixture is based on the lambda sensor.

The 1.4 12valve has a little stepper motor on the back of the throttle body casing that moves the Accelerator cable linkage To adjust the rpm between 800-1300

I think your RPM of 3000-3500 might be outside the normal idle control range so either the butterfly valve has something wrong with it like bad adjustment/accelerator cable holding it open or there is an air leak on the intake system somewhere between the throttle body and the cylinder head.

There is an adjustment screw on the throttle body that effects where the accelerator cable linkage but this should never be adjusted.

You can see what the black stepper motor assembly looks like in these pics its made by bosch and has one plug going into it You are safe to remove the plug and part.












Heres some related posts that might help, although it focuses on the throttle position sensor;
https://www.fiatforum.com/bravo-bra...v-throttle-potentiometer-position-sensor.html

Dirt build up on the butterfly valve is a common problem on older gasoline cars, causing higher idle rpm's, because it doesn't close like it should.
So, again, clean this with carburetor cleaner, and see what happens.

thanks for replies. so it's either the steppermotor that has gone bad og dirt in the butterfly sensor ?

it only does this when the engine is fresh started in the morning

In fact, several possibilities...
Our 1,6-16V did the same some years ago, it was a bad O2 sensor, but it has a complete different injection system.
Some time later, again bad idle, IAC valve gone...
Go to a Fiat dealer, and have the ECU read first, would be my advise here.