suddenly my marea has a poor idle, sometimes cuts out.

Suggested order:

1) Check for leaks/cracks etc in all air hoses attached to the inlet manifold. This include the brake vacuum hose. Also operate the brake pedal and listen for engine speed or note changes.

2) Sticking idle control solenoid - this could be either a mechanical operation on the throttle butterfly or an air bypass valve. If you have an air bypass solenoid then one should service this as sticking is a know problem. Easy to do. Just remove the valve a inspect inside. Gently remove any deposits. Flush / fill with WD-40 and agitate. If it is really dirty then wash out with white spirit, dry and give a very good soak with WD-40. Another trick is to allow the engine management system to modulate the valve when you have WD-40 in it. Easy to do by only making the electrical connection, fill with WD-40 and hand/finger seal the hose connection points and then get somebody to turn the ignition on (DO NOT START). The ECU will open and close the valve a couple of times. Repeat ignition on/off cycle a few times.

The vavle is offically called VAE Valve.

3) Incorrect static air bypass setting. Tempra Magnetti Marelli fuel injection systems had this identified by a grub screw and locking nut located on the throttle body. This sets a minimum air bypass and thus idle speed so that the air bypass valve has a nominal point about which to operate. To set this up one has to disconnect the electrical connection to the air bypass valve. The car should not stall be yours may. If this happens then reconnect the valve. Adjust the grub screw out. Initially nothing may happen as the bypass valve will automatically compensate for your adjustment. Get the revs to about 1000rpm. Now you can disconnect the valve connector and proceed to adjust the grub screw till the revs are about 650 to 700rpm. Now connect the valve connector again and the revs will briefly rise to about 1200 rpm or so and then drop back again to about 850 rpm.

Lastly blip the throttle and check that the car does not stall or idle too low. Test drive as well. You may find that you have to have a couple of cycles in setting the bypass grub screw. Setting too low revs will cause stalling etc. and too high will mean too fast and idle.

4) If all of 3) still does not work to your satisfaction then there was a Fiat service bulletin that modified the original set-up as in 3) to actually set the grub screw get engine revs of 900rpm (or as low a you can get to 850rpm) so that when the VAE valve electrical connection is removed/connected there is NO varation in rpm. I never had to do this as I found that the method and settings in 3) was perfectly OK for my Tempra. You may find that you need to go with this 4) method.

Lastly if the Marea uses a mechanical solenoid directly operating on the throttle body butterfly (Most Fiat single point injection systems like in the Tipo use this method) then just like the air bypass grub screw in

3 & 4, there will be a similar grub screw to set the base throttle opening from which the solenood lifts the engine revs.

I leave the rest for you to sort out :-)

Nick /////

p.s. Please report back you findings and/or success.

Hi

Did Nick's suggestion resolve your problem?

Rick