1.6 petrol poor idle

[mission]

Though it has been a little issue sinds I got the car, its getting worse and I like to sort it before it become a major issue;

The engine has a rough idle, the rev counter always moves up and down between id say 880 and 920 rpm, not much but enough to feel it.

But this week I had a few times that the rpms dropped quit bad to the point of the headlights and dashlights almost dying and almost stalling the engine.

Last week she had a full service (all filters including the fuel filter and new sparkplugs) and that didnt make a difference. I always use decent fuel without any bio crap so id say its not a fuel related issue either.

There is a small crack in the manifolt, but my garage says thats not a big issue besides a MOT failure, but can that cause the idling issue?

Im not familiar with this 1.6 engine, and cant find any information whatsoever but: how does this engine control the idle? Sinds its a fly by wire throttle does the ecu just control the throttlebody or is there like a idle control valve somewhere? Cause thats what im suspecting the issue to be.

[polar]

Im not up on the petrol engines but if you have a crack in the manifold its not going to help. Is it inlet or exhaust manifold.

[mission]

Its the exhaustmanifolt, sorry forgot to mention that.

[Sol]

It could well affect the lambda reading once you're in closed loop (above 50c coolant temp) so yes I'd get the cracked manifold sorted first and check again.

[mission]

It could well affect the lambda reading once you're in closed loop (above 50c coolant temp) so yes I'd get the cracked manifold sorted first and check again.

Im not a 100% sure when its worse, hot or cold but yes maybe its better to get that manifold fixed first.

[Henk50]

Are there any errors in the Engine ECU? The engine is TU5JP4 (1.6 16v)?

[saskak]

Apart from fixing the crack in the manifold, for the TU5JP4, I would remove the 4 injector electrical connections and test the resistance with a multimeter/voltmeter. It is a bit of a tight space, but the connections can be removed and tested.
As far as I remember this should be ~12ohms +/- 0.5. The resistance should also be uniform across the 4 injectors.

[mission]

Are there any errors in the Engine ECU? The engine is TU5JP4 (1.6 16v)?

Had the car in for a service a couple week backs, no error codes at that time.
But yeah good idea to check for error codes again.

Apart from fixing the crack in the manifold, for the TU5JP4, I would remove the 4 injector electrical connections and test the resistance with a multimeter/voltmeter. It is a bit of a tight space, but the connections can be removed and tested.
As far as I remember this should be ~12ohms +/- 0.5. The resistance should also be uniform across the 4 injectors.

Will a exhaustmanifold make such a difference, id expect it would be more of a problem if its the intakemanifold
Ill try checking the injectors and connections this weekend.

[saskak]

Are there any errors in the Engine ECU? The engine is TU5JP4 (1.6 16v)?

Had the car in for a service a couple week backs, no error codes at that time.
But yeah good idea to check for error codes again.

Apart from fixing the crack in the manifold, for the TU5JP4, I would remove the 4 injector electrical connections and test the resistance with a multimeter/voltmeter. It is a bit of a tight space, but the connections can be removed and tested.
As far as I remember this should be ~12ohms +/- 0.5. The resistance should also be uniform across the 4 injectors.

Will a exhaustmanifold make such a difference, id expect it would be more of a problem if its the intakemanifold
Ill try checking the injectors and connections this weekend.

But you will have two lambda sensors. If the crack is in between and gasses are leaking it will distort that signal and the ECU will take action according to the readings of the two lambda sensors. It may or may not affect idle. If I were you I would work on Zion's suggestion and check the readings of the two.

[mission]

Are there any errors in the Engine ECU? The engine is TU5JP4 (1.6 16v)?

Had the car in for a service a couple week backs, no error codes at that time.
But yeah good idea to check for error codes again.

Apart from fixing the crack in the manifold, for the TU5JP4, I would remove the 4 injector electrical connections and test the resistance with a multimeter/voltmeter. It is a bit of a tight space, but the connections can be removed and tested.
As far as I remember this should be ~12ohms +/- 0.5. The resistance should also be uniform across the 4 injectors.

Will a exhaustmanifold make such a difference, id expect it would be more of a problem if its the intakemanifold
Ill try checking the injectors and connections this weekend.

But you will have two lambda sensors. If the crack is in between and gasses are leaking it will distort that signal and the ECU will take action according to the readings of the two lambda sensors. It may or may not affect idle. If I were you I would work on Zion's suggestion and check the readings of the two.

I completely missed the lambda sensors, that might be something.

Today the thrustbearing suddely started screaming and later this afternoon the darn thing exploded. So I might juist let the garage take care of the idling issue, sinds they have the car in anyways.