Idle speed way too high at start up on '99 Lanos
Moderators: daewoomofo, Moderators Group
Idle speed way too high at start up on '99 Lanos
The fuel pump fuse blew the other day on my 99 Lanos. I disconnected the battery and changed the fuse as well as changed the fuel filter. I ran the car through the "idle learning procedure" only to have the cars idle wildly fluxuating up and down as if a 6 year old was playing with the accelerator. Advice?
Hi Walter
I am assuming that the fuel pump is working OK now and that you suspected a blocked filter as the cause, thus the filter change.
If this is true, then the injector rail has probably had poor fuel pressure for a while. Now that the new filter is in place, perhaps you are getting much better fuel pressure and the pressure regulator (which is controlled by intake manifold vacuum) is not handling this too well.
It would be worthwhile disconnecting the vacuum hose to the fuel regulator and plugging the hose while you run the engine. If the surging stops then the problem is the regulator (even if the car runs at high or low idle so long as it is constant).
I would try running a strong dose of fuel injector cleaner through the petrol to see if this will fix the regulator mechanism.
If the surging continues reconnect the regulator and then disconnect the wiring connector to the Idle Air Control (IAC) which is mounted on the throttle body above the Throttle Position Sensor (TPS). If the surging stops this time, then you should try removing and cleaning the IAC. There is a post somewhere in this forum about this.
Just another thought, Walter. If your fuel filter was mounted on the fire wall at the back of the engine bay, have you checked all the vacumn hoses that are in that area are still connected to their appropriate spot? There are hoses for the Manifold Air Pressure (MAP) sensor, variable intake manifold volume (VIR) control and a feed from the intake manifold down to the exhaust gas return valve. If any of these have become dislodged with the fuel filter change, it could cause the idle surging you are experiencing.
Good luck.
I am assuming that the fuel pump is working OK now and that you suspected a blocked filter as the cause, thus the filter change.
If this is true, then the injector rail has probably had poor fuel pressure for a while. Now that the new filter is in place, perhaps you are getting much better fuel pressure and the pressure regulator (which is controlled by intake manifold vacuum) is not handling this too well.
It would be worthwhile disconnecting the vacuum hose to the fuel regulator and plugging the hose while you run the engine. If the surging stops then the problem is the regulator (even if the car runs at high or low idle so long as it is constant).
I would try running a strong dose of fuel injector cleaner through the petrol to see if this will fix the regulator mechanism.
If the surging continues reconnect the regulator and then disconnect the wiring connector to the Idle Air Control (IAC) which is mounted on the throttle body above the Throttle Position Sensor (TPS). If the surging stops this time, then you should try removing and cleaning the IAC. There is a post somewhere in this forum about this.
Just another thought, Walter. If your fuel filter was mounted on the fire wall at the back of the engine bay, have you checked all the vacumn hoses that are in that area are still connected to their appropriate spot? There are hoses for the Manifold Air Pressure (MAP) sensor, variable intake manifold volume (VIR) control and a feed from the intake manifold down to the exhaust gas return valve. If any of these have become dislodged with the fuel filter change, it could cause the idle surging you are experiencing.
Good luck.
Lanos - Lots of engineering packed into one little space
Lanos SX 1.6lt DOHC 5spd 09/1997 220kms - No Mods
Lanos SX 1.6lt DOHC 5spd 09/1997 220kms - No Mods