Hi
Bought a 95 Lancer GSR 1.8 turbo with unknown history the other day.
On start up the engine races to 3000 rpm, then slows (slowly) by about 500 rpm then shoots up again. This repeats and starts to slow down, not revving as high but still hunting till the engine warms up when it sits apparently normally (steady) on about 1000 rpm.
Any suggestions as to what might be happening? It had a modified ECU and I got the original unmodified one with the car. I swapped them but no change.

Any ideas? Suggestions?
rory in sunny Queensland Australia

 

The idle is out of adjustment. If you've owned an old DSM you have encountered this. When the idle gets too high the ECU shuts off fuel. So, it bounces up and down. I could tell you how to make the adjustment to a DSM but maybe your car is different. You need to locate a FSM and do an idle adjustment.

 

Thanks barneyb.
DSM? FSM?
I've got a workshop manual arriving in the mail soon so maybe I can figure out how. to adjust the idle.
(That exactly what it does; speed bounces up and down as if the fuel is suddenly cut off then comes on again)