Motor surging

[Gippo]

I've got a 93 SE that surges up to about 2500 rpm on start up, after about a minute or two it settles out at 800 rpm. I checked the coolant fluid and also grounded out #10 connection and tried to re-adjust the idle sensor, works when it is grounded out but as soon as I remove the ground it starts to surge again. Anybody got any other ideas?
Please email me if you have or post here.
Thanks in advance

[psneddon]

Its normal for it to go to up to 1500rpm when you start it cold, its the ECU trying to get the car to operating temp. I think 2500rpm is a bit high, does it gradually go normal of does it jump down?

Paul

[EddieWelsh]

mine does the same thing, it goes down after it warms up.... seems normal to me....

[Gippo]

It gradually drops down. I've had other MX3s before and none of them have done this, especially the surging part where it goes up, then falls back, again and again till it warms up.

[IanL]

It should not do that (repeated up & down). You haven't got the throttle body coolant circuit by-passed, have you?

[Gippo]

If it is I didn't do, how can I tell if it is.

[DavidOS]

also check the idle control screw if its all the way in or to far out it can cause the idle to go crazy.

TPS can cause that and... i had that problem for a bit... reset ecu, ran diagnostic (pin 10) set the cars idle while in diagnostoc mode... car runs great now.