95 Tracker engine speed oscilating

[luigi daniel]

Hello all !
Another symptom without answer : when keeping the throttle constant to 1800rpm, the engine speed drops to 1500 then back to 1800 and back to 1500 and so on...... any reason why ?
95 Tracker 1.6l 16V 4WD automatic

[jtgh]

yes,
could be lean motor but..

top reason
1: TPS switch failing or not calibrated correctly

This switch on your car is closing (wrongly) while cruising , and then the ECU says.
hey this guy/gal wants to control idle at 1800 rpm.
ok , im a stupid computer , so Il'' just try that.

yup, it does.

there are lots of other reasons, but this is common.

[luigi daniel]

Thank you again, Jerry !
Yes, this makes sense, as it happens for this particular throttle position only ;
I will check the TPS first.

[jtgh]

see my tps cal page.
TPS testing

just a 99cent feeler guage and ohm meter.

dont let the actual ohms variances fool you, it just need to be below 300 at idle
and infinity above idle, using the feelers.

it is normal for the ohms to drift, at idle pos. 45-70 ,ect.