I have a Canadian 1990 Geo Tracker, 1.6 L 8V TBI, with 3-speed auto transmission and 4WD with 143K miles (220K km). Engine was swapped about 3 years ago and has about 120K km on it.
It starts fine and idles at about 800 rpm consistently, until I speed it up to 1500 or 2000 rpm; then it won't hold the idle speed after that - gradually slows down to 500 rpm, sputters a few times and stops. (I can easily keep it going using the throttle.) Then it won't start - just cranks, and unflood mode doesn't help (i.e. throttle pressed to floor). Is this a fuel problem (e.g. pump or filter or bad fuel?), or could the ISC be dirty?
I should mention that it coughs occasionally when I rev it - bad gas?? (It sat for months so we added some Seafoam and 2-3 gal more gas.)
Another quirk I should mention is that the throttle doesn't seem to control the engine as accurately as I would expect - engine speed sometimes changes without my moving the throttle, and is sometime slow to respond to throttle.
It has new NGK cap/rotor/spark plugs and wires, new air filter and new ECT sensor. Compression is about 130 psi (cold, WOT) on all cylinders. (We are at 3500 ft altitude so it should be 135 psi hot).
It starts fine and idles at about 800 rpm consistently, until I speed it up to 1500 or 2000 rpm; then it won't hold the idle speed after that - gradually slows down to 500 rpm, sputters a few times and stops. (I can easily keep it going using the throttle.) Then it won't start - just cranks, and unflood mode doesn't help (i.e. throttle pressed to floor). Is this a fuel problem (e.g. pump or filter or bad fuel?), or could the ISC be dirty?
I should mention that it coughs occasionally when I rev it - bad gas?? (It sat for months so we added some Seafoam and 2-3 gal more gas.)
Another quirk I should mention is that the throttle doesn't seem to control the engine as accurately as I would expect - engine speed sometimes changes without my moving the throttle, and is sometime slow to respond to throttle.
It has new NGK cap/rotor/spark plugs and wires, new air filter and new ECT sensor. Compression is about 130 psi (cold, WOT) on all cylinders. (We are at 3500 ft altitude so it should be 135 psi hot).