'95 Monte 3.4L DOHC, 250,000kms
Symptoms:
- Lack of power.
- Engine sputters during initial acceleration in the morning and after work. Throttle to the floor, car accelerates slowly then "comes alive" with more power, but it's not all there.
- Under wide open throttle, engine will not rev over 5500rpm so it won't make it to the shift point. Have to back off throttle to shift.
- During cruising speed, 60, 90, 100, 110, 120km/h, engine "bucks". Feels like a miss, but not consistant. Only happens under load, back off the throttle and it's gone. Doesn't matter if TCC on or off, in 4th or 3rd, same thing but less apparent with increased engine speed. Mostly around the
At WOT:
-Knock retard is at about 10° and spark advance is at around 24°
-Engine speed 4575rpm
-Vehicle Speed 61mph
-Throttle load axis is 99.96%, throttle position at 4.46 volts
-In closed loop
-TCC mode off, 251rpm slip
-Trans temp 72°C
-Incoming air temp - 16.3°C
-I have other data, but not sure what's important in this case
Previously thinking clogged cat, check the temps as per Shep's instructions and got 57°C before the cat and 97°C after the cat. I wish I could post what the LT and ST fuel trim values were, but I haven't learned how to get that data yet. I also wish I could quickly check fuel pressure without paying a garage to do it. I am not sure if any of the values I posted are out of the ordinary, especially spark advance/retard. Just looking for some opinions on where to go. I'm thinking motor mount, the timing belt I still never got around to changing, something stupid like a bad ground or something deeper.