97 sunfire 2.2 auto is sluggish

[strandedonearth]

I have a 97 Sunfire 2.2l auto. Lately it doesn't seem to accelerate at quickly at higher RPMs, like when trying to get to highway speeds. It gets there, but it seems to take longer. It still seems peppy enough off the line or when it upshifts, but the RPMs climb slower than usual as they get higher. I've replaced the catalytic converter as it was rattling like mad and I suspected it was plugging, but that only helped a little.

Anyone have any ideas? It seems to be running normally enough for a 20yo car.

 

[melsg5]

do you have a check engine light on?
when is the last time you did a tune up, air filter, fuel filter, plugs, etc.?

 

[strandedonearth]

Doh. Fuel filter (and pump) was done a couple of years ago, plugs and wires a year after. No check engine light. Thanks for reminding me on the air filter, I'll check that ASAP. Makes sense.

 

[melsg5]

how many miles on the fuel filter?

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[Lemming]

I had a similar problem with my work truck. It's a 1998 Chevy S-10 with a similar 2.2L engine. Like you, I did NOT receive a code.

During the course of doing a tune up (New Spark Plugs and New Spark Plug wires) I found one of the terminals on one of the coil packs had become rusty and wasn't making good contact. I replaced both coil packs and my problem was solved.

I think the coil packs are underneath on your model and get water and dirt kicked up on them. That is what appears to have happened to my truck.

Best of Luck with your repair.

 

[strandedonearth]

Sorry for the delay in replying, as I was waiting for a chance to test it on the highway (when it's my turn to drive the carpool). Normally by the end of an on-ramp I could be easily be doing 110-120 km/h (with two passengers). When I first posted here I could barely get it to 90 km/h (driver only!) at the end of the on-ramp, and after replacing the air filter I can get it to 100 km/h (with two passengers). It also doesn't have the same hill-climbing power, and fuel economy is definitely down

The car has about 258,000 km on it. It was probably driven hard by a previous owner, as it has a fair bit of valvetrain clatter. A new tick in the valvetrain also started about the same time. The fuel filter (and pump) was done about 40-50,000 km ago, not long after I bought it. I replaced the plug wires about 15 months ago.

The catalytic converter has been annoyingly rattling like mad for the past few months so I decided to replace it with a straight pipe in case it was giving too much back-pressure now, but that didn't help much. Replacing the air filter has shown some improvement, but it's still not back where it was.

I guess I'll have a look at the coil packs next, although, as Lemming says, they are in that difficult silly spot on the back of the engine almost (but not quite) impossible to reach from top or bottom, especially around an auto trans. I didn't notice at first, but it does idle slightly rough sometimes, although not enough to make the tach needle bounce.

 

[strandedonearth]

It turned out to be something really stupid. The floor mat was under the gas pedal. Not that it severely limited the available throttle, but when my new driver daughter killed the battery completely, the computer wasn't able to properly recalibrate the throttle range. My mechanic friend noticed that the TPS voltage was lower than it should be when the computer thought it was at WOT, so it was running rather rich.

I rarely go to full throttle, and I had no idea I should floor it after the battery died to calibrate the computer. Just mashing it to the floor while test driving brought some improvement afterwards. We moved the mat and disconnected the battery, then reconnected the battery and ran the throttle through its entire range a few times. That brought an amazing improvement, especially with the catalytic converter now gone. Next thing I did was cut the mat down so that can't happen again.

 

[melsg5]

ok havent run across that one before thanks for the update

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