1998 V70 Base barely accelerating from stops

[mghdi1120]

Revs to 5k
fuel trim at idle and at 5k
No white wispy smoke while still only when I pull away.

[mghdi1120]

Hello again,
Answer is on page 2. No mats in the way, factory Volvo floor mats, the pedal goes all the way to the floor. I could have pushed past 5k a little but didn't think is necessary. 0.8 id LT fuel trim. No wispy white smoke at idle, just when pulling away.

[yanga001]

The throttle position sensor probably needs to be changed based on your ohmic readings. I am unsure if that would cause downstream performance issues. Your LTFT seems to be on the money so probably not a fueling issue, spark, etc.

Time your car going from zero to 60 and post it up. Just a stopwatch or video as these cars are not exactly fast as an NA.

[RickHaleParker]

Any recommendations of what to check? I was thinking maybe to pull the O2 sensor at the cat or front ( which one?) to see if it could be a plugged CAT. I haven't replaced that in a very long time... Is that a wise move?

It has the symptoms of a clogged exhaust system. It could be any component in the exhaust system. A clogged Resonator or clogged Muffler has the same effect as a clogged Cat. Pulling a O2 sensor relives the back pressure and the symptoms go away if the clog is down stream of the O2 sensor.

If you pull the front O2 sensor and the symptoms go away, it could be any of the three ( Cat, Resonator, Muffler ).
No change and the problem some place other then the exhaust system.
If you pull the back O2 sensor and the symptoms go away, it could be Resonator or Muffler but not the Cat.

In park, rev the engine to about 5K and hold it. Does the exhaust system whistle?

[mghdi1120]

The throttle position sensor probably needs to be changed based on your ohmic readings. I am unsure if that would cause downstream performance issues. Your LTFT seems to be on the money so probably not a fueling issue, spark, etc.

Time your car going from zero to 60 and post it up. Just a stopwatch or video as these cars are not exactly fast as an NA.

Where I live ( around the corner from Villanova University) speed limits are 25 with 6 stops before a highway. I don't think I'll make it. If I cannot fix this, I will drive when there is no traffic so as not to risk an accident. The zero to 60 is not currently an option. This is also a hilly area making it a little worse. My mechanic suspects the clutch. I've been driving manual trans for 40 years and am very easy on a clutch . This one does have 80k on it so he may be right but I'm doubtful. No other symtoms accept the failure to accelerate are present, no noises, no sponginess, perfectly normal pressure on the pedal, smooth shifting between gears etc. So ill chase after a clogged exhaust and change the tps.
Thank you all so much, please stay with me as this is a little above my pay grade here.

[mghdi1120]

Any recommendations of what to check? I was thinking maybe to pull the O2 sensor at the cat or front ( which one?) to see if it could be a plugged CAT. I haven't replaced that in a very long time... Is that a wise move?

It has the symptoms of a clogged exhaust system. It could be any component in the exhaust system. A clogged Resonator or clogged Muffler has the same effect as a clogged Cat. Pulling a O2 sensor relives the back pressure and the symptoms go away if the clog is down stream of the O2 sensor.

If you pull the front O2 sensor and the symptoms go away, it could be any of the three ( Cat, Resonator, Muffler ).
No change and the problem some place other then the exhaust system.
If you pull the back O2 sensor and the symptoms go away, it could be Resonator or Muffler but not the Cat.

In park, rev the engine to about 5K and hold it. Does the exhaust system whistle?

Pulled the rear O2- no change, revving at 4K to go 15mph around the block
Pulled the front O2 and woo hoo! she zoomed up to 35 mph in 1/2 a block and no trouble coming up the 2 hills circling my block!
So is there anything that can be isolated. Does this indicate the CAT or could is still be the other 2 components ?
I cannot hear whistling but that might have been because of the high rpms...
Super grateful to you!

[abscate]

That’s a plugged cat , for sure. You can put a pressure gauge on the OXS bung and measure the back pressure for fun.

[mghdi1120]

Thank you!

[RickHaleParker]

Pulled the rear O2- no change, revving at 4K to go 15mph around the block
Pulled the front O2 and woo hoo! she zoomed up to 35 mph in 1/2 a block and no trouble coming up the 2 hills circling my block!
So is there anything that can be isolated. Does this indicate the CAT or could is still be the other 2 components ?
I cannot hear whistling but that might have been because of the high rpms...
Super grateful to you!

The clog is in between the two O2 sensors. The only thing between the two O2 sensors is the Cat ....

The whistling test is inclusive if you don't hear it. You can have a clog and no whistle when the exhaust system is quite air tight.

[abscate]

RickHP for the MVS win today! Approved by Nova, the official MVS dog