Won't rev up

[TxAurora]

2000 Silo with 120K miles on the clock. Van has always run good for us.
Responds well to part throttle and very slow inputs to the gas pedal. You floor it and once it revs up a bit it falls on its face. You can baby it to 4K...but driving around and u gas it to merge on a hiway and it is a little too eventful.

Fuel pump replaced at 100K miles.
Spark Plugs and wires replaced at 100K miles.
PCV valve replaced at 100K miles.

Doesn't burn oil, doesn't leak, doesn't make any bad noises.

Welcome to suggestions and tips!

thanks in advance

David

[gmtech1]

Sounds like maybe a plugged catalytic converter. Is the check engine light on?

[TxAurora]

Back in the day we would get the flashing check engine soon light.
After letting the van sit for about a year, cuz we didn't need it much, we put a new battery in it and fired it up.

The revving seems to be gettin better...still stumbles on acceleration. We'll pop the cat off it this coming weekend and see what happens.

Any other ideas let me know and we'll check em out.

David

[TxAurora]

Well popped the cat off and no difference in how the van revs up.

While i was disconnecting the O2 sensor on the exhaust mid-pipe I noticed I could rotate the wire coming from the O2 around-and-around in the sensor, is that normal?

No check engine lights have lit up in about 20 miles of driving.

Any ideas I'm all for em.

[Milo2001]

I had a similiar issue with a different car. I replace the throttle position sensor and it fixed the issue. At the time it did not throw a code because the part didn't fail. You may want to check that part, but you'll need a digital voltmeter to test. I believe the Haynes manual walks through the test procedure.


Good Luck

[maxwedge]

Simple here but how about the fuel filter?

[Tech II]

Did you drive the vehicle with the cat disconnected?

[TxAurora]

Sorry for the late replies..

No I didn't drive with the cat disconnected...just disconnected it and revved it up in the garage...loud as hell and still stuttered when revving up.

Fuel filter hasnt been changed lately...mebbe 7 yrs ago...prolly need to knock this one out while Im at it..

Driven mebbe 70 miles in the last few weeks (around town low speed stuff) and no check engine lights...

[maxwedge]

BTW, I assume you are not trying to get over 4k in neutral, as the pcm will prevent that.

[Tech II]

I would have driven it with the cat disconnected, and floored it to see if there was a change in pickup....YEAH IT'S LOUD.......but you will notice a big difference in pickup when you floor it if the cat is bad....