I've been having an issue with my '99 2500 V10 for a couple months now. I start it up in the morning it idles fine, I drive a few blocks, come to a stop, then go to accelerate and it bogs down, cuts out and takes about 30-40 seconds to recover and start running normal. Sometimes during the recovery period it would misfire and occasionally back fire. I was getting no CEL or codes. I know my cats are going bad and haven't been able to fix it due to funds. I also wasn't so concerned about it because when the truck finally gets done stumbling and misfiring, it would launch hard giving me the idea that the exhaust was able to flow somewhat ok. Well, this morning I go to Auto Zone to have them hook up a scanner just to see if anything would pop up for some reason. Nothing did. I drive a block and the CEL comes on. I drive to the parents house, truck sits for 2 hours, I start driving back to Auto Zone to have them hook up scanner and the truck is running worse then ever. I barely made it there or back home. They found an o2 code. Sorry for the long story, but my question is, why did I go months without a code, and the truck was still drivable, but after scanner tool was hooked up my PCM finally wakes und gives a code and the truck will barely run at all now. Just coincidence? Faulty PCM?.......they tested fuel pressure too and it's steady.

 

How many pre-cat O2's do you have? Try disconnecting them, and see if the truck runs any better. (will most certainly set a code.)

 

Will do. I've seen you mention in other threads about disconnecting the o2 sensors and see if the truck runs better. Does this only work for a short time to test them or can I drive for a couple days with them disconnected (granted it runs better disconnected)? I'm not sure how the whole loop cycle works on these things in effecting the other sensors.




I have two pre-cat sensors but the scan tool threw code on the bank 1 (high voltage). the guy at the parts store said that's the one that does the main"reading", which I didn't really understand. What would the other o2 do? Again, they are both pre-cat. Left and Right. I plan on replacing both.


Any thoughts on why my PCM started acting the way it did once the scan tool was plugged in?

 

What was the code? FYI: Bank 1 is in the cylinder 1 side of the engine.

 

the code was PO 0132. Thanks for the info in which side it is. I'm guessing these o2 sensors are going to be different in their parts listing and function? wanna make sure I put them in the right place


I do plan on getting under there and doing some voltmeter test later on .

 

http://www.obd-codes.com/p0132

 

If it runs better with them disconnected, yeah, just leave 'em unplugged until you can replace them gas mileage will suffer some...... not good for the cats either.. Few days won't matter over much.

If you have more than one pre-cat O2, chances are, they are going to be the same part number. After all, they are doing the same job.

PCM pays attention to both, and adjusts mixture ratio per bank, according to the readings it gets from the sensor. Replacing both at the same time is the best idea. Reset the PCM after doing so, that will clear the codes, and let the PCM relearn how to run the engine with accurate sensors.

Don't get Bosch sensors, our trucks don't always like them. NTK, or Denso.

 

Thanks for the help, both of you guys.

 

Let us know how it turns out.

 

Ah, I did get them unplugged and went for a little drive. So far so good. At least it looks like I'll get to work for a couple days and then drop new sensors in. I made an attempt to get them out with a 7/8' wrench but quit pounding on it. Gonna buy the right tool. Thanks for clearing up the little part I thought I knew about o2 sensors. The guy at AutoZone had me confused for a minute.


I'll keep you updated.