Hey guys, I have been having a very similar problem. A few days ago the truck wouldn't go above 20 mph so I looked over these posts and swapped out both Oxygen sensors, up/down stream of the Cat. I then took it for a test drive (seems to run much better!) and am still having the same problem. Looking at the continuation of this thread I removed the upstream oxy sensor and other than sounding terrible, nothing else changed.

That being said, do you have any suggestions on what else to check/look at/oil/duck tape?

I don't remember my sig... I have a '01 ram 1500 5.9L 4x4 ext. cab.

Thanks

 

This happened to me, I gutted my cat & threw headers on, I can again easily roast 80s & 90s camaros & mustangs.

Removing the upstream o2 is NOT the Be All End All of diagnosing converter clogs.

My converter had broken a large piece off & blown it very far up into the passengers side of the Y pipe and almost completely blocked the pipe BEFORE the first o2 Sensor. Take the Y pipe & converter out and check for clogs.

I cut my Y pipe with a sawsall in the center near the transmission inspection plate and a 2nd cut after the down stream o2 to easily remove it without messing with the transmission bracket. I also removed the pipes from the manifolds to make this easier. I left the o2 sensors in the main pipe and disconnected their harnesses so that I could easily remove them from outside the truck without messing up the sensors or rounding the hex heads off of them and getting rust in my eyes in the process.

This way you can view the pipes & make sure there are no pieces stuck in there.

I re-assembled everything with 2 connectors and 4 exhaust clamps from Auto Zone. Since I installed headers it came with new flange bolts, so I'd recommend you get new flange bolts.

 

Thanks for the reply. That was a bit much to be doing on my own so I took it to a local shop and asked them to diag the problem for me. I'm not to sure if I believe the answer or not.

He told me that my breaks were locking up and causing my truck to not go beyond 20 mph. He said that the calipers needed to be replaced, and the brake lines. He mentioned something about a piston that when it got hot it got stuck. The problem starts no matter how hot the truck is, turn the key in the morning and cannot get out of the neighborhood over 20. Honestly i don't see how this is all related, but then again, I don't have a great grasp on the inner workings of a truck.

I was honestly thinking that he would come back with the cat as suggested, or possibly the transmission. As for the oil pressure indicator dropping he suggested it was the oil sending unit needing to be replaced, makes some sense to me.

Do you think any of this is reasonable? The price to fix it was beyond me, more likely to sell my truck until I can afford to replace it. ($1k for calipers, break line)

Thank you, in advance

 

Did he actually check the cat? well easy way to check if the brakes are locking up is to jack the truck up and spin the tires by hand and see how much resistance there is. And 1k for calipers and lines? Yikes. Maybe try a different shop for a different opinion.

 

+1 To getting another opinion!

 

Easy test would be take it out, get it going as fast as you can, and let off the gas. Does it coast slowly to a stop? Or does it stop RIGHT NOW! If it coasts a bit, it ain't the brakes.

 

I'll have to try the coast-to-a-stop when I pick up the truck later today. If I knew where my jack was I could try spinning the tires (just moved.. yay).

Thank you for the great replies, much appreciated!

 

Just picked up my truck.. I'm assuming he had to take off the breaks to look at the calipers... which seemed to solve my problem.. for now. So other than a low oil pressure warning going off every 30 seconds it's running great! My specialty is computers, I can diagnose those just fine... my hats off to everyone that knows the inner workings of vehicles. I appreciate everyone who helped out!

 

He didn't replace the sensor while he had it? With the right tool, its a five minute job.... Even with the wrong tool, (channel locks....) its only about 15 minutes.