Power loss on and after hills, teachstream logging?

Morning folks,

I have a loss of power when climbing hills at 2500rpm in 5th at 70mph. It will gradually loose speed, even if I shift down and push the rpms above 3000. When I get to the top of the hill the problem continues for a few minutes and then everything rights itself. During the power loss there seems to be an engine vibration I am not used to.

Background - installed a completely rebuilt engine about 10k ago, top and bottom end. All ancillaries are original. Cat was totally clogged, so replaced that with an EPA spec one then, new O2 sensors and MAF at that point too (all OEM)

Power didn't feel right after the new engine, but assumed it needed breaking in. After a few thousand miles and no real change I started chasing the problem. I am taking a few longer trips and hitting hills, which I don't normally, which has shown up the more dramitic symptoms.

I have techstream, though I'm new to it. Noticed long term fuel trims were +14, so fitted the URD pump upgrade. This has fixed the fuel trim issue which now sits at +4.2%

Also replaced the plugs, air filter, PCV valve and checked the vacuum hoses visually.

I now have a P0420 code - so I have a new manifold gasket, exhaust gasket and studs, and I'm going to take that off and make sure there are no cracks or leaks that were introduced in the engine swap.

I'm doing another long run tomorrow, I can try running logging on techstream, up the hills. What should I look at?

 

Hey Blackfreighter,

I had the same issue with the hill climb with Code P0420, my catalytic converter was clogged. I was noticing a spluttering (like a playing card rubbing against a metal grille really fast). If I rev it high it will make the spluttering sound. If I paced the throttle smoothly to allow air to flow it will not make the spluttering sound.

You can test by having a friend sit in the driver seat while you look though your passenger wheel well towards the gap between the exhaust manifold and the catalytic converter. (Remove the weather splash cover of course).

Have your friend turn on the truck and rev high. While they are revving, look at the gap as mentioned above. If the connection is splitting apart while revving high (the spring bolts will hold it in place); like the catalytic converter is clogged, then it's a clogged cat.

I end up getting a aftermarket catalytic converter. I cleaned both upstream and downstream o2 sensors with carb cleaner. I had no issue with the up hill climb after that but the code came back on after 80 miles. I then swapped out for new up and downstream o2 sensors and it was good since.

This was on a 06 4cylinder at 300k mi.

Hope that was helpful.