P0147 & P1406 codes - loss of power above 3k

[MegaHertz]

So I got my 96 v6 camaro with now 135k back on the road this spring after sitting for a few years. After replacing a power steering hose I got the urge to figure out what codes are plaguing my car - and why it has felt lifeless at higher rpms.

So the engine has what seems like diminishing power after 3k rpms, and won't go above 4k under load. I was thinking maybe an intake restriction so i put a paper filter on while I clean the k&n as its been years. No change in performance really - maybe a bit more pull at the lower rpms. I will check the maf for filter oil / clogs when I have some light to work with this weekend. I scanned the codes that were set when i got home and I got a 0147 and a 1406 which relate to bank 1 sensor 3 o2 heater circuit and an egr valve position circuit respectively.

The o2 sensor is after the cat and I'm starting to think maybe an exhaust restriction is to blame in the cat as I have never replaced it since I got the car at 110k. I'm wondering if a rotting cat could have taken out the o2 sensor heater in the process.

I'm not really sure what the egr sensor circuit does or how it could relate to the poor performance. I know its for an exhaust gas regulator for emissions but I don't know where it is and how it functions.

Thinking about these codes has reminded me of a vacuum hose issue I had and forgot to fix properly. There is a vacuum hose on the throttle body and it got eaten by the belt so I plugged the throttle body nipple as the car wouldn't really run otherwise and I've forgotten to replace the hose for a couple months. Another item on the to do list this weekend. I don't know if this relates to either of my codes but I'm welcome of any and all input.

[MegaHertz]

Re: P0147 & P1406 codes - loss of power above 3k

So I've decided its definitely a clogged cat - so tomorrow it comes off. Going to autozone to pick up some pipe or a muffler to splice in its place. If I'm left without a bung the o2 sensor will be destined to suffer unless I can build a sim for it cheaply.

This is a temporary fix for the winter when I won't be able to do work on it myself. Inspection isn't till may so I hope to have a complete new exhaust in by then when I'll be doing the whole thing headers back come warmer weather. Weather isn't great for driveway work right now and that's what I'm working with for a workspace.

What I'm not sure of is the egr valve situation. It seems to be an expensive part and I'm hoping the TB vacuum line that is currently gone is to blame (plugged at the tb till i get a new hose). I will be searching more on that tonight so hopefully I'll have an idea by tomorrow when I go shopping.

[Mogobs30th]

Re: P0147 & P1406 codes - loss of power above 3k

1. Rerun your vacuum lines. There is a diagram under the hood of the car on the radiator cowl. Shouldn't have vacuum lines plugged.

2. The EGR valve is that, a valve. It is for emissions, but it does play an important part in fueling and the AF ratio of your car. Its connected to the drivers side exhaust manifold via a little metal (and crappy) crinkled tube.

3. Without tuning it out or a simulator, taking out the post-cat O2 sensor is a bad idea. "Splicing" the exhaust is also not the way to go, I would either replace the cat (which can be found for as cheaply as $50), or sub in a pipe in place of the cat. Either way, the post-cat O2 sensor needs to be in the exhaust path.

4. The 1406 code....no clue, might just need to clean out the EGR, who knows really. Its a goofy code, never seen it pop before.

I know you haven't posted much, but I seriously recommend not halfassing it. You can get parts relatively cheap and it will be a more permanent fix than what you're attempting.

[MegaHertz]

Re: P0147 & P1406 codes - loss of power above 3k

I guess 'splice' was the wrong word to use. I intended to mean that I would replace the cat with a pipe or muffler. However with that not having o2 holes, I went and ordered a magnaflow cat with o2's on both sides so now I can just replace that section with a new cat, a reducer and piece of pipe.

I replaced the vacuum line though the only hard line and nipples they had at the local auto stores were much smaller diameter. Still has got to be better than just plugging it and i had a pending evap code that hopefully will be explained by the vacuum line situation.

Hopefully the weather next weekend cooperates with exhaust work and I'll be held over till I redo the whole exhaust in the spring.