Hi

I got a P0430 code. My fuel trims are over 20% on both banks. A few days back I got a P0174 code but after disconecting the battery it cleared and hasn't come back. Are these codes related in any way?

I'm a bit confused because I removed both cats and put O2 spacers in on both sides. I never get a P0420 code. Is one of the spacers not working correctly? I sent Toyota an email about the 430 code and they want to know which of the cats were removed - front or back. I didn't even there were front AND back ones! I thought there were just 2 side by side.

When I analyze the O2 readings on Torque they look pretty similar for both banks although I admit I'm not the best person to judge. Both rear O2 sensors are fairly new.

Unfortunately living in the middle of Africa I can't get hold of a smoke machine. I'd love to look for a vacuum leak, as from what I've read about the subject this might well be the cause of my problems.

One mechanic wants to put a new fuel pump in but I'd like to postpone that because it's a pricey item.

Any thoughts?
Eric

What are the short term trims reading?

Off the top of my head around 4 to 6% but I'll double check tomorrow

LTFT's in the 20's are VERY high, its really trying to compensate for something. Putting on O2 spacers slows the response which could be the issue. If the ECM is not seeing the appropriate voltage adjustment response quick enough due to the spacers it can cause it to lean itself out. The MAF can also be the culprit as well. The rear 02 sensors simply monitor catalyst efficiency, the 2 front ones are air fuel sensors which mostly determine your fuel trims. Sorry if this doesn't make much sense, I injured my back and am all hopped up on Vicodin.

Thats OK Blackcat, you're still making sense!

Bank 1 short term is hovering at around -5 and bank 2 st is hovering at around +5

What does that mean?

Maybe i shall take out the spacers and see what happens to the fuel trim. I'm sure I'll get code 420 again though.

Off to work now. Will try to get more info later.

I removed the O2 spacers.

Here is a screenshot of Torque for Android running at idle in closed loop.

Im just learning to use all the info provided by Torque. Great so far.
Here is a good video on understanding fuel trims. A bit long especially if you watch both parts, so plan accordingly.

Thanks for the link. I had already watched that video. I found it really really great. Very informative.

What I find strange is my MAP sitting at 25 inches at idle.

From what I've read online it seems like there is an intake restriction.

Time to check the engine air filter then. And look down the air tube for birds nests, etc.

Chip H.

I have an 04 RX that I have P0420 & P0430 CEL. I've pulle both cats & the honeycomb material is intact & not burnt up. I have new plugs, new PCV, vacuum lines & new air/fuel & O2 sensors. It gets good fuel mileage & runs smooth. My long term trims are around 6 or 7 (lean) short term jumps around, but from what I've read if long term. & short term add to more than 10, lean or rich, you'll get these codes. I just don't get it! MAF seems to be moving too, so I don't believe it to be bad. I did clean it.

There's several things that can cause it to run as lean as it appears to be. Obviously, a vacuum leak would be the most probable, but if everything checks out I'd lean more towards a MAF.