New girl, need advice on CEL- P0172, P1133

Hi everyone. I'm new to the forum and to 4Runners, but not to Toyota trucks- husband and I have owned a number of them since the 80's. I recently purchased a 2000 T4R 3.4 5 speed that I could use some advice on. I'm in Idaho, it was a dealer trade in PA, which I sent my nephew out to drive home for me. Less than 100 miles into the drive the CEL came on (Surprise! dealer says they had no idea). Engine was running fine and he was on a tight schedule so went ahead with the 2300 mile drive. Had the code checked when I got it here- P0172 and P0171 were both recorded. Have driven a couple thousand more miles since and it has been running great, including at full throttle, no hesitation, consistently getting 21-23 mpg, but intermittent CEL with P0172. The only abnormal thing I've noticed is that on a recent start (warm engine) it raced until I tapped the accelerator.

I had my mechanic do a 90,000 service and clean the MAF/throttle body. He pulled one spark plug from each side- both looked new so didn't change them. Also had him extend the rear differential breather while he was at it thanks to helpful info on this forum. The muffler was rotten so got that replaced. We were hoping that cleaning the MAF would take care of the CEL, but still got a P0172 after a half dozen drives. Cleared the CEL and tried burning ethanol free gas per mechanic's suggestion. CEL is back on, P0172 and now for the first time P1133.

So, I'm hoping that with this (long) history the experienced members of the forum will know what's most likely going on and be able to suggest what order to test/replace parts. Does the P1133 point to a bad A/F sensor as the source of the problem, or is that sensor maybe failing because the engine has been running rich? Does the fact that the engine doesn't miss or anything rule out a clogged injector or some of the other possible causes of P0171/P0172?

Looking forward to hearing what you guys think and to learning more. Typical girl, I'm not exactly mechanically skilled, and haven't done anything much more complicated than changing the oil or a flat tire, but I don't like to just turn the truck over to a mechanic without understanding the problem/repair before work is done. Plus, after a lot of searching and reading on the forum I almost think I could tackle some of these things myself. Great forum!

Change the 02 sensor(s); use only OEM or Denso:
http://www.toyota-4runner.org/3rd-gen-t4rs/119357-cel-p1133-after-o2-replacement.html

If the P1133 still lingers, it may be time for a run to the junkyard or new MAF.

post pics. Then we'll help. Maybe. :biggrin1:

BlackCat914 said:

post pics. Then we'll help. Maybe. :biggrin1:

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Pics of me or the purple beast? I'm kinda old- note that I've owned Toyota trucks since the 80's.

MtnChick said:

Pics of me or the purple beast? I'm kinda old- note that I've owned Toyota trucks since the 80's.

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nevermind then. hwell:

BlackCat914 said:

post pics. Then we'll help. Maybe. :biggrin1:

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BlackCat914 said:

nevermind then. hwell:

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How old are you? Don't be a jackass.

Welcome to the forum, MtnChick. Stick around, we're not all prepubescent shitheads.

KidVermicious said:

How old are you? Don't be a jackass.

Welcome to the forum, MtnChick. Stick around, we're not all prepubescent shitheads.

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Thanks. No offense taken. I enjoy good sarcasm.

Pictures please ! , that's an awesome color In my opinion

KidVermicious said:

How old are you? Don't be a jackass.

Welcome to the forum, MtnChick. Stick around, we're not all prepubescent shitheads.

Click to expand...

I was being sarcastic, as apparently only you didn't realize. :moon:

Yeah, would definitely replace both O2 sensors and clean the MAF then reset to see if it does come back on. Make sure you buy the right type of O2 sensors that are Densos only.

Do you have any exhaust leaks up by the AF sensors?

BTW, www.rockauto.com has Denso sensors much cheaper than local parts stores.

Can't hear any exhaust leak, but will make sure. Thanks for all advice so far.

Went for a drive this afternoon and shot a couple of pictures- I'll get them off the camera tomorrow and post if any are worth it.

Update

My last update on this thread seems to have been lost- there was a notice up for a while that some posts had been deleted? Anyway, I guess I will do a repeat and a final update (I hope). As I wrote last time, I hate it when I find a thread with lots of advice on what to do, but then no follow-up to know how it turned out. This is too long, but maybe my experience will help someone else.

Changed the A/F sensor, which was a saga. First, the mechanic who has done most of the above maintenance work ordered the wrong part- twice. I got the right one (from Amazon), which is what I should have done in the first place but got lazy. Someone had previously tried to get the sensor out but failed because the nuts were rusted on. Ended up with one bolt broken off but still usable, the other re-threaded, but the exhaust still intact. CEL came right back on with P0172.

We also realized there was an issue with the throttle response, which if I had caught on to earlier might have helped us zero in on the problem. One of the first things we did to the rig when I got it was take slack out of the throttle cable. There was enough play in it to make smooth shifting challenging. Tightened it as much as possible without raising the idle speed but still had to move the gas pedal a little before there was a response. This felt like a cable issue to me, but it got worse to the point where the engine would bog down a little before taking off when you hit the pedal. This was obviously going to be related to the CEL.

The mechanic suggested changing the fuel filter because it's rusted. Also started considering other sensors, fuel pump, etc. I thought about it for a couple days and decided I didn't want to keep throwing parts at it without a good diagnosis, so went to a dealer. They found a VERY DIRTY MAF AND THROTTLE BODY! That was the first thing I considered, and it was supposedly cleaned when the timing belt job was done :frusty: FWIW the Toyota tech told me that when the MAF is that dirty the ECU defaults to rich. So, they cleaned it and also hooked up to their machine that cleans the fuel system and top end. Huge difference- instant throttle response, better acceleration, all around smoother power. I've put a little over 1k on and no more CEL.

The moral of this story is: Learn to do your own work and supervise whoever does it when you can't, especially when your mechanic is a frick'n screw-up!