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  #11  
Old 08-20-2010, 09:36 PM
frontrange frontrange is offline
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NOX is caused by too high combustion chamber temps. It can be caused by an EGR that isn't opening when it should, a too lean condition, advanced timing..

I've cleaned and flow tested 3 sets of 3FE injectors and never seen one that had a decent flow. I had to toss at least 3-4 of them because they were hopelessly clogged. But the sets I had may have come out of engines that were out to pasture for a long time too. Anyway, like I said I still have more of them then I need if you want to try some known good injectors.
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  #12  
Old 08-20-2010, 11:12 PM
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powderpig powderpig is offline
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O 2 sensors tell the computer how lean or rich the exhaust stream is. So it effects too lean or too rich or just right(simple version). So if the O2 sensors are not working, it can lead to a lean condition which leads to NOX. If you have a Factory service manual and a old style VOM(swing meter style), you can check them out per the manual. If not and you do not have any idea of how many miles(but feel they could be a bunch) I would just replace them, it could also lead to better fuel ecomany.
Looking at your number you gave, it looks like you are running on the lean side of the fuel flow.
So If we look at those numbers, you need to make it run richer. So yes it could be injectors, but it could be the O2 sensors as well.
With similar number, I have seen good results with the O2 sensors. But testing them first before replacing is a wise choice.

But as the other suggest, the injectors or EGR could also effect NOX.
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  #13  
Old 08-20-2010, 11:34 PM
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Scott at AAPerformance Muffler tested the cat a couple days ago and said the temps (180 degrees IIRC) shows its running rich and he suggested a clogged EGR pipe. Can bad 02 sensors cause it to run rich? I have put 101,000 miles on the truck myself so they should be on their way out. I don't have cash for parts that may good for a bit longer. The obvious thing is to find a VOM and test it, thanks Robbie.
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  #14  
Old 08-21-2010, 12:55 AM
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IIRC the voltage output across a narrow band O2 will look like a sine wave if the system is working correctly, but that means you have to have a system that is toggling between too rich and too lean and that means you have to have good (not clogged) injectors, right? If that's the case putting a VOM across the O2 won't really tell you anything.

One thing I don't like about the 3FE is there is no service port on the fuel rail for a pressure test guage. I have a nifty Kent-Moore injector test set that will drive the injectors one at a time with a calibrated pulse train. You just pressurize the system with Key-On, Engine Off, get a pressure reading, send the pulse train and read pressure again. Repeat for each injector and if there is a difference in pressure readings on any injector you have a clogged one.

IOT test the Toyota injectors I have to pull them out and put them on a Chevy fuel rail. In a Chevy I can test all 8 injectors in place in less than 5 minutes without getting my hands dirty. I don't know why Toyota skimped on a simple schrader valve for a fuel rail service port.
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  #15  
Old 08-21-2010, 08:58 AM
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Now you're way beyond me which is good because this is the kind of stuff I'm hoping for to help me nail down my issue.
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  #16  
Old 08-21-2010, 11:23 AM
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Here's a possibility for you if you want to test the injectors. I while back I got annoyed with the lack of a standard pressure test port on the Toyota fuel rail, so I made a few of these:



Haven't tried one out yet, but it's simple enough it should work. It replaces the OEM banjo bolt (on the right) for the hard line that goes to the cold start valve with a new one that has the standard Chevy test fitting. With this I can use my Kent-Moore to do an injector balance test without pulling the rail and injectors out.

So if you want to come by my shop it shouldn't take more than 15 minutes to install one of these and test the injectors. If they test OK and the EGR isn't leaking, I'd say go ahead and drop the cabbage on new O2 sensors.
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  #17  
Old 08-21-2010, 11:48 AM
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There should be a banjo fitting somewhere abouts the fuelrail. You'd hook up a double banjo bolt into that spot to check pressure ! (not 100% if your truck has it, it should)
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  #18  
Old 08-21-2010, 12:28 PM
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Quote:
Originally Posted by TIMZTOY View Post
There should be a banjo fitting somewhere abouts the fuelrail. You'd hook up a double banjo bolt into that spot to check pressure ! (not 100% if your truck has it, it should)
Ever tried to find a M8x1.0 banjo bolt? Now try to find an M8x1.0 in a double length. I'm sure they make them but how much time do you want to spend looking for one? Hell I can't even find the 8mm crush washers without searching all over the internet or going to the dealer.

Last edited by frontrange; 08-21-2010 at 02:53 PM.
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  #19  
Old 08-21-2010, 03:20 PM
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Quote:
Originally Posted by frontrange View Post
Ever tried to find a M8x1.0 banjo bolt? Now try to find an M8x1.0 in a double length. I'm sure they make them but how much time do you want to spend looking for one? Hell I can't even find the 8mm crush washers without searching all over the internet or going to the dealer.

I have one !! It comes in the master fuelinjection kit !
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  #20  
Old 08-21-2010, 04:34 PM
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Quote:
Originally Posted by TIMZTOY View Post
I have one !! It comes in the master fuelinjection kit !
Do you get douced with gasoline everytime using that type of setup? The port injected fuel systems I've worked on maintain high fuel rail pressure for a long time after you shut off the engine. The schrader valve is the way to test pressure as well as bleed the system down to open it without spraying fuel all over the place and risking a confligration.
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