I just did an SR5 cluster upgrade and now that I have a tach I'm noticing the motor won't rev past 4300 RPM when floored. If I use a small amount of skinny pedal the motor will rev all the way up to 5700 RPM or so then hit the rev limiter. But, when I use half or full throttle the motor will flutter around 4300 RPM.

I may have some questionable vacuum lines but I am not sure if this could be a culprit because this problem is dependent on how much gas I use.

First thing that comes to mind was the TPS. So I pulled the throttle body and checked the TPS. It was out of adjustment so I moved it around till I got these results:

VTA-E2 (0.0mm) .70k Ohms
IDL-E2 (.57mm) .11k Ohms
IDL-E2 (.85mm) Infinity
VTA-E2 (OPEN) 4.55K Ohms
VCC-E2 (ANY) 5.83K Ohms

All parameters are good so I know the TPS is good. I also checked the AFM and came up with this:

E2-VS 450 Ohms
E2-VC 180 Ohms
E2-VB 280 Ohms
E2-THA 1.87k Ohms

I know the E2-VS is out of range by 50 ohms (should be 20-400) and according to the FSM, the AFM should be replaced. But with the AFM only being off by just that little amount, I am sceptical if this would by my problem.

btw: this motor is a 88 22re (4runner) with a fresh rebuild about 2500 miles ago. The motor has a 268 cam, Street RV head, LCE Header and is bored .030 over.

And I am getting a code for the water temp sensor and o2 sensor. I doubt these are related to my problem because as stated before, the motor will rev all the way if I use a light amount of gas.

So... Here's where you chime in

 

Well for one, i wouldnt run one of these motors over 4300 RPM anyways...
But besides that.
So, what youre saying is that if you mash the skinny pedal, the engine flutters and won't rev?
However, if you hold it at 1/4throtle or less, it shoots to 5300?

And you'd be surprised by how few ohms it takes to make an engine run like trash.

 

There's nothing wrong with taking these motors up to 5K or a little higher. Toyota designed them for that and this is a fresh engine so I think it's fine. It is very possible that the AFM is causing this, but I wanted to get more info or opinions.

 

I wanna say the water temps sensor affects timing. (depending on which one is throwing the code) But I could be wrong. I would get rid of the codes first then see what happens as you know these have to be changed anyway.

BTW which o2 sensor code you getting? Cali spec truck with 2 o2 sensors? Or only one? If cali spec is it the upstream or down stream sensor? If upstream or regular spec then a bad 02 sensor can and will affect A/F ratio.

 

Is you engine completely warmed up when you test this?
While on the interstate if you stay in 3rd and over 4300 rpms does the same result happen when you floor it? Have you modified the air intake? like k&n. You should replace the AFM according to the FSM.

 

I did get rid of the air box and built a bracket to hold a cone filter. I'm trying to source another AFM to test it. I'm kind of leaning towards the AFM too seeing as it's the only thing that is out of parameters. I could be wrong but I'm thinking that it could make sense. When I use little gas, the flap in the throttle body isn't open as much, thus not pulling in as much air and not letting the AFM open completely. When I floor it, it floods the engine with more air and the AFM opens fully...?? Just a thought. Either way, if the AFM is out of spec and the resistance is off on one parameter by 50 Ohms, then it is bad according to the FSM.

 

I suspect the intake is causing the issue.