Hey guys, I have a buddy who owns an 87 4Runner SR5-22RE that is completely stock....well, with an aftermarket cone filter so 98% stock . He has an issue with his truck not wanting to rev past 4000 RPM and we're stuck on why it's doing this.
We tried resetting the ECU-nothing, swapping ECUs from my 88-nothing but runs kinda rough and check engine light pops up with the swap, did a whole tune up-ran smoother but still can't pass 4000 RPM.
Possible fuel cut off? Bad fuel pump/filter? Faulty injectors? Bad ECU? Anyone with prior experience that can help elaborate on this matter would be greatly appreciated, thank you guys in advance.

 

Likely electrical, related to the TPS, or the AFM.

Test those components and get back to us. The testing procedure is outlined in the FSM, which can be downloaded from links found on Yotatech.

 

Electrical huh? Maybe I'll have him swap back the stock filter and check his TPS. Thanks for the tip, will start there.

 

So we tested both the AFM and TPS and they checked out ok. Even did a swap from mine to his and things still ran the same. Seems like the engine struggles to maintain consistency when revving anything above 3,000 RPM then seems to redline at 4K. I'm just thinking it could be a faulty ECU? I'm just a little bit fathom as to why my ECU didn't work with his...

 

where are you revving from? Gas pedal or above the engine? I have seen bent gas pedals restrict throttle.

 

This is one thing I thought...

 

Have you checked both the cam and ignition timing. To check the cam timing, the valve cover will need to be pulled.

Sounds like the timing may be off...