Stumped! Why is my 02 PreRunner hunting/surging!?

Need help identifying the issue with my 02 PreRunner (3.4L v6 2wd, 204k miles) hunting/surging.
Starts right up, runs cherry, but once I’m out of the driveway & accelerating above 20mph, begins to hunt/surge and revvs, resulting in a loss of power.

History: driving home from work (from sea level to 1500’ elev) on st pattys nite, I experienced a loss of power when accelerating yet the rpm’s would surge. No Dummy Lights Ever Appeared on Dash. I managed to scoot home, and the next morning scanned it. Threw P0302 code.
Since then, up til this afternoon, I have replaced (using OEM):
•coils
•spark plugs
•spark plug wires
•valve covers
•valve cover gaskets
•throttle body gasket
•fuel filter
•distributor
•pcv valve + gasket
•idler pulley
•camshaft plugs + seals
https://youtu.be/NFmk_TnWxhw

 

Easy on the parts cannon. Some of that makes sense. coils, plugs, wires, fuel filter.. but the rest seems like you were just throwing parts at it. Not sure what you mean by the distributor, as EFI engines don't really have those.

Do you still have pending 302 or other 300 (misfire) codes?

I assume you did the valve cover gaskets (why did you get new covers?) as yours were leaking at it was just time? It's a bummer that you did all the work to get down there and didn't do the MotorWest Denso injectors as well. It's way more likely an injector would cause a misfire than anything do with the valve cover gaskets or cam seals.

 

This gets my vote!

 

No it’s not throwing any codes.
The valve cover gaskets needed replaced anyways as yes they were leaking so that entire project was undertaken as a possible remedy to this affliction.
Injectors have not been done yet….

I have the Bishko Toyota service manuals hard copies & goin thru the Troubleshooting section based on my truck’s symptoms

 

Surging is more likely to do with the MAF, TPS, or A/F (O2 Sensors) and cats.

A misfire is more coil, plugs, wires, or injectors.

I guess surging could be the fuel pump on the way out too. But that's tricky to get a handle on as you have to install a bung to get a reading.

Outside chance the ECU.

Actually, "saying that out loud" reminded me, it could be something like a cam position or knock sensor. All those sensors have trouble shooting steps in the FSM. You should find yourself a copy of that. I'm not sure what the bishko manual is.

 

These are the service manuals I have.

I replaced both downstream & upstream o2 sensors last year.

 

Gotcha. Never heard of them referred to as bishko.

Clean the MAF and check the MAF and TPS against the FSM would be the next suggestion then

 

For the surging try unplugging the front sensor (A/F ratio) for a quick drive and see if it stops. Mine surged after warm up and ended up being the replacement Chinese sensor I installed a couple years earlier, didn’t surge when new. I had kept the original sensor with 150k miles on it, put it back in at 170k and still working fine at 181k.

 

Fuel pump relay, maybe

 

I think Bishko is the publication hous who reprinted them. I bought them on Amazon a cpl years ago

cleaned the MAF during the VC gasket replacement.
Ordered a new TPS on Amazon, as I’m on an island in the middle of the pacific & none of the parts stores had any OEM in stock. Coming on Monday. Fingers crossed.

 

It’s not that, my truck starts & idles perfectly. I live at 1500’ elev, & once I venture out from my driveway & make my way down to the main road, that’s when the surging begins

 

Same thing on mine, started up and idled fine, drive away and fine but once warmed up surging started. I think that has to do with open loop/ closed loop. I just looked at your video and mine wasn't surging as bad as yours but as soon as I unplugged the front sensor it quit but obviously throws a CEL.

 

Mine hasn’t once thrown the CEL

Mine never once threw the CEL the entire time this has been going on. ‍♀️I just scanned it now, & this is all it said.

 

All I’m saying is as soon as you start it to do a test drive with the front sensor unplugged it will throw a CEL. Interested if surging goes away.

 

This morning took out the upstream o2 sensor. Drove around the block. Surging went away but drives sluggish.

 

Looks like you found part of your problem, is your sensor the correct Denso part number? I'd install a new correct Denso as it seems like you need it anyway and go from there.

 

The TPS that arrived today is Toyota part #

$75 89452-35020 Throttle Position Sensor

89452-35020.
The TPS that was already installed in my truck is #89452-35030. Fml. Returning immediately.
So now it’s throwing 2 codes: P0222, P2135.

 

Is your connector three pin or four pin? My 2002 is three pin and takes

$75 89452-35020 Throttle Position Sensor

89452-35020, from what I can find 889452-35030 is for some 2003 3.4's, is a four pin connector and is not sold individually, comes connected to a new throttle body.

 

DTC P0120, P0122, P0123, P0220, P0222, P0223, or P2135 (ls2.com)

 

Fuel pump itself? Surging sounds like what they do when running out of gas just before dying.