98’ 3.4 auto 4runner
Just recently starting having issues on acceleration, I surges/lacks any sort of power untill after 3500rpm. Also at highway speeds you can just slightly feel it surging as well. This issue occurs from a stop and when at any speed. I did a tune up with ngk wires and plugs and replaced the upstream o2 sensor with denso brand sensor just as preventative maintenance because I’m not sure how old everything was that was on the truck. I ohm tested the maf and it came back at 1.5ohms at operating temp which is definitely out of range according to my manual, tested the tps and could not manage to get a good reading no matter how I probed the wires (3 pin tps)…no cel or stored codes and it definitely smells a little rich coming from the exhaust.. any ideas?

 

I should also mention that it does it both when cold and at operating temp but it is far far worse when cold.

 

did you get this resolved?

 

Not yet, ordered a ob2 adapter to read some live data.

 

Looking at the live data, the LTFT is usually around -5 at WOT and goes up to around +3 when I let off abruptly. But when I ease into the throttle to recreate the surging condition I’m seeing -15 which seems like alot, any thoughts from anyone who knows more about this stuff?

 

Resolved the issue as of now, turned out the PO had put in a aftermarket TPS and it was a crappy Dorman brand, installed a OEM sensor and all seems well currently

 

I lied, issue is still there. Can also hear a very light miss coming from the intake. Almost sounds like a popcorn machine, very hard to hear the miss from the exhaust side but probably just because it’s stock. Replaced the fuel filter for good measure with no change. Any thoughts? Maf is new (denso) and tps is new (oem).

 

I had one with this problem that about drove me mad. The crank sensor might be a place to look. You really gotta bow up and tighten the ˟˟˟˟ out of the balancer. Make sure you get a OEM ckp sensor. Check and make sure it’s at correct depth to the reluctor wheel. Your trims “from my experience goes out the window at wot” but your o2 voltage should jump up immediately when you cod on it. I’ve never seen an ecm go bad on one of these. Hook up a lab scope to the ckp. Good luck