2.7 surges badly under acceleration

1995 tacoma 2.7 surges bad under acceleration. New fuel pump,injectors,fuel filter, fuel regulator,tps,o2 sensors,and mass air flow. No vacuum leaks

 

Find a place that has an OBD scanner, and run a scan. Shops like O’reilly have them on tap.

 

could be your torque converter or clutch slipping if it’s under acceleration. But I agree with trexgrrr OBDII is a good place to start.

 

Scanned it and no codes. Backfires bad under load.

 

Too much fuel? Occam's razor implies tracing simplest explanation and most obvious variables first. Sounds like problems started after recent work? What brand parts?

 

How does it idle? Smooth or rough?

 

great point/analysis

no vacuum leaks OP stated

what about air intake leaks?
(Un-metered air causing surge)

believe me, I have been known to forget to put/tighten a clamp in the past

 

I was also going to recommend maybe IACV depending on OP’s answer about idle condition

 

yeppers
Mine at 212k….no issues
But I was “in there” might as well just clean

 

After:

 

Not sure how the IAC would make it surge during acceleration but didn’t see anyone mention TPS. Those can do some weird stuff if they are failing.

 

OP said TPS has been replaced. IAC can cause similar issues to what has been described, I wouldn’t completely rule it out. At the very least it’s worth cleaning it.

 

Sure, clean the IAC. It’s still a less than 1/4”x 1” opening letting air in when wide open, roughly 1200 rpm’s, that over a base idle of 700rpm. Not sure how that is gonna make rpms surge when under load but maybe I ain’t thinking hard enough.

I do know I put an aftermarket tps in my truck thinking I was doing something constructive during “tune up”. That when the original tps was giving no issues. Well guess what? That aftermarket tps started going out with less than 5k miles. Had occasional severe stutter when accelerating like getting on the highway. Chased that a while till I saw tps reading on scan gauge drop from 10 at idle to 1. Then saw it go wonky as stutter occurred under acceleration. Replaced with new OEM TPS and all was well. So maybe check tps again. Just trying to help here. I been all around the world with IAC myself.

 

A lot of new parts changed. If they were not OEM I side with checking those first.

I agree with THatt with regards to the TPS. Simple swap back to original is a good first step.

Good luck.

 

I just cleaned mine today and it took away a stumble or a surge once clutch was out in first gear. It would kinda hesitate for a split second then power on again and you would kinda give it to much throttle then your into a little learch forward like a surge.
Just wasn't smooth.
To be honest replacing my cracked exhaust manifold helped the problem but didn't remove it all together.
But cleaning the AIC her purr!

Hope you get to the bottom of it soon!!
Goodluck

 

Just went back and replace cap,rotor, and coil it improved alot. I can go over 70mph now. Gonna go ahead and put wires and plugs in it. I'm assuming they used cheap parts and didn't get anywhere woth it.

 

Would love to see plug condition

glad you have no surging !!!

 

Control car I'll post pics when I change them. I have a set coming.

 

how's your voltage? I chased fuel issues for while before realizing I had voltage drop. Whether it was affecting the injectors, pump, or ECM I dunno. But fixing the electrical solved my issues

 

I came here to say this. I had a similar issue in my ranger. After chasing down all the vacuum leaks I would unplug a coil pack and drive down the road, finally found one that was failing under load and causing the issue