okay, here's the story:

i have a 1988 4runner 22RE 5spd 4x4. truck had emissions removed from it BEFORE I BOUGHT IT. it ran perfectly fine for the first few weeks i had it, the clutch started slipping really bad so i went ahead and changed it. well, ever since ive changed it, its been running horrible. the only thing thats different on the truck now is that i went from aftermarket header to a stock exhaust manifold. now i only have power at low rpms when i barely press the gas, and i dont actually have good acceleration for the vehicle until i reach the top of my band band. whenever i went too far into the gas at lower rpms it would bog down and not go anywhere. i was just dealing with it, i put a brand new tune up (plugs, wires, cap, rotor) on it and it rans a little better for a day then went back to how it was. the other day it was raing pretty good and it started the entire bog down deal again, it actually did it to where i couldnt go anymore. the enigne runs perfectly fine without a load on it. i changed the MAF sensor' that wasnt it, i have great spark, i cannot find anything that would make my rig do this, no pulled wires, nothing unplugged, all vacuum lines are good. could anyone shed some light in this for me? the truck will actually start now, but it will stall out on me after about a minute. please help.

 

check timing, unplug throttle position sensor. if un-plugging the tps helps, and you care about the truck, try to adjust or just replace and adjust it

 

I am by no means an expert or mechanic or anything of the nature but I recently rebuilt the upper half of my motor and had a crazy issue. Worth looking into on yours. I got mine all together and it ran but not well. Let it set over night and it just turned over...no fire.

It was the battery connection. The connection was bad so it would not get power to the ECM correctly and was not telling the injectors to fire. Took the terminals all apart, cleaned the piss out of them and tightened them all up as best I could. One turn and it fired and ran great.

Maybe try that? Yours could be getting bad power to the ECM causing it to make things run bad. Again, just a thought..and free to look into.

 

I checked timing. Its all good, its newer everything on timing
I still need to get my hands on a fuel pressure tester to see if I can rule out a fuel delivery issue. I also need a feeler gauge so I can tighten my rockers too, I noticed they're a little loose

 

There is a ground wire on the back of the cylinder head, it might be broken. Clean all your electrical connections & grounds. Cleanliness is cheap & and its just good trouble shooting.

Loose rockers can wait till it runs again. Run the distributor test in the FSM to check coil resistance. Also test the coil the same way. Throwing parts at it only adds confusion. Check voltage when running, low voltage will not run the ECU correctly, should be 14.5VDC.

 

I second checking all your grounds. four main grounds and heres the guide.

https://www.yotatech.com/forums/f116...-guide-194413/

ur problem definitely sounds electrical

also might check resistance of the tps and air flow meter to see if they ohm within spec just as a diagnostic measure

 

Okay. Will be checking all of these on sunday.

 

Hi, I had a similar problem on my 1994 which had federal emissions. It only has one o2 sensor. When it would run like crap stall and bog I would inplug the o2 sensor and it would run great. I think I eventually replaced the sensor. I do remember putting dielectric grease in the connector for the o2 sensor. Disconnecting the sensor is easy. Try it.

 

I would agree with the grounding issue, Check all 4 ,and a new battery ground cable ,I have seen those look new and still be bad.

 

Well I unplugged my o2 sensor. Helped a ton. But while unplugged I can drive it again but it still has a little bit of a bog to it. But im think that's because its not plugged in. Right?

 

Hey 88runner330. My 95.5 with the 2.7l 4 cylinder is doing the samee thing. Let.me kno if u got any luck

 

checkd for breaks in the intake? if you dropped the trans and let the engine move much that could've broken the boots on the intake

 

Not necessarily. IOW's, by removing the O2 sensor, you've disabled the ECU's ability to correct any a/f ratio imbalance and, for a short time, that's seems to be working to your favor, but the bogging may not necessarily be because you've unplugged it. Without the O2, the ECU runs on it's basic, open loop fuel injection program and can work rather well without the aid of the closed loop/feedback system were there no real a/f problems to begin with. So, if you were running rather lean with the O2 connected, now you're constantly running richer...which, again, seems to be helping. Sorry.... I don't feel like going into more detail about the dynamics of all that right now, but I'd done the same thing a while back; disconnected the O2 to try and troubleshoot a problem on my V6. With the O2 disconnected, the vehicle initially ran much better. Eventually, though, it lost power, again, and started hesitating under load. Turns out the fuel pump was going south. Apparently, you're checking into that, though.

You could try installing a new O2 sensor as your old one may actually be sluggish to respond to a/f changes, but if you have an a/f problem outside the closed loop system, it will only help for a short time.

The other thing I'd be suspicious of is whether or not the person who installed the header had also installed an aftermarket cam. I mean, it's possible and something to check into since those can change the powerband and the type of exhaust can affect how that powerband works. I'm not an aftermarket cam guy, so someone else with more experience will have to help you with it should this be the case. Again, sorry.

So, if I were you, I'd first check into the fuel delivery possibility and a possible degraded O2 operation. That is, after you've followed everyone's grounding suggestions. That's never a bad idea. Then see if anything else needs looking into.

 

so you removed a header and installed a factory exhaust?
did the header have the PAIR ports? did the OEM?
How 'bout some pics?