1997 4runner 3.4l lacking power

[zerocirca]

So i have a 1997 4runner 3.4l thats lacking power. it starts right up and idles perfectly. when i go to drive it its really slow and lacks power. when i hit it WOT the rpms go up but it does not have nearly enough power as it should. at about 3200 rpms it almost has no power and then gains some power at about 4300 rpms. Initial codes were 02 sensor and coolant temp sensor. i replaced those and the codes went away but it still didnt fix the power issue. It has a real hard time getting up hills and i can only go about 45 mph up hills.

What I have tired:
-Replaced o2 sensor
-replaced coolant temp sensor
-replaced MAF sensor
-cleaned TB and PVC
-replaced plugs, wires and fuel filter

Any Ideas or people with similar problems?
I just dont understand becuase it starts and runs perfectly at idle but when under load its really slow.

Thanks

 

[snivilous]

Hows your tranny fluid look and smell?

inb4 people say it's supposed to be that way...

 

[zerocirca]

It is clean i just changed the fluid. its shifts smoothly.
could it be the trans even if it shifts good? could the filter be clogged causing this issue?

 

[snivilous]

I don't know a whole lot about the driveline, but from the sounds of it if the engine is running smoothly then the power isn't getting transferred to the axles at some point which I would assume would be an issue with the tranny or torque converter or transfer case. Maybe your torque converter is having issues and just slipping a lot so you're losing power? Though that's just a guess and I don't know how you'd diagnose if that was the problem...

 

[Runner4liife]

Yeah I've got sorta the same problem, 97 3.4L ive done plugs/wire, fuel filter, TB, MAF, air filter. My acceleration from 20-50mph is offly slow. I'm still tryin to figure it out too.

But have you checked your MPG lately? Any gas mileage affects?
I'd recommend a Motorvac treatment, or seafoaming it. That's my plan next

 

[zerocirca]

[MENTION=57929]4RUNNER4[/MENTION]liife -Ya my gas millage is shitty cause i drive back and forth to the mountains and it can barely stay up around 45-50 mph on the hills at like 3500+rpm. its starting to piss me off haha I can get up to speed on flat ground but its still way slower than it should be. I Just sea foamed and gas treated it and its still the same. I might be thinking its the cat. Its been a progressive thing and now its almost unbearable.

Its frustrating and there is no check engine light!ahhhh

 

[montana_jeepn]

I just dumped in an entire can of SeaFoam into a 3/4 full tank yesterday and the results were amazing. After about 10 miles, it had more power, felt smoother, and was more responsive. I was getting 13-14 mpg in town, so I will have to get back to you in that department after I run a few tanks through her. I am going to do this to my 2008 Honda Odyssey that only gets 12 mpg in town as well after I do a little research on that forum (the one where all the cool cats hang out).

 

[BrianSD_42]

You could do a DYNO on it and check the printout against stock expected HP. DYNO is not that expensive.

 

[KSWAY]

So i have a 1997 4runner 3.4l thats lacking power. it starts right up and idles perfectly. when i go to drive it its really slow and lacks power. when i hit it WOT the rpms go up but it does not have nearly enough power as it should. at about 3200 rpms it almost has no power and then gains some power at about 4300 rpms. Initial codes were 02 sensor and coolant temp sensor. i replaced those and the codes went away but it still didnt fix the power issue. It has a real hard time getting up hills and i can only go about 45 mph up hills.

What I have tired:
-Replaced o2 sensor
-replaced coolant temp sensor
-replaced MAF sensor
-cleaned TB and PVC
-replaced plugs, wires and fuel filter

Any Ideas or people with similar problems?
I just dont understand becuase it starts and runs perfectly at idle but when under load its really slow.

Thanks

Have you tried resetting the ECU after replacing all those parts?

 

[fun_runner]

A partially plugged catalytic converter will cause those symptoms. How many miles are on it? Has the timing belt been done? Maybe the old belt jumped a tooth and is throwing the timing way out of whack?

If the belt is good, the exhaust isnt plugged and you've done all the maintenance stuff then the only way out now is the S/C. :cheers:

 

[541joseph]

If your getting rpms then its probably not the engine. What happens if you put it in park an stab the throttle? Do the rpms jump or is it sluggish? But my guess is something in the trani

 

[JBurt]

You could also do a compression or leak down test. Engine health contributes a lot. Here's some good ideas:

Seafoam, Marvel Mystery oil, Methanol injection, they really work! - YotaTech Forums

 

[amalik]

Stupid question here but, are you sure you aren't driving with overdrive off?

 

[Polar_Bear_3rd_Gen]

Throttle Body Positioning Sensor

Have you replaced or cleaned the throttle body positioning sensor?

So i have a 1997 4runner 3.4l thats lacking power. it starts right up and idles perfectly. when i go to drive it its really slow and lacks power. when i hit it WOT the rpms go up but it does not have nearly enough power as it should. at about 3200 rpms it almost has no power and then gains some power at about 4300 rpms. Initial codes were 02 sensor and coolant temp sensor. i replaced those and the codes went away but it still didnt fix the power issue. It has a real hard time getting up hills and i can only go about 45 mph up hills.

What I have tired:
-Replaced o2 sensor
-replaced coolant temp sensor
-replaced MAF sensor
-cleaned TB and PVC
-replaced plugs, wires and fuel filter

Any Ideas or people with similar problems?
I just dont understand becuase it starts and runs perfectly at idle but when under load its really slow.

Thanks

 

[zerocirca]

Its now starting to Have hard starts every once in a while. When its in park it revs up but I'm not sure if its as responsive as it should be. I probably should do a compression check. Do you think this could be the tranny? It shifts fine.
Oh ya and when its cold it is extremely slow, slower than it is when it's warm

 

[bpowa]

You could also do a compression or leak down test. Engine health contributes a lot. Here's some good ideas:

Seafoam, Marvel Mystery oil, Methanol injection, they really work! - YotaTech Forums

I just read the link.. I really like how one guy tried it and locked his motor. :/

i have been been using a half can of seafoam 300-500 miles before oil changes from time to time. When drain the oil it is very dark.

Im not sure if it helps compression. I never checked.

 

[REDSANDFORME]

Pcv

I had some of these same problems and changing the PCV valve helped on these uphill situations. Mine was plugged up and it wouldn't rattle anymore and once replaced the power returned. I also replaced the hose and the grommet as they were worn out.

 

[Canuckrz]

A partially plugged catalytic converter will cause those symptoms. How many miles are on it? Has the timing belt been done? Maybe the old belt jumped a tooth and is throwing the timing way out of whack?

If the belt is good, the exhaust isnt plugged and you've done all the maintenance stuff then the only way out now is the S/C. :cheers:

I have to second the partially plugged cat. If your exhaust bolts/flanges arent totally shot try unbolting the cat and taking it for a quick drive and see what it does.

 

[fun_runner]

I have to second the partially plugged cat. If your exhaust bolts/flanges arent totally shot try unbolting the cat and taking it for a quick drive and see what it does.

Or, alot of times its easier to remove the oxygen sensor in front of the cat.

 

[zerocirca]

The bolts aren't being cooperative so I might just cut it out and see how it drives. Would a clogged cat be worse when it's cold?