losing performance slowly

[Antpwr]

ok so after changing out my TPS, i have noticed that the 4runner is starting to slowly loose performance, its more of a longer time between shifts, takes longer to get there, you can feel it and hear it too, its not a s quick as it was a week ago, no check engine lights, plugs wires pcv tranny filter, engine oil, tps, cleaned out throttle body, and maf, all a couple of months ago. Was running awesome, quick as it can be alot of pickup, but now not so much, any ideas would be great, thanks

 

[theizzardking]

tighten the throttle cable? it tends to stretch and could be a bit loose after the work was done or came loose since?

just throwing that out there as it's easy and wont take more then a few seconds to check, i can't think of anything else that's not related to the induction system really.

maybe check your trans fluid as well and see how that's doing.......

i dont know about our runner's but on my old jeep you could just pull the battery and let it sit for a minute then fire it up and let the computer re-learn and it would sort issues like these out from time to time. maybe see if thats an option to us.

i don't really know how to help so i thought i would throw some ideas out there and see what you thought.

 

[Antpwr]

thanks for the idea, but i already adjusted the cable a while ago, still tight, have reset the computer a few times now, and here is the kicker, this morning, ran great, then later on it didnt, i have no idea, never ever ran into this problem, especially on an obd2 vehicle, but thanks for the ideas, well thought of.

 

[TFJ-4runner]

Try and put some seafoam through it and see if it improves.

 

[FdcCal]

No real objective measure here.. Has the gas mileage changed? If it has, then something may indeed be wrong. Why was the TPS replaced? It is also possible that your fuel has changed to a "winter" blend, perhaps that has something to do with it. Did you install OEM type double electrode plugs? If not, I would immediately suspect that, as these engines do not respond well to any other plug. I understand "seat of the pants" impressions of performance, but we really need something more concrete.

 

[theizzardking]

No real objective measure here.. Has the gas mileage changed? If it has, then something may indeed be wrong. Why was the TPS replaced? It is also possible that your fuel has changed to a "winter" blend, perhaps that has something to do with it. Did you install OEM type double electrode plugs? If not, I would immediately suspect that, as these engines do not respond well to any other plug. I understand "seat of the pants" impressions of performance, but we really need something more concrete.

yeah i'm thinking with you now, it's not going to be a fuel issue meaning the injectors are most likely firing correctly, so that leaves spark and air, maybe the wrong plugs or a failing 02 sensor that hasn't crapped out quite yet?

you need 3 things for your engine to run and run well, 1.air 2.spark and 3.fuel
so within one of those 3 lies your problem, i know that's not much help but it does help me think about the problem and where it might be coming from, maybe tinker around with each and see where your getting your problem from, it sure would be nice if it was throwing a code at you right now so you can narrow it down a bit.

maybe chuck some octane booster in the tank and see if it has anything to do with winter blend, though i don't think it should be all that noticeable.

again, just trying to get your mind turning and chuck some ideas out there.

 

[Antpwr]

nope oe plugs and wires, some dumb $$$ had freakin bosch +4 in there, moron, so swapped in new ngk's, and denso wires. lets say that when it happens, it is at 70% of its power potential, and the tps was replaced because it was bad, ohm'd it on and off 4runner, bad. gas mileage never really changed, and like i said, it is not a constant problem, runs great then it doesnt, nothing different in driving ranges, home, work, home. Temp has dropped a little bit but at a steady rate, and usually it runs better as opposed to the hotter weather. Like i said i have really never ran into this problem, even after 18 years of doing this, its either worked or not and there was a reason for not. gonna get some seafoam from work and throw it in see what happens, keep you posted, thanks by the way for the ideas, gets me thinking

 

[Pikeman]

I would check the O2 sensor as slowly going bad but not bad enough to throw a code. Another option is the catalytic converter is clogged. I have been dropping a little performance and mpg's the last few months myself. I am planning on O2 replacement first, then Cat(Walker Dynomax) and see how it goes.

 

[FdcCal]

I agree with the O2 sensor replacement, mine died at about 100k. I prefer to replace both.

 

[Antpwr]

thats what i was leaning towards, its 140k and i can tell its all still oe, so i think i will be investing in cat and o2's, thanks again guys

 

[FdcCal]

For the sensor replacements, get the Denso parts from Sparkplugs.com. Exactly the same as OE Toyota for a better price. It seems that the aftermarket Bosch, etc don't seem to to work too well for many. You can buy a tool from Harbor Freight cheap, and it works fine. The exhaust needs to be cold. You will need to spray with PB Blaster a few times to loosen up the rust. I had to heat the pre-cat sensor and fitting with torch after the PB Blaster treatment pretty hot to free it.

 

[Antpwr]

yeah they never seem to just come out, at least the 2 dozen or so ive had to change were that way, lol, but seriously thanks for the web site, will look into it, cause they are not cheap at all to replace and im not about to go and get universal replacements and start chopping wires, not that i dont have a problem doing it, just rather be able to plug and unplug if need be, thanks again.