I am getting to know this new (to me) 99 Tacoma 3.4L automatic trans with 137k miles. I recently bought cheap and had a few things going on that I wanted to post on here. After reading a lot of threads I've found some answers but am starting to have doubts.

Purchased the truck with a check engine light that read 0330 knock sensor and seems to have a misfire most pronounced just when the truck is coming out of idle and also had a O2 code that I didnt write down at the time but I believe read bank 1 starved. I realized quickly that the MAF was broken off at the air box and have not seen that error again since making the fix but also replaced the O2 sensors incase that they were causing the whole thing go down because one was out (plus I purchased them before realizing the air box was broken).

When I drive the truck it will start to try and gain power with no increase in RPM or speed at around 1800 or 2000 RPM and then eventually when I push it through that to a higher RPM catch up through over accelerating. It seemed to be having that issue consistently until after a few resets the truck had similar issues at much higher RPMs then drove fine at lower. And would, on occasion drive fine across the board especially after sitting for a few days. Or a computer reset. I read on here about the knock sensor being bad and it causing these power issues to protect the truck and thought I had an answer. Im about to pull off the manifold and clean everything up, replace the knock sensor and maybe do the head gaskets while Im in there.

BUT this week after not driving my truck for about a month out of town, I got home and finally put a full can of seafoam at the bottom of the tank (the two ounce to 1 gal ratio) and the truck drove great. The misfire was still there and check engine light still on but there were no power issues until I got to the very bottom of the tank going up a steep bridge on the interstate at high speeds. Then I put regular gas in the tank (only a few gallons) and saw the problems return, though not as pronounced as before. I want to drive through another tank, see what happens, then try another seafoam tank to test and see if this was just a fluke.

This has led me to believe that the power issues are not a response to a sensor being bad but that these are separate issues.

Any input would be really helpful.

 

Anybody have any input here? It seems like the truck is having trouble making it through the gears at high speeds and stumbles similarly. But the problems seems to do better with the seafoam treatment. Then on regular fuel it feels fine around town until I get back up to high speeds.

 

I'd still get a look at the knock sensor and see if maybe it's lose or dirty/damaged. May be just that if no other pending DTCs.

Vibration can do unspeakable things sometimes. Check before replacing.