Please help-02 3.4l horrible mpg/ power loss no cel

I have a 02 Tacoma double cab on 35" tires. I was averaging 200 miles per tank before this issued developed. It continues to worsen.

Symptoms-
Rpm bounces when around 2100-2500 and has a 300 rpm bounce
Horrible fuel mileage- went 100 miles on full tank.
Intake seems extremely loud.
Loss of power

I cleaned maf
Replaced plugs and wires
Replaced IAC
Replaced tps

Problem still is here

Could it be my cataylic converter?

 

If more than 100k I'd replace the 02 sensor. With the engine idling tap the MAF sensor lightly with the handle of a screwdriver. If the idle fluctuates the sensor is bad.

 

Yeah I have 112k

 

I had something similar but a little different. I just had crappy fuel milage and no power. My air fuel sensor was going bad. It never threw a code or anything. That sensor is right before the cats on a 2004. But for you I would replace the maf sensor and if that's not it start checking your 02 sensors. Hey any chance you have a sooty exhaust? That will tell u a lot

 

maf and o2 sensors are all big time money ($80+ a piece) id test them with a multimeter before i threw down that kind of cash w/out any cel codes to confirm it

 

LOL That's big money?! Id drop that to see if it was the problem..

OP I was having this issue too I just cleaned my MAF and it worked for me. I was getting a CEL though.

 

Ya 80 bucks on nothing lol u can burn that in fuel with that crappy
Of fuel milage. Worse come to worse take it to the stealership. Ya I know it's $$ but they fixed my problem with out me trying 10 different things before it got
Fixed

 

maybe try some seafoam? i hear good things about it.

guy at work had the same prob after filling up with bad gas just the other day. It fouled his plugs

 

well my estimates were a bit low. the maf is $182 msrp or $131 from camelback toyota dealer. the rear o2 is $152 or $110 from camelback and the front is $235 or $169 from camelback.

but if that is change to you go ahead, certainly isn't to me

with gas prices about $3.5 your spending about $60 twice as often for 18 gal tank. with the prices from a normal dealer (182+235, since front o2 is what the ecu uses for fuel) it adds up to $417. assuming you fill up once a week now you'll be spending nearly 7 weeks worth of extra gas money in those parts. seems worth it to test parts before you throw away 7 weeks worth of gas

but what do i know

 

Still not that bad of a price if it fixes it. I spend more than that on a bar tab that I don't need. So if it would get my truck running right I would be ok spending that.

 

Good point. Ya it's best to try testing stuff first but I don't have the skills to test all that electronic stuff

 

yikes! i hope that much money on a bar tab covers a month. i bring a 20 dollar bill and when im out im out. you can get 2-3 beer or liquor pitchers with that where i come from. with a few buddies you i got all the alcohol i need for a night.

you must be a popular guy with that kind of money to spend on drinks though, you should visit me sometime.

 

I've been getting shit mileage lately as well. And it does not feel as powerful as when I bought it. I've cleaned my MAF and that hasn't done anything. Was not dirty at all.

 

Ill try cleaning the maf again today. And I'll pull my o2 sensors and check those out as well. I'd love to take to a dealer or mechanic but I'm in North Dakota and the oil boom has pushed the mechanics to a 3 month wait to get a vehicle in.... Not happy. Ill drop the money because I want my truck back on the road

 

Just a thought, the RPM changing and the change in intake note could be a timing belt that has skipped a tooth This "could" change the intake sound, kill power and let the crank and cam position sensors "fight" each other causing the mid range rpm fluctuation.
A quick check of timing marks, 2 cams and the crank would remove this from the list of possibles. Outside of your labor it is also free.

 

Well hell, I wish my shop had a 3 month backlog. I am only at about a week and a half backlog right now. Enough to keep me busy on a regular basis.

I have seen a lot of good suggestions and I have an idea, if you care to check it. Go to your tailpipe and see how much pressure you have blowing out at idle, and at 2000-2500 RPM. Your description is almost identical to two other members here who ended up with a clogged catalytic converter. It changes the intake sound because it can't pull in the amount of air it needs, because it can't blow out the exhaust. The sound is similar to a low tone "wwwwoooooooo" noise.

 

x2 I spent about $60 out and about on friday night ... damn you downtown denver .... then again the cougar was worth it

 

I bought some seafoam. What is the best vacuum line to use??

 

I also pulled my o2 sensors out to see if my cataylic converter is clogged

 

Cougar... Ahh you dog! I'm jealous.