Tacoma Grinding, No Power, Horrible MPG, Help!

[RememberTheFallen]

I had a bunch of great replies and help when I couldn't figure out what to do with my sliders so I figured I would see what you all thought about this problem.

Something "happened" to my truck last fall and it has been driving me nuts ever since.

Coming back from Overland Expo my truck just kinda fell flat and felt like I was towing a boat. Thought the supercharger that I had just put on was wearing out so I took it off without change. I was pulling 6-7lbs of boost just to pull hills on the freeway in Georgia. (Read:small!)

The issue persisted thru a 7000 mile road trip and alluded any and all attempts to fix it.

It basically feels like I am towing a boat anchor. Truck is loud and doesn't wanna pull. At highway speed on the interstate it will down shift twice before it will pull. Even on flat ground it will not pull until it down shifts and then it is anemic. It is getting about 11-12 mpg. The issue is not constant. It has gone away for short periods of time but always comes back. There is also a rotational roaring sound that is a slower whump whump whump is is noticeable when the truck is running poorly.

I added a supercharger, tundra brakes, and a transmission flush shortly before the issue start. SC has been removed, brake are not rubbing, and Trans coolant is appropriate level and color.

It is a lower mile 2003 3.4l Tacoma w/ auto transmission. 255/85 tires and a good bit of weight. Truck ran "fine" after the tires and added weight so it is not a gearing issue or truck struggling with a ton of armor and camping gear.

No check engine lights. I have reset the ECU several times without change. checked for vacuum leaks, cleaned TB and MAF, changed fuel pump. Shop in the middle of no where during the road tripped pulled the CATs and drove it without change. They also changed fuel filter with no change.

I am leaning towards some sort of bearing failure or diff going bad. Wheel bearings seem fine. Front wheels are somewhat hard to spin when truck is off the ground. Removed rotors and still hard to spin.

So looking for ideas on what the hell it could be! Any help would be greatly appreciated!



Joe

 

[RememberTheFallen]

Edited-

 

[SLC97SR5]

Spark plugs, wire and igniter (coil over plug) condition?

Is the cooling fan clutch stuck engaged?

Fuel pressure regulator? Correct fuel psi?

Is the air intake hose collapsing or getting pinched?

Recent timing belt change? I'm kind of leaning towards a skipped tooth on the belt.

 

[RememberTheFallen]

Wires, plugs, and boots all seem to be good.

Haven't looked at the fan. Will have to check that.

Also don't know about the pressure regulator. It has had issues through two separate pumps now.

Intake is intact. When it first started I thought it was a clogged exhaust or something in the intake.

Truck only has 76k miles. Timing belt is still original.

Thanks for the ideas! I will check that stuff tomorrow.

 

[toyotech]

Sounds like timing belt jumped. Your well over due for a t belt change. It's due every 7 years/90k


Sent from my iPad using Tapatalk

 

[brianjwilson]

Regular maintenance really should have been a priority over a supercharger. I would suspect timing belt too. Regardless it is time to replace it if it's going on 12 years.

 

[RememberTheFallen]

Regular maintenance really should have been a priority over a supercharger. I would suspect timing belt too. Regardless it is time to replace it if it's going on 12 years.

Well the supercharger was sitting on a shelf from another truck. It has been regularly maintained other than the fact I did not know there was a time span on the timing belt. Thought it was just mileage.

 

[bkg]

If it not consistent, not sure how it could be a timing belt, but still worth checking. As for changing... Are some of y'all saying that my 40,500 mile 04 is overdue for a timing belt? Lol

 

[toyotech]

If it not consistent, not sure how it could be a timing belt, but still worth checking. As for changing... Are some of y'all saying that my 40,500 mile 04 is overdue for a timing belt? Lol

Rubber ages. Just like tires. Would your run a brand new set of 10 year old tire on the shelf.

Diy t belt cost you what? $200 vs an engine. It's cheap insurance imo.
Just like guys going cheap on oil changes on their 30k truck. Doesn't make sense but maybe that's just me


Sent from my iPad using Tapatalk

 

[toyotech]

I think plugs on the 3.4 is every 30k


Sent from my iPad using Tapatalk

 

[ca18_sean]

Rubber ages. Just like tires. Would your run a brand new set of 10 year old tire on the shelf.

I agree to an extent... but rubber breaks down much quicker when left outside (used tires) than when in an engine bay under a timing belt cover. I've pulled very old timing belts off that still look relatively new. I don't know that I'd have any issue running 10 year old tires that had been in a climate controlled storage kind of warehouse. What's to say the "new" timing belt you're installing hasn't been sitting on Toyota's shelf for 10 years?

 

[4x4x4doors]

Shot in the dark from a non-Toyota guy.
Is this 4x4? If so, I'd take a look at the engagement of the front axle. You've mentioned difficult to rotate fronts.

You mentioned sounds (whumpwhump). Do they continue when vehicle not moving but engine running?

You ought to be able to narrow it down to engine (running) vs driveline (moving) just through some observations.

 

[Watt maker]

I'm going to guess you have a bad wheel and/or diff bearing. Could also be the front diff is not disengaging when it should. Some other possibilities are, brake caliper sticking, parking brake sticking, bad u-joints.

 

[1MK]

Definitely check timing belt. Had a similar case here at my shop (I manage a Toyota specialty shop) where the vehicle had a lack of power with no check engine light. When hooked up to our scan tool, we could see the ECU was throwing timing all over the place to try and get it to run correct, therefore the power would come and go.

Belt jumped one tooth. 2004 Tacoma with 75,000 miles.

I've seen countless timing belts that the rubber still looks great, but has snapped. More commonly, they stretch further then the tensioner can account for and jump position.

The 5VZ 3.4L is not a interference engine, so even if the belt lets go, it won't cause internal damage.

------------------------

Front wheels will always be hard to turn since it's always spinning the front drive axles. A bearing that has that much resistance that's it causing a massive lack of power would most likely be associated with excessive noise and/or bad driving characteristics.

 

[RememberTheFallen]

Shot in the dark from a non-Toyota guy.
Is this 4x4? If so, I'd take a look at the engagement of the front axle. You've mentioned difficult to rotate fronts.

You mentioned sounds (whumpwhump). Do they continue when vehicle not moving but engine running?

You ought to be able to narrow it down to engine (running) vs driveline (moving) just through some observations.

That's why I was leaning towards a driveline issue. The engine runs and idles fine in park. It only acts up when going down the road. I have checked the front end several times. Haven't pulled anything large apart yet.