5,500 miles and now a clogged cat?

[SliderNH]

Drove from TX to NH and back. Heres What I have 2000 v6 auto 4x4 and TRD sc. Pre trip: 112XXX mi. Post trip 118XXX mi. Before the trip I had done the 2nd gen supercharger with the trans and fuel upgrades to make sure I was good to go. The trip up to NH went fine. Towing 1200lbs and having another 600lbs of cargo here's the numbers. (same amount of weight both directions) I used 10w-30 on the way north, and 5w-30 on the way south. I had a friend help me drive north (he is a lead foot). Drove south by myself. I know it doesn't seem that bad. 1.1 MPG difference I know isn't much but it does not feel right. On the way north I drove pretty hard. often pushing 80mph. But the boost was staying at -8(vac) to 2 PSI. On the way south I drove like a grandma, seldom going above 70mph. I tried 80 mph a couple times but it didn't feel right. I was at 2 to 7 PSI of boost just to maintain speed.

MPG going North: 16.9, 17.7, 15.6,14.2, 14.9,16.9, 14.5, 14.2, 16.2, 17.1, 17.3
North AVG: 15.9
MPG going south: 14.1, 16.7, 14, 16.3, 16.1, 15.8, 15, 14.5, 14, 15.5, 12.7, 14, 14.5.
South AVG: 14.8

I inspected the truck when I got back to texas. The only thing I found was a frozen piston in the front caliper. ONE piston in ONE caliper. (sh!tty advance auto tundra brake upgrade). But not bad for 5,500miles. It was dragging a little but not enough to make a huge difference. It rolls and coasts downhill just fine. I have complete faith in my truck. It runs like a champ, but I know something is not right. She's struggling more than she used to. Boost is frequent. And sometimes at highway speeds, boost will happen, and is unavoidable. It shouldn't be that way. It wasn't on the first half of the trip.

Other info: other stuff that is new on the truck: plugs/wires, timing belt, timing belt tensioner, water pump, thermostat, coolant, oil, trans fluid, front/rear diff + Transfercase fluid, air filter, clean MAF and Throttle body.

I'm beginning to think I have to replace the cats - I believe they are Original to the truck. This would suck big time. about $2K to replace both cats with toyota OEM. Please help!

 

[Stick Figure]

I feel your pain on the cats (if that is your issue) my truck most likely will need a new pair if i want to pass CA emissions this year.

As for the performance issue. You went superchargerd, did you do any other fuel upgrades at the same time? If you reset the ecu (battery disconnect) and drive it how does it feel? have you pulled the plugs to inspect them, or checked fuel trims to see if anything seems out of whack on the fuel side? Final suggestion is check the trans fluid, you didn't have a heavy load, but fluid could be a little burnt if you don't have enough cooling capacity.

 

[pcleary1210]

Find an air/fuel ratio guage and see what's going on. Not sure if your 4runner comes with a wide-band 02 sensor or not, but I'd look into one if it doesn't.

Also -8psi on a supercharger? Am I missing something? I'm not exactly a forced induction Guru but I'm fairly certain you shouldn't have an 8psi vacuum, with a peak at 2psi if you're pushing your truck.

My only other thought here is that gas quality from state to state is huge. A friend commutes from Reno to Sacramento area on a routine basis and tracks his mileage, he found a 2mpg difference based on what state he fills up in. Anything big enough to manifest 2mpg in change will certainly effect the engine of a freshly supercharged vehicle.

-PC

 

[SliderNH]

Thanks for your suggestions StickFigure,

You went superchargerd, did you do any other fuel upgrades at the same time?

Yes, I did the URD 7th injector, has some trouble in the beginning and now it is set-up well.

you reset the ecu (battery disconnect) and drive it how does it feel?

Nothing changes.

you pulled the plugs to inspect them, or checked fuel trims to see if anything seems out of whack on the fuel side?

Haven't pulled the plugs. They have maybe 7K mi on them... Fuel trim is good, and consistent. I have the innovative AFR gauge, so I was able to monitor it the whole time.

suggestion is check the trans fluid, you didn't have a heavy load, but fluid could be a little burnt if you don't have enough cooling capacity.

Checked the trans fluid. It was brand new before the trip, and after the trip it still looks good. for additional cooling I have the B&M trans cooler. Thanks for the reply.

 

[SliderNH]

8psi on a supercharger? Am I missing something? I'm not exactly a forced induction Guru but I'm fairly certain you shouldn't have an 8psi vacuum, with a peak at 2psi if you're pushing your truck.

Maybe I wasn't clear, sorry. Under normal driving conditions driving like grandma, It is (was) easy to stay in the vacuum which is goes from -23 to 0 Hg. Driving a little more aggressively gets you into the boost, which goes from 0 to 8PSI. The issue I'm having now: even though I drive like grandma - I am pushing boost anywhere from 2 PSI to 6 PSI, compared pre-trip I would see readings -4Hg to 0 PSI.

only other thought here is that gas quality from state to state is huge. A friend commutes from Reno to Sacramento area on a routine basis and tracks his mileage, he found a 2mpg difference based on what state he fills up in. Anything big enough to manifest 2mpg in change will certainly effect the engine of a freshly supercharged vehicle.

I fully agree. When I was on the trip I only filled up at shell stations. I know that from state to state, Shell might have different quality gas but for the most part they are consistent in their quality across state lines. Filling up with the same brand is the only control I have over consistent quality. (Note) Since I have been back in Texas I have filled up at my normal gas station and I am seeing the same reduced mileage. Thanks for the ideas pcleary.

 

[SliderNH]

I forgot to mention in my OP that there is no CEL, and the fuel filter has also been replaced. Thanks for the replies so far. I'd like more ideas if anyone has anything. Is there anyone who has attempted to clean the cats or has hollowed out the innards and used the URD 2nd O2 sensor signal simulator?

 

[SliderNH]

well its not the cat

I spoke with Gadget from URD to see if he had any ideas. He said I can check the functionality of the cats just by reading the boost gauge. 1. Make sure the car is warmed up. 2. Read manifold pressure at idle. 3. Increase to 4,000 RPM and hold it there. Read the manifold pressure. 4. Decrease RPM back to idle. With fully functioning cats you should see that the manifold pressure at idle and at 4,000 RPM is the same. If the cats are bad you will see increased manifold pressure when holding the RPM stable at 4,000RPM when compared to idle.

So I tried it. and there was no difference at all between Idle and a stabilized 4,000RPM. My cats are good. I'm glad I eliminated that as a possibility but if it isn't the cats is it the o2 sensors? Ideas anyone?

 

[fish0281]

Have you checked the obvious, like make sure nothing wiggled loose or somehow broke (vacuum lines, spark plug wires, spark plugs, wheel bearings, tires, etc...)?
Also, try engaging/disengaging your 4wd; I think Pitbullrescuer fixed his mileage problems cause his truck was unknowingly engaged in 4wd.

 

[SliderNH]

Have you checked the obvious, like make sure nothing wiggled loose or somehow broke (vacuum lines, spark plug wires, spark plugs, wheel bearings, tires, etc...)?

I have to an extent....I have been able to eliminate rolling resistance as a factor. Wheel bearings, tires, rotors/pads/calipers, differentials/CV's are all smooth and good to go. Wires were replaced 10k mi ago. Plugs were replaced no more than 7K ago with the SC install. Other obvious stuff like filters, fluids, TB, MAF etc were previously mentioned.

, try engaging/disengaging your 4wd; I think Pitbullrescuer fixed his mileage problems cause his truck was unknowingly engaged in 4wd.

Yeah...I read that thread... mine isn't in 4wd.

Additionally, all parts on the truck non-performance related are OEM Toyota. The only stuff that is not: SC pulleys(URD) fuel control unit/7th injector (URD), front tundra calipers (advance auto)..I think thats it. The other threads about gas mileage I've read include replacing o2 senors, and resetting the EFI relay. I already reset the EFI. I think o2 sensors are next, expensive but maybe thats the cause.

 

[20034RunnerV84x2]

If you want to try to clean the cats remove then and drop them in a bucket of water with laundry detergent in them, or if you want to leave them on the truck get a gallon of lawyer thinner and pour it into the tank with 1/2 a tank of gas. Burns pure and will often burn the impurities out of the cat, since it Burns so pure.

 

[SliderNH]

keeping the thread updated. Changed the rear diff fluid again just to check it. real clean still after about 12K. Today I bought new O2 sensors from toyotapartsales.com Ill let you know what happens when I get them and drive them for a few hundred miles...as for now I'm still at 14/15 mpg.

 

[20034RunnerV84x2]

My computer says I'm avg. 10. I have a 03 V8 tho...I tjinknits my. O2 sensors.

 

[BootyFister]

I feel your pain on the cats (if that is your issue) my truck most likely will need a new pair if i want to pass CA emissions this year.

As for the performance issue. You went superchargerd, did you do any other fuel upgrades at the same time? If you reset the ecu (battery disconnect) and drive it how does it feel? have you pulled the plugs to inspect them, or checked fuel trims to see if anything seems out of whack on the fuel side? Final suggestion is check the trans fluid, you didn't have a heavy load, but fluid could be a little burnt if you don't have enough cooling capacity.

Do they hook a pipe up to your exhaust? or do they just plug into the obd2?
Here in Ohio they only do the obd2, which means you can buy the 02 sensor emulator and pass no problem, even with gasoline spewing out the tailpipe. Haha

 

[BootyFister]

keeping the thread updated. Changed the rear diff fluid again just to check it. real clean still after about 12K. Today I bought new O2 sensors from toyotapartsales.com Ill let you know what happens when I get them and drive them for a few hundred miles...as for now I'm still at 14/15 mpg.

Do you have any warning lights on in the truck, check engine? vss? or is it just bad mileage.