nadrojcote

It could very well just be some residue built up on the cats too, I'm taking a 250km trip tomorrow night. I'll be watching for it to come back.

I'll update if it comes back.

Just a heads up to anyone going to do this after as many miles as I have on my truck (over 70,000km/45,000 miles). I was just doing some errands and I noticed my mileage decreasing big time, went from my average of around 20l/100km to almost 27l/100km and then I noticed my idle started to get pretty rough while in drive and stopped at a stop light. When I went to accelerate my check engine light came on. I used torque to find the code, having a feeling a head of time what it would be and I was right. P0420 catalyst bank below threshold. Now I am not 100% certain the seafoam caused it, but I don't think I'm being unreasonable by assuming the free'd up carbon is now stuck in my catalytic converters. I reset the check engine light and my mileage has dropped back down to 23l/100km just in the short trip home. I checked torque again when I got home and the truck hasn't finished runnning its test on that catalyst bank yet so I can't update on this. Luckily if it does come back it should be covered under warranty. The other possibility is that I have an exhaust leak, hopefully they do not give me any grief about my welded on muffler if I have to take it in for warranty.

I found it was taking for ever to spray it, I did about 45 sec - 1 min intervals and then I would check to see how much was left in the can.

ya their brake cleaner is awesome, I use it to clean everything on my truck that gets oily/greasy. Its readily available in Canada.

I have a feeling seafoam is stronger. Hence the 5 Min vs 1 Hr heatsoak time.

If you look back I showed how I did it with seafoam.

Ethanol burns cooler than gas, but your engine has to burn more e85 which makes it run hotter than burning gas.

Or buy a can of seafoam to get your hands on one of the little u shaped hose protectors.

All you would really need to do is drill a hole in the top of the air tube right before the throttle body and use a rubber grommet to seal it.

Yes you could use a nos setup into your pcv hose that you hook a catch can up to with seafoam or CRC. Give it a little shot every now and then. The only way to prevent this build up is to use products like CRC every 10,000 miles or even every oil change in conjunction with a catch can. They also say for people that perform short trips all the time it will build up worse. There are some good services for cleaning the valves which will become more common at your local repair shop as time goes on and all vehicles become GDI.

But not all of it.

Spray for 30 seconds and then wait for idle to go back down to normal. Repeat. I too was waiting for an oil catch can before doing it, but decided why wait? I can always do it again when I get one.

what is e85 equivalent to octane wise?

Pretty sure you will not see any mpg increase using higher octane, but the engine is most likely rated for high HP with 91. EDIT - This guy had good results with 93 http://www.gm-trucks.com/forums/topic/156449-christmas-road-trip-results-87-octane-vs-93/

I also have an aftermarket muffler and the resonator removed, I wonder if that has anything to do with it.

That's very odd, maybe that wasn't a good place to suck it in? could have pooled up in the air intake. Either that or after an hour it evaporates. Edit - Reading other forums and people say it should blow out smoke after sitting for an hour. I would maybe try again going right into the throttle body if there is no smoke.

You shouldnt get any smoke until you start it up after heat soaking.

I wonder what the chemical difference between seafoam and crc is because seafoam says on the can to let it heat soak for only 5 minutes. Thats what I did and when I started it up it puffed out some black smoked. I took it for a drive and when I stepped on the gas it bogged down and blew out a big cloud of smoke.

Im sure it wouldn't be hard to make some sort of piece like the one that came with the seafoam. You could really use anything to jam between the boot and the TB.

I used the j shaped hose that came with my seafoam, OP used CRC that does not come with that hose., I would assume he went in where the air box connects.another option is to take the hose off the TB and spray directly into it while keeping the RPM up. As long as you keep the rpm up around 2000 it wont matter where you spray it because there should be enough air suction to get it in the intake manifold.

Seafoam comes with the hose like that for putting in the air boot. For CRC just disconnect your air box and put the hose in the air tube, make sure you put it in far enough so that the hose is passed the MAF sensor.

You could probably just use a little of the CRC to clean it.

Wind kills these trucks, a soft tonneau helped a fair bit for me.

you should definitely change your filter. Might as well get a better drop in like a k&n, clean your throttle body with carb cleaner and put a can of CRC or seafoam through it.