2007-2008 Acural TL Type S

What: Throttle Body Bypass and Crankcase Filter
How long: 1 hour
Why: To prevent horsepower losses

I've seen several older write-ups on this and wanted to update with some pictures. If you're like me, you don't want unnecessary oil or warm air entering your intake. This mod will stop both of them.

Normally, at idle, the crankcase ventilation hose is sucking air from the intake into the crankcase. That is a good thing, since it provides fresh air to your crankcase. Unfortunately, under N/A applications and during WOT, the system actually reverses and can throw oil vapors back into the intake. The result with this small filter will continually ventilate the crankcase, only not under a vacuum anymore. If you are weary of this, I just change my oil more often. No worries here. Just be sure to cap off the port in the actual intake. Here's the solution:

Picture 1:


The throttle body bypass achieves the same result, and it prevents the intake air from seeing the +200F coolant. It cost $0 to just reuse the existing hose. Just reconnect the IN to to the OUT of the coolant system. It does a sort of loop-d-loop.

Picture 2


Finally, you can plug the 2 ports that went to the throttle body. I don't know if air will leak from the system if left uncapped, but I wanted to be sure. Watch out for draining fluid, as a shop rag will be handy when disconnecting the hoses. I'd say about 2-3 oz spilled out. Also, be careful not to drop any plugs during this step because it sucks to fish them out in this tight engine bay!

Picture 3


Finally, make sure everything's plugged back in before reconnecting the battery. You don't want any unnecessary error codes. Mines been running great so far after these 2 mods. Enjoy.

 

The coolant block is a good free mod.

The crankcase vent isn't going to do much on a healthy engine. Maybe when it has 400,000 miles on it and tons of blowby. The PCV is where the vapors actually exit the engine. That area on the inlet tube is not under vacuum.

 

What are those plastic things you're using to block off the hoses? Also, would you say you noticed a difference in power after doing this?

 

I don't get the crankcase/oil bypass bit. Where did the filter come from?

Do you just plug the intake side and mount the filter on the engine side?

Why is this beneficial - is keeping oil out of the intake or is keeping the crankcase cooler?

Sorry if the questions are elementary, but any explanation would be helpful.

 

You know how the flow of air through the crankcase starts at the point where he put the filter and ends up at the PCV valve getting sucked into the intake and burned in the engine.

The OP's thought is that under heavy throttle, there's enough blowby past the rings to overpower the PCV and reverse flow, blowing crank case vapors into the intake stream. True, the PCV valve is no longer under vacuum but I don't see the benefit to this mod, especially on a NA motor.

 

where did you get the caps from for tb by-pass?

 

FWIW, I just connected those two ports with a peice of coolant hose and spring clamps - it's like a dead circuit - just to keep grime out.

The cap look better/cleaner though.

 

where did you get the filter from, can you post a link, or atleast give the size???? Thank you....

 

^autozone my freng autozone, last I checked is a cheap ass part like $1.99

 

More like $9.99.....as I buy them like all the time. If you do this...get ready to replace that filter all the time as it WILL get oil soaked and end up dripping on your engine/exhaust if you are not careful. I have been running the same setup for a while now....and it works for a short while...but eventually gets overly saturated. I just got a catch can system that I am going to install...just havent gotten around to it. For NA applications....it will work for a LONG time before it gets soaked....but supercharged guys can plan on changing this setup once every two weeks if you race. Possibly every week if you get a LOT of track time.

 

True. On the Buick with boost barely under 30psi I had to use the enclosed breathers, one on each valvecover with a 3/4" heater hose exiting underneath the car. With the open element breathers, they would drip on the headers constantly. Now that it has Total Seals I'm back to open breathers with no saturation. I'm very surprised the TL runs into saturation problems.

 

Thanks for all the insight guys, much appreciated.

The filter is just an Autozone special ~$8.99 like they said. It was lying around in my garage and it fit my purpose. I will eventually get a 90 elbow so the filter can sit upright.

Yes, the intake port is plugged to prevent air from escaping the intake tube. See Picture 1.

I don't want to have any possibility of oil entering the intake manifold, therefore the filter bypass serves its purpose.

Oh, and those poly-rubber plugs are another Autozone special. They're about $3 for a package of various sizes. Luckily, I had enough left to plug the various ports on the engine.

Any other questions, feel free to ask!

 

No difference in power, just wanted to keep all the horsepower it's already putting out. Colder air = better horsepower. Less oil in the intake = better service life. It's more of preventative maintenance than anything else.

Although, my cut/scraped up hands aren't liking me very much right now.

 

Mod is working great and just made sure the caps are still holding. So far so good. I didn't even put those pressure clamps back on the rubber hoses. Those evil things destroy fingertips!

 

This would never pass CA smog test. I would have thought the coolant bypass might have helped a little in LV summers. Good write up and pictures though. Well done.

 

I highly doubt this would fail a smog test. Unless you took it to an Acura dealer that knew what to look for. As long as there's no error code on the computer, it will pass the sniffer and computer test with flying colors.

 

It would pass through the tailpipe and fail the visual.

Back when I had to smog the turbo car I forgot to take off the open breathers from the valvecovers and the smog guy laughed, shut the hood, and told me to come back when it was legal.

 

Just one more reason why Cali sucks. Come live in Vegas, we don't even have state taxes. Ha.

 

I'll agree with you there. I lived in Vegas for a year and a half one time and another year the first time. Came back to Ca last January.

I learned my lesson the first time and stayed far from the strip the second time. I pretty much limited myself to PTs and occasionally Green Valley Ranch except for when friends were in town.

I even had the GN registered in Pahrump for a while so I didn't have to worry about smog.

 

This was done on my 2006 TL base Automatic while I was doing a IM spacer.





Your throttle body should look like this now with the hoses removed.

 

More pictures of the same thing?!
I would go the safer route and just buy a catch can...

 

from 08 funny

 

You can run a catch can from where that filter is back to the intake and what you need to put inside the catch can is a loofah sponge, the plastic/fabric ones you can get in cvs or walgreens etc. The oil will stick to the loofah and help prevent it getting back into the intake.

 

i just did the coolant bypass mod and crankcase vent mod. however, what do you guys use to cap off the hole on the intake tube? my car actually runs fine without it being capped off but i feel its safer to cap it off. all the caps at autozone are too small.

 

ummmmm....... yeah the car is map sensor based, so an intake leak does not really matter "per sa"



as far as being safer; i just want to ask you one question first though; would you run the car WITHOUT an airfilter?

 

He's not talking about the filter he's talking about the coolant lines under the TB that he removed for the coolant bypass.

 

sure as hell sounds like the actual intake tube, not the coolant lines to the tb


the other thing with how the DIY, says to loop the old coolant lines back around, he would already have that hose (let alone the advantage to doing that method, is that you will never loose the hose if you do need to reconnect it one day)

 

you know something I must've read thru it too fast. Lately my mind is not with me. Too much stress!!

 

lol

 

Just went outside and did the TB coolant bypass... only took 30 minutes or so

 

i was talking about the hole i have i on my intake tubing. i already completed the coolant bypass mod and created the loop. now...does anyone know where i can get a cap big enough to cap off the hole on my intake tube? or should i just get one of those small filters from autozone for it? i thought it'd be better if it was completed sealed as opposed to just having a filter?

 

Go to a home improvement store and but a brass pipe plug and put it into the hole with a clamp on it. Thats what i did to block my BOV hole on my intake for another car. Looks clean and works perfect.

 

you can also find some hose that slips over the nipple on the intake tube, then just stuff a bolt in the end of that hose to seal it up

using a couple of hose clamps would also be good to use too

 

pipe plug? i googled it and the pictures all show thread pipe plugs? my intake tube doesnt have threads though :/

yea i thought about using a small piece of hose and using a bolt to plug it up, i gotta find a fitting bolt for it though, i'll look for some this weekend.

 

biggest hassle is finding the correct hose (which you should actually have from the hose that goes to the valve cover)

then the next thing be finding the correct bolt, but again just go to home depot's (or where ever) bolt area, and find one that fits snugly in that hose

 

If your going to run to a hardware store you might as well do it cleaner and just get the copper pipe end... and who cares if its threaded? Just put it in the rubber hole and secure it with a hose clamp.

I think i put brass the first time. but google copper water pipe cap and you will see it. Ether will work, brass or copper.

 

btw, i have an AEM v2 cai, so it matters if the bolt is threaded since it would be cutting my intake metal tubing, lol.

anyways i cut off about 2.5 inches of the rubber hose, put a 1/2 inch bolt on 1 side and tightened it with a clamp. then other side i put on the intake hole and clamped it. now my intake port is sealed. it looks clean-ish, but since the breather hole on the aem v2 cai is on bottom, no one sees it anyways.

 

 

I just did the coolant bypass and have been logging IAT. This might add more HP than people think, I was sitting at 20 degrees above ambient even on the freeway driving for 30+ mins. After I got off the freeway the IATs could go 60-70 above and this is with the UCM. With the TB bypass I can hold ambient or a few above for quite awhile with little creep up even after getting off the freeway. I know the temp of the air entering the engine has not changed but the temp the computer is seeing and setting a timing map for is. I am very happy with this mod and can only imagine what the IATs look like on a stock non vented engine bay and CAI.

 

Errr, I mean,