I have to ask this, as I am in the process of building an ITB setup for my engine now, and just want to know exactly the in's and out's of using this system.
First off, I'm hearing from all sorts of different people, all sorts of different things and would like to clarify a few of these speculations before proceeding with the build.

So, one thing that has me really confused is the statement that ITB's are very difficult to tune; and once tuned, they need to be constantly retuned? I'm understanding that these ITB's somehow get out of tune by themselves. This makes no sense to me as there are only stop screws and air bleed screws on the unit that could vibrate out of adjustment. -But, if you have them really tight or use locktite to ensure they don't rattle loose, then what's to come out of tune here? The ECU? I've never had my Hondata just drop out of tune like this just by itself, so I am totally baffled.

Now, the MAP sensor issue is one for the books, I hear. Supposedly, what happens here is the reason they are so hard to get tuned in the first place. Honda's have MAP's instead of MAF's. So, when moving to a ITB setup, you have a small runner instead of a plenum that doesn't allow vacuum to build up, throwing off false signals, making it a bitch to adjust. I'm understanding that at an idle and low rpm's up to 3k or so, they create a vacuum that's in the normal range, but as soon as you floor it and get the engine into the high range, the vacuum drops next to nill. I assume this is the case with homebuilt systems. If this is the case, then surely something can be done to increase vacuum with chambers or something? Like the TWM ones that have "vacuum accumulators".

Also, I've been hearing that there's an unusually strong odor of gasoline when using this setup. Is this the case? I really don't care as the car is going to be a track vehicle anyways. I highly doubt that it would be allowing that much atomized fuel into the atmosphere to be prompted to relocate the fuse box and other such electronics, or else the juice going to the injectors would be close enough to ignite it. I haven't heard of this happening, so I'm not worried about the smell. I assume this is all stuff from people that put these on their daily drivers that still have all the interior pieces in to absorb the fumes; so they're just warning you what to expect.

 

Search 92TypeR, he lives near you and can answer some of the bad info you have.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Twistedframe &raquo;</TD></TR><TR><TD CLASS="quote">
So, one thing that has me really confused is the statement that ITB's are very difficult to tune; and once tuned, they need to be constantly retuned? I'm understanding that these ITB's somehow get out of tune by themselves. This makes no sense to me as there are only stop screws and air bleed screws on the unit that could vibrate out of adjustment. -But, if you have them really tight or use locktite to ensure they don't rattle loose, then what's to come out of tune here? The ECU? I've never had my Hondata just drop out of tune like this just by itself, so I am totally baffled. </TD></TR></TABLE>

I have been running my TWM 50mm ITB's since April. Being the first car I had ever encountered with ITB's, tuning was a little stressful at first, but eventually got ironed out with minimal issue. I have experienced multiple temperatures/humidity levels, and not once has the car deviated from the tune based on ambient condition.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">Now, the MAP sensor issue is one for the books, I hear. Supposedly, what happens here is the reason they are so hard to get tuned in the first place. Honda's have MAP's instead of MAF's. So, when moving to a ITB setup, you have a small runner instead of a plenum that doesn't allow vacuum to build up, throwing off false signals, making it a bitch to adjust. I'm understanding that at an idle and low rpm's up to 3k or so, they create a vacuum that's in the normal range, but as soon as you floor it and get the engine into the high range, the vacuum drops next to nill. I assume this is the case with homebuilt systems. If this is the case, then surely something can be done to increase vacuum with chambers or something? Like the TWM ones that have "vacuum accumulators".</TD></TR></TABLE>

Rule number one of TWM's - The vacuum accumulator is junk.

My car idles and cruises with a steady MAP signal. This was accomplished using a suggested method from (like DonF mentioned) "92TypeR" here on Honda-Tech. I drilled and tapped each runner, and ran equal-length vacuum lines to an external canister in which I ran the MAP sensor off of.

There you go.

Good luck,
- Derek

 

Thanks so much, guys!! Excellent Info :D