Ok i have a guy whos car has switched over to the obx itbs. He has a golden eagle vacuum manifold split to all 4 cylinders and 1 line going to the map sensor. I thought bad map sensor so we swaped it out still idleing in column 8-10!!!!

havent changed to alpha n yet but should still run on map sensor. plan is to run map sensor base for idle and small part throttle then set up secondary table to switch into alpha n during hard pulls etc. S300 is being used.

Has anyone had this problem before or anything similar. this was also looked at on crome, ectune, and he bought an S300 so software and hardware is ruled out. Wiring is correct and matched have not ohm'd anything yet. I would upload the files but HT doesnt support hondata files sadly.

 

that's just the nature of itbs. try adjusting timing at idle, up or down. You'll be able to get some more vacuum, but to me its just a band-aid. I'd just go full Alpha n and get that dialed in.

 

Poor quality ITB's maybe. OP must sync throttles. Will chase this issue forever until he does.

 

Alpha N would kill the car every time. but it would stay running on the map.

The owner switched his source to his vacuum manifold he found a spot after the butterflies closer to the head and now it sits around column 3. we are going to try alpha n now and see if it works. its weird as if you see any crome or ectune itb table its column 1-5 in kpa, mbar, etc then 6-10 in %. with this i figured we could obtain decent idle and ok part throttle being in map base then switch to alpha n during high loads.

 

What does your MAP actually read? That will tell you when you need to switch over to Alpha-N. Keep an eye on what your throttle % is just before it hits atmospheric pressure (1031mbar) You want to set the switch over before it does.

 

First issue. OBX.. Those throttle are horrible, took me 3 hours to get them synced because the linkage is so poor, even then they weren't perfect. But, yes you must sync them as closely as possible, and use a large volume for your vacuum canister (not a vac block) and they will drive nicely. I've tuned a couple sets on Map like this with no issues. The trick is the SYNC and having enough volume in your vacuum, setup..

 

Yea we are in the process of building a vacuum canister. hoping it helps out.

 

My Twm Itbs are idling off of the map with a GE vacuum Block. I would also say that they are not synced.

 

IIRC TWM's are internally synchronized for vacuum, as are most automotive made individual throttles. There is a small port that runs inside the throttle body casting. It connects all 4 throttles and balances out the vacuum between them. Now whether or not your throttle plates are synchronized, that could be a different story. This is usually not so much of an issue with quality throttles.

 

I assume the size of the vacuum block makes a difference?
What size should we be using on ITB's on a B-Series?

I plan on using an IACV so I assume I'd have to go bigger again?

I was actually thinking that it might be better to run 2 vacuum blocks...one for the IACV and the other for the MAP sensor and FPR. I do not have a servo in this car (Mini)

 

You do not want your IACV running off your vacuum box. You should set up a different set of fittings for the IACV. The IACV does not really need a box. It would need an adapter plate that would allow the IACV to feed all 4 runners equally.

 

That's roughly what I thought, thank you :-)

 

To the thread starter;
What size was the original vacuum block which caused the high readings and what size is the new block? Are you happy with the newer set-up?