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[FreshDA9]

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 attach the log file to show but i get an error saying file is to big!

[crttaz]

How big is the cam?
How retarded is the cam?
Is the cam even in time?
What is the idle vacuum?

[clwtwizted]

I made a set of itbs out of a stock b16 intake manifold and a set of cbr600 throttle bodies. I had tried them on my crx reccently and I was using the stock map sensor placement for the cbr which is all the runners going to a 5 port T fitting to the map. It also Idled in the low vacume part of the map. I need to do a little re-enginering/nigger rigging and I'll try it again. Yes they are stupid, but when they work, they are quite badass. http://youtu.be/hkWyZJqdCsA

[FreshDA9]

How big is the cam?
How retarded is the cam?
Is the cam even in time?
What is the idle vacuum?

Bone, cams are 1 b16 and 1 gsr i believe the gsr is the exhaust came. cam gears set to zero. I do hope he has it in time i can double check. Hondata shows -2inch of vacuum as for a gauge have not put one on to check.

clwtwizted so i am not alone then.

[FreshDA9]

i moved his source and now it settles around column 3. i believe we have it fixed and now i can tune it. thank you.

[fe3tcourier]

Moved it where?

High kPa and highly variable MAP readings are 100% normal for ITB setups.

Alpha-N is what you do in the low load regions and MAP in the high load. Or, if NA, just Alpha-N everywhere.

[FreshDA9]

he found a fitting past the butterflies and closer to the head flange and sourced the brake booster and vacuum manifold from there.

yes car is na but it will not stay running Alpha n. havent tried since moving the source that will be for tonight.

I did not know high kpa ratings were normal thank you. this is my first go at it.

[JaredKaragen]

Grrrrr.


Alpha/n indexing was created specifically for itb's.

Only at idle you see this problem;  same with a big cam.   You really have to tweak the fuel mapping in regular mode to get it to run right.

There's a few good itb write ups on pgmfi.org.

[FreshDA9]

Grrrrr.


Alpha/n indexing was created specifically for itb's.

Only at idle you see this problem;  same with a big cam.   You really have to tweak the fuel mapping in regular mode to get it to run right.

There's a few good itb write ups on pgmfi.org.

Im going to have to look for those write ups put it in alpha n and it will idle now and stopped surging but i believe its because i pulled the timing since it doesnt have an iacv. i will tred through more.

See i was planning on tuning the map sensor for low and high then set secondary table to switch to alpha n from say 60%+... i guess i cannot.

[DasPoop]

just the tps signal to the map signal with a 3.6v zener  tune away

[JaredKaragen]

Ok; row one and two, maybe 3 and 4 will need to have timing set to base; fuel the same.  You will get rock solid idle.

Another way to attempt to get a map reading is all four itb vac lines to a vac block; and map off the block.  It will help substantially.

Alpha n is really the way to go.... But the tips above will solve a lot of issues.

[walter]

did you adjust it?maybe one of these are more open. i adapted a obx DC5 in Ep3 and worked great, idle was as perfect as stock, alpha no used 

[PhilStubbs]

Grrrrr.


Alpha/n indexing was created specifically for itb's.

Only at idle you see this problem;  same with a big cam.   You really have to tweak the fuel mapping in regular mode to get it to run right.

There's a few good itb write ups on pgmfi.org.

Im going to have to look for those write ups put it in alpha n and it will idle now and stopped surging but i believe its because i pulled the timing since it doesnt have an iacv. i will tred through more.

See i was planning on tuning the map sensor for low and high then set secondary table to switch to alpha n from say 60%+... i guess i cannot.

You have it backwards. You get a shitty map reading at low rpm. Alpha N is there to cure that. Tps readings are consistant. You can get a good map reading at wide open.

[fe3tcourier]

Correct!

You can electronically combine multiple map sensors to produce a low signal all the time. This could be a nice approach.

I hate to link to these faggots, and not everything on here is accurate, but some of it is, and it might help you, so:

http://synchromap.com/

Fred.

[HiProfile]

That synchromap looks interesting. However, I'd think it would have been better to read the lowest vac value off one cylinder (or more) and float that number til the next time vacuum dips. You're fueling for the lowest vac value it hits anyways, and that will change when the plates open up. Then switch to normal MAP reading at a certain TPS angle or MAP value.

[fe3tcourier]

I'd think it would have been better to read the lowest vac value off one cylinder (or more) and float that number til the next time vacuum dips.

What if you're opening the throttle? Then it ain't ever going to dip, you're going to hold an artificially low value until the end of time. What it does is about as close to ideal as possible.

If you have a limited setup with 1 map input then it's about as good as you'll get. If you have sufficient ADCs you can just run them directly in and take timed readings in the low vacuum area for each runner.

You're fueling for the lowest vac value it hits anyways, and that will change when the plates open up. Then switch to normal MAP reading at a certain TPS angle or MAP value.

No idea what you're saying/smoking there :-)

Fred.

[PhilStubbs]

i dont see where alpha-n could be improved upon for itbs. anything else is over complicated and just something else to break. 

[JaredKaragen]

i dont see where alpha-n could be improved upon for itbs. anything else is over complicated and just something else to break.

[DmC]

Make a vacuum tank that the brake booster feeds off of and has a vacuum line from each runner inside the throttle bodies. That trick works for me it clears up that transistion column between tps and map.