I'm tuning a quad throttle setup for the first time, and ran into problems.

The main issue is,
I can't get it to idle properly.

My setup
OER ITB (shaft type) idle bleed all balanced properly.
B20B 85mm, 11.8CR
tuned with Hondata, using TPS based map indexing.

Was tuning and running a plenum setup on the same engine before and it ran fine, just tried messing around with the quads for the first time, and encountered a problem. It revs up properly, no lean spots around 13AFR. No problems with bogging or lags associated with a bad tune.

It's just the idle that I can't solve.

I suspect it's an air leak, but can't seem to locate the leak. But it also might be a characteristic of ITB's I don't know about, so I just need a confirmation on that.

So far, I can only get it to idle at 1500 around 11.8-12 AFR with 22deg ign advance.

Any lower, the MAP sensor attached to the vaccum log will hit something like >360mbar vaccuum, and the idle will osscillate, just like what happens when a plenum setup has a leak. It seems like it cannot get a lower vaccuum pressure below that.

I understand that ITBs need more fuel to idle, but at 11.8-12AFR, it's ridiculous!

Any ideas?

 

I'm not familiar with OER type individual throttles. Do they have any type of idle adjustment screws on each body?

My GSXR bodies have an adjustment screw on each throttle body to allow synchronization between the 4 throttles. They are like the idle adjustment screw on a regular Honda throttle body. If you do have them and they are adjusted wide open it could act like a vacuum leak.....

I have yet to tune any ITB's. So this is just a shot in the dark suggestion for ya!

 

i would recommend synchronizing them. When i had my setup running, synchronized vs not was a pretty difference in how the engine idled.

 

Yeah. I got them syncronised. I mentioned that they were balanced. And GhostAccord, Yeah, they had idle bleed screw for each individual body, like yours.

Finally got them working. too. It seems I can'd get a good idle with TPS indexing with hondata. ATM, I've tuned them with MAP indexing.

Works fine now, at least for full throttle and idle. 13.5 afr throughout, and plugs are nicely coloured too. ignition tune will be held off till I've solved part throttle issues.. which is a marked lack of response at part throttle, which is kind of obvious because at part throttle, the buildup of vaccuum last for a few milisecs before going to full atmospheric.

Kind of negates the benefit of having quads in the first place. Which is having quick response, which my first TPS based mapping did, but couldn't get it to idle.

I'm going to try the roundabout way of TPS indexing on the secondary map of hondata to curb that problem.

I do wonder if the secondary maps are totally seperate of do they do the load correction for the TPS from the primary maps or vice versa.

With hondata forums down, it'll take a while before I'm able to ask hondata directly.

Here's a video of it.
http://s82.photobucket.com/alb...g.flv


Modified by shiroitenshi at 10:20 AM 9/19/2008


Modified by shiroitenshi at 10:25 AM 9/19/2008