Chris22215

Alright, I've installed a homemade set of ITBs on my brother's jdm b18c. I'm using crome to tune it, cause of the itb tools. Which work great by the way. Anyway the problem is that under a slight load (20% throttle on my datalog) there is a spike in the a/f. It spikes/studders from 14.7-15.9, but only under that slight load. Is it a timing problem? Any help would be greatly appreciated.
Thanks,
Chris

093turbo16

iTrader: (2)

there seems to be a big gap between the map vaules and the TPS values. It just needs some messing with to get it worked out. I am tuning one this weekend with crome on the dyno. We street tuned it a little bit, and crome idles very nicely, but man you are never in any vacumm with ITBs, I was really surprised when tuning, it was the first one I ever did.

Look at the 2D graph to see the jumps.

Chris22215

I didn't check to see when I lost all vacuum. I've recorded the tps and it only happens at around 20-25%. the car idles great and 14.7 at cruise, but with I put it under a slight load, it almost misses. does it need more or less timing? Other than that everything is fine

Katman

I don't know if Crome has the option or if the factory honda ecu can handle this, but you need to setup the ecu to handle speed density (throttle mapping), because the OEM MAP sensor can't handle the duties ITB's call for (you'd need a map sensor on each throttlebody to get better throttle response).

An AEM EMS has this 'speed density' feature and once setup & enabled, your throttle response is awesome

Chris22215

Hmm, I'm using crome because it uses map/tps for the fuel and ign values. so the reason it studders is because I don't have a map on each itb? I thought I just needed a lil timing or something. That's wierd
Thanks though

Anyother thoughts from anyone

Katman

Put it this way, your car from the factory, has 1 map sensor because you have 1 throttlebody. Now that you have 4 throttlebodies you need 4 MAP's for each of those tb's if you want better throttle response & F/A ratio readings.

Using one map sensor to take on the duties of 4 tb's will cause the problems you're currently having. It may idle perfect but your throttle response will be garbage-like.

My info could be a off a tad, but that's what I've learned about using ITB's with the factory ecu/chipped factory ecu. You need a stand alone ecu if you want to have full tuning capabilities and to optimally run the ITB's.

Chris22215

I've got the readings for the map coming from all 4 throttle bodies. throttle response is great, top end is fine, normal acceleration is good, cruise is fine. So you're saying that i'm always going to have this problem until I get an AEM EMS. Well that sucs.

Katman

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Chris22215 &raquo;</TD></TR><TR><TD CLASS="quote">I've got the readings for the map coming from all 4 throttle bodies. throttle response is great, top end is fine, normal acceleration is good, cruise is fine. So you're saying that i'm always going to have this problem until I get an AEM EMS. Well that sucs.</TD></TR></TABLE>


okaaaay...so you got things figured out (no more studdering?) since your last post I assume?

hah, no, i meant you should get a stand alone system in general (doesn't have to be an EMS), to fine tune the ITB's and your engine to run it at its maximum potential.

Chris22215

Sorry. Everything is fine except for the studder under slight load. I can't figure it out. I guess that I'm just stuck with it.

Chris22215

Anyone else?