Bucking on deceleration and light throttle

uncledan · Post by **uncledan** » Mon Oct 01, 2007 5:31 pm

My car is an 02 RSX-S.
K-pro ser. no. 4030. Mods are injen cai, img, dcshorty header, PRC intake manifold.

My problem is bucking on deceleration and light throttle. In the datalog attached, you can see where the car decelerates and goes into "open driving". I know it is supposed to do that. But then it goes into "open cold", the ignition timing drops down about 20 degrees, goes back into "open driving" and the timing goes back up. Is the car supposed to go into "open cold"? You can see it between 30 to 45 seconds and again after 1:05 on the datalog.

uncledan

Post by **Hondata** » Tue Oct 02, 2007 9:05 am

The engine is making more vacuum under decel than normal. Under advanced decrease the overrun cutoff pressures. Currently they are around 21-29 kPa, decrease them to 15 kPa or so.

You also should look at the fuel - as a rule, short term trim should be 6% or less (except with transisitions).

Other changes you may wish to try.
- Adjust the TPS so that it goes to 0%
- Disable the fuel overrun delay.
- Decrease the tip in retard a little.

uncledan · Post by **uncledan** » Tue Oct 02, 2007 3:47 pm

Thanks, I will try your suggestions.

Would the different intake manifold, PRC, be the cause of the higher vacuum? If not, what then? A vacuum leak would cause a decrease in vacuum wouldn't it?

uncledan

talonxracer · Post by **talonxracer** » Tue Oct 02, 2007 6:18 pm

You mentioned Decreasing tip-in retard. How is that done, I have not seen that option, or am I blind. LOL

updated...
OK, YES I WAS BLIND,,, I found it in about 5 seconds

Doug

Post by **Hondata** » Wed Oct 03, 2007 8:47 am

High vacuum on decel is either from a bigger engine (K24) or different cam timing. Either way, it is nothing to worry about.