Got to drive my buddy's '06 Si the other day, and I noticed an issue with what felt like a misfire/hesitation. The car has the Injen CAI, with a "filter condom" on the end of it, so I am fairly sure he hasn't sucked any water up.

It will have a SLIGHT hesitation right around 3,500-4,500 RPM in all gears. I have personally checked all the filter connections, hose clamps, vacuum lines and electrical connections, all to no avail.

The car isn't throwing any DTC's, so a computer scan is out of the question (because I have already put my OBD2 scanner on it, with no stored codes).

Any ideas?

EDIT: I know for sure it isn't the DBW throttle lag common to these cars, because he already has the Hondata Reflash, which has ALMOST eliminated the lag all together.

 

While i can't tell you what it is that's causing the hestitation, i can tell you that my stock (except for K&N drop in) Si has absolutely no lag anywhere in the powerband. My thought is that it's because of the intake, did you unplug your battery for 1-15 mins then let the car idle for another 15 mins? If not, i'd suggest trying that...

 

We did that... to let the ECU "relearn" the idle fuel mixture or whatever, as the instructions suggested, so that SHOULDN'T be the problem.

I am thinking something electrical, or there is an air/vacuum leak somewhere. When he get's off today, I will take a look again and see what I can come up with.

 

Try putting the stock setup back on and see how it reacts.

 

Well... we found that problem fairly quickly with a quick check...

When he installed the intake, he didn't screw the MAF sensor all the way in it's setting.... it is running right now, relearning the idle air mixture... and we will see how it goes from there.

 

Only slight hesitation I had was around 3100 rpm where the I-vtec begins to "kick".