Idle question (RPM vs. Ignition)

joejoe3 · Post by **joejoe3** » Wed Aug 29, 2007 11:38 pm

03 Acura RSX Type-S
Mods: JRSC, 11psi pulley, 750cc, I/H/E.

I have a idle issue which has been bothering me for awhile. When the car sits idles (set at 900rpm), it will occasionally dip to 830-850rpm range and the car will rumble and the rpm will climb back up to 900rpm.

I played with the slider and not much help. I decided to datalog the idle and found something very intresting. It idles normally, but when the rpm dip occurs, the ignition rises and hangs at 10-12, then drops back down to normal and the rpm goes back to 900 again.

It's more annoying then a real problem to me. Just sometimes sitting at a light the car sends chills down my spine as it rumbles.

Here's the datalog, if you look at a graph showing RPM & IGN you'll see what I mean.

Thanks!

Post by **Spunkster** » Thu Aug 30, 2007 10:00 am

Honda has chosen to use ignition controlled idle and this is completley normal operation.

joejoe3 · Post by **joejoe3** » Thu Aug 30, 2007 11:12 am

How come I never feel this "rumble" when it was still N/A? Even though it was doing it I never noticed it until after I went supercharged.

Is it due to the bigger injectors?

Post by **Spunkster** » Thu Aug 30, 2007 11:24 am

Have you done anything to the engine mounts? Stock idle is lower than 900 as well.

joejoe3 · Post by **joejoe3** » Thu Aug 30, 2007 12:35 pm

yup, i have energy suspension motor mount inserts and raise the idle to 900 rpm because of it... this was all during the time I was N/A.

It wasn't this noticable until I went superchaged... everytime that rpm dips and the ignition rises, it send chills down my spine with the rumble

jerseyjew · Post by **jerseyjew** » Fri Aug 31, 2007 4:45 pm

lol @ chills down your spine... hahah

jimmyjames · Post by **jimmyjames** » Mon Sep 03, 2007 8:21 am

I have the exact same issue.
I had noticed it mostly though after swapping race headers from the dc sports to the JR with high flow cat (enabled OBDII)then.

The car will have this slight sputtering at idle and the sputters coincide with an ignition spike of 10-14 all of a sudden.

Also, when cruising sometimes, I feel as though the car is hesitating slightly in a cyclicle manner (as though the wind was blowing against me every 4 seconds for a 1-2 second duration)

I am also supercharged.

Looking at your datalog, there is something similar happening; notice the 12 degree ignition plateau every 7 seconds (at 2.5, 9.5, and 16.5) and a rough patch increase every 7 seconds as well (at 6 and 13)

So I guess what is happening every 3.5 seconds that is causing this? (I'd like to know)
..and this doesn't seem normal to me.