Hondata

Unless I have misread your posts, it doesn't seem to me that there is a problem. Vacuum at idle varies with engine, cams, idle speed, compression and ring seal, but as a guide 20 inches is good and 21-22 inches is excellent. Low compression turbo engines can be 17-18 inches. If that makes the car idle in column 3 & 4, that is fine. If our tuning guide says your engine is broken if it doesn't idle in columns 1 and 2, tell me and I'll fix the tuning guide.

Well it doesn't say it is broken explicitly, it just says it should idle in those columns. I've been driving the car hard like this for a while, so I know it's not broken, but if it screws up the tuning process, I would like to know. Thanks again for the input.

Mine still idles in columns 3-4 as well. I have cleaned the IACV, adjusted the TPS, tried a different MAP sensor, etc.

Looking back at my datalogs I noticed that past 3000 rpms, when I let off that throttle, it will go to columns 1-2. But once it hits around 1000-1500 rpms it idles in columns 3-4 again.

Is that normal?

I wonder if it is caused by my cams. My compression numbers where decent.

Just saying somethign is in columns 2-3 or 3-4 dowesn't really tell us anything unless you tell us what the actual vacuum reading is at idle.

my vacuum reading at idle is 20" using a vacuum pump gauge.

Spunkster wrote:Just saying somethign is in columns 2-3 or 3-4 dowesn't really tell us anything unless you tell us what the actual vacuum reading is at idle.

Thanks Spunkster? that is a good point.

My column 3 = 281 mbar and my column 4 = 406 mbar with the vacuum unit set to ?absolute.? When I changed the setting to in/lbs and ?atmospheric,? column 3 = -21.4 in/lbs and column 4 = -17.9 in/lbs.

If I understand that correctly, that would mean I am in the correct range...right?

That sounds ok

Idling in columns 3-4 is completely normal and the error is in the documentation.

Thanks for the feedback. One thing less to deal with...

At least in the process I found out that my preset TPS wasn't set correctly.

Ya'll should make a sticky about this. This thread cleared up a lot of questions for me.

For reference:
A stock GS-R will pull roughly 22" Hg at 750rpm.

My previous ITR-cammed GS-R engine = 270 to 299mbar absolute (21.9" to 21.1" Hg) at 850rpm. The compression test was 265psi with JDM ITR pistons (std bore), block undecked.

My current Sk2 Pro2-cammed GS-R (.010" over) = 335 to 350mbar absolute (20.0" to 19.6" Hg) at 1000rpm. It did 220psi on a Craftsman gauge with JDM ITR .25OS pistons that are 0.002" above the deck. It does lump and misfire some.

Thanks for that Ben, those are some great reference numbers.