Vacuum and Hondata

Post by **Hondata** » Sun Aug 20, 2006 8:02 pm

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.

TurboLS · Post by **TurboLS** » Mon Aug 21, 2006 5:21 am

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.

strider · Post by **strider** » Mon Aug 21, 2006 9:21 am

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.

Post by **Spunkster** » Mon Aug 21, 2006 10:28 am

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.

TurboLS · Post by **TurboLS** » Mon Aug 21, 2006 10:40 am

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

strider · Post by **strider** » Mon Aug 21, 2006 11:35 am

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?

Post by **Spunkster** » Mon Aug 21, 2006 1:41 pm

That sounds ok

Post by **Hondata** » Mon Aug 21, 2006 2:04 pm

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

strider · Post by **strider** » Mon Aug 21, 2006 3:02 pm

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.

sulsa76 · Post by **sulsa76** » Mon Aug 21, 2006 6:44 pm

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

ben · Post by **ben** » Sat Sep 09, 2006 5:54 pm

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.

sulsa76 · Post by **sulsa76** » Mon Sep 11, 2006 6:04 pm

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

Hondata

Vacuum and Hondata

Sticky for the win!

Nice