Vacuum and Hondata

TurboLS · Post by **TurboLS** » Sat Jul 29, 2006 11:39 am

OK, I read in the partial throttle tuning article that the engine should idle in columns 1 and 2 in Hondata. My car idles in columns 3 and 4. I figured I had a vacuum leak or something. I went ahead and checked compression and came out to about 180 on all 4 cylinders which is damn good i might add (for B18B1 engine). I then spliced a vacuum pump into the vacuum system and idled the car. The car idled dead nuts on at 20", yet Hondata displayed in columns 3 and 4. Does this mean I have a bad MAP sensor or does this mean that Hondata is reading the signal incorrectly? Any other ideas?? thanks guys.

sulsa76 · Post by **sulsa76** » Sat Jul 29, 2006 2:06 pm

I have the same issue. However, I have a BBK Throttle body, and my mechanic told me the throttle plate doesn't always seal well with these. So I need to take the TB off and check to make sure the throttle plate can close all the way. If that's not my issue, then I'm at a loss... Cause I checked the intake manifold and all the tubing for leaks already. I can't figure it out, yet.

TurboGSR96 · Post by **TurboGSR96** » Sat Jul 29, 2006 9:49 pm

I have an VictorX and a BBK 70mm and I idle about 530 mmHG which I was told is perfectly fine, I also idle in column 3 & 4. I have every available vacumn port on the back of the VictorX used and if I have a leak I cant find it.

sulsa76 · Post by **sulsa76** » Sun Jul 30, 2006 12:08 am

TurboGSR96 wrote:I have an VictorX and a BBK 70mm and I idle about 530 mmHG which I was told is perfectly fine, I also idle in column 3 & 4. I have every available vacumn port on the back of the VictorX used and if I have a leak I cant find it.

Who told you it was perfectly fine? Your tuner? Not that I'm suggesting they are wrong. I'm just curious.

In this thread -> http://hondata.net/forum/viewtopic.php?t=4223, Spunkster said this is because the map sensor is reading low vacuum. Is it possible to adjust the amount of vacuum each column represents? I've not yet found a way. Not that I know this would be a good solution, if I could.

TurboLS · Post by **TurboLS** » Sun Jul 30, 2006 12:58 pm

I know you can change the RPM levels and you can change the units of vacuum, but I don't think you can change the magnitudes. I think Spunk may have to clarify this one. thanks everyone for your replies.

TurboGSR96 · Post by **TurboGSR96** » Sun Jul 30, 2006 5:14 pm

sulsa76 wrote:
TurboGSR96 wrote:I have an VictorX and a BBK 70mm and I idle about 530 mmHG which I was told is perfectly fine, I also idle in column 3 & 4. I have every available vacumn port on the back of the VictorX used and if I have a leak I cant find it.
Who told you it was perfectly fine? Your tuner? Not that I'm suggesting they are wrong. I'm just curious.

I know its fine when I went to order my Tial BOV, and you have to order certain springs for it depending on what the vacumn is in your motor, and mine was the same reading that every body else orders there BOV in.

sulsa76 · Post by **sulsa76** » Sun Jul 30, 2006 7:58 pm

Ahhh. That's a good bit of information. I hope Spunk reads this.

TurboLS · Post by **TurboLS** » Mon Jul 31, 2006 5:10 am

sulsa76 wrote:I have the same issue. However, I have a BBK Throttle body, and my mechanic told me the throttle plate doesn't always seal well with these. So I need to take the TB off and check to make sure the throttle plate can close all the way. If that's not my issue, then I'm at a loss... Cause I checked the intake manifold and all the tubing for leaks already. I can't figure it out, yet.

just get a vacuum pump from Advance Auto Parts and splice it into the vacuum system. Once you are sure you have 20", you can rule out leaks and focus on sensors and calibrations.

Post by **Spunkster** » Mon Jul 31, 2006 10:07 am

IF you have cams, then they may not pull much vacuum at idle.

TurboLS · Post by **TurboLS** » Mon Jul 31, 2006 10:27 am

Yeah, my engine is essentially stock. Any ideas??

strider · Post by **strider** » Mon Jul 31, 2006 10:29 am

Spunkster... So, someone like me with Skunk2 stage 2 cams would have this happen? I have been running around in circles trying to figure this out. Mine idles in columns 3 and 4.

BTW, in the process of casing down my problem I noticed that my TPS sensor was not set properly. It read .53 volts closed throttle. (2% throttle when closed and 103% throttle when open, according to the Smanger.) I adjusted it to .45 volts closed.

Is there a way to adjust my fuel and timing maps to reflect the change in my TPS settings? Or do I have to go to the dyno and retune? It looks like WOT richened up a bit. I haven?t been driving it since then. Just taking my time with it to be on the safe side. :)

Thanks

Post by **Spunkster** » Mon Jul 31, 2006 11:12 am

Do a comression and leak down test to make sure it's not the engine.

strider · Post by **strider** » Mon Jul 31, 2006 11:31 am

Compression was around 225 all 4 cylinders. Made 196 whp on a Mustang dyno.

TurboGSR96 · Post by **TurboGSR96** » Mon Jul 31, 2006 11:48 am

Would my Ported Head and Oversize Valves cause me to idle in column 3 & 4? I had alot of problems with my TPS, my Comp #'s are 195 across on an 8.8:1 GSR, and I am also reading 103% at WOT.... think mine is set to .50v, gonna go try to set it to .45 and see what happens.

TurboLS · Post by **TurboLS** » Sun Aug 20, 2006 6:41 pm

Well I popped in the new MAP sensor and it reads exactly as the old one. The vacuum is still at 20" at idle. This leads me to believe that Hondata is receiving the wrong signal or that it is calibrated incorrectly. What are my options here? Should I make a custom MAP sensor and do a voltage vs. MAP pressure plot, should i mess with Alpha-N?? Any input is appreciated. thanks again guys.