928mac

I am not getting a good map signal as the vacuum is tee'd into the source on top of the throttle body farthest from the firewall.


I am wondering if the source under the TB would be a better spot to draw Map vacuum from?

here is a pic of the spot under the Throttle body that I am thinking of.

Mike Simard

That looks like a good plan. When I design throttles I like to 'hide' the port behind the throttle shaft and avoid the changing airflow around the blade. You have that vast area of the plenum to drill and tap, anywhere away from the throttle blade itself should be just fine.

Lizard928

Brad,

T into the fuel pressure regulator line and forget about it. This will be the most stable vacuum.

There are 2 ports on the top of the butterfly, its the big one that should be connected to.

928mac

Thanks Colin

That's the one I had it connected to.
The reason I was questioning it is because my map signal on the laptop dash never goes above 1/2.
I was wondering if ported vac would give me a stronger signal?

Lizard928

It never goes above half because you likely use a 330kPa or so sensor.

Atmospheric pressure is 101-102 kPa at sea level, the higher you go, the lower it goes.
I doubt that you will see anything below 20kPa, and that would be while you are decelerating.
If you are running naturally aspirated you can just modify the MAP bins (normally found vertically to the left of the VE table), so that you have more adjustments available throughout the table.

However, you really dont need that many cells for a NA engine.
The most cells are needed around idle, and low RPM cruise due to fluctuations. In the upper RPM less bins are needed, and a smoother table is just fine.

928mac

Colin, don't you need to go on a road trip?
Fort McMurray would be a good rip and Radar detectors are legal in alberta

I wish I had someone here that I could bounce this stuff off of but most guys are just parts replacers.
Brad
My map is the GM#1 but ILL get back with my details
Thanks again

Lizard928

HAHA,

your welcome to pay for my time to come out there in Oct....

928mac

Thats not unrealistic. BTW it is a 10 to 104 Kpa 1 bar Map sensor

The flight recorder saw it as high as 80 once but it normally sits around 28 and when rev'd in the drive way will go to 38-40 Kpa

Oct eh, maybe I can meet you near Edmonton.

Brad

Man just think how much you could make installing systems in Ft Mc in the month of Oct.

Lizard928

You must be fairly high up.

Sitting at 28 in the drive, how much advance are you running at idle????

You must be around 6500' above sea level to see that number. When you hit sea level, you will see 101.33

928mac

McMurray is at (1,210 ft) above sea level
I don't think it is wired wrong.
Initial adv is 10 and Ign adv table starts at 14/750rpm
coolent adv zero
Duel Plug timing split zero
MAT density adv -40 to 80 zero and -1=90, -2=100, -4=110 so on

TDC 11th tooth and zero deg mech offset

Lizard928

at 1,210' above sea level, you should have 96.5 kPa (give or take).
This should be when you turn the ign on, as well as when you have your foot buried through the floor.

If you put the key in the on position, and you do not see 96.5 (or close to), then disconnect the MAP tube, and read again. If still no, then you need to recalibrate the sensor!

928mac

Its at 38.9

Lizard928

When you turn the ign to the on position, but the engine isnt running, it needs to read atmospheric pressure for calibrations...... if you are accurate in that altitude correction, then something is amiss.

928mac

Ok thanks. I checked the A. C. terminal and have 4.98 Volts
I checked the A. B. terminal (ground to ECM) and have 1.49

At least I know where the problem is.
You wouldn't believe the trouble I'v been having trying to tune it ha ha
It must be I got a defective Map Hmmm

Lizard928

I can believe it,

But it is possible that you just need to calibrate the MAP sensor in the software so check that first.....
Or get the specs of that sensor, and put a vacuum pump onto it
and check the signal voltage through the range.