Shawn MacAnanny

iTrader: (12)

I've been tunning my car with the MAP sensor and trying to get the carb all setup for it. At idle my car has 10.7psia according the the MSD MAP sensor. That converts to like 21hg" vacuum. Is that right? I am trying to select my power valve by using vacuum reading and i just think that 21hg seems high for a 236/236 cam on a 110lsa. I admit i dont know much when i comes to tuning these but from what i understand you select you powervalve based on half of your engine idle vacuum correct? I have a 6.5PV in there now which seems to work pretty good WOT but i dont have my wideband yet so i dont know. I know it stumbles down low when stepping into the throttle so i already ordered a 50cc accelerater pump.

Any help guys?

Shawn MacAnanny

iTrader: (12)

After reading and reading and reading i have determined i am reading my MAP sensor wrong. I noticed when my engine is off the map reads 14.7psi (i am at sea level). When it's running it reads 10.7psia. I asumed this to mean 10.7psi of vacuum. That is incorrect. I really have 4psia vacuum which is more lieke 8hg right? I was tuning the idle screws for max vacuum thinking that i was reading it right haha. I thought 3 turns out was an awful lot haha. I'm going to try reprgramming it again tonight and see if i can get it to run better.

S10xGN

iTrader: (11)

Shawn,

A bit off topic here, but what MAP sensor does the 6010 use? I have one and the instructions don't say...

Russ

Shawn MacAnanny

iTrader: (12)

A 1, 2, or 3 bar map sensor. I used one from a 99 pontiac grand prix. I ended up ordering an MSD one just because but both required swapping to a different connector than the one that came on the 6010 harness. You have to select whatever bar map sensor you are using the msd option menu.

Here's the map i bought

http://cgi.ebay.com/ebaymotors/ws/eB...B:EOIBSA:MT:11

And the connector i needed

http://cgi.ebay.com/ebaymotors/ws/eB...MEWN:IT&ih=012

Pop N Wood

iTrader: (1)

You select a power valve based on the vacuum at cruise, not idle.

I got a couple of MAP sensors out of JY GM vehicles. Plugged right into the MSD harness. Pretty much anything with a 3.8L 6 will work.

And you are right, map sensors read absolute pressure (hence the name). Inches of vacuum is the difference between the engine off pressure and the running pressure.

Shawn MacAnanny

iTrader: (12)

Cruise vacuum... Hmm i guess ill have to bring my laptop driving with me tonight then.

LS1MCSS

iTrader: (18)

Shawn, here is a chart that converts psia to vacuum. 10.7 psia looks to be about 8" vacuum.
http://www.erowid.org/archive/rhodiu...onversion.html

Shawn MacAnanny

iTrader: (12)

After re-tuning the idle mixture and changing the curve i have it idling at 8.6psia now and seems to run much better. Still getting the off idle stumble but have a 50cc pump on the way and some lighter secondary springs.

S10xGN

iTrader: (11)

I was hoping to find a 1 BAR MAP that would plug into the MSD connector...

Russ

Pop N Wood

iTrader: (1)

Then hit a JY and pull one off of any GM 3.8L 6 you see.

S10xGN

iTrader: (11)

Has to be a later version than the 3-BAR I have in my GN powered S-10. The '87 version has a Weatherpack connector that looks just like the one Shawn bought off E-Bay...

Russ

forcd ind

iTrader: (7)

i gave up and zero'ed out my map sen.-i think i used one from a supercharged colbalt(2 bar, i run a supercharger), but the 1 bar from an ls6 intake plugs right in
use a VACUME gauge and read your idle vacume, then select a pv around 3 pts lower, depending on your findings, which will dictate the size-if you try and use cruise vacume, which is higher, and select a pv and the pv # is higher than your idle vac., it will be open at idle, causing all kind of rich problems
i tried to figure out map, vs vacume, i figured the vac was pulling against the 14.7 press, which reduces the map reading from 14.7 on start up, and when i go into boost, i erase the vacume, which then the map should be reading 14.7, plus any boost #'s,-but for now, i just use the retard system, and fire it off a hobbs switch which sees boost
man, life used to be simple, lol

forcd ind

iTrader: (7)

thats a great chart-look at 0 hg, you would see 14.7 map, which would be engine off or wot, which should also be close to zero vacume
looking at the chart, vac and press dont go 1 for 1, which is how i thought it went, seems like it takes more vac to pull down press., like 2 to 1-my guess is the map reading is more acurate, being in smaller inc. kind of like metric wrenches, lol

rojs234

iTrader: (5)

Russ, here is a picture of the one I use with my MSD 6010. This one came off the L76 manifold that I got when I bought my engine. Everything was new , so I assume this is available at any GM parts supplier, or could be cross referenced at a parts store like Auto Zone or O'reilly. You got to be careful, cause some look just like it, but the locating notch is in the wrong place. By the way, if anyone needs a new (except 5 hrs dyno time) L76 complete with a new Holley 90 MM CABLE throttle body, mine will soon be for sale. Just click on thumbnail and you should be able to read numbers on MAP sensor.

rojs234

iTrader: (5)

Can't speak for anyone else, but I would sure like to THANK YOU for the link to that chart. I have always tuned the vacuum advance curves in all of my street cars because it plays such an important role in gas mileage, but ever since I got the MSD 6010 I have been confused by the way they display the readings. Now I can tape the chart to the dash while I'm driving with the lap-top reading PSIA and I can see what I'm doing. THANKS AGAIN!! Ron

Shawn MacAnanny

iTrader: (12)

Yes thank you! it helped me alot in figuring out i had the right power valve and reassuring me that i had the wrong timing curve lol