Boost-Vacuum issue on Scanmaster

[Just a Six?]

Hey Everybody I hope you are all ready for another season with the Hot Rods!   
Spring is here & I have an old Gremlin I'm tired of & need some pointers.
I have a Mechanical Boost-Vacuum gauge along with Scanmaster 2.1
They both work great when the under the hood engine temps aren't too hot.
When the engine bay gets hot after some city-highway driving & some quick blasts the Scanmaster Boost readings get all crazy.[size=78%] [/size][/size]It shows 5-10 lbs boost while just cruising along & I think it also shows some Knock when this happens. Vacuum is also Screwy. I'm not sure if the dash Boost Lights go funky? Meanwhile t[size=78%][/size][size=78%][/size]he Mechanical gauge works fine through all this nonsense.[size=78%][/size][size=78%][/size]Once the engine is c[size=78%][/size]ooled down a bit then everything works Normal again?[size=78%]
Again I need to confirm but I think the Scanmaster shows some Knock Retard when this happens yet the Audible Knock Detector didn't go off. The engine never goes over 160* & the Dual fans work properly.
I will hook up the Powerlogger for some readings the next time I go for a drive.


Separate issue l[/size]ast couple years had the Audible Knock sensor chirping when the car was cold at start up & the first 5 mins driving so I unhooked the Engines Knock Sensor last year. [size=78%]

[/size]Any suggestions are Appreciated! [size=78%]

[Just a Six?]

Man I had to reset the Font Size 10x for that post & it's still screwed up?
I can't Cut & Paste here or even Deleting words makes my post come out messed up? 
 
Sentence should read: Once the engine cools down a bit everything works fine again?

[Steve Wood]

sounds like you need a new Map sensor to me

[Just a Six?]

Thanks Steve,
I may have a spare in the pile but I forget how it goes, 2 bar is stock & 3 bar for Power Logger of something like that? Can I just plug in the Stock one for testing or will it affect the Scanmaster on Boost setting?

[nocooler]

If you look at it - the glue might have melted out of it. It's possible to fix it.

[daveismissing]

You have both in there? Yes 2 bar for the stock gauge to work.

[daveismissing]

What chip are you using? Boost isn't used unless you got some kinky setup

[good2win22]

sounds like you need a new Map sensor to me

That's exactly what I was thinking when reading your post. 2 bar is stock and makes the stock dash boost guage work but doesn't read as much boost as a 3 bar will.

[Steve Wood]

Most of us would like to know what the boost is doing while we are looking at our PL files...and those of us that spray alky would like it to work correctly so we don't lose an engine

David, the three bar sensor must be used with the SM or PL to get the right answer above 14 psi.  You can select 2 bar sensor in the PL set up and get the correct answers up to 14 psi, I believe, altho I have never tried it.

[Just a Six?]

Thanks Guys I think my plan will be to look at my existing 3 bar for something obvious but I'll probably just order a new one. I got this one when I installed PL so that's at least 6-7 years ago from what I can recall? Maybe a local will have a spare if I get lucky? If not I'll see what the vendors have for sale. Cheers!

[Just a Six?]

Dave the chip is an Alky from Turbo Tweak for Power Logger & I think it has AF correction but I've never really gotten that far into it since the car is set at 21 lbs on the adjustable waste gate rod.

[Scoobum]

Call Norbs...he may have one. Mike Ricketts may have one to...tho he uses race gas like I do...but his dads GN may have alky for street use...so he may have a spare. Julios alky kit requires a 3 bar map sensor...the old ones from Steve used the 2 bar. Grab a 5.7 112 race chip from Eric...and turn the alky off. I'll come out to Cayuga and put the fukn thing on the back bumper for ya'. Tell him to throw 28 pounds of high gear fuel at it.

[Just a Six?]

Brad I don't know if I'll make it to Cayuga but I think I found a 3 bar to borrow & if not I'll try Norbs.
It's the ALKY Control from Julio. Maybe today I'll take a look at it to see if anything looks weird?
Only other thing I need to do is pull some fuel from my Cruising RPM's as it smells rich.
I have a Gen 2 but need to refresh my memory on how it works. Never really used it much after I set it up.

[daveismissing]

I forgot about the alky bit- being a teetotaler myself

[daveismissing]

If you look at it - the glue might have melted out of it. It's possible to fix it.

If I'm thinking straight an absolute sensor has a vacuum chamber reference internally. As long
as that is intact then sealing up any housing leaks should fix it as nocooler says.
Test it in water like a tire.