I made my own boost leak tester and used it today because im tryn to figure out why it is i hit fuel cut at 10lbs of boost.The only leak i could find was a small vaccum hose attatched to the tb and the other thing is the bov didnt seem to hold at all the air would blow right through it.Maybe my issue?But i wouldnt think it would boost at all if that was it.
boost leak test
- Thread starter tomsupra8683
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hvyman;1756272 said:
+1 on that, if you pull it off and can blow thru it, its toast, as its only open under vac.
also 10 psi is stock fuelcut, so unless you've done lex/550 mod or something similar to boost higher, thats all your gonna get. (helps to post mods done to car)
Anywhere from 10 - 13 is fairly normal. There is more than one factor in the pressure there, and since your AFM is measuring volume, the cut psi can change due to elevation, air temp, etc. Typical rule of thumb is the colder and closer to sea level, the lower the psi of fuel cut. The higher the elevation and warmer the air temp, the higher the psi before cut. It can very easily make a difference of +/- 1 or 2 psi.
Vancouver, BC, Canada. Sea level. Air pressure (ambient 20 deg C) 14.7PSI. Calgary, AB, Canada, 3442 ft above sea level. Air pressure (Ambient 20 deg C) 12.7PSI In other words, you have to be running 2 lbs of boost in Calgary to get the same performance as at zero pressure in Vancouver. FCO difference of at least 2 lbs as well. A 5 deg C (9 deg F) change in temperature makes about a 1% difference in the air density(though not necessarily pressure) which will also affect FCO.
Add in that there will be differences in fuel injectors, AFMs and the like on 20+ year old cars, and 10 PSI is well within the realm of normal.
Add in that there will be differences in fuel injectors, AFMs and the like on 20+ year old cars, and 10 PSI is well within the realm of normal.
Mods are high comp pistons,na cams,divorced down pipe,2.5 inch strait pipe exhaust no cat meow,2.5inch intercooler piping,large front mount intercooler,open air filter.Fuel cut is deffinetly worse in the cold nite on the way home from work.I do live at sea level in tacoma washington.gonna try and replace the bov tmrw.
Large intercooler = denser air charge = FCO at lower manifold pressure. Sea level... 'nuff said. 10 PSI FCO is to be expected.
As we've been saying... Warmer temperature raises the boost level of FCO, as well as higher altitude (Though Costa Mesa is pretty much at sea level) as well as individual differences in 20+ year old engines.
yeah the exact point of FCO does vary by car and weather conditions, but generally speaking 10 psi is max without doing some upgrades to the fuel system.
well i installed a aftermarket blow off valve that i got from a friend and the fuel cut issue got worse.I think it may be because the bov has a nut and a bolt for adjustment on top and i have no idea how to adjust it correctly or why i would need to adjust it at all.I did score a lexus maf for free today so now i need some injectors and the money to buy them.
worse? that makes no sense, unless you got one that vents to air and not recirc like stock. got a pic of the new one?
yea it vents too air its the only spare i had.I need to buy a cammera so i can post pics.But yea hittn fuel cut in 2nd gear,i suspect the aftermarket bov leaks or may have to do with the nut and bolt on top thats adjustable.