No Boost Days....

Ok, this is something i've noticed, and so has pureadrenaline, (who has the prob at the moment and is dynoing this arvo).

have you guys noticed that some days or sometimes your car just doesn't want to boost, like nothin comes up on the gauge and you can feel it's just not working? it happens from time to time with both our cars (pretty standard JDM turbo's) but it comes and goes and aside from no boost doesn't show any other signs or problems...

has this happened to you?

Knock maybe ...
http://www.jekylhyderacing.com/knock.htm

... or maybe something is tripping your T-VSV and limiting your boost (too cold ambient temps, coolant temps too cold, etc.)

i dunno, but whatever it is it did it right in the middle of the dyno run.

boost dropped right off, air/fuel went way rich power and torque died (60mph in 3rd)

ended up getting one ok run but it showed we weren't imagining it.

no codes came up when we checked the check engine light thing... graphs will prob be up on MR2OC as soon as we can work out how to post them...

if it starts knocking wouldn't there be a code for it?

You only get a code for knock is you knock excessively ... usually resulting in a broken knock sensor.

Your engine hears knock ALL the time, it's just a matter of how much and how it responds to it. It is part of the normal operation.

Interesting though that the fuel air was bellow 10:1 (rich) and boost was about 7psi

If you are running too rich (which you are), you also run the ris kof detonating.

If you were only making 7 psi of boost, that is an indiation that the ECU was limiting your boost for some reason. Something it not right there. You should easily be able to hit 11 psi without any mods to the car.

thing is it doesn't do it all the time.... it did it on the first run, stayed like it for the second, then the third was ok... boost was still below where it should be but power was ok..sort of... for stock. and the graph looked a lot smoother.

if it did it all the time it might be a lot easier to find and fix... the ONLY diff on the last run was that sensor was unplugged so no boost gauge and no fuel cut... but the fuel wasn't cutting anyway! so i don't think it was anything we did that brought it right, makes it hard to go through and work out what it is when it randomly does it and then runs ok.

ok here's the graphs. 1st run is red, 3rd run was an hour or so later in blue. only difference was the vac line to the fuel cut/boost gauge sensor was disconnected.

power
http://files.automotiveforums.com/gallery/watermark.php?file=/503/195871dyno1small-med.jpg

air/fuel and boost i THINK
http://files.automotiveforums.com/gallery/watermark.php?file=/503/195871dyno2small-med.jpg