I'm going to make a few statements that others may not agree with. Here goes:
Low ambient temperatures may make testing the fuel pressures difficult. If you don't have a heated garage, it may make more sense to ignore that for a bit and focus on eliminating unmetered air until the ambient temperatures rise. The important part: Focus on one or the other - not both. If you start chasing air leaks then please ignore system pressure and control pressures for a while.
I have used two different methods to reliably find air leaks:
#1 - Smoke test with a smoke machine - Lots of threads here on that. Cap the exhaust pipe, remove the air duct and cap the throttle body, connect a smoke machine to a vac port on the air box, and watch for leaks.
#2 - Soapy water with the shop vac test - Remove the air duct and cap the throttle body. Connect a shop vac in blow mode to the tailpipe. Spray a little soapy water on all joints (including every air box seam and connection) and watch the bubbles.
CAUTION: For both tests, you want to limit the air pressure inside the intake system to a couple inches of water or else you will damage things.
You need to treat the air leaks and pressure issues as two separate issues. Fix one, then the other. Checking / fixing air leaks first makes sense as you then only have to set the idle/mixture and ignition timing once.
While you're in there, you can make sure the air flow metering plate rests where it should and is centered in the bore.
Everything from here on out assumes the air leaks are sealed (as well as they get).
Quote:
Originally Posted by McGalliard
Latest round of pressure testing, basically done at 10 deg C, the bottom of the temp/pressure charts.
CCP - 1.6 bar
SP - 4.55 bar
WCP
@ 4.5 min - 2.7 bar
@ 7.0 min - 2.95 bar
So it would seem CCP is a touch high. SP is in the lower end of the normal range. And my notes say WCP should be 2.9-3.1 bar, which it eventually is but maybe it needs to get there in 3-4 minutes instead of 7 min. Does it matter that it takes a little longer to plateau at that level? These numbers obviously aren't as bad as we originally thought. Doesn't feel to me like they are so out of whack as to be the source of hard cold start, rough early idling, and a poor air/fuel mixture.
Where do I go from here?
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Question #1: Did you ever validate your pressure gauge against another known pressure gauge? If not, please do so (just to ensure the pressure readings are meaningful).
My opinion (which assumes that you have a good, working gauge): Your system pressure is on the bottom edge of the limit and needs to be adjusted back up toward the 4.9 bar range as a starting point. CCP / WCP don't matter unless the SP is correct.
Question #2: Do you have vacuum applied to the WUR for your test? If not, you need to (and see the WUR chart for the correct vacuum amount).
The -009 WUR uses a vacuum enrichment system: Vacuum drops at wide open throttle, the control pressure drops, the air sensor raises a little extra, and you get richer fuel mixture when you need it.
Please retest with both vacuum applied and without and report both. It's relatively easy to do - Hook a vac pump to the vac fitting. Apply/release vacuum when cold and again when warm.
Summary for the next pressure test:
#0 - Wait for warmer temperatures and seal air leaks while you wait; put the air flow plate in the correct position. This won't affect the pressure test but it will affect drivability eventually and you will make progress.
#1 - Validate the gauge is good.
#2 - Get system pressure back toward the top end of the setting spec.
#3 - Test control pressures with and without vacuum applied to the WUR.
#4 - Report back.
Once we've got air leaks sealed, air metering plate in the right place, and a confident pressure test - then we can figure out what needs to be adjusted.