BabyGT

Something is releasing pressure, unless you got a puddle of gas under your car or in the engine bay it's not a hole in a line. And your pressure stays fine when running so it's not the pump. That means it's going somewhere, I'd suspect an injector just bad enough that the little bit it's loosing is just barely squeezing by until the pressure drops enough for it to seal itself. Try some injector cleaner, other than that, sounds like it's not really an issue.

SteelerNation82

In my case, after I shut the car down and left the gauge hooked up I noticed the pressure rose slowly up to 42PSI. When I came back to look at it about 40min later the pressure dropped to 30PSI.

Besides the starting issue after the car sits for extended periods, I do experience poor performance under light loads mainly in the lower RPM range below 2k RPMs

BabyGT

This doesn't sound like a fuel issue, I can't think of what it would be at the moment, but the rise in pressure is prolly from the fuel in the lines not moving anymore after shut off and the heat still coming off the engine heating up the lines and fuel without the fans and coolant circulating which will raise pressure a bit till it cools. That's my theory anyhow.

SteelerNation82

Thanks for the help

I datalogged the car late last night during a hwy drive. I ran live data as well as vehicle monitor test (mode $06). Keep in mind the car hasn't thrown an CEL's

When I open Test $53 which shows individual misfires, all of the cylinders show PASS with 0.00 test results except for #6 which came up 0.18 (max allowed is 33.26 or something). I suppose I'll have to look into this further (comp test, injector)

I also have a few failures when going into the HO2S functions.

Also, the 'Delta Pressure for Downstream Hose Test' came up as FAIL. Still can't put my head around this one. DPFE is new MC plastic unit (less than 8k miles). Both hoses are perfect, I've pulled them out for inspection and blew through them and also carefully ran a wire clothes hanger through them.

BabyGT

If it's leaking just a little it's not going to misfire noticeably, I'd start with that injector, try running some cleaner through it, can't hurt anything and it's cheap. I know it generally doesn't work but the cost versus the chance it will is worth it.

SteelerNation82

I'm afraid I've run probably 3 bottles of injector cleaner through the car in the course of 8k miles (2x Techron, 1 Regane). I don't drive it much other than just weekends since I walk to work.

When I replaced the fuel filter last year the original was still on there with over 100k miles and sure enough some nice blackness poured out of it.

I don't have a problem pulling the upper intake off (again) but is there a way I can test that #6 injector with it on? I'll have to take a look at it to see which way the connector is turned.