97 evap question?
Thread Starter
Burning Brakes
Joined: Apr 2009
Posts: 946
Likes: 2
97 evap question?
My corvette came with a blown ls2 and had serious issues with wiring routing, hose routing (had 2 PCVs routed to each other, etc).
EVAP purge vac switch:
He had the the evap purge vacuum switch (see pic) teed off the same line as the FPR. I hooked my FPR to vacuum and kept this module teed into that line. Now, I'm getting some random misfiring and sloppy idle at times. I'm wondering if this should be left open to atmosphere?
Hose routing diagram:
EVAP purge vac switch:
That diagram is about as useful as a wrench made of wet cardboard, but I don't see a second line going to the switch (and I don't see #7 connecting to anything but the FPR). Anyone know for certain?
EVAP purge vac switch:
He had the the evap purge vacuum switch (see pic) teed off the same line as the FPR. I hooked my FPR to vacuum and kept this module teed into that line. Now, I'm getting some random misfiring and sloppy idle at times. I'm wondering if this should be left open to atmosphere?
Hose routing diagram:
EVAP purge vac switch:
That diagram is about as useful as a wrench made of wet cardboard, but I don't see a second line going to the switch (and I don't see #7 connecting to anything but the FPR). Anyone know for certain?
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
The OEM FPR connects to a fitting on the AIR BRIDGE!
I had a 98 and remember it. I plugged mine with a small rubber plug!
I purchased a FPR improvement kit from ECKLERS that rerouted it to the PCV port. They claimed that the re-rout would lean a factory rich C5 for better performance. Did it help?? Who knows??
I never dynoed it or data logged it.
That would be my recommendation. Do some EFI Live or HP Tuners data logging and see if its running RICH or LEAN.
Bc
I had a 98 and remember it. I plugged mine with a small rubber plug!I purchased a FPR improvement kit from ECKLERS that rerouted it to the PCV port. They claimed that the re-rout would lean a factory rich C5 for better performance. Did it help?? Who knows??
I never dynoed it or data logged it.That would be my recommendation. Do some EFI Live or HP Tuners data logging and see if its running RICH or LEAN.
Bc
Thread Starter
Burning Brakes
Joined: Apr 2009
Posts: 946
Likes: 2
Running a stock 97/98 FPR to a vacuum source will allow you to set your IFRs to a single number (43 in my case) and the vacuum draw on the FPR will adjust your fuel pressure at the rails.
The way the factory has it set up, it is essentially mimicking a non-vacuum referenced FPR like in the returnless systems. In later years, GM abandoned this practice in favor of drawing a vacuum and letting the FPR do it's job. It's much easier to tune this way, no IFR tuning needed. I've done the OLSD and OLMAF tuning on the car already (and am debating just leaving it in OLMAF mode).
My main question is on the EVAP vacuum switch? Anyone know if the "extra" vacuum nipple is vented to air?
The way the factory has it set up, it is essentially mimicking a non-vacuum referenced FPR like in the returnless systems. In later years, GM abandoned this practice in favor of drawing a vacuum and letting the FPR do it's job. It's much easier to tune this way, no IFR tuning needed. I've done the OLSD and OLMAF tuning on the car already (and am debating just leaving it in OLMAF mode).
My main question is on the EVAP vacuum switch? Anyone know if the "extra" vacuum nipple is vented to air?
so I left it off...
