air/fuel mixture
07-14-2005, 10:20 PM
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air/fuel mixture
On my 951, my bypass valve was bad, so I'm got a new one, and it doesn't want to idle. I'm thinking that the previous owner set the air/fuel mixture to work w/ the leaking valve. Now how do I change it back to what it should be?
*And the valve is getting vacuum, so thats not the problem*
*And the valve is getting vacuum, so thats not the problem*
07-14-2005, 10:24 PM
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what are the mods on the car? to control the air fuel mixture u have to have fuel controller of some type like the arc-2.i can PM u my # and i can try helping u through it since i live in colorado too.
07-15-2005, 06:32 AM
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"*And the valve is getting vacuum, so thats not the problem*"
It's not a matter of getting vacuum in black & white, all-or-nothing, yes/no terms, but exactly HOW M UCH vacuum is the real question. You need to get a vacuum-gauge and vacuum-Ts and measure vacuum at various points in the car:
- KLR line near KLR box
- FPR
- fuel-dampener
- compressor-bypass valve
When the engine's cold, it should be getting 12-16 in.Hg at all these points. And warmed up is 18-22 in.Hg at all these points. Most likely the FPR has the highest amounts of vacuum because it's hooked direclty up the intake-manifold with its own vacuum line. Then the others will be lower since they are T'd off the same banjo and all the multiple hoses ends up with various leaks here and there. You can however, get identical vacuum at all those points at idle when there's no leaks.
What happens is the leak cause less vacuum at the FPR than the design specs and the FPR doesn't reduce fuel-pressure enough. The richer mixture ends up causing stumbling. The other possiblity is you've got a leak in your J-boot somewhere in the process of installing the bypass-valve. There was a guy with a 944NA last week that had a very bad idling and running problem and it turned out to be a leak in a hose somewhere... of course at the time, he could've sworn that all the hoses were tight...
It's not a matter of getting vacuum in black & white, all-or-nothing, yes/no terms, but exactly HOW M UCH vacuum is the real question. You need to get a vacuum-gauge and vacuum-Ts and measure vacuum at various points in the car:
- KLR line near KLR box
- FPR
- fuel-dampener
- compressor-bypass valve
When the engine's cold, it should be getting 12-16 in.Hg at all these points. And warmed up is 18-22 in.Hg at all these points. Most likely the FPR has the highest amounts of vacuum because it's hooked direclty up the intake-manifold with its own vacuum line. Then the others will be lower since they are T'd off the same banjo and all the multiple hoses ends up with various leaks here and there. You can however, get identical vacuum at all those points at idle when there's no leaks.
What happens is the leak cause less vacuum at the FPR than the design specs and the FPR doesn't reduce fuel-pressure enough. The richer mixture ends up causing stumbling. The other possiblity is you've got a leak in your J-boot somewhere in the process of installing the bypass-valve. There was a guy with a 944NA last week that had a very bad idling and running problem and it turned out to be a leak in a hose somewhere... of course at the time, he could've sworn that all the hoses were tight...
07-16-2005, 12:01 PM
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Well i went ahead and just tried the new factory bypass valve i got later yesterday, and now it works great, must of been something w/ the other valve of my boss'. Anyways thanks for the help, but allswell now.
