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Abnormal psychology Posted by Ari [Email]  (#2847) [Profile/Gallery]
(more from Ari) on Thu, 13 May 2004 12:55:00
In Reply to: FPR hose connection, Roy, Thu, 13 May 2004 08:26:18 Members do not see ads below this line. - Help Keep This Site Online - Signup |
Is this the automotive equivalent of "why did the chicken cross the road?"
By removing the line between the throttle body and the FPR, the FPR no longer sees engine vacuum. The FPR uses engine vacuum to keep fuel pressure constant - at idle (high vacuum), it drops the fuel pressure. It increases it as the intake manifold pressure approaches atmospheric pressure.
So what? By seeing atmospheric pressure all the time, the FPR provides max fuel flow. This effectively richens the mixture up at high vacuum. My guess - they had an idle problem, and they found that by running a richer mixture, the engine idled more smoothly. It also probably helped with a low-speed hesitation issue. Downside? Reduced gas mileage, increased emissions, and more carbon buildup on the valves. And done to excess, the opportunity to do the Amazing Exploding Catalytic Converter Trick. (Don't try this at home!)
Of course, plugging the throttle body nipple is required, otherwise the resulting vacuum leak would more than cancel out the extra fuel.
As to a cabin fuel smell, that could be due to the over-rich mixture. Not sure how, though.
I'll bet that if you hook the FPR back up, you'll find an idle problem. Of course, the solution is then to fix the idle problem. But that's for another post.
posted by 192.249....
, Thu, 13 May 2004 12:55:00 <-- Viewing This Message
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