Quote:
Originally Posted by 67ragtp
still has me stumped, the A/F at idle goes from 14.0 down to 13.7 at idle with the vacuum hose plugged and removed from the regulator. I waited until it was dead cold and it still seems to drop to 35 psi when I hit the throttle and it takes its time to return to about 40. Both filters are clear.
This may sound nuts, but is it possible for a new engine after about 750 miles to actually improve its vacuum response at the manifold? This thing seems like its pulling more vacuum now, even my old data logs show a lower KPA value at idle. When we did the tune on the engine it had maybe 10 miles on the engine.
I pulled the hose, plugged the line and have a solid 44psi always, as soon as I can get out I will se how it runs. Is it prefered to run a vacuum reference?
Thanks Rich
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most prefer to run it but I've never had a problem without on a naturally aspirated setup. If your tune is made to have it I'd run it.
It could be that you're making more vacuum. If the tune improves, more timing at idle, as the engine breaks in, etc. it can and will improve. Put a gauge on it and see. I just don't remember any regulators that change the psi more than 3-5 psi. Plus, it should go up under load, not down.
What size return line on the regulator, and what pump are you running? What filter are you running before the pump?
Jody