Quote:
Originally Posted by flynjay
It is interesting that you are having this issue with the "injectors on top" install. I was assuming some puddling of fuel was occuring since the MAP sensor inlet is towards the bottom of the TB in the "injector on bottom installs.
But you having the problem means the injector pulse is continuing past the point where the cylinder is creating a vacuum in the TB therefore allowing the vacuum in the MAP sensor line to injest fuel when it equalizes to atmospheric.
Advancing the injector pulse timing should fix this. Basically you want a little airflow before and after the injector pulse so no residual fuel remains in the throttle body.
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It may be both, but I think its obvious that puddling is occurring.
Example: If you took a garden hose with a spray nozzle and shot it through a 12" hole in a board from 3 feet away, most of the water stream would go through the hole, but some of the spray is going to land on the board itself and start trickling down. That is what is happening with the throttle bodies.
In both kinds of install, the vacuum port is too close to the injector. But with the upside down installs, it does imply that the injector is drowning in trapped gas. One way to find out (for upside down people only) is to go for a ride, then remove one of the injectors to see if gas runs out.