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injectors to large?
Posted: Mon Mar 29, 2010 4:46 pm
by Fullhouse
I am running 43lb pico (eldelbrock) injectors at 45 lbs of pressure, Having a hard time getting this thing to idle. (rich) I was wondering if turning the pressure down will help? Maybe the injectors are to big?
I have a 462 ci and I was wondering what size injectors and fuel pressure other people that are using Pontiac motors are set up at? Naturally aspirated of coarse.
Re: injectors to large?
Posted: Tue Mar 30, 2010 4:07 am
by Matt Cramer
The engine may like to idle slightly rich, like 13:1, and this is pretty normal. You should be able to get away with injectors that large; we're running bigger ones on a 1.6 Miata...
Re: injectors to large?
Posted: Tue Mar 30, 2010 6:36 am
by Bernard Fife
Fullhouse,
As Matt correctly says (as always), those injectors should be fine.
Just too add some info, one thing that can cause a too rich idle is having the injector opening time set too long. If you have it set to 1.0, you might try 0.9 or even 0.8. This will require a retune of the VE table around idle conditions, but might give you much more control over the fuel.
Other things that might cause a rich idle include:
- having EGO feedback on and having a rich misfire (the misfire will drive the fuel even richer), make sure EGO control is disabled at idle (most codes have a 'minimum rpm for EGO control' setting - you should make sure it is set at least 200-300 rpm higher than your highest cold idle speed)
- a damaged diaphragm in the fuel pressure regulator (the fuel can be drawn directly into the manifold by the intake vacuum).
If you post a log of the engine at idle, we might be able to comment better.
Lance.