MicroSquirt.com read only forum (Jan.15,2018)

MSnS-E 029q2 mainboard V3 megatune 2.25 NA buick V6 oddfire TBI injected fuel only. LC-1 wideband


Well I did some quick tunning and got my popping problem settled down a bit I kept upping the VE bins in the problem area but now is there something else I need to look at my VE bins are in the 130's-150's and I still think I need to go a bit higher to get rid of the problem.And the rest of my VE table looks normal 40's to 110.
The motor seems to do it when I stab it hard and get it in passing gear going up a hill it will pull hard for a bit then just start to pop through the intake indicating lean making me back off.
So my question is do I just keep tunning till it goes away or is there something else I need to have a look at ?
Checking the plugs and the feel of the motor says to me everything else is great I just am afraid to keep going if I am going to hurt something.
Do need to do something with Decel?I have it set at 100 right now.
Thankyou guys for your time 71jeep

So my question is do I just keep tunning till it goes away or is there something else I need to have a look at ?

71Jeep,

This sounds an awful lot like a fuel system reaching it's limits. Do a datalog and see if the duty cycle is reaching 100%. If it is, all the tuning in the world won't help.

Then you'll have to figure out if it's the injectors limiting the flow because of their flow rating (see: http://www.megamanual.com/v22manual/minj.htm#size) - what is you req_fuel? - or if there is some restriction in the fuel supply system (could be a too small fuel pump, too small fuel line, too small or clogged filter, kinked fuel line, etc., etc.)

Lance.

Hi Lance ..

My Req Fuel is 8.6 I am using the external pump that is recomended in the Megamanual .
My injectors are two 45.9lb injectors the megamanual calculator calls for 47lb is this a big enough of a difference?
I am running 3/8 pressure line and 5/16 return the only thing I was going to do and did not is to run a sump tank could it be cavatating?
I guess I will have to take a look at the fuel system.
I will take a look at the duty cycle and see what I come up with to.
If I find a problem in my fuel system do need to go back and redo all my tunning or just the upper limmits?

Thankyou for helping 71jeep

Without doing any calculations I would have to say that the 45lb/hr injectors are more than sufficient for your application. GM 305s came with ~40lb injectors stock.

If you have to run that high a VE, you might want to look at your engine constants again. How many squirts? If you run more than one squirt per cycle I think it reduces the effective size of your injectors because of the opening and closing time overhead.

But I would like to see the duty cycle of your injectors, thats probably the first real indicator if there is a problem with the fuel system or if something else is acting up.