JPrevost

Okay, so it's a blown, intercooled, stroked, ported, cammed 93 Lt1. He's been having a REAL hard time getting it to run and I'm at a loss. I've tried giving it timing, taking it out, giving fuel, taking that out, nothing is fixing his problem. The engine feels fine when it's past 3500rpm with moderate throttle and up. Less, like just after a shift (this is a T56), and the thing bucks and backfires through the exhaust. The bucking is so bad that it's almost violent. I have a feeling it's ignition related but would it make sense that it clears up at higher RPM (not a lot of throttle just moderate) and brakes up with low RPM high throttle? He replaced the coil but not the ignition module. I have a feeling that this might be the problem so I'm having him go back to the stock coil and if that doesn't do anything I told him to decrease the gap on the plugs from 35 to 25.
In anycase, here's the real technical question; Since the VE tables top off at 100% and this engine should easily go above that with boost, what is the best way of implementing this using a 2-bar map sensor? It's got the 2 bar already running on the engine and it has 42# injectors. I turned down the FMU to it's lowest setting and then halved the injector constant and halved the VE tables. Wouldn't this theoretically be a multiply by 2, divide by 2 for the fueling? When I did this the thing started right up better than it had ever done and drove really good until we leaned into the throttle a bit. I know the AE is off but I figured with the supercharger and the backfiring he was having out of the intake that it would have fixed this... and it greatly improved. So is there a better method? I'm looking into how hard it would be to swap to the 94/95 $EE mask. I like that mask better for boost (MAF makes it easier). Any help or suggestion would be much appreciated because as of now I'm fresh out of ideas.

rooster433

Do you have any datamaster datalogs?

I've got quite a bit of experience on that subject actually.

RednGold86Z

iTrader: (1)

Let me start by declaring I have no LT1 experience. And, I have a terrible fever...
But, by halving the injector constant and halving the VE, the fueling shouldn't change, output wise.
It didn't compensate for the 2 bar sensor, though. Did you do something code-wise for the 2 bar? If not, well, once the throttle opens, the MAP will only go to about half of what it needs to get the right fuel. If you could double the displacement, you could get away without the other i.c. and ve change, but I have no idea how big that can go in the code.
If you did do something about making it 2 bar compliant, this is a useless post.

funstick

did anyone check inside the opti unit to make sure the rotor tip isnt scorched ???the other thing is a good solid ignition. the accel 300plus digital box work very well at curing alot of opti ignition problems. as for AE on that mask i dunno. but with a halved injector constant youll probobaly need to double the AE. the other thought im currently having is AE vs Baro. the baro at key on is 48-52 kpa now with a 2 bar map and at WOT its changing from 48-52 to 100kpa. under boost. ive got a feeling there is a conditiong multiplier. email me a copy of the file.