heres the short short history

355 Speed Density
SLP LS1 injectors
FP set @ 38lb at idle

heres the deal

on start up, the car is dumping fuel like a mother. Dyno Don has hooked this up to a wide band O2 and in closed loop the sucker is dumping fuel to where is will not hold an idle at all. once the car reaches 130*, the car now holds an idle and acts normal, and the wide band reads its normal as well.

we have set the chip to read 28# injectors, so it pulses less.

we have check the chip and everything is correct. we have traced all the wires to make sure the MAP and all sensors are correct.

here is also another strange thing:

when cold, if you unplug the MAP or CTS, the car will idle.. now correct me if im wrong it should die. but it doesnt.

my guess is one or more of the injectors is stuck open. they are pretty new, but its possible.


we need help ASAP, we have ran out of ideas and really need some guidence. thanks in advance.

 

im not sure what the advertised flow rate is on the LS1 injectors, but you say the chip is programmed the drive 28lb injectors. you most definatley have too much injector. your modifications should have no problem getting away with 19 lb injectors with increased fuel pressure. or no larger than 22 lb. my old tpi combination used 19 lb on a 357 c.i., the car ran high 12s all day long. with the fuel pressure adjusted on the high side, around 50 p.s.i., we were able to make my 357 run pig rich with 19s, a tpi engine is very efficient in converting fuel to H.P..they yield a good BSFC. why not try swapping out the larger injectors for smaller ones. alot of people are trying to use too large an injector, and these engines just dont need that much injector. my 436 in my formula had 36 lb injectors and they were just plain too big even for my combination. ive had this combination running fantastic with 24 lb svo injectors with increased fuel pressure, and no more black smoke out the tailpipe. im not trying to be a know it all , but i hear of this same problem all the time. 30 lb would probably be ideal for my engine. just wanted too share my experiences with too large of an injector. ......tom

 

Don says that if you program the chip with a higher injector rate it makes the injectors pulse less so it wont dump as much fuel.

 

He is right. If you have a 22 lb injector, and add to the injector constant in the chip, the ecm thinks there are bigger injectors, thus cutting the pulse widths and cutting the amount of fuel being let through the injectors.

Anybody know the fuel rating of the LS1 injectors?? Is it the standard GM 43.5 or is it the 5x psi like the LSx cars run??

Its probably dumping fuel when cold and under 130* because its in open loop, and its using the MAP etc and other sensors to guess how much air is coming in.

 

does it make a difference that i have moved the intake air temp from the bottom of the plenum to just after the air filters in the black box?

 

better throttle response in warmer weather.

 

That's weird!?! I have the same problem with my 30Lbs SVO (maybe worst than you) and I got a chip burnt for my application and it runs very bad... In fact, my OE chip handle the 30's better when the O2 is detecting (in close looo). Now that I spoke with John from Fastchip, I will probably send it back to him for a double check. But he told me that there might be another problem. He NEVER mentionned that the 30Lbs were too big tho!!!???

I am still anxious and my buddy really think that it's a program problem. Did you finally settle yours?

Pat