cis injector fuel quantity

T77911S · 04-15-2008, 03:34 AM

i adjusted the valves this past weekend so the week before i took out the injectors at let them soak in carb cleaner. i connected them to the fuel lines then put the all the ones on the left side in a bottle and all the right in a bottle so i could check the spray pattern. i had one on the left with a different/bad pattern than the rest. anyway, when i was done, i weighed the fuel from the right side, 792 grams, i pured it out, then poured the fuel from the left side into the container from the right, (to elimate the container weight), well, it was 680 grams. so, is 110 grams enough to worry about?

also, when i started it back up, it was smoking. after letting it warm up, when i would blip the throttle, the rpm's dropped like it was rich. so i leaned it out about an 1/8 th of a turn and that cleared up the smoke. there is still just a very slight dip in rpm. do you think that cleaning the injectors is putting more fuel into the engine making it run rich? i had been getting a little spark knock at high rpm which is why i was keeping it slightly rich so maybe this will help with that.

stlrj · 04-15-2008, 05:39 AM

Slight dip from blip along with knock at high rpm means it's still too rich.

T77911S · 04-15-2008, 07:07 AM

i have not driven hard since all this so i dont know if it still pings. also, timing is set to 0 TDC. my point was that with nothing else changing, i had to lean it out an 1/8 th of a turn to get the mixture back to where it was. so the cleaning seemed to have some effect and maybe i can lean it out some more without worry of spark knock.

stlrj · 04-15-2008, 08:07 AM

[QUOTE=T77911S;3887431 and maybe i can lean it out some more without worry of spark knock.[/QUOTE]

Leaning will help prevent knock. Rich mixtures have the tendency to produce the highly reactive free radicals that are responsible for uncontrolled combustion resulting in knock.

Paulporsche · 04-15-2008, 08:44 AM

If you try leaning further do so in as small increments as possible, say 1/32 or 1/16 turn. Conventional wisdom says to adjust from lean to rich. If you believe that, you would go slightly past where you want, then come back each time. Personally, I don't know how the car "senses" this, especially since the engine would be off while adjusting. Maybe that advice only pertains when the adjustment is done while the engine is running.

T77911S · 04-16-2008, 03:49 AM

my real concern was the different amount of fuel supplied to the left and right sides of the engine. 792 grams for the left and 680 for the right. is there a tolerance for injectors? kind of like doing a compression check, all cylinders should be within 5 or 10% of each other. i did not have a way to accurately measure the amount of fuel so i thought i would use our postal scale and weigh it.