knock sensative 5th injector???????? [Archive] - SaabCentral Forums

: knock sensative 5th injector????????

23rd December 2003, 05:54 AM
i was talking to a guy earlyer in the year and he was saying that his apc didnt control his boost pressure on his 900 all it did was messure knock and by connecting an led to a pin on the apc ecu the led would light up when the apc dettected knocking, well i have three questions.
1 which pin on the apc ecu do i connect to
2 would it be able to drive a 5th injector to try and stop knocking when it happens
3 is there any where on the engine that will take a second knock detector so i can fit 900 apc to the car aswell as my di/apc.
if the 5th injector only sprayed when knock was detected it would not use as much fuel as if it would if it spayed at a given boost level
but would it work any thoughtspeople

25th December 2003, 05:37 PM
You have an early non-trionic 9000 right? You may find more help on the 900 performance forum on this question because the early non-trionic and non-DI 9000s are basically the same as c900s.

I can't remember for certain the pin number for knock but I thought it was pin 19 (the c900 guys will know. It wouldn't be any use for running a 5th injector if simply set up to work when knock was detected because (a) you want extra fuel just before knock is detected and (b) the knock detector tends to 'flicker' when what you really want is a really good, sustained electrical signal to provide a decent dose of fuel.

Most people use a fifth injector based on boost pressure or, better still, mapped to include revs as well.


27th December 2003, 06:01 AM
thanks for that will have to think again then :idea