Trip/milage computing
Thread Starter
Burning Brakes
Joined: Nov 2000
Posts: 810
Likes: 4
From: Austria
Trip/milage computing
hi all
there was a thread a time ago, unfortunately i haven´t found it...
topic was.."tinkering with the trip/milage computer.."
anyways, i installed 42# injectors, and changed the constant at
L8824 (FCB824) from HEX 76 to HEX E1
im getting now exorbitant high readings, thats just unbelievable..
can someone bring light in this situation?
thank you
there was a thread a time ago, unfortunately i haven´t found it...
topic was.."tinkering with the trip/milage computer.."
anyways, i installed 42# injectors, and changed the constant at
L8824 (FCB824) from HEX 76 to HEX E1
im getting now exorbitant high readings, thats just unbelievable..
can someone bring light in this situation?
thank you
Melting Slicks
Joined: Aug 2003
Posts: 3,389
Likes: 391
From: Lakeville MI
I was probably involved in the original thread along with Trog and others.
Found it:
http://forums.corvetteforum.com/show...hlight=display
Have the normal (single fire and double fire) injector constants been increased to the appropriate values also?
A mismatch here could cause the behavior you described (very high indicated fuel consumption) since the injector pulses would still be long (assuming 23 #/hr constants) but the displayed fuel rate would be about double.
Increasing the injector constants will shorten the injector pulse width, so the increased display rate change should offset this.
Note: changing these constants, if not already done, will condiderably lean out your tune, so you will need other changes to compensate.
I have to do some digging to verify the addresses for a 90 bin, but it sounds like your change has had an effect on the displayed mpg.
Found it:
http://forums.corvetteforum.com/show...hlight=display
Have the normal (single fire and double fire) injector constants been increased to the appropriate values also?
A mismatch here could cause the behavior you described (very high indicated fuel consumption) since the injector pulses would still be long (assuming 23 #/hr constants) but the displayed fuel rate would be about double.
Increasing the injector constants will shorten the injector pulse width, so the increased display rate change should offset this.
Note: changing these constants, if not already done, will condiderably lean out your tune, so you will need other changes to compensate.
I have to do some digging to verify the addresses for a 90 bin, but it sounds like your change has had an effect on the displayed mpg.
Last edited by tequilaboy; Apr 14, 2007 at 05:11 PM.
Melting Slicks
Joined: Aug 2003
Posts: 3,389
Likes: 391
From: Lakeville MI
My bad, it seems the 8D mask only has the single fire constant, and not both like the earlier MAF masks (6E, 32B, 32, etc). Sorry for any confustion.
I'm not that familiar with 8D or speed density.
This value is found at address L841C. This is likely the value you have already adjusted in the constant table. So it sounds like you got it.
Perhaps your running into fixed limits or offsets in the injector pw calculation that are affecting the results.
I'm not that familiar with 8D or speed density.
This value is found at address L841C. This is likely the value you have already adjusted in the constant table. So it sounds like you got it.
Perhaps your running into fixed limits or offsets in the injector pw calculation that are affecting the results.
