gday guys,
im having some issues with idle control related to load.

im running a lt12s, the idle will be solid during the day at 880rpm 18"hg
at night tho with lights on the idle will drop down to around 500 causing the car to start hunting wildly
the vacuum then varies between 16 down to 12 " hg

is there a way adjust to compensate for this.

the only way i have been able to deal with this so far is adjusting the idle up at night time to the point where it doesnt hunt (1050rpm to 1100rpm)

ive tried putting more fuel in at screen 1 (idle) at the appropriate points but it did nothing ... actually made the car seem to get worse what am i doing wrong.

my cars had 20 plus hours on the dyno everything else is setup perfectly.. just this idle is bugging me

my idle settings on screen 29 should be ok
#1 = RPM_on = 3000
#2= MAP ON = off
#3= aux RPM OFF = 5000
#4= auxFanadd = 0.10
#5= auxFan Air = 0.29
#6= auxAir Min = 10.76
#7= auxAir Max= 12.14
#8= auxAir wat= 0.71
#9= auxAir afr= 10.00
#10= Rpm Set= 0880
#11=auxpmwLow= 1.00
#12= auxpmwHI= 12.14
#13= inp Rpmlim= off
#14= inp air add = 0.86
#15= inp enrich = 0.24
#16= timing= 00

heres a link to my screen 1 pic sorry i couldnt work out how to post pics
http://img28.imageshack.us/img28/1697/idlejw.jpg

 

Looking at you HG it's street ported right?

 

91 S5
Street port turbo 2
T70
750cc primarys
1600 secondary


Screen 1
30-0.14
25-1.52
20-2.33
15-1.71
10-1.95
5-1.95
0-2.62
2-3.48
4-3.48
6-3.81
8-3.86
10-4.43
14-4.62
16-4.95
18-4.95
20-4.95

 

yeh its a street setup. i tried adjusting the 12hg point it made the car run worse tho

 

What about your air temp is it working properly? Check for vacumn leaks that causes idle issues as well ....

 

Are you using a BAC valve?

Without the valve, higher load on the engine by the alternator will always cause the idle to drop. You can compensate a little by richening it up a bit and giving it more timing. That's about all you can do other then just turn the idle up.

The LT12 supports a BAC valve, doesn't it?

 

need more info, like injector setup , if in matrix mode, do you have the BACv hooked up and also what is specifically in screen1 idle/500 rpm settings
clearly by the vac scales i can see it has a 3 bar map
( need data for all bins vacs 30 down to 12 in Hg )
also need same data for the load screen 2 and 3 ( or screen 8 if in normal mode )

also,, who's tune is it ,, mic, mick or mike ?

i see several potential moves to make but need to know more about the setup

ie,, if BACv,, we can play the setpoint and the aux air min/max values

if no BACv we can lift the idle stop position , tune the car with the lights on

if matrix mode then you may find you have to tweak the 500 map to be similar to the 1000 map

if in normal mode you may find you have to bring the 12 inch Hg screen 1 map similar to the 18 inch Hg map
( and also the 24 and 30 " maps same as the 18 one to prevent decel / braking dips )

the issue may also lay in the wax cam or dashpot hanging up as the engine warms to throw out the TPS cal and thus make the engine idle on the load maps
- you need to be sure the TPS cal is happy cold and hot,, and be sure the wax cam if delete cooling flow is wired out of the way so its mechanism does not passively play


------------------

personally i think the idle set point is too low for a ported engine , needs to be closer to 1000 and setup fully warmed with the lights on
also,, the min and max aux air values supplied for the BACv ( if fitted ) are a little whack and they need to be played with
and also the BACv checked for operation and flow
( no carbon blocking the manifold port )

my observation of the idle map is that this is possibly a roto's tune for 12at - 1000 cc primary injectors with 1600 secs and the stage% number is 95% +
( thus realtime the idle numbers are 1.8 -2.20ms,, 1.8 would be 1000 cc,, 2.2 is for the 12at injectors )
however,, at idle 0.95 - 1.14 is what i expect in the map table
( adding the 95 + % value in the staging % )
as such you look a little rich at 0 psi [ usually a bandaid over a staging hole at this point ]

PS
can you relate to us what happens with the displayed voltage when your at idle with lights on
may well be an issue with the field for the alt switching , or slipping belt
micro has no battery latency correction,, low volts means slower reacting injectors with worse dead times= less fuel

 

sometimes i have seen these symptoms on micros as they are very sensitive to the voltage and the wiring config

you may find you have your micro red wire taken from the alt ,, and instead it really needs to come from a battery feed,, at worst from the EGI/ main fuse bus or starter motor connection
( for moved battery installs )
[ to get a cleaner DC that is a steadier supply ]

PS
also suspecting you have a late alt that you need to lift revs to self excite the charging circuit
and fix may be a simple correction in the wiring or maybe adding a 30 watt resister

 

gday mate,
thanks for the info., the car was tuned by mick from rotormotion ages ago.
its actually a 300 zx not a rotor sorry for the confusion, running a lt12s.
you guys seem to have all the information about the microtechs.

one thing i have noticed with the microtech (plug and play harness) is that the battery voltage displayed on the microtech is slightly lower then the voltage at the battery itself im not sure if that could be a issue in itself. id rather not go hacking up my plug and play harness tho

battery reads 14.4 volts at idle yet the microtech only shows 13.8 im not sure if that has something to do with it .
car is tuned in both normal and matrix mode aswell.

ive never heard about the resistor trick before.. how does that work.
the car is running a standard idle valve aswell.

tps cal is spot on aswell. and the car has no errors. it did flash a Batt error the other day but i havent seen that since.. weird..

battery is fully charged (trickle charged )