Hey guys. I was wondering what the general consensus was to cure a surging problem on cold starts. Is it mostly in the ve table, raf, iac effective area, or timing department? thanks
Hey guys. I was wondering what the general consensus was to cure a surging problem on cold starts. Is it mostly in the ve table, raf, iac effective area, or timing department? thanks
98 M6 TA, mods: tsp torquer(233/233 .589 112), Patriot golds, ls6 oil pump, ls6 intake, tsp lid, pacesetter LT\'s and ORY, magnaflow, fra, HPTUNER!
In my observation it's mostly (mis)fueling though some
mods like lighter torque converters will aggravate it.
The idle control loop gets destabilized when things
change the "natural frequency" of the motor, its
response to steps in airflow as the IAC wants to do.
Sleepy O2 sensors, a stock VE table vs an aggessive
actual cam / heads / exhaust airflow, and elevated
idle MAP all contribute to rich mixture error - O2s in
closed loop, MAP via the Open Loop Fuel Air table
in open (duh) loop.
I'd start with truing up the VE table to the actual airflow
of the present combo, then look at where idle MAP falls
and shave back the OLFA table to improve cold idle
(you can use the in-car O2s during closed loop for these
if it appears to be "lit"; headers work against this though
at low exhaust flows).
Adding timing will help make the motor more responsive.
It's lag that seems to destabilize the loop. But I'd focus
on the fuel side first.
Right when I first start it its fine for a few seconds then it starts doing the minor surging until it hits closed loop. I have my olfa reduced to something like 1.13 in the areas where its doing it and my 02s were reading somewhere around 750 on the cold startup in open loop. I don't really want to reduce the ve much more b/c it seemed like when i tried that before it didn't behave as well when it was warmed up. Is it possible that being too lean can cause the surging? I also tried reducing the idle spark control and this seemed to make the surging worse...it would overshoot/undershoot worse than before.
98 M6 TA, mods: tsp torquer(233/233 .589 112), Patriot golds, ls6 oil pump, ls6 intake, tsp lid, pacesetter LT\'s and ORY, magnaflow, fra, HPTUNER!
ttt.
98 M6 TA, mods: tsp torquer(233/233 .589 112), Patriot golds, ls6 oil pump, ls6 intake, tsp lid, pacesetter LT\'s and ORY, magnaflow, fra, HPTUNER!
up top
SRT 10 without any mods. But still hella fun too drive.
93 fox coupe with a 427 in the works.
agin!
SRT 10 without any mods. But still hella fun too drive.
93 fox coupe with a 427 in the works.
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