Mediocre Performance?
Thread Starter
Staging Lane
Joined: Jun 2004
Posts: 76
Likes: 0
Mediocre Performance? I have a mazda Miata with an LS6 engine and a 4L60E transmission.
I have a 1999 TA PCM which I downloaded a 2002 stock Camaro bin into.
Using an a Gtech PRO accelerometer I measure HP (2nd gear) at about 205 HP.
I then ported the LS6 spark, fuel and air tables into the PCM (from a 2002 Z06 corvette bin).
I measure HP at exactly the same thing 205 HP.
I am at 6000' elevation but I that should have that much of a dramatic impact.
I also have a TCI streetfighter torque converter.
I replaced the MAF thinking that it may have been defective. No luck. Still same power output. My performace feels good, but not where I expect it.
Right now 0-60 is about 4.9 seconds. Given the weight of the car (2580 pounds) I believe it should be much better. Yes, there are some traction issues, but not in 2nd gear where I measure HP.
Intake Air Temperatures is cool and breathing shouldn't be restricted at this point.
I had the fuel pressure set at 58 PSI. After I put in the Z06 tables, I set the fuel pressure at 67 PSI to compensate for the Camaro injectors (26 pound).
Any thoughs would be much appreciated.
Sam
I have a 1999 TA PCM which I downloaded a 2002 stock Camaro bin into.
Using an a Gtech PRO accelerometer I measure HP (2nd gear) at about 205 HP.
I then ported the LS6 spark, fuel and air tables into the PCM (from a 2002 Z06 corvette bin).
I measure HP at exactly the same thing 205 HP.
I am at 6000' elevation but I that should have that much of a dramatic impact.
I also have a TCI streetfighter torque converter.
I replaced the MAF thinking that it may have been defective. No luck. Still same power output. My performace feels good, but not where I expect it.
Right now 0-60 is about 4.9 seconds. Given the weight of the car (2580 pounds) I believe it should be much better. Yes, there are some traction issues, but not in 2nd gear where I measure HP.
Intake Air Temperatures is cool and breathing shouldn't be restricted at this point.
I had the fuel pressure set at 58 PSI. After I put in the Z06 tables, I set the fuel pressure at 67 PSI to compensate for the Camaro injectors (26 pound).
Any thoughs would be much appreciated.
Sam
check the obvious first.
stuck throttle blade? unplugged wires? enough juice in the spark?
vacuum leaks? compression check all cylinders?
can you post some logs (which tuning software you using?)
stuck throttle blade? unplugged wires? enough juice in the spark?
vacuum leaks? compression check all cylinders?
can you post some logs (which tuning software you using?)
Thread Starter
Staging Lane
Joined: Jun 2004
Posts: 76
Likes: 0
I have a new set of the truck coils. Could this cause the problem. Seems to run fine...
My power is very good right up until the higher RPMS. Then it seems to be a bit sluggish.
The throttle blade is not stuck.
Sam
My power is very good right up until the higher RPMS. Then it seems to be a bit sluggish.
The throttle blade is not stuck.
Sam
Thread Starter
Staging Lane
Joined: Jun 2004
Posts: 76
Likes: 0
Originally Posted by Steel Chicken
check the obvious first.
stuck throttle blade? unplugged wires? enough juice in the spark?
vacuum leaks? compression check all cylinders?
can you post some logs (which tuning software you using?)
stuck throttle blade? unplugged wires? enough juice in the spark?
vacuum leaks? compression check all cylinders?
can you post some logs (which tuning software you using?)
Sam
Have you compensated the IFR table for the
high fuel pressure? If you're varying pressure,
is this a fixed and atmospheric-referenced or
a manifold-referenced reg?
I don't know as I'd trust the GTech horsepower
computation especially in a flyweight vehicle.
For relative improvement/not, fine; absolute
accuracy, read the fine print.
As to elevation, figure your torque and HP will
scale roughly as BARO/100kPa against the sea
level rating, and any reduction in MAP against
that is a further subtraction. If you see MAP=
BARO all the way out to the upshift, you're all
good on the intake side. Fuel/spark, valve events
and exhaust, is another matter. If your upshift
MAP is better than 97% of BARO then it's probably
not an intake side airflow shortcoming.
Sluggish at high RPM, look to your commanded
fuel air multiplier. COT or just dumb stock PE
table settings can take away a lot of output
as they throw down excess fuel. With all the
fuel system meddling I'd give that end a very
careful eye. Especially trying to raise the rail
to 67PSI, you may see that the flow-pressure
drop in the plumbing is -worse- in terms of
the deviation from idle to full flow demand,
and this is not a well modeled aspect of fuel
delivery. If the regulator is on the rails then
you have a bit less of that, until the pump
just can't support flow*pressure and then
fuel fade can be abrupt as the regulator falls
out of regulation. See this as an increasing
AFR error on the wideband relative to commanded,
with RPM, presuming low-flow is trued up.
high fuel pressure? If you're varying pressure,
is this a fixed and atmospheric-referenced or
a manifold-referenced reg?
I don't know as I'd trust the GTech horsepower
computation especially in a flyweight vehicle.
For relative improvement/not, fine; absolute
accuracy, read the fine print.
As to elevation, figure your torque and HP will
scale roughly as BARO/100kPa against the sea
level rating, and any reduction in MAP against
that is a further subtraction. If you see MAP=
BARO all the way out to the upshift, you're all
good on the intake side. Fuel/spark, valve events
and exhaust, is another matter. If your upshift
MAP is better than 97% of BARO then it's probably
not an intake side airflow shortcoming.
Sluggish at high RPM, look to your commanded
fuel air multiplier. COT or just dumb stock PE
table settings can take away a lot of output
as they throw down excess fuel. With all the
fuel system meddling I'd give that end a very
careful eye. Especially trying to raise the rail
to 67PSI, you may see that the flow-pressure
drop in the plumbing is -worse- in terms of
the deviation from idle to full flow demand,
and this is not a well modeled aspect of fuel
delivery. If the regulator is on the rails then
you have a bit less of that, until the pump
just can't support flow*pressure and then
fuel fade can be abrupt as the regulator falls
out of regulation. See this as an increasing
AFR error on the wideband relative to commanded,
with RPM, presuming low-flow is trued up.
Thread Starter
Staging Lane
Joined: Jun 2004
Posts: 76
Likes: 0
Thanks for all the advice. I will do as you recommend.
FYI: The fuel pressure regulator is about 4 inches from the fuel rail. It should hold pressure pretty well. The pump is a walbro 255 (I just replaced it).
The reason that I raised the fuel pressure was to compensate for the smaller camaro injectors (26 lb) vs the Z06 injectors (28.8 lb). I guessed that they would have had to use a shorter duty cycle on the Z06 (bigger injector) but that could be wrong.
Do you think I should drop the pressure again (58 PSI)?
Newer camaros and corvettes have the regulator sitting very near the tank. This will result in a drop in pressure at the rail as fuel flow increases.
Maybe I don't need to worry about this. Expecially here in colorado where atmospheric pressure is about 82% of sea level.
Sam
FYI: The fuel pressure regulator is about 4 inches from the fuel rail. It should hold pressure pretty well. The pump is a walbro 255 (I just replaced it).
The reason that I raised the fuel pressure was to compensate for the smaller camaro injectors (26 lb) vs the Z06 injectors (28.8 lb). I guessed that they would have had to use a shorter duty cycle on the Z06 (bigger injector) but that could be wrong.
Do you think I should drop the pressure again (58 PSI)?
Newer camaros and corvettes have the regulator sitting very near the tank. This will result in a drop in pressure at the rail as fuel flow increases.
Maybe I don't need to worry about this. Expecially here in colorado where atmospheric pressure is about 82% of sea level.
Sam
