Car seems to be down on power, where to start looking?

[alkemyst]

I have new plugs (NGK Vpower), wires, injectors (stock 270cc), fuel filter, exhaust and hi flow cat, header, did the 248/232 cam swap (248 is +2.5 adv), injen intake.

Car doesn't seem like it wants to launch hard...anything I can look at for the 'tune'.

Timing is at 20BTDC. I have a OBDII reader that can check O2 volts, temps, etc.

The clutch doesn't seem to be slipping.

I am curious to the O2 sensors...my MPG (mostly city about 5 miles back and forth to work) is only 16-18MPG.

Here is a data dump.

Calculated Load: 24.7%
Coolant Temp: 171F
Short Term Fuel Trim B1: -5.65%
Long Term Fuel Trim B1: 2.3%
Manifold Pressure: 9.8 inHg
Engine RPM: 1000 (788 without A/C on)
Ignition Advance: 20deg
Intake Air Temp: 117F
Air Flow: 0.7 lb/m
O2 B1,S1: 60-800 mV
O2 B1,S1(Fuel Trim): -3 to -7 %
O2 B1,S2: 680-740 mV
O2 B1,S2(Fuel Trim): 99.2%

Thanks

Å

[Mikey213]

Try.a.lighter.flywheel.and.a.LSD/welded

[alkemyst]

have the lsd...wasn't looking to keep trying though. A lighter flywheel should always help, but is probably not a solution to a problem.

I am thinking although my clutch isn't slipping that I can see it probably is.

[LA_phantom_240]

Doesn't launch hard? Look at motor/tranny mounts. Mine are toast, and it lurches....

[infinitexsound]

i honestly dont understand if your trying to produce more power or trying to solve a mechanical issue.....

[tt99ol]

your vacuum is at 9.8 inHg at idle?
that cant be right
those cams aren't big enough to cause that
maybe vacuum leak

[SoguRacing]

manifold "vacuum" at idle should be 17-21 inches of mercury. yours says pressure so that would be negative 9.8 right? bad intake valves/vacuum leak? your short term fuel trim is rich that's why your short term fuel trim is -5.% you want those to hover around zero. O2 B1,S2: 680-740 mV i think bank 1 sensor 2 is bad. it should read min voltage of <200mv - >800mv but less than 1 volt. your range is way off thus your ecu is getting a mis calibrated signal and making you run rich.

[DudeYourSoOOJDM]

Compression test?

[ngibson]

Check your ground connections as well. I had a problem with low end big time, it would hesitate like all hell then pull like mad. Turned out the ground connection to the chassis from the negative terminal of the battery was very corroded - a quick check with an ohm-meter showed it had very high resistance.

[alkemyst]

Doesn't launch hard? Look at motor/tranny mounts. Mine are toast, and it lurches....

New nismo motor and trans mounts.

Check your ground connections as well. I had a problem with low end big time, it would hesitate like all hell then pull like mad. Turned out the ground connection to the chassis from the negative terminal of the battery was very corroded - a quick check with an ohm-meter showed it had very high resistance.

I will check that...I upgraded the grounds, but you never know...

Where to you check at ground point and battery neg post?

Compression test?

did that 175 on all 4.

[koukimonster139]

seems like its running too rich when you dump it and then clearing out after it starts revving



whats fuel pressure like?

[alkemyst]

manifold "vacuum" at idle should be 17-21 inches of mercury. yours says pressure so that would be negative 9.8 right? bad intake valves/vacuum leak? your short term fuel trim is rich that's why your short term fuel trim is -5.% you want those to hover around zero. O2 B1,S2: 680-740 mV i think bank 1 sensor 2 is bad. it should read min voltage of <200mv - >800mv but less than 1 volt. your range is way off thus your ecu is getting a mis calibrated signal and making you run rich.

I didn't check the O2 S2 actively like the S1...I thought the S2 was only used to check if the cat was good and not for any ECU changes.

The OBDII shows Manifold Pressure inHg...it's not shown as a negative number. I checked again and some cars show 9.8inHg at idle would be normal. I will recheck and use my brakes to see if this number changes properly.

If it is a vacuum leak, where do I start looking?

[alkemyst]

I can't find the info on how much the brake booster should affect manifold pressure.

Mine was 10.1 inHG today and went up to 11.5ish when I release the brakes and then back down.