ok...don't spend much time at the top of 3rd gear WOT so the problem hasn't been noticed until now.

in second gear everything is gravy...~11.3 afr all the way to redline.

in third gear...approaching 6krpm it begins to break up...AFR goes to ~9.89. same thing when shifting to 4th, so it's only apparent when the motor is really being loaded down.

also this was at night...i'm going to give it a run tomorrow and see if it's possibly from running headlights and pulling too much current.

i don't think it's a lack of fuel but i'm a bit stumped.

ported S4 t2
rtek 1.8
s-afc
720/880
walbro 255lph
10psi on stock s5 turbo
9s all around
89 octane

 

I have the same prob with a e6x and i noticed the same thing about having my lights on. But i blamed the after market hella projectors noticed my tach is off at the same time this happens about 500-1000 rpm It did get better when i switched to some different coil packs !

 

9's for AFR would be too much fuel, not a lack of it. So your plugs could be fouling, or if you just need a tune. Sounds like you need to get on your AFC and lower the fuel that the car is getting at those higher RPms, Work it out so that your getting a soild high 11 at that higher RPM. If worst comes to worst and nothing your doing on the AFR is working, and the AFR's are still jumpin around, you could have my friends problem, which is a cracked wastegate arm. So try those things see what happens, let me know.

 

well i was thinking the missfire was causing the rich readings.

i may try switching back to 7s on the leading as well.

 

with the 7s i did a 3rd gear pull with the headlights off...everything was fine.


headlights on...the AFRs started creeping up toward 11.57 at redline.

it appears i don't have enough juice to push the fuel pump :[

so, would a fuel pump rewire solve this? or is my stock alternator just not adequate?

this car is also equipped with an electric fan that runs while the engine is on.

 

uhh there is no way you should be running 7's in the leading. Only stock or near-stock turbo cars should run 7's. Change all the plugs and see what happens. If you still get breakup, you need an ignition amplifier like an MSD box or an HKS twin power.

 

i don't feel like im making nearly enough power to have to upgrade the ignition though...

i may try a spare set of plug wires, but the ones on the car look to be in ok shape.

i guess ill toss the 9s back in. what sort of whp does the colder plug become a necessity? i doubt mine is making more than 230 at the wheels due to the turbo falling off so much in the upper rpm.

 

well this is lovely...wanted to check my fuel pump voltage.

so i hook up a volt meter and crank the car up to make sure im on the right wires..

4.3 volts at idle -_-

so i check one of my tail lights...10.2 volts...

so i check the battery...12.2 volts. at idle. headlights off. awesome.

unplugged my fan and only got .2 extra volts. swapped alternators(all i could find was a GSL-SE alt 60amp) and the problem remains.

so..i'm in the market for a higher amp alternator it seems.

 

it's supposed to be lower voltage at idle (though not necessarily 4 volts). search "resistor relay"

 

well the car is a bit strange...i'm losing voltage somewhere.

my volt meter in the car only reads as high as 12 volts, while at the battery i can see as much as 14 volts at 1,500rpm.

i tested voltage on both sides of the resistor and only saw 10.50 volts on one side, and 7.9 on the other.

i'm going to rewire the fuel pump after i go buy some wire. also i regrounded the fuel pump and picked up around .5 volts at it.

still...something in the car is robbing 2 whole volts before it gets to the electronics.