02BlackMachine

I recently raced a buddy of mines 2001 Z28 a4 stock , we raced on a roll about 35mph and he kept up with me and we were both on overdrive and my car has lt headers , knn filter , lid, slp loudmouth, quicktime performance y pipe with dual cutouts. It feels like my car lost power with these mods and i seafoemaed 3 months ago .. i have no tune after the headers ,can bad 02 sensors rob your horsepower???? Or do i need to change my spark plugs because i havent since i bought it brand new...car has 47,000 miles on it . i have an OBD2 scanner and it doesnt throw codes for front 02's except the rear ones . can it read good for the front 02's but still be bad 02 sensors in the front?

ae13291

iTrader: (8)

there is alot of things to consider man. you cant just judge it by racing a car! everycar is different! but change the plugs and clena the o2's for now. and make sure u dont hav spark knock!

02BlackMachine

spark knock is when it sputters and pop's when driving??

ae13291

iTrader: (8)

i meant lik knock retard! maybe the knock sensors are taking too much timing! but your cars sputters and pops??? thats not normal, seems like you might be running a bit rich, check the o2 sensors man

02BlackMachine

I think my 02 sensors are good ... as far as not throwing any codes except the rear one because i have race headers ....could this be a problem .....my car has shitty mileage

ae13291

iTrader: (8)

check the MAF sensor, u can try cleaning that and the tb and do seafoam mod, and change the plugs!

RooRnZ28

iTrader: (14)

get a tune and then you'll wax him

Badguy7

iTrader: (6)

Since you seafoamed the car 3 months ago, how many miles have you put on it??? If you've put atleast over 10k miles. You should seafoam it again, then do the following....

- Change Plugs & Wires
- New Fuel Filter
- Clean MAF & your K&N Filter (**** seem's to get dirty alot)
- Clean O2's
- Get a Tune for those Headers

Did you ever Tune Out the Rear O2 Sensors after you installed the LT's???

Im in the same process of doing most of this to my car. It's wasting gas alot more now, then it would. It doesnt seem to deliver all the power at times either. I do believe my O2's need to be cleaned though.

02BlackMachine

i never tuned out the rear 02's...as far as cleaning them how would i go about this.

davered00ss

iTrader: (4)

Your car is in limp mode from the code.

jsteele90

iTrader: (13)

tune that **** out and marvel at your newfound power.

Arc00TA

iTrader: (17)

Sweet jesus why do people run around with O2 codes and wonder why thier car sucks *****. Get it tuned to fix that problem and you will be fine. Alternately, you can just disconnect your O2's, front and back, and see how your car runs in open loop to get a taste of what it would be like with a decent tune.

Brock w/ da black Z

If you don't tune out the rear o2's your comp thinks the cats are not doing thier job and can cut fuel or run more fuel depending on the reading.... Someone mentioned limp mode which can also happen...... The popping you're hearing is probley unburned fuel in your exhaust igniting in the exhaust which means running rich and running rich can make a car fall flat on it's face at WOT...... Ever notice some black smoke out the back when you stomp on it ? Tune it, and watch it wake up......

1999 SS

iTrader: (3)

you might have the shitty 2:73 gears in your rear end and that will slow you down alot too.

94'BLKBRD

iTrader: (76)

Get rid of the O2 codes. If problem still persists than change the plugs/wires

wtomlinson

iTrader: (6)

if you can tune the o2s out so the car thinks the cats are good, will o2 sims do the same?