92 silverado

iTrader: (11)

i have an m6 2001 z28 and my car keeps throwing both of these codes randomly but never at the same time. it hardly ever throws the P0174. i have cleaned the maf and changed the fuel filter. I was thinking the tune had somethin to do with it because the car has never had a good tune on it. i didnt want to take this thing from wilmington, nc to rpm in garner, nc to get it tuned just to find out i had to bring it home to fix something. i took out all the plugs and they all looked the same a little black. i found a broken wire going to one of the rear o2 simulators so i soldered that back together. also i took out both of the front o2's and heated them up a bit with a torch and wire brushed them clean. while the car was running i saturated every vacuum line and the whole motor with brake clean and rechecked the lines and couldnt find a vacuum leak. The car just surges sometimes at idle and seems like it doesnt know what to do with timing at low rpm (1500-2000) cruising.

92 silverado

iTrader: (11)

noone?

DrkPhx

iTrader: (15)

* Did you modify the MAF in anyway or replace it with an aftermarket unit?
* Are the front O2's switching within range at idle?
* Check the exhaust forward of the O2's for leaks. Also check the intake and TB for leaks as well.
* Are you setting any other DTC's?
* What datalogging software are you using? Most record history freeze frame data which shows the exact conditions (rpm, mph, ect load %, etc) the DTC were set. View this info before deleting the code.

Intermittent problems are harder to diagnose because they don't happen all of the time, but usually occur under the same operating conditions. That's why the freeze frame data is helpful. You can compare the conditions when the DTC is set and pinpoint the problem. Try resetting the fuel trims and run the car at idle to see how fast (and if) they come back on at idle.

92 silverado

iTrader: (11)

thank you for your response....the car takes around 40 miles for it to throw a light and the car does have an 85mm slp maf all i have is a regular code checker and all i can do is check codes as they come on. these are the only codes i throw and like i said 90% of the time its the P0171 bank 1 lean
here are the mods..........
6.0 lq9 out of an 02 escalade
-bottom end-
arp rod bolts
clevite coated bearings
moly rings
ported oil pump
stock 317 casting heads ported with a 3 angle valve job
dual gold valve springs
magic stick 3 cam advanced 4 degrees
rollmaster double roller timing chain
ls6 intake
bbk 80mm throttle body
centerforce dual friction clutch
aluminum driveshaft
k and n intake
85mm slp maf
pacesetter headers
off road y-pipe
magnaflow catback

edcmat-l1

iTrader: (10)

If you have a brand new MAF, chances are you just need a tune. If you still have the OE MAF, throw it back in there and see what she does.

DrkPhx

iTrader: (15)

Ed is correct about the MAF; switch to the stock MAF and the problem should go away. I had the same problem with a Granatelli MAF. The SLP MAF is modified which usually tricks the PCM to go lean.

92 silverado

iTrader: (11)

thanks guys i will do that till i get it tuned