solarofthesix

ok...hooked the car up to a scanner. Trying to track down what is causing my bas gasmilage, running rich, and a lil performance hesitation.

came up with 2 codes. 91 (1-4 Lamp Circuit) and 18(injector circuit). I checked the ohmz on each injector and all were in the 12-14 range, didnt have a noid light, but removing each harness while running caused a momentary drop in rpm. I reconnected each one after blowing a little air in and this code appears to have disappeared. The other one is still in. I looked in a book and it says this is skip shift, i had this programmed out of hte computer so I guess that is why?

here is the info i gathered form the scanner at idle.

RPM: 990-1018
LInt: 122-125
RINT: 125-127
Ignition(v): 12.9-13.0
Spark Adv(deg): 23-25
BARO(v): 4.96
BARO(kPa): 102
Knock: 11
MAP(v): 2.1-2.20
MAP(kPa): 49-51
MAT(degF): 115
AirFlow(GM/SEC): 11.59-12
IAC Pos: 79-81
Left BPW(MS): 3.6-3.8
Right BPW(MS): 4.2-4.3
TPS(v): 0.66-0.68
A/F Learned: Yes
FT Cell: 16
Closed Loop
Left O2S(MV): 44-900
Right O2s(MV): 160-951
Left BLM: 117
Right BLM: 134

ok with all of waht given, would you say that the o2s are both dead? I have all of the emissions removed and a gutted cat. Also do all of these numbers seem about right? Any information would be great! thanks in advance

Dave89IROC

why do you think the O2s are dead?

solarofthesix

i thought they were supposed to only fluctuate between like 8-9?

ricehammer

O2's are fine. If they were shot, the output voltage would be low which your computer would take as a lean condition. Check out this web site, there's a write up about O2 sensor operation.

http://www.bobblick.com/techref/proj.../o2sensor.html

You might want to try and get some data while driving since this is when your gas milage goes south. If there's something in it, I'll bet someone on here can pick it out.

solarofthesix

thanks for the link! reading it now. I reved the car up and maintained like 3grand for about about 45 secs and it kept jumping around

ricehammer

The O2 readings should jump up and down. The ECM constantly regulates according to the high or low reading. Say the output is low, the ECM will interpret this as a lean condition and add gas which eventually will cause the O2 output to go high. The high O2 reading will be taken as a rich condition, the ECM will then reduce the amount of gas fed into your engine. Does it by varying the pulse with to the injectors. Back and forth is the way it works.

solarofthesix

ok so then no on the o2.....on ls1tech someone is saying that the split BLMs look a bit odd...what do you all think?

Injuneer

For a bit of insight into the scan data you've collected:

http://members.aol.com/InjuneerZZ/ScanMast.htm

Seems like you may have some programming and a cam. You need to include ALL the info like the engine modifications with a post like this, or you are not going to get accurate answers.

RPM: 990-1018 - Has your idle been reprogrammed? These readings are too high for stock programming.

LInt: 122-125
RINT: 125-127

INT's should average 128 over an extended period of time. If not, the BLM's will start to change to return the average to 128

Ignition(v): 12.9-13.0 - Normal

Spark Adv(deg): 23-25 - A shade high, but results from elevated idle speed.

BARO(v): 4.96 - Normal, for near sea level
BARO(kPa): 102 - Normal

Knock: 11 - Is this the knock count or knock retard?

MAP(v): 2.1-2.20
MAP(kPa): 49-51 - I'd guess this is not a stock cam. Not very radical, but not stock - correct?

MAT(degF): 115 - Unless the ambient air temp was 115*F, you have some heat soak on the IAT sensor.

AirFlow(GM/SEC): 11.59-12 - Higher than normal, but again reflects the elevated idle RPM

IAC Pos: 79-81 - Probalby needed to reach the reprogrammed idle speed. I'd try and cut this down to 40 or less, using the throttle stop screw.

Left BPW(MS): 3.6-3.8 - Reflects the elevated airflow, which reflects the elevated idle.

Right BPW(MS): 4.2-4.3 - Same as above. The "split" BLM's are causing the injector pulse widths to not be the same.

TPS(v): 0.66-0.68 - Normal

A/F Learned: Yes - Normal

FT Cell: 16 - Normal at idle

Closed Loop - Good

Left O2S(MV): 44-900
Right O2s(MV): 160-951

See my writeup for more info on O2 readings. Yours are normal.

Left BLM: 117
Right BLM: 134

Yes, they are "split".... drivers bank is pulling out 8.6% fuel to correct what the PCM perceives as a rich problem, passenger bank is adding 4.7% to correct a perceived lean problem. Not good, but not uncommon with an aftermarket cam.

You really need to provide a "signature" with some usefull info in it.

solarofthesix

crap thought I had all of that in my signature, thats why i didnt list it in the post.

mods tuned for:
LT4 Hot Cam Kit (cam, RRs, springs), K&N CAI, 160deg thremo, emission removed

On the programming. EGR was removed, Skip Shift, 160deg therm, Fans to come on sooner, and tuned for cam. Might be a few more things, but I beleive that is alll...

here in columbia, sc we are close to sea level, temp was around 93 outside yesterday the heat index was pretty high as well not sure if htat makes a difference, and this was scanned inside a shop without AC.

i do appriciate the help man!