My IAC position is 0 at idle after adjusting? need help.

[Abdullah]

today i begun tuning the idle of my car. the mods are in the signature. after turning the idle screw and unplugging the TPS and then keyying on the engine for 30 sec. then keyying off then plugging in the TPS and starting the car and repeating that many times the IAC position settled at 0!. i use hp tuners for tuning, here are the data from the VCM scanner :

TPS voltage = 0.82 v
TPS % = 1%
idle RPM = around 1000 RPM
IAC position = 0
IAC desired position = 0
fuel trim cell = 20

other info the might be helpful :

MAP = 54 to 55 KPA
MAF airflow = around 1.35 lb/min
MAF Hz = around 2950
all STFT and LTFT values were 0, i don't why? although the engine coolant temp was 194* F and that shows that the engine must be in the closed loop.

ECT = 194* F
IAT = 120* F

O2 voltage B1S1 = 447 to 451 mv
O2 voltage B2S1 = 443 to 447 to 451 mv
spark advance = 19.5* to 21*
knock retard = 0*

dynamic airflow = around 1.30 lb/min
idle desired airflow = 0.46 lb/min

inj PW Avg. B1 = 3.7 to 3.8 ms
inj PW Avg. B2 = 3.7 to 3.8 ms


for DTC's at idle :

[PCM] P0121 = TP sensor circuit insufficient activity (Old)(Current)(Immature)

[PCM] P0122 = throttle position (TP) sensor circuit low voltage (Immature)

[PCM] P0134 = HO2S insufficient activity bank 1 sensor 1 (SES)(Old)(History)(Current)(Immature)

[PCM] P0154 = HO2S insufficient activity bank 2 sensor 1 (SES)(Old)(History)(Current)(Immature)

[PCM] P0300 = engine missfire detected (Old)(Current)(Immature)

[PCM] P0405 = Exhaust Gas Recirculation (EGR) position sensor circuit low voltage (SES)(Pending)(Old)(History)(Current)(Immature)

[Restraints] U1000 = class 2 communication malfunction (History)(Immature)

[Restraints] U1016 = loss of class 2 communication with VCM (History)(Immature)

[HUD] U1000 = class 2 communication malfunction (History)(Immature)

all that info while the car in idle. why i get 0 counts for the IAC i thought after adjusting the IAC i would get 30 to 50 counts.

need help.

thanks



Abdullah
2000 green M6 Z28 Mods: SLP flow pac, self ported LS1 heads with stock valves, TSP 233/239 cam, QTP 1-3/4" long tube headers, Borla cat back, Fast 90mm intake, NW 90mm throttle body, BMR adjustable panhard rod, BMR adjustable LCA's, BMR strut tower brace, BMR boxed SFC's, Koni Single Adjustable shocks, ES hyperflex bushings kit.

388 rwhp/367 rwtq on stock tune.

hand touched up CNC trickflow LS1 215cc heads from RayMac racing engines by Chris Frank are on the way (got the heads).

[The Alchemist]

I think the IAC's are at zero because you're getting too much air, which is why you are seeing 1% throttle position. Try backing off the set screw a little, allowing the throttle body to close, which would net less air, and then probably raise your IAC count.

[WS6FirebirdTA00]

Didn't have time to read through it all, but that is what it sounds like to me. Most of the time the IAC will go to zero is you are passing too much air through the TB blade or have a leak somewhere on the other side of the TB.

TPS voltage is too high as well, you want it get it around 0.57 volts or so.

[The Alchemist]

My IAC counts are in the mid 70s, and I tried doing this, but when I did the throttle position reset, the % is zero, but right now my voltage is 0.61v where before it was 0.55-0.57 at 0%.

No matter what I did, the voltage would not go back to 'normal'. Any advice would be great.

[Abdullah]

me too, i got IAC counts at around 90's and got a TPS voltage at 0.65 v and TPS % was 0 but the car will die if i close the throttle blade more, this was btw by pressing gas pedal and let it after 1 min or so to let the PCM learn.
if i start the car and let the gas pedal off the car will die.

do i have bad TPS or IAC?

i think i need EC_tune help.

what would say WS6FirebirdTA00?

thanks.

Abdullah

[WS6FirebirdTA00]

post a log with what you describe

[Abdullah]

WS6FirebirdTA00, here is the log, also i included a copy of my PCM file :



thanks for help.

[WS6FirebirdTA00]

You need to log the STIT and LTIT

[Abdullah]

You need to log the STIT and LTIT

if you check my hpt file you will see that under engine>fuel control>OL & CL>

you will see that the LTFT and STFT are enabled, i have no idea why the LTFT and the STFT are not working?

could it be a bad O2 sensor or that is not plugged in properly?

thanks.

[WS6FirebirdTA00]

No, LTIT and STIT is in the hpl file, you log the idle trims. You have to log the data to get it (same with the fuel trims). I am not concerned about the fuel trims, only idle trims.

[Abdullah]

No, LTIT and STIT is in the hpl file, you log the idle trims. You have to log the data to get it (same with the fuel trims). I am not concerned about the fuel trims, only idle trims.

oh sorry i wasn't concentrating i thought you meant the LTFT and STFT.

OK, i have to make new PID's to obtain the LTIT and STIT values in the VCM scanner?

thanks.

[WS6FirebirdTA00]

Yes, just add them. The are under the idle section.

[Abdullah]

Yes, just add them. The are under the idle section.

got the log, here it is :

thanks.

[Abdullah]

WS6FirebirdTA00, i got the hpl file, it is in the above post. i need your help.

thanks.

[WS6FirebirdTA00]

you should be able to close the blade up more while it is hot

[Abdullah]

thanks WS6FirebirdTA00, i will try that.

btw, why the LTFT's and STFT's are not working? could it be the O2 sensors?

thanks.

[WS6FirebirdTA00]

Is the car in open loop?

[Abdullah]

i'm not sure but the ECT was 194*-196* F so i thought that was closed loop?

how do i know wether i'm in closed loop or open loop?

thanks.

[WS6FirebirdTA00]

make sure your tune is set to run CL

[Abdullah]

make sure your tune is set to run CL

is that in the VCM editor engine > Fuel Control > OL & CL >

then STFT openloop enabled and LTFT enabled

if so, i already did that and still the STFT's and LTFT's are not working?

do you have any ideas?

thanks.