dheck

iTrader: (9)

Ok, this is really frustrating me. The car fires up with no surging. Drives great. Idles fine. My problem is when I give it gas and let off the idle dies to around 500 RPM. I have tried changing my IAF VS ECT. My primary VE. High and low octane spark tables. Nothing seems to fix this. For some reason my IAC counts are down around 5-10 when the car is completely warmed up. Yesterday they were around 45-50. These are the same 2 tunes. I don't know why it has dropped so much. I don't even know if the IAC's have anything to do with this problem. Can someone shed some light on this form me please?

Black02SS

iTrader: (36)

Adjust the throttle follower decay table or the throttle cracker and it should help.

dheck

iTrader: (9)

Tried both these with no changes. My STIT's are at or around 0. My IAC's are between 35 - 50 at full temp. I have no idea what else to change????

dheck

iTrader: (9)

I don't think the base airflow vs ECT table is where my problem is. I can completely exagerate this table and I still get the same result. Even after the STIT and LTIT relearn.

Blacker

iTrader: (3)

What did you multiply the 400/800/1200 columns by? My IAC would do the same thing as yours. I would have it 25-35 and a couple of days later, it would be hitting 0 steps. I have resolved mine and the timing was a lot of it. Right now, I have have my 400 coulmn set to 40%, 800 column set to 50% and 1200 column set to 67%. Also, did you tweak the MAF Table?

dheck

iTrader: (9)

I hate to admit this. But through all these tunes I had, somehow I had the VE table all out of wack. I scaled it up by about 15% and the problem totall went away. Rookie mistake. Car idles like it's stock now. Thanks for all the help.

Black02SS

iTrader: (36)

Sorry about not calling you back, I have been swamped here lately. Nice to see you got her all tuned and running good.

dheck

iTrader: (9)

It's alright. I will call you later for some PE tuning help. I logged my LTFT's using this method. The car is a different animal not. VE table looks great. Car gets a lot better gas mileage and pulls a ton harder.

2. LTFT TUNING –
A. In the VCM Editor>Edit>Engine Diagnostics>General>MAF Sensor Fail Frequency = 0. This will set a P0103 code and turn on the SES light. Don’t worry about the light at this time.
B. In the VCM Editor>Edit>Engine>Spark Advance>Main Spark vs. Airflow vs. RPM Open Throttle/Moving. Copy the High Octane table to the Low Octane table. The computer reverts to the low octane table when MAF is unplugged, this will assure optimal timing.
C. Start the VCM scanner>Histogram display. File>Connect then Tools>VCM Controls>Fuel & Spark>Fuel Trim Learn>Reset Fuel Trims.
D. Changes to the LTFT’s do not take effect immediately – the PCM requires at least 50 minutes or roughly 100 miles to allow for the PCM to relearn it's fuel curve. Try not to enter PE mode while driving and logging for this procedure. Stop logging and save the log. Do NOT turn off the engine until the log is saved or it will be lost. Go to VCM Scanner>Histogram display>LTFT's. Open the VCM Editor>Edit>Engine>Airflow>Main VE and select Primary VE vs. RPM vs. MAP.
E. The goal is to get ALL LTFT’s between 0 and -4. Positive LTFT's indicate fuel is being added because of a lean condition. Richen this cell by increasing the VE table value by the amount of the LTFT value. The operation is opposite for negative LTFT's.
If LTFT = (4), VE cell value is 67, result would be (67)+(4)=71 - increasing the VE, which is adding fuel. If the LTFT was (-4), the result would be (67)+(-4)=63, decreasing VE and thus reducing fuel. To decrease LTFT values, a smaller number or number closer to zero, ADD the difference between the positive LTFT value and zero to the corresponding cell in the VCM Editor>Edit>Engine>Airflow>Main VE>Primary VE vs. RPM vs. MAP table. To increase a LTFT value, a larger number or number farther away from zero, SUBTRACT the difference between the LTFT value and zero and SUBTRACT from the corresponding cell in the VCM Editor>Edit>Engine>Airflow>Main VE>Primary VE vs. RPM vs. MAP table. For example, In the VCM Scanner>Histogram display, the (.8, 40) cell, 800 RPM's and 40 kPa, is 4. To bring the VCM Scanner>Histogram display>LTFT cell (.8, 4.0) DOWN to 0 from 4 ADD 4 to the (.8, 4.0) cell in the VCM Editor>Edit>Engine>Airflow>Main VE>Primary VE vs. RPM vs. MAP table. If the VCM Scanner>Histogram display>LTFT cell (2.0, 30) is -10, SUBTRACT 10 from the (2000, 30) cell in the VCM Editor>Edit>Engine>Airflow>Main VE>Primary VE vs. RPM vs. MAP table to bring it UP to 0. This will not work out exactly but will be VERY CLOSE.
F. Repeat steps D-F until ALL values in the VCM Scanner>Histogram display>LTFT are between 0 and -4. Try to complete this on the same day for best results as LTFT values can vary +-4% per day.
G. Once all values are between 0 and -4, look at the VCM Editor>Edit>Engine>Airflow>Main VE>Primary VE vs. RPM vs. MAP>3D Surface graph. If the 3D Surface graph looks choppy, click on polynomial smoothing ONCE. This will smooth out the table values and provide a more crisp throttle response. Now rescan, and do step E.

Now I just need do do some PE tuning.

gtodoug

iTrader: (1)

Question about this very topic. The only real driveability issue I have is when driving and I put the car in neutral from certain speeds the car's idle will drop so low the lights go dim and I almost lose the ability to brake and stop the car properly.

I went to the throtle follwer decay table and the values are all 3.0000.

When I went to the throttle cracker table there is a portion of the table in the low rpm area from 2200rpm down to 1000rpm and from speeds 64mph down to 16mph the value is 1.0000. I'm thinking I should shift this number upwards to fix my stalling problem. Would I be correct in assuming this?

dheck

iTrader: (9)

I tried these values/tables as well with no luck. Maybe the problem lies in your VE table as well???