Rough Idle Trim issues after VE-MAF Tuning

[TAQuickness]

B4307 establishes the base running airflow. Think of it as a starting point for airflow calculations

[Bruce Melton]

Chalky's car is basically stock> only intake and headers.. Seems odd that it would need much in that it idled fine before Auto VE?

[superls1]

Ok, so let’s think about it as a starting point for airflow calculations. While I agree that figuring stuff out is half the fun, I don’t think stating this helps the situation much. Not picking on you as I certainly don’t have all the answers, but when I read through all the threads after searching “RAFIG” all I see are posts saying get B4307 in order. Wasn’t there a post recently about needing/wanting more tutorials? AutoVe is fairly well documented. Why can’t we (I’ll help where I can) document idle tuning better?
Something like:

Idle tuning
· If you have installed an aftermarket cam, raise your idle speed. This is subjective, and can be easily changed in the future. This will help ensure the engine will start and stay running after a cam install.
o Desired Idle speed (B4603)– This is very subjective. Generally, a performance camshaft will require the idle speed to be increased. The challenge is likely to find the lowest RPM at which the engine will maintain a stable idle with which you are comfortable with the engine’s response (and sometimes sound).

With automatic transmissions, there are 4 columns used, but with manual transmissions there are only 2 columns used (the Park/Neutral tables are not used with manual transmissions).

Automatic Manual
In Gear AC On In Gear AC On
In Gear AC Off In Gear AC Off
P/N AC On
P/N AC Off

· Get your VE table established for the idle area. Refer to the AutoVe tutorial under the Help menu. This will help ensure properly fueling will occur. Note that large cams with lots of overlap may need “extra” fuel to obtain a clean/stable idle.
· Determine the amount of air that is being added by creating a PID file logging the long term and short term idle air correction factors. In the Scanner, select “Idle” in the “System” drop down menu box and find:

- IAC - Long term correction, In Gear, A/C Off IAC_LTD_DMA
- IAC - Long term correction, In Gear, A/C On IAC_LTDAC_DMA
- IAC - Long term correction, In P/N, A/C Off IAC_LTPN_DMA
- IAC -Long term correction, In P/N, A/C On IAC_LTPNAC_DMA
- IAC - Short term correction, In Gear, A/C Off IAC_STD_DMA
- IAC - Short term correction, In Gear, A/C On IAC_STDAC_DMA
- IAC - Short term correction, In P/N, A/C Off IAC_STPN_DMA
- IAC - Short term correction, In P/N, A/C On IAC_STPNAC_DMA

By logging these parameters, the base or “Desired Airflow” (B4307) can be determined. There are four calculated PIDs that can be derived/monitored as a result of including the above parameters. These calculated PIDs are simply the addition of both the Long Term and Short Term correction that is occurring for a given operating condition. These PIDs are (under Idle System parameters as well):

- Idle Airflow Correction AC Off, In Gear RAFIG
- Idle Airflow Correction AC Off, P/N RAFPN
- Idle Airflow Correction AC On, In Gear RAFACIG
- Idle Airflow Correction AC On, P/N RAFACPN

…

Maybe we could even create the PID file, maps, and dashboards, briefly discuss differences between ETC and IAC (give some general guidelines for IAC counts), briefly mention the set screw and general ranges for reasonable TPS voltage, etc.

Just some thoughts.

[eboggs_jkvl]

I agree with superls1. So many things to consider and the fact that I have invested a shitpot full of money in my engine makes me a dab nervous when "experimenting" to find solutions.

I was in the process of doing an SD tune, made my first run, adjusted the VE table accordingly and started for my second run. Missing, stumbling, felt really bad so I immediately stopped, reloaded the stock tune and replugged in the MAF. I found out later that "EVERYONE" knew to "zero" the trims prior to making the next run. Well, I didn't know and I'm sure "EVERYONE" doesn't know that either. I followed the instructions to the exact letter and as I said, I will not "experiment" to find an answer when it can cost me thousands of dollars to repair from the experiment. If the instructions are there I can do the rest. SD sounded simple to do but...

[Chalky]

News to me about resetting trims after 1st VE log.

I was just beginning to feel stupid. Someone had posted that if you didn't understand what you were doing, you should not have bought EFILive. My position is I believe that many of us that want to learn more about tuning and other PCM functions and depend on this forum to gain knowledge and ask questions.

There was no disclaimer indicating "Experts Only" when I bought my EFILive. There are many knowledgable people on this forum that were asking questions last year about processes.

[TAQuickness]

SuperLS1 - Please check out the tutorials section of this forum. You should be delighted that progress is being made to develop a more comprehensive set of tutorials.

Eboggs - I feel you pain. I have quite an investment (flux capacitors aren't cheap) into my motor as well. But, rest assured, if you built the motor right, they are quite resilient. Tutorials or not, I would always encourage small changes.

Eboggs & Chalky - fuel trims are reset when you perform a flash. No need to zero them out if you are following the AutoVE to a "T". The initial rough drive is likely due to the rich mixture (recall the step that has you scale your VE table up by 15%?).

Chalky - you by no means need to be an expert. In fact, all experts new jack shit at one time . But, tuning a PCM is not for the faint of heart. It takes a while to develop an understanding of how the tables work together. Much similar to developing the understanding of the mechanical side of an engine.

Bruce has a good point, and I may have steered you in the wrong direction. With MAF enabled, at idle, the PCM relies heavily on the VE table for fueling. Assuming you're running closed loop, perhaps what you are seing is a discrepancy between the NB's and your WB. What is your WB AFR at idle? Since your trims are positive, I would expect the WB AFR to read slightly richer than commanded. How old are your NB's?

[Chalky]

WB @ idle @ right 14.7-14.8.

NB are original. Car is an 02 with 18K for miles.

As far as rough idle, car still exihibits a rough idle with car tune back to normal, no OL.. FWIW, the low end of the VE table is pretty rough. I have been working on trying to smooth that out but not sure if I am going in right direction.

[TAQuickness]

how long did you have the headers before trying to tune?

[Chalky]

6 months! Put them on in Nv, 2005 and parked car until April of this year!

[superls1]

SuperLS1 - Please check out the tutorials section of this forum. You should be delighted that progress is being made to develop a more comprehensive set of tutorials.

Already joined, got rhs to give and started trying to contribute.