[Gregski]

HP Tuners - Part IV - Turn Off Exhaust Gas Recirculation EGR. (1999-2001 donor engines only)

So there you are cruising on the freeway at approximately 70 MPH when all of a sudden the PCM commands the EGR valve to open and dump a bunch of dirty, hot, unburned exhaust gases into your intake manifold, bypassing your K&N air filter. The engine goes WTH, I can't burn this! And so the PCM commands more timing advance! Well except your EGR valve is on the garage floor, so you don't need all this extra timing, as there is no dirty gases entering your intake manifold. Since those of us using 1999-01 donor engines most likely ditched the EGR system, and disabled the seven EGR related codes in Section C (ie the last article) we might as well do a little tuning and eliminate the need for more timing advance do to EGR.

Your engine runs off of a main Spark table but then there are a number of timing tables that modify the timing depending on the conditions and engine needs. The EGR Base table is one of those modifiers, and if there is no EGR there is no need for the modifications.

[Confusion] For those of you following along, you may have noticed that I changed the article naming conventions, in Serries 1 articles which we called Housekeeping we used Part I, Part II, etc as the titles... where as in Series 2 which focuses on Code Deletes we call the articles Section A, Section B, etc. that is deliberate as it allows us to inject articles into each Series. What the hell are you talking about? Well when tuning you will realize that there comes a time when you need to Zig Zag a little bit and everything does not always happen in perfect order. So we return back to the first Series and add Part IV.[/Confusion]

1. Again we start in the comfort of our own home, we fire up our laptop and launch the Editor. Open the file we saved in Step 3 of Section C. (Our last saved file is always our starting point).

2. Make changes in the Editor, this time we will make changes effecting the EGR. First we edit the EGR Base table found under Engine\Spark\Advance. Zero out any cells that are not green, ie contain 0s already. There are many ways to do this but for beginners just go to each cell and type 0 and move on to the next one. Then we show the Navigator tree view by clicking on Edit \ Navigator and go to the Exhaust yellow folder and on the right in the General section next to Enabled we use the pulldown and select Disabled. Finally under Engine \ General \ Airflow we zero out that entire table. (Additional instructions with each pic)

3. Save the changes you made to a new file and call it something like "07 - EGR Base Tuning"

4. Now you get to move the operation to your truck, hook up your HP Tuner to the OBDII port and then your USB cable to your laptop, turn the key to the ON position, launch the Editor program, and simply write the new changes to the PCM.

Note: sometimes you have to write the entire tune file to the PCM, sometimes it is perfectly happy with only writing what's changed, more on this later.

More words with each pic: