Things to Think about After Installing Test Pipes in 05 + G-35 Coupes and Sedans

[Jacko3]

Most 03 and 04 G-35s will almost not throw a CEL light with test pipes---I have a friend whose 03 G-35 Coupe has never thrown a CEL light with test pipes, though having a CEL fix (spark plug anti-fouler) is a good idea.

The headaches with CEL seems to be more in the 05 + models--seems their ECUs are different. However, if done properly with a CEL fix (spark plug anti-foulers) , the ECU of the 05 + models will generally retune itself based on the new O2 sensor data coming through the test pipes, and htis is assuming the ECU has not been altered in any way. This process may take a week or two, depending on how you drive. So, don't be alarmed if you have a couple of CEL lights during this period of adjustment, with test pipes, if you have an 05 + model G-35 with test pipes and a CEL fix. Once the computer adjusts in that time frame--the CEL will most likely not come on again--no guarantees though. I just speak from my experience--mine came on twice--once in each each week of the first two weeks I had it, and has not come on in more than three weeks.

Best way to speed up the ECU readjustment process is to try to flog the car routinely for about 1 - 3 days, and at the same time try to drive the car gently as well for the same period---those variations matter in how the O2 sensor picks up data sent to the ECU for the re-tuning or re-adjustment process. (If you read your owner's manual, it is adviced to avoid idling the car for too long and I think drivng it too constantly at a specific speed for too long--this situation i discuss may explain why--our cars don't like constant anything for too long because of how the ECU is designed)--another reason why our cars behave better on a track---many variations, than on a regular highway or street.

I find this re-tuning process interesting, and it works pretty quickly, and well. After a day or two of constant flogging--high acceleration and high speeds, then give it a day or two of slow and soft driving under 50 miles per hour or less at constant speed for moderate durations at a time---what this does is that the large variations in your driving behavior forces the ECU to find an optimum level of performance---it is this optimum that keeps the CEL off as the ECU will sense these wide variations in its data set as okay/normal and so the CEL light will not come on. However, the new data wil affect your gas mileage--the farther away your O2 sensor is to the test pipe, the worse your MPG--rich mixture, and the closer the O2 sensor is to the gases in your testpipes, the better your MPG--leaner mixture. While a leaner mixture will generally lead to higher engine temperatures, a good synthetic engine oil like MI will help reduce any potential rise in temperatures.

Driving too slowly and gently constantly with test pipes will most likely lead the ECU to try to be efficient and thus a possible CEL especially when you suddenly move away from that slow driving habit and want to drive fast--it confuses the ECU as it has no data stored for those extremes, and driving too fast and wildly constantly and for too long , will lead the ECU to seek an effective level for performance, and most likely a CEL as well, but much less likely than driving slowly, especially when you suddenly decide to drive slowly.

What you want is an optimum, which is somewhere between efficiency and effectiveness, and the ECU cannot come to this conclusion with narrow bands of performance data it gets from the O2 in the new exhaust set up when you are used to either driving slowly and gently or at WOT or fast --it needs a wide band of data that will come from the wide variation of driving data behavior----some slow driving data and some WOT driving data, in order to reach an optimum.

If the CEL does not come on during this period or process of adjustment, it probably won't come on for a while or never so long as you keep that wide variation in driving coming along, but not as routinely as when you first installed the test pipes during the first two weeks. Each time the CEL comes on, just disconnect the negative battery terminal for 5 minutes, reconnect it back, and the CEL is gone. Make sure your post cat O2 sensors as new or as healthy as possible. A new set of post cat O2 sensors or a very healthy set, will produce the best data for the ECU.

NB: I love messing around and manipulating my cars ECU by adjusting my driving behavior--your driving behavior sends data to the ECU. When i want my car to have a certain sound, all i do is patiently drive a certain way for a while--sometimes a day or two and then I get the sound I want. I love this car.

I forgot to add that the G-35 takes a little longer to adjust to intake modifications such as cold air intake/spacers/mrevv than it does with exhaust modifications. Adjustments due to intake modifcations can take as long as 1 month or more, and adjustments due to exhaust modifications can take as little as 2 weeks. I am not sure why this is so.


Modified by Jacko3 at 1:55 PM 10/24/2008

[Tampa G35 Sedan 6MT]

WOW that is good info..

I wonder if Steve can Back up your info with hard data.

I think your mind is a lot like the ECU in the G's

Think alot and get one result and then let it rest and you get another!

You need to be thinking all the time

DJ

[Jacko3]

That's why our Gs actually learn how you drive.