insertclevername

Background:

I have an 04 C5Z, headers, no cats, intake. When I got the car, it had a decent tune, but after I put the stock CB back on from Borla. The car felt like it lost driveability and definitely lost mpg. I bought HPT and found the car had a OL MAF/SD tune, with standard changes to avoid DTC's, and added a ton to the MAF table, tuned timing table, PE set to 12.9 AFR but left VE table alone.

I have since found the O2 fuse blown, put it back to CL and tuned light throttle VE and MAF with FT's, but recently got a wideband for WOT, and will now get it even closer.

Yesterday I noticed my Z has the screened MAF (19330121), not the unscreened MAF (19330122) Z's are supposed to have. I looked over the MAF table from an 01 Z vs 04 Z and they differ slightly.

Now since I'm still in the beginning phase of wideband AFR err tuning. Should I make the change to the unscreened MAF, or stay with the screened? I do have only a K&N filter attached to the MAF, and I think having the screen could help smooth out turbulent air readings. Or do I even need to worry about turbulence, being that I can tune the MAF table?

What would experienced tuners do?

Thanks!

insertclevername

I went un-screened. Tuned very well, I guess mild bolt-on M6 trans don't mind.

The un-screened MAF needed approx 3-4% more fuel above 8500hz vs screened.

tblu92

if it came with a screen--put it back on----You can re tune an unscreened MAF But it takes hours of data logging with learning (by driving) in between adjustments---is virtually no HP advantage by removing the screen In my opinion---
And you are correct it NOT a screen at all---It is a airflow stream straightener --It takes the turbulent incoming air and straightens it out so the air passes smoothly over the MAF wires to read correctly------
PS: On a auto car--removing the screen can cause your trans to fail--As the trans pressure in controlled by engine load and the MAF is used to determine load--If the MAF reads incorrectly the trans pressure will be wrong for the engine load--

insertclevername

Thanks for the reply. After I did some research on why GM removed the screen/straightener in the 02-up Z06. I decided to go with the OE MAF (no screen) for my 04 Z. The factory MAF has a great airflow smoothing design with aluminum outer cone and the center piece that directs air to the sensors on either side. I have had no tuning gremlins yet without the screen. Those aftermarket designs are horrible in comparison for smoothing airflow though the MAF. I already had some tuning done with the screened MAF, and while scanning/logging the un-screened, under 8500hz did not change much at all. Over 8500hz the fuel was leaning out and I added 2-3% to correct. The un-screened MAF appears to be flowing more air over 8500hz. If I run into issues, I'll just pickup another MAF with screen, but so far there has been no issues. I'm sure I won't get big gains without the screen, but there might be a few ponies gained. I really just wanted the car to have the factory MAF.

I recently pulled my fuel rail and injectors and performed a full service on the injectors. Removed the inj. micro screen baskets, pressure flushed the injectors, then replaced the micro screens with new. The Idle and AFR stability is incredible from what it was. I also noticed I got back a more linear throttle pedal. So far cleaning the injectors and replacing the filter baskets have had a more noticeable effect than going to an un-screened MAF.