Thanks I never knew that. I'm yanking mine tomorrow. It's 10 good post to 1 bad and I'd be willing to bet that the bad ones are removing it incorrectly in some fashion.

 

Removed mine when I installed my Blackwing. No Problems!


[Modified by Jettech, 10:09 AM 2/12/2003]

 

As has been said earlier in this post, the screen actually comes from a GMC truck application and is intended to directionalize (a word?) air flow toward the sensors and may be considerd redundant and perhaps restrictive in the C5 application. However, some in these forums have noted some surging in their C5 applications. Perhaps those with problems have employed those dual cone filter set ups that may encourage directional/turbulent airflow just forward of the MAF sensor.

With my Blackwing, I removed the MAF screen and experienced perhaps some SOTP increase (that may be explained away as adreniline), but no surging or other such problems.

again, my $0.02.

 

As mentioned in other posts, the screen can be removed but is destroyed in the process. However, most people have learned by personnel experience or other means that the screen is not required. The problem with screen removal is the MAF is no longer calibrated for an accurate measurement of air flow. You will get an effective leaning of the A/F ratio as a net effect but the LTFTs will adjust to compensate over time but not completely. WOT runs are leaned out since the settings used are read directly from the MAF. The best option is to get the harness adapter from Pace Performance and install the stock '02 Z06 MAF which would be properly calibrated but would not use a screen. To take full advantage of this conversion, you would need to update your MAF cal table entries for 750Hz to 11250Hz in the PCM with the '02 Z06 MAF cal data. '02 Z06 MAF data has additional data points from 11250Hz to 12000Hz. These data points would not be used. If you go this route, you'll also need new coupling to connect the MAF to the air bridge and filter since this MAF has a large diameter than your original unit. The original IAT sensor in the air bridge could be left but it would be best to remove it then plug and seal the hole.


[Modified by Philip Long, 7:55 AM 2/13/2003]

 

If this data can be changed, How can I and what do I need, to change this data in the PCM?

Again, all this info is really great.

 

The best tool to use is LS1 Edit and a laptop with a 9-pin serial port. You'd want to backup your original files and get a copy of the MAF tables for an '02 Z06. You may be able to get the info from someone on the forum.

 

Philip, I beg to differ.

I disagree that the change in metering is enough that the trims can't compensate properly (at least not from my expereince,and testing). I think all will agree with the physics, that reducing restriction, slows velocity, but increases volume. This changes how the heated elements in the maf perceive, and transfer, the flow signal to the PCM. What is happening is that more air is getting into the engine than it is perceiving. Initially the O2's pick this up as a lean condition (since the injectors are firing for less perceived air), they (o2's) then tell the pcm, and it increases the fuel trims in a positive direction, to add fuel to the equation to compensate. Anytime the fuel trims are operating in a positive range, that amount is added to WOT (power enrichment mode) to protect the engine from going to lean. So in essence, the trim correction being made for the perceived change in airflow, is carried over to WOT operation. It's a locked value, and can be seen with an OBD-II diagnostic tool. Is this the best state of tune to be in? Not necessarily, but at the same time, it doesnt mean that WOT, will go "lean" due to the removal of the screen.

Something else to add, is that if your engine is being compensated for a rich condition, and you remove the screen, this will help WOT some, since trims compensating for rich are not carried only to WOT, like trims compensating for lean are.


[Modified by kewlbrz, 12:06 PM 2/14/2003]

 

I too removed mine after seeing how rich my car was running after a wide-band dyno. I'm told there are two ways to improve your AFR's electronically (PCM) or mechanically (forcing more air through the MAF assembly). After removing my screen the car felt much stronger, runs great and has had no side effects.

I am scheduling a dyno-tune in the next month so I'll see if there wany any improvement in power with the screen removed. BTW my car dyno'd at 292 and my AFR's fell to 10.9:1

Tom
USAF Retired

 

If I understand the PE mode correctly positive LTFTs are added to the PE values during WOT operation with the LTFTs locked to the last value updated. So when the LTFTs adjust over time to compensate for the leaner A/F condition due to the MAF screen removal, the lean condition will slowly be corrected. This rich setting of LTFTs may also provide a compensation to the PE tables during WOT. The only true benefit I see gained is that you will be able to flow more air at the limit due to the MAF screen removal.
Where the PCM settings are adversely impacted is when the MAF ends are modified or changed without recalibrating the MAF sensor elements. I've tried several versions to see if they give a long term benefit. I found my idle was effected causing surges during the air compressor cycling and fan operation resulting the engine dieing when performing slow parking maneuvers. I did have a sotp feeling of more power but the overall engine performance felt degraded and didn't seem to have the same crisp response. Without Autotap or EFI Live to log the actual changes, I can't say what was really occurring. I believe the best long term goal would be to have the PCM tables optimized for the greatest torque output or HP (whichever is desired) via dyno and wide-band o2.
To summarize, on a stock MAF, the screen removal is a minor change which will yield some benefit through improved airflow. However, having inaccurate airflow measurement may be effecting settings we know nothing about. It's never a good idea to let unmetered air into the engine.