ported tb + no screen = bad

[John_D.]

<blockquote>quote:</font><hr>Originally posted by Dominic:
Both my 2000 and my 2002 have had no issues with the !MAF Screen, so it must be an issue only on the angled throttle bodies of previous years. Sorry you cut your finger!<hr></blockquote>

It's not that bad really... Just had to whine a little bit. [img]graemlins/crybaby.gif[/img] I think the worst part was that sinking feeling you get, when you realize you just did something not too bright that was avoidable...

About the screen, I think it's more pronounced because I got rid of the post too. The post normally funnels some of the air, and then through a hole directly to the sensor wires.

[Dominic]

<blockquote>quote:</font><hr>Originally posted by John_D.:


It's not that bad really... Just had to whine a little bit. [img]graemlins/crybaby.gif[/img] I think the worst part was that sinking feeling you get, when you realize you just did something not too bright that was avoidable...

About the screen, I think it's more pronounced because I got rid of the post too. The post normally funnels some of the air, and then through a hole directly to the sensor wires.<hr></blockquote>

Yeah that could change the MAF readings a lot. Luckily my 02 doesn't have a post, I can't even find a reason to "port" it - and its plenty polished as it is. I have a throttle body flow sheet posted at http://angelfire.com/my/fastcar/tbflowchart.mht if you would like to see what the stock TB is capable of. Keep in mind we only flow a maximum of 370cfm @ 6250RPM - and rarely does anyone even go that high.

[98v6]

chew on this: the screen is flat, so what if more air hits on one side than the other? back pressure until the air flows evenly through? I am not sure, but i have run !MAF on my 98 and had no problems, so i will be interested to see what you guys think, it might be that way or it might be that the air just flows on through, screen or no screen and doesn't get straightened either way.

[Dojo2000]

Wow, this **** is over a year old.

General consensus since then:

Pre-99: angled TB - leave screen in
99+: straight TB - fine to remove screen

[slomaro]

still with 99+ your idle will be alittle weird with it out not alot but still some

it will also act up when you take your foot off the gas but your still in gear it acts up

[jonny985]

I havn't had any problems with a ported TB and MAF! screen. I still have the top half of the post. It might be rough every once and a while but nothing at bad as John's.

[Magnus]

<blockquote>quote:</font><hr>Originally posted by jonny985:
I havn't had any problems with a ported TB and MAF! screen. I still have the top half of the post. It might be rough every once and a while but nothing at bad as John's.<hr></blockquote>

Did you keep that backing plate off?

[jonny985]

I removed the backing plate because I stripped the screw holding it in.

BTW, I do plan on cutting the post and using the 98+ MAF now that I got one for free from a junkyard.

[Magnus]

K, .. fyi for others, you can't run the backing plate if you cut otu the bottom half of the post, you WILL run terribly lean at WOT.

Also, 99+ is the change, 98's still use old style MAF sensor.

[jonny985]

<blockquote>quote:</font><hr>Originally posted by Magnus:

Also, 99+ is the change, 98's still use old style MAF sensor.<hr></blockquote>

Sorry, it slipped my mind. It was a 99+ throttle by wire TB that I got it off of.

[speedy-v6-camaro]

<blockquote>quote:</font><hr>Originally posted by jonny985:
I havn't had any problems with a ported TB and MAF! screen. I still have the top half of the post. It might be rough every once and a while but nothing at bad as John's.<hr></blockquote>

A MAFT or MAFT+ would help you out....the MAF is calibrated to the design of the stock TB. If you change the design (port it) you need to adjust the MAF reading so that the engine "sees" that it is getting more air...that is why everyones engine runs rough...its running lean.

[Jerriko]

I am not sure if this has been brought up or not but the reason screens are used is to even out air flow. That's why it affects cars with bent MAFs more than straight ones. That's why the readings were so far off on the signal voltage. The incoming air stayed in its natural arc so it read maybe 40% of the intake air. Straight MAFs are great. Unfortunately, GM knew about this the whole time they have been using MAFs but they didn't design them better until the late 90s. My personal opinion though is just to leave the screens in. Gains do not justify the problems (unless you correctly reprogram your pcm in which case it still doesn't justify the cost). If you really want to increase flow, rework your heads. Really, how restrictive do you think a little screen can be?