NYSS Guy

iTrader: (1)

I hope this is the right forum for this question...I recently had to pull the MAF off because I got some moisture in my charge pipe (don't ask!), so I had to dry the MAF. While I was at it I took out the screen to see if it would help anything. Well, throttle response feels a little better, but when I am slowing to a stop, the idle lopes from 600 to 100 rpm's. Once I come to a complete stop, it settles quickly at 800-850, and stays solid. On the Scanmaster, IAC is stuck at 78 (it's not loping like the idle). IT does it a little less when the A/C is on.

Is this due to more moisture that I didn't get out, or something to do with the removel of the screen? Finally, now that HP Tuners is on the way, is there some sort of recalibration that I can do to fix this problem.

Another_User

You need to recalibrate your MAF and your RAF tables. Both sound like they are off. I don't know all the details about the conversions for airflow, but your calculated airflow is way off, and you IAC counts should be about 20-30 less than that anyways, so your set screw needs adjustment. :::sigh::: If you want to do it right, then you have a lot of work ahead of you. You could probably just adjust your set screw to about 30-40 counts and it would run fine.

NYSS Guy

iTrader: (1)

But the thing is that it was working fine before this. And I only did it since I had the MAF off anyway. I didn't think it would have created a problem. Now, I thought the idle was controlled strictly by the IAC valve??? I didn't know there was any screw?? So, your saying that the IAC counts should be more like 55-60?? Now that I think about it, I was having a problem with the idle with my initial tune, and the tuner did something to adjust the idle, which made it better. Is that why my counts are so high?

I haven't seen the HP Tuner software yet, and don't know a ton about tuning, so forgive the beginner type questions. Thanks.

Another_User

I could be wrong, but since descreening the MAF affects calculated airflow, and since the running airflow is which affects IAC is (I think) determined by airflow, then that is probably why it messed you up. Heck, an idle-relearn might fix it if you want to reset the computer and go through it.

NYSS Guy

iTrader: (1)

Thanks for the help, I don't want to reset the computer though. I have a pretty good tune in there now. But, once I get HP Tuners (hopefully in the next couple of days), than I can start messing with the tuning aspect.

Anyone else have some ideas?

Scooter70

iTrader: (1)

Resetting the computer (pulling the fuse) won't lose your tune. It's just like rebooting your pc.

HUGGER ORANGE SS

iTrader: (2)

So you say it's only when you come off the throttle coming up to a light it surges, and almost dies.. Well your IAC motor is open a little more than it should be, but after you took off the screen on the maf the Turbo is still spinning and providing ait flow in the tubes when you come off the throttle. With the MAF DE Screened the maf is reading airflow easier and giving your motor fuel when the Throttle Body is closed. A Few ways to handle this.. Put your MAF closer to the Throttle body. Have your throttle follower tables adjusted so that your car wont stumble too much.. Idle air, have that go up, also drill the throttle body or adjust your set screw..

Good luck

Clint

NYSS Guy

iTrader: (1)

Thanks Hugger. I assume the throttle follower table is something that can be adjusted in HP Tuners, right? Again, I didn't even know there was a set screw! But I'll work on that. Moving the MAF would be to big of a job. Thanks again for the info.

Scully

iTrader: (4)

i could be wrong, but i've always heard not to descreen the stock mass air sensor.

Dan_the_C5_Man

I agree, or at least not w/o PCM adjustments.. Change the MAF tables.

NYSS Guy

iTrader: (1)

Well, I did it in my last car, and I had no issues. The only difference is where the MAF is located now. I will get it adjusted next week. Thanks for the info!

Slowhawk

iTrader: (12)

Descreening a MA with a FI setup is not a good idea.The screen straightens the air flow which really helps when air is being forced in by a blower or Turbo.What happens with the screen out is the air swirls in the pipe(expecially at idle) and hit's the MA element at an angle and totally screws up the MA reading.

We've pushed FI LS1's past 800hp with the stock / screened mass airs.

NYSS Guy

iTrader: (1)

Hmm, who knew. Oh well, can't put it back in. Hopefully messing with the tune will take care of my issues.

HUGGER ORANGE SS

iTrader: (2)

I'm running W/O the screen.. It's okay, but I agree it's better to have it screened in a FI motor.

CLint