bstjnky

I've searched to no avail, so here goes:

I just purchased my 98 Z28, auto. The mods are as follows: Shaner throttle body, air lid, Hypertech Power Programmer, Mac coated headers, SLP y-pipe, B&B cat back, and a Vig 2800.
Here is the problem: The car is hunting for idle, surging around 200 rpms at all times. I've pulled the following codes from Autotap: P0507 four times and P1416 twice. I know what the codes mean, but I do not know how to fix the problem. The idle is high, around 1000 rpm, and dips to 800 rpm. It also throws the check engine light. I'm somewhat unfamiliar with LS1s, but I can learn fast. Someone mentioned messing with the MAF, but I do not know how to adjust it. On a small sidenote, sometimes the car smokes black a little bit, I think it may be running rich. I couldnt find the Autotap area to see the A/F ratio, does anyone know if Autotaps can read it on 98s?

Any suggestions or possible remedies? The car feels somewhat sluggish, but I'm not sure if it's related to the problem. Could the ECU pull timing in relation to this problem? My O2 voltage is normal...

Thanks,
Jason

The Dragon

iTrader: (6)

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by bstjnky:
<strong> I've searched to no avail, so here goes:

I just purchased my 98 Z28, auto. The mods are as follows: Shaner throttle body, air lid, Hypertech Power Programmer, Mac coated headers, SLP y-pipe, B&B cat back, and a Vig 2800.
Here is the problem: The car is hunting for idle, surging around 200 rpms at all times. I've pulled the following codes from Autotap: P0507 four times and P1416 twice. I know what the codes mean, but I do not know how to fix the problem. The idle is high, around 1000 rpm, and dips to 800 rpm. It also throws the check engine light. I'm somewhat unfamiliar with LS1s, but I can learn fast. Someone mentioned messing with the MAF, but I do not know how to adjust it. On a small sidenote, sometimes the car smokes black a little bit, I think it may be running rich. I couldnt find the Autotap area to see the A/F ratio, does anyone know if Autotaps can read it on 98s?

Any suggestions or possible remedies? The car feels somewhat sluggish, but I'm not sure if it's related to the problem. Could the ECU pull timing in relation to this problem? My O2 voltage is normal...

Thanks,
Jason </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">A lot of variables here. First: make sure there is no "power-tuning" from the HPP3. It has been proven many times to actually negate horsepower on LS1's. Shift points, idle, rev-limiter, fan-settings, etc. these are fine.

Depending on your problem, the 'puter could pull timing. Check your IAC's at idle using Atap.
Do a real-time log on all 8 cylinders for misfires as well.
Definitely check that HPP3 thing though.

Good luck <img border="0" alt="[cheers]" title="" src="graemlins/gr_cheers.gif" />

<small>[ February 03, 2003, 04:49 PM: Message edited by: The Dragon ]</small>

bstjnky

Thanks the quick response, I'll Atap her later and see what I come up with (i have to go to a friends house who has it). I'll also take out the power programming as well.

BTW,
Is there a way to clean the IAC? Where exactly is it located? What should the IACs be reading on the Atap?

Any more suggestions?