chip or coincidence?

[DavidT]

today, I noticed the car surging (quite noticeably) at WOT. It did it twice. First time, I pulled out... it shifted to second, pulling strongly, then at about 4500 rpms, it bogged bad.
Second time, I was punching it on a roll, as it started to shift to 2nd, it surged again. This time I felt it in the shift, and just before the shift.

Also, I have driving around for a couple of days with the exhaust cutout uncapped. <----Yeah, thats right, I'm cool
The cutout is AFTER the 3rd cat.
I started the car and as it was idling, I am pretty sure I was hearing backfiring. I went ahead and capped the cutout, and I didn't hear it anymore.

My gas tank was on EMPTY during all of this. What little gas I had was 93 octane. I put 7 gallons in last week for the track.
Any thoughts?

 

[MilTownSHO]

My gas tank was on EMPTY during all of this.

DING DING DING, fill the tank and see if it happens again. If your on E you could be sucking in sand and all the other nasty particals along with not having enough gas going to the engine.

Could be the chip too as I have heard of some people having problems with chips for the V8 (granted not Dougs.) But first see if it happens again when you actually have gas in the car!

 

[99V8SHO]

Your exhaust always makes those backfire-type sounds. You just don't hear it when it is bottled up. When mine was uncapped I was hearing the burbling and popping every once in a while, too. It was cool.

 

[DavidT]

I started it up this morning, and I noticed it again (backfire/miss/?)... this time with the cutout CAPPED. Apparently it does it on a cold engine...

 

[Mr. SHO]

I had all kinds of wacky problems with the chip, but never backfiring or making exhaust noises like that. It would surge quite frequently though, both at idle and at WOT. I have also heard of these problems with CAI setups where the MAF picks up interference from engine noise or when the airflow doesn't enter the MAF sampling tube head-on. As a result, the MAF can't properly sample the air flow, and then the engine bogs/surges because it's dumping in too much or not enough fuel.

About the chip:
After cleaning, sanding, polishing, soldering, and re-polishing the PCM contacts, I determined that the problem was NOT really related to poor contact, as most people had suggested. I covered the whole chip-end of the PCM with about 5 or 6 layers of aluminum tape to shroud it from EMI. Then I systematically cleaned up all the contact points in the engine that I could find (yes, it took a while.) Finally I removed the engine to firewall ground strap and cleaned up & tightened the attachment points.

I haven't had a problem since.