My SS ran a best of 13.3 @ 109.7 a week and a half ago. I ran the car last night, in almost identical conditions and only trapped 105.9. A buddy of mine ran his car on the same night I trapped 109.7 and ran it last night as well, and trapped nearly identical so it wasn't the conditions. This is with same driver, tires, etc....nothing has changed since the LTs were installed.

The car has felt sluggish for the past week or so...pretty much after the trip to the track where I trapped 109. I figured it was a psychological thing and the car was running just as strong.

Here are my mods: Whisper lid, Jet-hot LTs and dual cutouts 12-14" after the O2 sensors.

The car had also been idling rough (which it wasn't doing a couple weeks ago) so I hooked it up to my friend's laptop and drove around a little.

Here's what I have found out so far:

O2 voltage is normal at idle and part throttle (fluctuating between ~200 and 900 mv.).

O2 voltage does not stabalize at WOT. I made a few WOT pulls and the voltage was fluctuating the whole time.

No misfires.

4* of knock retard at one point, but y-pipe is hitting on floorboard pretty good.

Here's what I'm thinking so far:

Possibly running with both cut-outs open (being 12-14" from the O2s) could have 'fouled' the O2 sensors. I've read a little about this online and have seen a few people have problems with this.

Possible bad or dirty TPS sensor - if the TPS wouldn't read WOT, it wouldn't put the PCM in open loop mode...hence the fluctuating O2 readings at WOT.

Clutch is not in the greatest shape (slips occasionally)...could be slipping just enough to cause the drop in MPH (however....keep in mind I ran 4 MPH faster a week prior). A Spec stage 4 is in the mail.

A bad tank of gas...?

Bad fuel filter?

The fact that the car doesn't appear to be entering open loop worries me. What all could cause the car not to enter open loop at WOT?

Any help is greatly appreciated.

 

how many runs did you do? your trap speed is not the speed that you cross the finish line it is an average of the last 66 feet so keep in mind you may still have finished the race at 110mph but maybe a bad launch kept you from getting there quick enough. If you only ran it once then that is not enough info to tell you that something is wrong.

 

I know how the traps work.

I ran the car four times with the same results. These are not the types of responses I am looking for. I know the car is down on power, I'm looking for any help regarding a sudden loss in power given the symptoms I provided.

Thanks.