massive flat spot into third WOT

**redynscire** · 06-22-2011

02' GTP has a massive flat spot when it shifts into 3rd at WOT...
What could this be? Could it be from not running a rear o2 sensor?

**Explicit_Spade** · 06-22-2011

No, the rear 02 is for emissions only.

Can you describe "flat spot" a little better?

**JoshsGTP** · 06-22-2011

For 2000 And Up I believe the rear o2 is important 97-99 not so much

**Explicit_Spade** · 06-22-2011

I don't have one on my 04. Its either plugged or my wideband is in it.

**JoshsGTP** · 06-22-2011

I dont know about the 04 difference, Just the 97- 03

**redynscire** · 06-22-2011

alright. i jump on the highway and hammer it. let second gear crank out.
when it shifts into third it dogs out bad, if i keep it floored it bogs for like 3 seconds, then pulls hard again..(under WOT the whole time)
the 01+ cars need the rear o2..something about cat diagnostics, and without a rear o2 on 01+ it will run pig rich.. what i dont get is it only does it in third gear at WOT..? could it be knock retard?

**matt5112** · 06-22-2011

cat diagnostics is when cruising.

**redynscire** · 06-22-2011

so then its prob not cat diagnostics...
would a person feel knock retard?

**redynscire** · 08-01-2011

still have this prob cant figure it out

**blueguy** · 08-01-2011

Solved your problem...don't go faster on the street than you can trap in the 1/4.

Which shouldn't be over 100.

Therefore...quit going into 3rd @ WOT.

Or, it's knocking like a b1tch...there is TONS more load on the motor in 3rd gear than in 1st/2nd...my advice...get a way to scan it and see what is going on and stop beating on it.

**SMazza** · 08-01-2011

It could be knock retard.

It also could be misfires under boost. How old are your plugs and wires? Have you checked the plug gaps lately?

**redynscire** · 08-01-2011

plugs are a month old..wires almost a year..
would knock retard feel like a bog?

i rarely do over 80
"stop beating on it"... i dont beat on it much.. i have only made it do this a handful of times. i am afraid this IS knock retard, i dont want to blow it up..
if i could just find someone to scan

could it be from a shotie exhaust system with a few splices?

**torq455** · 08-01-2011

Try checking fuel pressure. Maybe as you run it up the psi is slowly dropping causing it to stumble, then build up some psi to get things running. If you can, check psi while this happens, but after scanning first.