LS1 in 69 Camaro chugging

[69MyWay]

My Camaro just started acting strange - looking for ideas.

2000 LS1 with SLP Stage III head/cam and 36# injectors - TCI steet fighter and 4L60E trans through a 3.5 Ford 9" - headers, x pipe - and tune by Speed Inc.

If you accelerate up to speed (hard or easy) to the point it goes into 4th and lock up (around 60 mph) - then throttle back - it starts bucking and chugging like a tractor. It stays locked up and just thumps like a manual shift car in too high of a gear trying to drive too slow.

If you throttle down it will go.

No check light - the misfire codes and other sensitivities have been turned off in the PCM tune due to the cam...etc.

My guess is a bad coil or plug - but not sure.

Fuel pressure is good.

WOT, tip in, acceleration - all good.

Cruise in lock up - bad.


Thoughts?

[70rs]

Fouled plugs?
Are you running cats in the exhaust? If so, maybe getting choked up inside? (kinda doubt that one)
02 and temp sensors ok? TPS sensor calibrated? Full voltage to ECM?
Any grounds work loose? Throttle body get any junk in it?
Just some ideas. I am a total rookie with the LSx motors. However, my truck has a 5.3 and it was doing similar things and it was the plugs and wires.
Good luck.

[69MyWay]

No cats - but I tend to agree with you on the plugs and or wires - and or coils.

They have age but little overall miles.

I think I'll start by pulling and reading the plugs - and go from there.

[AM.MSCL]

Have you checked you trans fluid? color and level

[69MyWay]

Originally Posted by AM.MSCL

Have you checked you trans fluid? color and level

Yes, and while I won't rule anything out it seems very much engine as it litteraly bucks and is load/pull related in the motor. I am not detecting any attempt to lock/unlock - or shift up and down in the trans.

[70rs]

Originally Posted by 69MyWay

No cats - but I tend to agree with you on the plugs and or wires - and or coils.

They have age but little overall miles.

I think I'll start by pulling and reading the plugs - and go from there.

My stock original plugs and wires had about 180k and 10 years on them. All on the original factory parts from 2000. I was amazed they went that far.

[Rybar]

I chased an issue with mine for a few months earlier this year, ended up needing new O2 sensors. Maybe Try new ones out.

[69MyWay]

Put some new NGKs in there today. It chugged once coming out of my neighborhood, but cleaned up and ran perfect. The check engine light came on though - still running strong just didn't have time to put the scanner on it to see what is popping.

[70rs]

What did the old plugs look like?

Im glad it runs better now.

[Rybar]

Good stuff, I also put in new NGK's and it made a world of difference.