2000 Camaro, lots of mods….drivability issue and performance issue-
Car was running fine, changed plugs, changed oil and filter, tranny fluid and filter, cleaned nitrous filter, new fuel filter, did front brake pads, polished out headlights, added rebuilt alternator (160 amp)…
Drove fine, had nitrous in the line (didn’t race anyone that night), shut the bottle and hit the button (ran hard for a second, then flooded with fuel), check-engine light came on, drove it for a few minutes to clear everything out, light went out, felt fine. Next day, too friend for a ride, ran weird, idled high, very unresponsive, rpm’s came up real slow (like an ultra tight converter or something)…tried it on and of the bottle, same response until above 5,000 rpm, then the rpm’s came up faster. When driving, car would accelerate on its own all the way to 45 mph or so and stay there (from a dead stop with no gas being applied), when shifting into neutral at 45 mph, the rpm’s would climb to 1500 or so, and then slowly fall. If you hit it on a 40-50 roll, it would accelerate slowly until 5-5500 rpm then it would pick up speed.
Here is what I have done (unsuccessfully) to address this problem:
Disconnected/reconnected battery after every change-
Replaced IAC with another IAC from a good running, same year Camaro
Cleaned IAC
Replaced TPS
Checked for intake leaks with carb cleaner (none found, no surging at all)
Autotap- no codes
Snap on scanner- no codes
Had friend rev engine to 1800 rpm or so, disconnected IAC (per mechanic friend), car was more drivable down low, did not want to idle high or go to 45 mph on its own, but still felt sluggish (again like a ultra tight converter)
Went to Livernois to have car re-tuned…used a brand new ECM, did the tuning, made good power (dyno pulls were at 70 mph and above) made 580 rwhp and 644 tque so engine is not damaged, and everything ran great on the dyno-
Test drove it and the exact same problem as before with drivability. Tried replacing Metco breather with standard oil cap, seemed to help lower the idle a little but no major difference. Put foot on brake and foot on gas…floored gas…rpm’s went to 1800 at WOT on the brake, did not go above 1800 rpm’s or spin tires. At this point I thought the converter was bad, drove back home and shipped it to P.I. for a check. Everything checked out fine, they are restalling and sending back to me this coming week.
Having mechanic check intake gaskets for possible leaks, do a compression test, and putting 3.42 gears in rear end, and sending computer back to Livernois for gear swap. I believe the computer is now set to not lock the converter at all until 3rd gear at about 50 mph.

I can’t figure out what to do next IF the converter comes back and doesn’t fix the drivability issue….any thoughts about what to do?

SDB

 

Hmm interesting.. When the problem is happening does it feel like a miss fire? Do you have access to a scanner that will show miss fire counts? It sounds like it could be an iginition problem but could be anything. good luck.
-=Rick

 

the scaner did not show any codes, some real minor misfires but nothing major. I am checking/replacing the intake gasket and will check th plug wires (only a year old, Taylor wires)....just weird how it happened all of a sudden...