Loss of power at high revs
 

On my last day at the track, I could not get the car LS1 Z28 to get over 4800rpm, with the gas pedal to the bottom of the floor in areas I usually get to red line, no hesitation, misfire, etc. it just would not get higher on the revs.
Any ideas?, feels like a gas supply problem but I am not sure.

RE: Loss of power at high revs
 

make sure the detent cable for the trans is not too tight and not allowing the full throttle? Or put it to the floor and make sure its opening all the way..

RE: Loss of power at high revs
 

it wouldnt be a gas supply problem unless the fuel pressure is dropping but then you would know, or if there was hesitation or bogging as well, i agree with tommy it sounds like the transmission, maybe the converter is causing a problem, thats of course if its auto

RE: Loss of power at high revs
 

Thanks guys, sorry I did not mention this is a 6 speed, so the tranny would have nothing to do with it; and the clutch it's not slipping, in that case I would have revs but no speed, and I have no revs; maybe it is the gas pedal cable that has stretched and the throttle is not opening all the way; or a problem with the linkage, what do you think? I do spend about 90% of the time at full throttle at the track, Lime Rock, Watkins Glen, Pocono, etc.
Thanks for the advice, keep it coming!!!!!

RE: Loss of power at high revs
 

[&:] 1le still got cats on the car?? kurt

RE: Loss of power at high revs
 

Is the LS1 a direct connect to the throttle? I know some of the LS1 kits come with wire connection between pedal and throttle. Most of the things I can thing of would set your Check engine lite. It almost has to be a semi-pluged exhaust. I have seen the older cats fall apart on the inside and plug the muffler. I used to use a vacuum/presure gage that would read up to 15PSI of pressure. Until I was checking a 89 350 Z28 andblowmy gage apart.

RE: Loss of power at high revs
 

Yes still got CATS in, as far as the throtle connection it is a direct linkage with the gas pedal cable, no wire connect; interesting idea about a plugged cat, but wouldn't I feel it bogged down all along? that is not the case.
No check engine light came on.
I will get the car out of storage this week and run it again, then I can read the OBDII computer codes and see if anything comes up there, if it is emissions related I am sure it would show up there.
Thanks again for the comments and advice

RE: Loss of power at high revs
 

Exhaust is a lot like your intake. Its a matter volume. According to my GM training a normal engine and handle about 3 PSI exhaust presurre before it will effect the way the engine runs. Since an engine running at high RPMs has more exhaust volume the presure would raise with RPM. Onceexhaust pressure reachs 7-10 lbs the car will no longer start. A restricked exhaust would feellike a car with too small a carb.

To check it you remove the O2 sensor and check for Back pressure. Your issue may not show up at idle.Ido not know much about OBD2 system but I did a lot of work on the OBD1 (up to 90). I know of no code that this condition will set. Tho sometimes it will set a rich O2 sensor do to the no start condition.

RE: Loss of power at high revs
 

[&:] no it wouldnt necessarily feel bogged down all the time, this can be relative to the amount of restriction the cat is causing. can use vacuum gauge to test for plugged cat or is usually most noticeable higher in the rpms or load as this is when the most volume will be wanting to move through the motor kurt