Code 33

I need to know what a code 33, MAP sensor signal voltage too high, means. The only time my car throws this code is when I put it in drive and hold the brakes. It is a 1995 Camaro z28.

It means the MAP at idle (or with throttle position less than 4%) is above 68kPa for more than 5 seconds. With a stock cam, that would likely indicate a problem with the sensor, or excessive misfires, or extremely unstable/low idle speed. With an aftermarket cam, if its big enough, it could be normal. Do you have an mods..... like a cam?

yes i have a cam. the specs are lift intake .510, exhaust .540, and duration at .006

If you don't have a reprogram for the cam to bring the idle up, you are probably going to get that code.

I have had this car for about a year now and I never got this code but I just changed a o2 sensor about a week before it started throwing this code.

yes i have a cam. the specs are lift intake .510, exhaust .540, and duration at .006
Its not the amount of lift that determines the intake manifold pressure, its the duration and overlap. What are the specs on duration and lobe separation angle?

You might also want to look at the harness connector for the MAP sensor. They dry out and crack, resulting in intermittent voltage problems.

Duration at .50 intake 229, exhaust 245, lobe lift intake .3400, exhaust .3610, and lobe separation 112.0

With a 16deg split on the exhaust duration, you're way beyond my knowledge of expected vacuum at idle..... I don't think I've ever seen an LT1 cam with that much split.

What kind of MAP you see will depend very much on how good the tune is.