I have a 94 z28 That has been not shifting at wide open throttle. I have 2 transmissions that are doing this. So we are looking for other problems other than the transmission. We came across a map sensor fault code of 34. According to repair manual when checking map sensor voltage you should have 5v for refrence voltage and 5v for signal voltage with switch on. We only have 5v for refrence voltage and 0v for signal. So we happen to have a 97 z28 that we checked also, it has the 5v refrence voltage and 5v signal voltage when switch is on.

Can anyone help me with this issue.

Thanks for all the insight.
Brad

 

The code sets when MAP sensor voltage drops below 14kPA. Could be the sensor, or it could be a problem with the harness connector. I've seen a couple cases (including my own 94) where the connector dried out and started to crumble, producing intermittent MAP sensor voltage problems. The sensor itself is fairly indestructible, so check the harness connector first.

 

I just spoke with someone at the dealership, and they told me that the throttle position sensor is also tied with the map sensor, could this be the source of the true problem???