Hi I just bought a 86 firebird, pulled my engine code and came up with code 34. I understand that it is caused by low voltage/high vacuum. How can this be corrected? thanks.

 

Code 34- This indicates a faulty maf or map sensor, depending on your tpi system. MAF: This code is se when the ecm sees the following conditions: airflow less than 2.5 gps, engine speed of 600 rpm or greater and the tps is above 6% angle. The typical problems are usually false air, vacuum leaks, or residue build up on the maf element or behind the throttle plates. Check the wiring and connectors very carefully, especially if this code is also present with a code 33 and 36. MAP: This is set when the ecm sees a indicated low air flow, or in other words a unrealistic high manifold pressure. Usually a bad map sensor is at fault, but check the wiring and connectors for shorts.

 

34. Low voltage (high vacuum) at MAP sensor.
Could also be a vacuum laek on hose to MAP sensor. Hose should run from MAP to center port, rear of TBI unit.

Here's a link to full GM diagnostics for each code:
http://www.gearhead-efi.com/gearhead...c/TBIcodes.pdf

 

http://chevythunder.com/maf_code_34.htm

 

So it's TBI...?

Yes if it's TPI MAF.

Here's a link to complete TPI error codes and diagnostcs for MAF.
http://www.gearhead-efi.com/gearhead...c/TPIcodes.pdf
Which explains Code 34 is MAF as you described above but has no code for MAP...

So I must be missing the one for TPI S/D?