I have had this code show up every once in a while but has been showing up a lot more for no appearant reason. Usally if it shows up it is only on the first start of the day and then I would never see my SES light again. But lately it shows up almost every time I start it and don't matter wheter the engine is warm or cold. I have done the following modifications to it.
ZZ4 Cam
Ported factory heads with Manley valves
Ported intake and plenum
Cutt off bottom of airbox and put in K/N filters
Fuel pressure regulator changed to adjustable
180 stat and lower temp switch.
The engine runs great and kicks *** on low end and through mid range but the SES light gets a little anoying sometimes. I use a Auto X Ray to get my codes and check things out but this one has got me a little puzzled. Also do you guys think I would gain further benfits with a aftermarket chip and who is the best to work with on getting on made? Thanks for your help Dennis

 

Check all the relays, and check your TPS voltage, try to set it a little higher if it'st too high already.

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GTA -89:383, 4-bolt,Free flow muffler,dual 3" HF cats, Edelbrock headers, Canfield heads, 1.52 RR 7/16, ZZ-9 cam, Big Mouth, AS&M LTR, !plenum, 52 TB, MSD 6AL, TPIS level V prom, Superior shift-kit and all the minor mods,looking for a SR ...
http://www.itv.se/tacs/members_cars/m279/m279.html (Swedish Trans Am Club)

 

code 34 is a vacuum circuit.Check your wires and connections.Might have to replace the vacuum sensor circuit.

 

also if your car is a later model,this is a map sensor code.