ok. 1992 firebird 305 (E) tbi its been in the garage for quite a while because i can't get it running right. ok. i have replaced all the sensors in the car but i keep getting a code 34 (map sensor) which i have replaced 3 times and nothing changed and have even tried 2 ecms and still get that 34 code. car is running so rich that its fouling out the plugs which i replaced tonight. at around 1000 rpm runs ok but as idle comes down to 675 its running rough. had the aldi hooked up tonight and the o2 reading start low and continue to climb, i have run out of ideas and am thinking about taking it to the shop. just looking for any idea i could have missed before i pay a shop to find it.

 

Check for exhaust leak. Extra oxygen detected by O2 sensor will result in ECM commanding additional fuel. Extra oxygen may come from exhaust manifold gasket leak, crack in manifold or from a leaky AIR check valve. Make sure that AIR diverter valve is not stuck in on position.

Another possibility is a leaky injector or a bad injector o-ring seal. Look for a large drops instead of nice cone of fuel.

All of this assuming that your O2 is in good working order.

//RF

 

i pulled out the replacement injectors i had for it and install the old ones and it helped some with the cone. when i pulled the plugs 6 were black and coated in soot while 2 also had gas on them and were not firing. replaced the plugs. the o2 sensor starts at around .400 volts and in under a minute had climbed to .750 before i shut it down because it was starting to carbon up the new plugs. so i will check the AIR system and the o2 sensor and exhaust.

 

is this a stock 305 that came in the car? was it running good at some point in the past?

 

yep. car is completely stock. it used to be my daily driver. but its been sitting in the garage because i can't figure out why its running so rich. i can drive it around the yard but once it warms up it idles badly and it stalls itself out.

 

since its outta the blue, i'd say look at the exhaust too. specially the gaskets around the o2 sensor or just a new o2 may be in order? as RFmaster has said. can you data log?