leafspring

I have a 91 Firebird 3.1 that is throwing a code 45. I've done the basic tuneup, plugs, wires, cap, rotor, icm, fuel and air filter replacement and fuel pressure test. Replaced the o2 sensor twice, reset the codes, seemed to run fine. Took it to the smog shop and it failed horribly. the guy who did the smog test suggests that I replace the fuel injectors. He stated that the springs in the injectors get weak which keep the injectors open to long there for resutling in a rich mixture. My question would be is there any thing else that could make it run that rich, mechanicley the car seems to be in pretty good shape, starts right up and dosent seem to use any oil. Any help from you guys would be appreciated. thank's in advance.

mike
smog results
rpm-765 (hc492) (co 3.29)

rpm-2653 (hc200) (co7.32)

jstrdn90rs

I would say that mechanic is probably right..the only thing I would add is a fuel pressure regulator..if its set too high it (could) set a 45 code.Check the pressure and if its okay then I would say ..time to go after the injectors.Once you get the top plenum off you can Ohm them right then.If I remember they should be right around 12 Ohms +/- 2 Ohms.This was a common problem with these engines..the injectors would get weak and dump additional fuel and sometimes plug up the Cat convertor.Good luck..

1TUF92Z

i doubt it's the injectors. better check your CTS voltage. I bet you it is sending wrong voltage signal to the ECM. you can use a scanner if you have one or can access one. you can also use a DVOM if scanner is not available. If you have a DVOM hook up the the + to either one of the 2 wire and the - to ground. You should see about 1.7 volts when engine is at operating temp. If not PM me and i'll walk you thru diagnosing it.

leafspring

Thanks for your replys, im hoping its the injectors on the count i orderd a set yesterday $70 shipped. 1tuf92z, im going to test the cts first thing after work tomorow.

thanks again

mike

leafspring

Replaced my injectors today, passed smog with flying collors.

Thanks again