Hey guys this my first post and just looking to get a little help to get my car running a little smoother. I have an 89 convertible 305 TBI and have been having some idle issues. Two years ago I failed my smog test so I took it to my dad's friend whom is a mechanic and he retarded the timing and barely got it to pass. Now I'm trying to get the car running good so I can pass this year. I've recently replaced the distributor cap and rotor along with the plug wires and had the timing set by a professional but it is still not idling the way I think it should be. If I break too rapidly than the engine sputters and the rpms drop real low. There is also a strong gas smell if I try and stick my foot through the floor. My ex-brother-in-law replaced the spark plugs about a year ago but he is a shortcut taker so I'm not too sure how good of a job he did. I'm thinking of replacing them and the O2 sensor. Any thoughts. I did get a nice boost in power when I replaced the cap and rotor (clearly signs of a lot of arching) but it still runs rich when I accerlarte hard. It's like not all of the fuel is being burned. Any thoughts? Try not too flame me to bad, I'm just starting to learn the innner workings of the automobile

P.S. I did the test when you bang on the cat and see if you can hear a rattle and heard nothing so that leads me to believe the cat and o2 sensor might be alright.

 

My z28 was having a very similar issue, it ended up being the distributor. I replaced the whole thing, and it instantly ran better and the fuel smell was gone and idle was perfect. Mine had 142k on it and was just worn out.

 

I would suggest performing a compression test to verify engine health. This will save you chasing ghosts. Be sure to disable spark by unplugging the gray connector at the coil. Then hold the pedal to the floor while you crank the motor atleast 4 full cycles (16 revolutions)when testing each cylinder.

Once you verify good compression, check fuel pressure(should be 9-13psi), test spark KV using an inexpensive adjustable KV tester. You should get 40KV at every plug wire. If not, then suspect a weak coil. Distributors are a big issue on these cars. Unless you know how to properly test the components, it almost better to simply replace the unit if there's any question of its condition. You can look for corrosion or a loose shaft bushing, but generally if it looks old and even a little crappy, replace it. Stay with AC Delco or Standard Motor Products for the dist.

Check injector spray pattern. The best way is with a dial back timing light. By dialing back the flash, you can get it to illuminate the injector spray so that the droplets are perfectly visible. Look for any holes in the conical spray or for dribbling. These indicate a dirty injector nozzle that will need to be removed for servicing. Have the injectors serviced by an injector service shop where they will test the coils and sonic clean the nozzles.

Hope this helps.

 

Wow what great replies. ASE doc all of that might be a little over my head right now but my dad has a few friend's with shops so I might me able to get a compression test done. I've got a small oil leak coming from somewhere that I need to find and I think I'm getting some blo-by in the air filter box which I would think would indicate a future rebuild or engine swap if I decide to keep the car

 

Got some free spark plugs with mail in rabate at pep boys so will see if that changes anything : )

 

You should have started with your blowby... you may need a new PCV valve...

 

Good point! I passed over the blowby test. Its a quick, simple way to check ring seal. I perform the test as part of a prepurchase inspection, especially when I see oil in the air cleaner. Just pull the PCV and make up air lines out of the valve covers and observe the amount of combustion gases expelled from the open holes as you rev the engine. A small amount is normal but a large volume of crankcase gases means poor ring seal.

 

Im having the same problem except mine is a 90 camaro rs with the 3.1 liter v6. Maybe the distributor or pcv valve. I put a new distributor cap on and it seems to be doing the same thing, any more ideas?