I would appreciate it if somebody could help me. Over the past couple of months I have noticed that my car has begun to have a bad exhaust smell. No way to describe it, except that whenever I give it any gas it the exhaust smells like something coming out of a 79 Honda. I've noticed some lost power and I'm embarrassed. It's not a rotten egg smell, and I have already replaced my cat. converter. I'm thinking it needs new spark plugs. How often should they be changed? Thanks for any help.

 

Replace plugs around 30k. Why did you replace the cat? If it was because it blew out, there could be a chunk lodged somewhere and this could be your restriction/smell.

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Rob
'86 TA 305 TPI
Gutted MAF
Ported Plenum
TB Bypass

 

What year? What engine? What induction?

Regardless of that info, all thirdgens have O2 sensors, which will produce the symptoms you describe. You may need new plugs as well. As many on these boards will say, get the basics,like tuneup, taken care of first, then start working on what's left. Plugs & O2 sensor fall into the "tuneup" catagory.

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82 Berlinetta, orig V-6 car, now w/86 LG4/TH700R. 2.93 limited slip. Cat-back from '91 GTA, Accel HEI SuperCoil. AMSOIL syn lubes bumper-to-bumper. Daily driver, work-in-progress (LG4 w/LB9 block, ZZ3 cam and intake, WP 305 heads ported & polished, Hooker headers & y-pipe, hi-flow cat).
57 Bel Air, my 1st car. 0.030 over 396, Weiand Action+, Edelbrock 1901 Q-Jet, Jacobs Omnipack, 1-3/4" headers, TH400 w/TCI Sat Night Special conv & Trans-Scat shift kit, 3.08 10-bolt w/Powertrax, AMSOIL syn lubes bumper-to-bumper. Best 15.1 @ 5800' Bandimere. Daily driver while Camaro was being put together.

 

It's a 91 305 TBI, 120k miles. Spark plugs were last changed a little over 30000 miles ago, so I guess I should have already changed them. The cat was changed about a year ago, and although it was breaking up, the problem with the smell just started recently. The O2 sensor had popped up in my mind as a possible problem as well. Who knows if its ever been replaced. I bought the car with 80k miles on it, so it may have never been replaced. Oh, and another thing. It idles poorly on somedays, and a couple of times when I stepped on the gas from a stop it hesitated and then took off. Generally its just been acting goofy. I'll do the tune-up and see what happens.

Josh

 

had the same problem. plugs and wires should make a big difference, then oxygen sensor, check ur EGR too

 

If the O2 sensor isn't working right, then you may be getting a rich mix in the cat which would cause the smell. I would say the plugs are due (several thousand miles ago)

-Rich

 

I agree with everyone. Definetly go to Napa and get a new O2 Sensor, a set of Accel 300+ race wires and some AC/Delco rapid fire plugs, it'll cost you under $120 and should clear your problem up.

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1987 Chevy Camaro IROC-Z
L98 TPI 350 (5.7L)
TH 700R-4 Transmission
Borg Warner 7.75" 9 Bolt Rear End

Current Mods: LT4 Hot Cam, Comp Cams 1.52:1 Roller Rocker Arms, Edelbrock TES 1 5/8" Headers, Hooker 3" Aerochamber Cat-Back System, Performance Resource Chip, Accel Ignition Coil, Cap, Rotor, 8.8mm Wires, K&N Filters, JET TPI Air Foil, All Free Mods, Falken ZIEX Z-Rated Tires.

Best ET (w/o LT4 cam): 14.32 @ 97.7mph
(corrected for elevation)

7.5" 10 Bolt with 3.42s soon to come!