Hi MC I have a ‘96 Targa and the check engine light keeps coming on. It has been shut off numerous times but always comes back on in a few weeks. The diagnostic codes that set don’t make sense to me but my mechanic says that the secondary air system has failed. He asked a few grand to pull the motor and correct the problem. To me this is absurd and besides, the car runs great. Can I get a reality check on this? Mark
Be aware that the check engine light can set for numerous reasons and that computer is still not smart enough to diagnose the problem. It only gives you clues. I know a number of clients who have fired the “parts cannon” at their cars only to discover that the computer lied.
Your mechanic is correct on one point. Odds are, the secondary air system is the source of the problem but pulling the engine to fix it further than you need to go. The likely culprits are clogged holes in the cylinder head exhaust ports near the exhaust valves.
Fortunately, the holes can be accessed from under the car by removing the exhaust and heater boxes. On an older car, this might be easier said than done. The nuts securing the exhaust are usually rusty so finesse is required to remove the exhaust. If you do not have a source of heat to warm them up, don’t try it, the penalty for breaking a stud is pretty stiff. We have had more than one car towed in after the owner tried to do it himself.
Once the system is off, you probably will not be able to see the holes since they are packed with carbon deposits and somewhat hidden behind the valves. I fabricated a “port cleaning reamer” out of an old accelerator cable chucked onto a common drill.
Once you clean the deposits off the exhaust port surface with carburetor cleaner, you can find the holes and start feeding the cable into the holes to break through the clogs. Work at it gradually and let the carburetor cleaner do the work for you since you do not want to push the carbon up into the ports.
Once you get the ports nice and clean, reinstall the exhaust and you are on your way. The total cost; about $800 dollars or so, plus gaskets and hardware. This is not a guaranteed fix, but for the money it is a good option and every car I have inspected for this has hadclogged secondary air holes.
By the way, while the exhaust is off it’s a good time to clean all that stainless steel with Scrubbing Bubbles and Scotchbrite. This is a great way to clean around the exhaust cutouts on the rear valance and to get the tail pipes back to new as well. You’ve already got all that apart, why not clean up while you’re there? MC