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Tech / General EngineIs your car making a strange sound or won't start? Thinking of adding power with a new combination? Need other technical information or engine specific advice? Don't see another board for your problem? Post it here!
I'm new to the 3rd gen ownership world as well as this forum. I appreciate all the posts and time people contribute to the cause. I'm hoping some day I can return the favor. For right now, I'm trying to identify the part circled in red on the picture. It is on a 1992 RS with a 305 TBI. There is a rubber hose leading off the of the "box" that travels down under the car towards the rear. It then (at some point) converts to a thin metal tubing/pipe. When I bought the car, the tubing was hanging out under the passenger side door so I don't know where it should be attached to underneath. Any help in IDing this piece would be much appreciated.
Thank you for the reply, and yes, I believe you are right. I just found an AIR diagram in an online service manual that looks like what I am referring to. I believe that this is a common part that people remove, especially in my case where the car doesn't have a cat on it. If anyone is familiar with removing these, please let me know.
The AIR system is basically a pollution control device. It's purpose is to push air into the exhaust system when the engine is below operating temperature to lower the emissions coming out the tailpipe. Once the engine reaches operating temp, the AIR does nothing. The car will operate fine without an AIR system however depending where you live, it may be required to pass an emission test if required. There should be a belt driven pump as part of the system. If the previous owner removed the pump, then you can simply remove everything else related to it.
The AIR system is basically a pollution control device. It's purpose is to push air into the exhaust system when the engine is below operating temperature to lower the emissions coming out the tailpipe. Once the engine reaches operating temp, the AIR does nothing. The car will operate fine without an AIR system however depending where you live, it may be required to pass an emission test if required. There should be a belt driven pump as part of the system. If the previous owner removed the pump, then you can simply remove everything else related to it.
Thank you for the input. I will look into removing it then as long as I know it will still pass emissions test
Thank you for the input. I will look into removing it then as long as I know it will still pass emissions test
That is the AIR system diverter valve. There is a belt driven air pump that is piped to that diverter valve. When the engine is cold, the air pump and diverter valve sends air to the exhaust manifolds. The additional oxygen introduced into the hot exhaust gases which contain excess unburned fuel due to ECM's cold start enrichment program (same purpose as the choke on a carburetor) causes a secondary burn of this unburnt fuel within the exhaust manifolds. This reduces the hydrocarbon (unburnt fuel) emissions during warmup and also helps to heat the oxygen sensor faster.
Once the engine is warm, the diverter valve changes position and sends the air from the air pump to the catalytic converter (that's the tube you were asking about). The particular type of catalyst that these cars used back then required additional air to be pumped in for them to work correctly. There are catalysts available now that don't require the additional air injection.
As for removing the AIR system, you can remove all of it and it won't affect the ECM or how the car otherwise runs. You will need to remove the AIR pump and install an AIR pump delete pulley. If you still have the original catalytic converter, you would need to cap the AIR tube connection so you don't have an exhaust leak, however I'm not sure if not having the air injection to the catalyst will cause any problems over time with the catalyst. Be careful though if you are in a state that does emissions testing and especially if they do a visual inspection under the hood (ex. California). They look for all of the emissions equipment to be in place. In reality though, if the only issue you are having is the air tube to the converter being disconnected, I would just reconnect it and leave everything be. The AIR system really doesn't cause any issues and the amount of horsepower the air pump robs is negligible.
That is the AIR system diverter valve. There is a belt driven air pump that is piped to that diverter valve. When the engine is cold, the air pump and diverter valve sends air to the exhaust manifolds. The additional oxygen introduced into the hot exhaust gases which contain excess unburned fuel due to ECM's cold start enrichment program (same purpose as the choke on a carburetor) causes a secondary burn of this unburnt fuel within the exhaust manifolds. This reduces the hydrocarbon (unburnt fuel) emissions during warmup and also helps to heat the oxygen sensor faster.
Once the engine is warm, the diverter valve changes position and sends the air from the air pump to the catalytic converter (that's the tube you were asking about). The particular type of catalyst that these cars used back then required additional air to be pumped in for them to work correctly. There are catalysts available now that don't require the additional air injection.
As for removing the AIR system, you can remove all of it and it won't affect the ECM or how the car otherwise runs. You will need to remove the AIR pump and install an AIR pump delete pulley. If you still have the original catalytic converter, you would need to cap the AIR tube connection so you don't have an exhaust leak, however I'm not sure if not having the air injection to the catalyst will cause any problems over time with the catalyst. Be careful though if you are in a state that does emissions testing and especially if they do a visual inspection under the hood (ex. California). They look for all of the emissions equipment to be in place. In reality though, if the only issue you are having is the air tube to the converter being disconnected, I would just reconnect it and leave everything be. The AIR system really doesn't cause any issues and the amount of horsepower the air pump robs is negligible.
Great explanation, thank you. Unfortunately, there was no cat on the car, so I can’t just hook it back up. I did however order a new Magnaflow cat which has the air intake port on it. I will just leave everything in place and hook up to the new cat, assuming the tube is salvageable. If it is not, does anyone know where I could find a replacement piece/hose for the connection point between the cat and the AIR system?
Great explanation, thank you. Unfortunately, there was no cat on the car, so I can’t just hook it back up. I did however order a new Magnaflow cat which has the air intake port on it. I will just leave everything in place and hook up to the new cat, assuming the tube is salvageable. If it is not, does anyone know where I could find a replacement piece/hose for the connection point between the cat and the AIR system?
That explains why the tube is hanging down, not connected to anything. Put a new converter on with an air tube connection and you should be good to go. Hopefully the end of the tube is still intact, but probably it was cut off. I have used a high temp silicone tubing repair kit and had no issues.
