Long story short, having lots of good times right now. The distributor pickup died and the resulting backfire was tremendous. Ended up with looks to be 6 different broken exhaust manifold bolts, all broken at or below the head surface. Planning on trying to drill and use extractor to get them out, but may have to pull the heads if I can't find a 90 degree drill that will fit. Hate to pull it down, it only has 29k miles on it and no leaks.

This truck has 2 air pumps in it, each feeding down to the respective exhaust pipe. No cat as it was exempt from the factory. The question I have, should there be a O2 sensor somewhere? Thought that if it had an air pump, it used the sensor to set mix and such. This critter has the throttle body if it matters.

How does this engine use the air pumps if no o2 sensor?

Any advice, I'd sure appreciate it.

Also, if anyone wants to help, my wife would appreciate it also. I think she is tired of the language education she is getting. I hate working on my own stuff. Pay is terrible.

ED

 

I thought '89 was the last year for a carburetor on Dodges?

O2 sensor has nothing to do with running an air pump. All the O2 sensor does is tell the PCM whether the mixture is rich or lean so the computer can change the pulse width on the injectors or the mixture control solenoid in the carb.

Air pumps have been around since the late 60's, computers to run the fuel mixture didn't happen on a widespread basis until the late '70's. Air pumps are typically run by vacuum solenoids.

 

Ok, thanks. How does the pump work then? It appears that it just dumps into the exhaust. With no cat, I guess it is just used to cool the exhast or something.

Nope, it's a throttle body. Kinda wish it was a carb. I'm lot's better on them when it comes down to working on it.

Guess I'll need to do a little book learning. Would like to understand what I'm dealing with.

Ed

 

The air pump is used to supply lots of extra oxygen to burn fuel that gets through the cylinders. With EFI the mixture should not go rich when you close the throttle at high RPM, the carbureted systems had what was called a gulp valve that momentarily diverted the air under high vacuum conditions to prevent a massive backfire. Catalytic converter equipped vehicles needed other control valves to keep the cat from getting overheated. Since you have no cat and no carb, there's no reason not to dump the air straight into the exhaust uncontrolled. Saves money and trouble.