I have a 92 Aerostar, and it has been running like crap.
It is sputtering and has no power. It doesn't always do this, sometimes it runs ok. I also smell exhaust that has that rotten egg smell. Thats why I'm thinking cats. Could it be injectors, or some sensor of some sort? Any thoughts would be helpful.
Thanks,
Rusty Fuls
91 F-150
92 aerostar

 

Cats would be not be the first choice. Lots of possibilities but start with the most obvious. Plug wires cause lots of misery. If they haven't been renewed for several years replacing them is fairly cheap and easily done. Ditto on plugs. From there, it could be injectors or various sensors. Check and clean the mass-air-flow sensor. You can obtain read out codes with a tester which may help narrow the focus of your problem. The egg smell would probably rule out fuel system (filter/pump) as it indicates a mixture problem not lack of fuel. It would help myself and others to know what type of engine you have, mileage, previous problems, etc.

 

As I recall, someone once told me that most well-equipped (and knowledgeable) exhaust shops can perform a simple tailpipe test that can easily detect any obstruction in any part of the exhaust system. A probe is put into the tailpipe, similiar to states that have emissions testing (I am in Sacramento, California, the hotbed of emission testing, which is a glorified, state sponsored rip-off of man and machine, but that is another topic for another time) while the engine is at idle. There is factory specs for the amount of airflow from a stock engine through various rpm range. You may have to pay anywhere from "free" if the shop performs the repair, to no more than $19.99, which will pinpoint your problem in the exhaust system. Engines running rich, even for a short period of time, will quickly weaken any catalitic convertor (spelling) the high temps basically melt the inside of the cat, causing problems like you have mentioned. Just my 2 cents...

 

 

I have an 89 3L with 160K miles that runs pretty sluggish but occasionally runs quite well. I also suspect the cat conv. Do any of ya'll know of anyone just removing the damn thing and staight piping it. Since I am in a rural TX county they don't check for it at inspections so I figured what the heck. I ought to give me better mileage and performance just by letting the engine breath easier.

 

If the performance varies, your problem is unlikely to be a faulty catalytic converter. Their usual failure mode is that the supporting structure for the catalyzing material melts down from too much heat from trying to oxidize too much fuel from too rich of an exhaust mixture, whether from a dead/missing cylinder (burned valve, ignition misfire, injector stuck open) or a fault in a FI sensor leading to an overall too-rich mixture (TPS, temperature sensors, MAF sensor, etc.).

If you occasionally get decent performance, look for FI trouble codes stored in the PCM ("computer"), and leave the exhaust alone.

Contrary to vehicles from the '70s, removing a cat on most anything built in the 80's-on will not improve your performance OR mileage, unless you can recalibrate your PCM to compensate for its removal.

Regards,
Al S.

 

Well maybe I'll just get the vehicle running as best I can then sell it to someone who has the time and knowledge to keep it running well.