88 running really rich

this is a wierd deal..........88 4cyl alltrac. i have had it for a few months now.it's got over150k on it. it is what smells like it is running extreamly rich, it makes me almost sick to be in it.here's the wierd part.it's pretty rusty and i was getting lots of dust in the trunk and filtering into the cabin. so i filled the rust holes in the rear wheel wells with expanding foam..........no i get terrible exhaust fumes in the carthe exhaust system is very solid with no leaks, the tailpipe is pretty black and there is carbon splatters on the bumper. it doesnt load up and runs fairly well other than on deceleration it tend to surge. timing is right,compression is175# all across .i did connect a lose plugged vac line up to the cruise servo, as it looked like it was originally on there this hose ran to the intake plenum and then to the evapcanister. i have since disconected that. but still the same. any ideas would be helpfull

Test the oxygen sensor, then coolant temperature sensor, etc.

It can be that your cat (catalytic converter) can either be clogged or burnt through. At the same time, your O2 sensor could be faulty as well.

A burnt cat smells usually like rotten eggs....

A faulty O2 sensor can give bad readings to the ECU, resulting in the ECU dumping too much fuel (running rich).

I would check both of these things, as well as your injectors.


Good luck,

teh previous owner had all new exhaust put on it and there's no cat on it. will that screw with the o2

The O2 screws into the exhaust manifold out from the engine, before the exhaust gases reach the cat. The cat acts as a filter before the gases reach the muffler.

The path that the exhaust gases travel based on the components mentioned is:

Exhaust Manifold (with O2) -> Cat -> Muffler

There should be a cat on the system. Replacing the exhaust system (under normal circumstances) involves replacing everything after the cat. Besides, without the cat, he would never have been able to pass emissions when he owned the car. :nono:

If the passage thru the cat is clogged, it could likely send gases back to the O2 sensor, making it worse.

I would check the O2 sensor for starters, for the reasons I posted before. If you expect to pass your inspection, you will have to install a cat if it turns out that there isn't one.

Good luck...

thanks i'll check the o2 sensor. it is a complete muffler shop made system from the manifold flange-back. here in nebraska there's now inspections or emission tests to pass. thanks again

how does a cat get burnt?

Too rich mixture - the excess fuel burns in the c/c

teh previous owner had all new exhaust put on it and there's no cat on it. will that screw with the o2

Only if there is supposed to be a sensor after the c/c.