1990 RS 305 TBI Have been having problems with running rich, replaced TPS Sensor and MAP Sensor. Last night coming home from work, car was running like normal, then turned onto road and car had no power. Took approximately 1 mile to get up to 55 mph! Never got above 50. Shaking kind of like it was fixing to blow, but wasn't making knocking sound. Got me home though. Checked oil today, and oil is fine. Oil pressure gauge was reading amost 60. It's never ran that high before. Someone said may be catalytic converter. Anyone have any ideas?

 

is it still running/driving bad?

if it is the catalytic converter, you can check it by pulling the o2 sensor out and taking a quick test drive, (it will be loud, so don't do it in the middle of the night), if it runs better with the o2 out, the cat is plugged

 

I second the motion on the cat being plugged, thanks for the suggestion on removing the o2 sensor to check if that cat is good or bad. I always drilled a hole or two in the cat to trouble shoot.

 

I'm thinking it's going to run really rich with the O² removed, so determining if the performance is a lot better may not be that easy. Still, it's a clever method to reduce exhaust system pressure in front of the cat.

I've always just dropped the cat and test driven it. Usually, the matrix is visible once the cat is removed, so clogging can be fairly apparent even without a test drive.

 

not quite true, at first it will be in open loop, so it dosen't even need the o2

 

do you know it's rich or just guessing? i'm inclined to believe the cat also, but i'd also want to make sure the tune up is good and run a compression test.

 

Excellent point. On a cold starup, you should have about 300 seconds of open loop operation.

That might be helpful to diagnose the exhaust for some, but I'm in the habit of not moving a vehicle until I see a deflection of the temperature gauge, or about a minute or two. I also don't get into the throttle by more than about 25% until full operating temperature. That might still be enough to differentiate between a clogged exhaust or not. I suppose that extra 5/8" opening can make a difference to a completely clogged system.

 

My dads van would start but wouldn't rev about 2000rpm, hit the gas and it was like it wanted to go but it was stuffed up. Drilled holes in the cat and it took off like a rocket..hello straight pipe hehe.

My gf's car did the same thing..felt like omone had a brake on, it just wouldn't go like it was supposed to, hard start and wouldnt rev when ti did.. cat

If I had a quarter for every plugged cat I came across i'd be rich. I think when some cars go into safe mode they rn rich as hell, on an old car alot of people get used to the check engine light all the time, and just run it that way.

Taking out the o2 sensor will make enough differnce so it can run better, no performance but ou can tell if it is plugged for sure. It also saves cutting holes in a possibly good cat, or dropping exhaust, we all know how those bolts can be -- ick