View Full Version : Catalytic converter & exhaust system.

09-03-2006, 03:08 AM
I'm just wondering if anyone's had any problems with their catalytic converters or the exhaust sytem in general being restricted. If these symptoms sound similiar to yours please post!

1. The car starts up fine cold and idles. After about 2-5 minutes of light driving the car begins to slowly lose power and engine response.
2. The thing that makes it undriveable is the lack of power and engine hesitation. The powerband seems random, although between 1 and 2k is basically unuseable, yet still driveable.
3. After about an hour on the highway, the car would fail to start after sufficient cranking, although if left for say, 30-45 minutes, it'll slowly come to life.
4. Once it's started up, in this condition, i can floor the pedal in Neutral and the RPM slowly rises. I can do this in 1st gear as well, however it creeps very slowly along the road. Although when I lightly push the pedal, it seems to run a tad smoother.

(5sfe) 1990 automatic Celica GT with 425,000 kms. The only other thing i can think of would be the fuel pump, although the symptoms dont seem quite right. As far as I can figure, there are no vacuum leaks.

The fix for the cat is theoretically easy since all I need to do is put on an aftermarket header or a stock exhaust manifold without the cat attachment (if they exist). Im just wondering if anyone has a part number to see if it's even worth buying a new one. Also, any suggestions would be much appreciated.

Is it possible to just remove the cat and run a pipe where it once was? Any ballpark figures for what this might cost at a muffler shop? There's no aircare/emissions restrictions where I live.

Would the exhaust manifolds on the 4th gen(3sfe) celicas fit the 5SFE and be long enough to bypass the cat? There are a bunch of them at the scrap yard, although there's never any 5th gens.

Ian Hoyte

09-03-2006, 03:31 PM
It's unlikely it's the cat if it doesn't do it when the engine is cold.
It sounds more like a sensor or connection is going bad.
Do you have a CEL [Check Engine Light]?

As far as the 3SFE manifold, it should bolt right up to your engine, but I don't know how well it will line up with the rest of your exhaust.

09-03-2006, 05:35 PM
I didn't have this problem on my celica, but try the engine coolant temp. sensor. I had similar symptoms on my 89 Grand Marquis and all I had to do was replace that little sensor and they all went away. Also you could try the EGR valve, though I wouldn't put much hope in that being your problem. AND I would check my tranny fluid and my engine oil. Hope at least one of those helps

09-03-2006, 07:22 PM
Coolant temp sensor wouldn't cause it to run that bad.
The EGR wouldn't either. If it was stuck closed, it wouldn't hurt anything, and if stuck open, it only hurts idle. And a slight degradation at full throttle.
Vaccum leak wouldn't cause it either.

How is your ignition timing?

09-04-2006, 03:54 AM
The timing is fine as well as transmission fluid, oil and fuel/air filter. I was fairly confident it was something to do with the exhaust since i have no other ideas. I dont have a CEL on, and no codes are coming back from the ecu so i'm skeptical that it's a sensor problem.

I took it out for a drive tonight, and i noticed it really doesnt have any power when cold, but the engine runs fairly smooth. My theory was that the exhaust gets backed up in the cat when run for some time and slowly leaks out when left off, although I may just be picking my brain. I suppose the only way i'll find out will be to do something about it. I'll keep you guys informed. Thanks for the replies fellas.

Ian Hoyte

09-17-2006, 12:52 AM
Hey guys, fooled with the car again today and found out that the problem wasnt exhaust related at all. I took it out for a drive and got it so it wouldnt start. That got me thinking it probably just isnt receiving fuel, so I took out my trusty hammer and banged the gas tank a bit. Once I cranked it it fired up like nothing had even happened. The fuel filter was extremely clogged when I replaced it but thought nothing of it since it didnt fix the problem. Anyways, a heads up for anyone experience these symptoms.

I looked in my chilton manual for replacement and it looks like theres an access hatch below the rear seats. Anyone replaced their pumps before and have an idea how difficult it is to remove those seats? Not sure if I even need to since it seems to be running fine.

Thanks again guys,