Hunter4Life

Has anyone ever had a clogged cat on their fc? I'm the same guy who posted a couple threads about a lack of acceleration around 6000rpm. Car is really sluggish and I noticed yesterday when I revved it up I could smell a mixture of fumes including gas. I know its not a fuel delivery issue and i am pretty sure my igntion system is working properly. So I'm thinking it's an air/exhaust problem. Also is the main cat more likely to be clogged then the two precats? Is there a way to check and is there a different procedure for a rotary engine? Also am I able to just cut it out (if it is a cat) or is it nessecary for the survival of my engine(backpressure) These are all the questions i have

Note: It's a 91 NA

jjwalker

I'd check for a gas leak first man. All the inlet and return hoses run under the driver side. Right under the driver side door is where the hard lines meet the rubber hoses

Hunter4Life

Don't have a leak but thanks

SecondGenPat

if you have access to a vacuum gauge you can test for a plugged kitty cat.
Remove one of the vacuum lines to intake vacuum (emission one preferably)
hook up your gauge
Start engine
now rev up the engine and hold it at a steady rpm (3000/4000)
watch the gauge, if the vacuum slowly drops (closer to baro) then you have a restricted exhaust.
Best of luck
-Pat

psalad

Hunter4Life I wuld be really interested if you have had it checked out/resolved/ checked the vac with a gauge as SecondGenPat suggested I have a similar problem,
Car is fine up until 5000RPM then all power goes and it creeps up in revs from there, I have noticed more recently that power seems to be going at lower Rpms and the exhaust glows RED hot up to the Precat and then a duller red there after until it dissapeers in heat sheilding.

RotaryRocket88

iTrader: (7)

Remove the precats and main cat. Usually it will be very clear if they're plugged or not. When my original cats nuked themselves, I found pieces of metal honeycomb broken off and resting inside.

You can also try to look through them to see if any spots are fused together. If they're plugged up, break all of the honeycomb out so you have a straight pipe to use until you decide to replace it.

And it is just about exactly like you describe; the engine just hits a wall around the upper-middle rpm range and creeps along from there.

jjwalker

I have an 88 GMC s-15 with a V6 when I was a teenager. It had a lopey cam, no emissions besides the cat. I went racing one night and I blew the honeycomb out the tailpipe. It was like fireballs rolling down the street. I was redlining and all the sudden fireballs came out.

The next day, I pulled the cat, tipped it, and watched the entire substrate fall out.

Slightly off topic, just sharing

psalad

Cheers, I will try that the weekend when I have the time to jack the thing up rear and front .......geez I hate that job!

I will take the main cat off coz it is really easy and look at the pre cat to see how easy it is to remove, but I think this is a bit of a pig? If the precat is breaking up I will see bits of it in the main cat wont I? also if the pre cat is breaking up can I just break that up and tap the bits of it lodged in the main cat out?

Also if I find it clogged I am prepared to break it up to get my baby running right, but will it affect my backpressure to the point of backfire?

Sorry for the stupid questions but I have never had Cat problems before on any car so it is all new to me, my car has done 119,000 miles is it normal for a cat to fail after this milage? also what is the average life of a cat in years and miles if anyone knows I would really appreciate it for futire reference.

freemanrx7

I would check the first one and chances are it has fallen apart into the second one. If your first one is bad just hollow it out. Check the second cat and if clogged hollow it out to. The main cat should be fine and you can pass smog with it. I've done this to a few 7's over the years and the mileage seems to be around 120-130K.

RotaryRocket88

iTrader: (7)

Depends on how bad the precat might be, but you could find pieces of it in the main cat. But go ahead and clear out the precat if it's bad. Backpressure is not a concern; if anything, your turbo should be begging you to remove both cats and let it breath .

As far as emissions go, the precat is only there to clean the exhaust when the engine is cold. Once everything warms up, only the main cat is necessary.

Hunter4Life

Okay so today I went and took off my exhaust from and I just took it for a quick test, nothing, I could tell it breathed better but I still have the problem. My car has lost power especially 6000 and up ( I can't even redline the dam thing.) In first gear its not as noticeable, in second it really struggles to get to eight and third it won't go past 6100 rpm. I'm almost positve it's not a fuel issue, what could be happening. No engine light, simple stuff like air filter is good.

*NOte I also noticed that sometimes when I rev it I here this zzzz sound, i think it's coming from the back of the engine bay, not sure. What the heck could it be???? I want my power back

freemanrx7

I'm confused! You drove it with no exhaust?


Maybe check the smog pump cause it controls the VDI/acuators/ports or whatever they are called. At a certain rpm the 5th&6th ports open up to let more air in. Maybe if they are not working then it's getting to much fuel but not enough air

Hunter4Life

Yah, no exhaust

freemanrx7

The smog pump is working?

SecondGenPat

I got that sound after i removed the muffler for the smog pump, when the car still had the smog pump. I thought it sounded kinda cool.