Cat failure stops car from running?

[BartusCompater]

Driving down the freeway today I noticed the car was acting pretty funny. The throttle didn't seem to be responding very well and the RPMs were staying really high. I pulled over to the side of the road and the car died. Looked under the engine bay and noticed a little bit of smoke. Turns out the smoke was originating from the catalytic converter. It looked really thin, not like exhaust, like something may have been toasted inside the cat.

The car starts now but just dies instantly.

Is this a common problem? Would a failed cat cause the car to just stop running? And is it safe to just install a straight pipe? I'm in Washington and I believe the car is old enough that I wouldn't have to worry about any emissions regulations.

[TulsaSpider]

Well if it becomes plugged it would not run. Kinda like sticking a potato up your tailpipe! If it's legal get rid of it!

[majicwrench]

A plugged cat can do exactly as you describe..the engine starts, runs for a second and builds pressure in the exhaust, then dies. If left to sit a few moments, the pressure will bleed out of both ends, and it will do it again.
That does NOT account for the RPMS staying high.
Need to test some things first.....

Anywhere you can let the exhaust out before the convertor will work for testing purposes, pull Oxygen sensor, EGR, whatever. Start car and see if it runs.
Another easy thing to do it drill 1/8" hole in exhaust pipe before cat. Now try to start car. If cat plugged exhaust gas will shoot out under high pressure. Then just run screw into hole when done testing.
Keith

[BartusCompater]

It looks like someone already drilled a bypass into the side of the exhaust before the cat. I took the plug off and the car still wouldn't stay running, no improvement. Also tried disconnecting the cat completely, but it just makes the car really noisy when it fires up. It will barely stay running if I nurse it with the throttle.

To be honest, this is how it was acting when I was having issues with poor fuel injection seals, but I just had that professionally redone and I can't think how that would cause the cat to smoke.

[majicwrench]

IF car runs the same with cat undone, cat is not the problem. Anything that makes car run poorly can make cat glow red and thus smoke from the heat.

[BartusCompater]

I think my AFM might be going out. The door inside has been squeaking a lot. Yesterday I tinkered with it and did a little sanding. Got the car to run, but very poorly. However there were points driving it home from where it was stored where all of a sudden the idle would smooth out and it would seem to run fine. Then suddenly the throttle would do nothing and after parking the car it refuses to start again.

[2ndwind]

Dustin,
Is there anyone nearby with a good AFM that you could try for a test?

[BartusCompater]

I know that there are Fiat owners around because I've seen Spiders parked around where I live, but I haven't made friends with any of them (that I know of) unless they're somewhere out here. There's a chance that my mechanic might have a good AFM. I'm thinking it would definitely be a good idea to try switching it out before ordering a whole new one for 500+ dollars.

[majicwrench]

Mthinks there is a wonderful FI testing article somewhere here on the web. Brad Arigue?? My car has a carb so I don't know where it is at. Testing, as opposed to guessing, is a good thing.
AFMs, IMHO, are pretty trouble free..

[BartusCompater]

Started up and ran perfectly yesterday. Drove it about a mile and then on my way back from where I was going it started to suddenly have some burps and then eventually lose all power and die again (luckily just as I was pulling into my driveway). Noticed that the burps and the loss of power seemed to be triggered when I pushed the engine into the higher RPMs (i.e. past 3,000)

[BartusCompater]

Months later, after losing the keys and having an ignition switch debacle I'm back to dealing with this issue. The car won't start and I need to come up with a checklist of things to go over before I commit to taking it back into the mechanic. I've sanded the AFM a little bit and it doesn't stick anymore. I'll check the distributor and possibly the fuel filter too.

But I'm wondering if anyone has any good ideas as to what would cause the car to stall and die once RPMs are pushed higher into the 3000s. Does this sound like a fuel or a spark issue?

[wikkid]

This ia a very good FI diagnosing/fixing article, even though it is more specifically for the Alfas - same Bosch setup, though.
The AFM flap door should open and close smoothly and freely, with a good spring-back. That is easy to check just by unhooking it from the big black air intake rubber piece. It's also not hard to open one up and check the sweep contact to be sure it is smoothly and solidly making contact throughout the entire rpm range (as dictated by amount of air flow is pulled through and operating the flap). The article is a big help, with all the instructions you will need.

[manoa matt]

"But I'm wondering if anyone has any good ideas as to what would cause the car to stall and die once RPMs are pushed higher into the 3000s. Does this sound like a fuel or a spark issue?"

Have you replaced the ignition control module located behind the coil? $20 part and available at most auto parts stores. They go out about 2-3 years if a daily driver.

[So Cal Mark]

I'd check the connector at the coolant temp sensor on the tee. Once you get it running, try wiggling that connector and see if there is any change

[BartusCompater]

So took the ignition control module out today and I'm gonna throw the new one on tonight after I pick it up. Noticed after I took the AFM out to get it out of the way that I smelled gas, and I think it was coming from the big rubber intake hose. This might be a silly question, but can these cars get flooded like a carbureted engine would?