Wednesday, November 15, 2006 - 10:07 pm, by: Mark Paddick(Sparks)
But the diags won't tell you !
It's interesting that some of the more mundane Toyota ECUs (Corolla, Camry etc) always get this right. An airflow meter fault code means exactly that; the AFM is crook (usually the inlet hose to the engine has come off or is leaking rather than the AFM itself being faulty). Maybe the Karmann Vortex variable frequency Soarer one is harder to monitor correctly.
Oh, and I figured out why a V8 will run OK with the AFM disconnected. The AFM output frequency is used to modify the frequency of an internal oscillator. With the AFM disconnected the oscillator still outputs its' unmodified frequency so the AFM signal is still there, just doesn't change from near its' max output.
Friday, November 17, 2006 - 10:34 pm, by: Michael Hutton(Lexual)
Mechanic pulled off the cats - found out the are pretty much stuffed and blocked to the proverbial s...house, so he's gonna clear it out and se how it goes from there - fingers crossed!
Monday, November 20, 2006 - 12:23 pm, by: Harry Lemmens(Wombat)
Question is: What caused them to overheat in the first place ... Although it is usually a stuffed coil, all of the items mentioned in this (and another?) thread will need to be checked.
There must be a reason that the cats overheated in the first place. The usual reason is unburnt fuel. This gets down to the cats and the reaction there is essentially to burn the fuel. Except ... theres about 1000% more fuel (and AIR) there than should normally be the case. Little wonder the converters get hot enough to melt down the guts!
Friday, December 01, 2006 - 08:56 pm, by: Michael Hutton(Lexual)
well, 45 days later, got my car back, good as new. Turns out one of the new coil leads was crap, and shorted out, leaving only 4 cylinders firing. Thanks for your help guys, now I have to relearn how to drive it
Monday, January 01, 2007 - 02:23 pm, by: Brian Timms(Turbo_brian)
I had similar issues with my own car (a Nissan 180sx), took it to be detailed, got it back and was sweet.
Next day, runs like a mofo, nasty, horrible, running on 3 cylinders instead of 4, sounding like a wrx and running pretty much like one as well.
Anyway, it threw a Cat warning light while trying to drive it to a mechanics to get looked at, and it turns out there was water in the cylinder heads around the spark plugs, causing the plug lead to short to the head, thus not spark, no combustion, and unburnt fuel going into the exhaust and cat converter.
It melted the cat converter, and threw a code on my car.
Anyway, got the water removed, and it drove ok, but wouldn't boost past 4psi (usually set at 19PSI), I went to the point of removing the wastegte hose completely, and it didn't fix the issue.
So after due consideration, I removed the Cat Converter completely, took it for a spin without the cat and exhaust, and she boosted up and hit 19psi, and boost cut-off within 2,800rpm, it was back.
After checking the cat converter, it was clogged up like a public toilet at a concert, so I took to it with a hammer and pinch-bar, and it's now the world's highest flowing cat (but not a cat converter, because it converts NOTHING!!)
Needless to say, New cat converter, and a nice cleanout fixed my issue, but it's good to see that your issue is also fixed up now as well.