clipod

Hi, I have a 2001 base boxster. I had this car for almost 4 years. A little history, after my AOS failed, I replaced it and change my MAF, cleaned my throttle body. After that one of my CAT failed and replaced with a used CAT and it was working fine. Changed my O2 sensors, replaced spark plugs, did a techron run.
Couple of months before I got my clutch changed. And again yesterday my CEL came up and when I tried to read with my durametric it mentioned my CAT failed. I dont know if this is the same CAT or different one. I showed it couple of mechanics before and they all say car is fine. I am sure that the performance went down. When I press gas pedal A LITTLE IT ACCELERATES FINE BUT IF I PRESS HARDER IT SLUGGISH. I see this problem especially in stop and go traffic. Generally if I am in my first gear for long periods i got this problem. My car temperature hits 210 and all fans start right away. Also idling increases my engine temperature and all the fans kick in.
I would like to monitor stuff with my Durametric cable but I don't know which values I have to check for and I can post it on the forum.

Byprodriver

Post the trouble codes from the Durametric scan

clipod

I was such an idiot. Forgot to take back up of the code and erased the code. Now its not popping up. But I know my CAT is gonna go off soon as I can hear clanking sound for the first few minutes as soon as I start the car from a cold start. What should I do next.

Macster

Depending upon the side probably either P0420 or P0430.

The SOP is if there are any O2 aging codes along with the above code or codes to replace the sensors indicated, clear the codes and road test the car. If the converter code or codes come back replace the indicated converters.

I had something similar with my 2002 Boxster for a couple of years. The converter would knock about when cold the buzz when hot. Engine performance was unaffected.

I sourced a couple of used converters at a Porsche salvage business and had them installed. Cost me $450 (or $475?) for the converters and an hour of labor.

When I picked up the "new" used converters I gave both of them a shake test and they were rattle free. I never even put them down after that but carried them with me to the car and put them in the car then paid for them.

Afterwards the knocking and buzzing were gone. Oh, and no more P0420 error code.

If you have a good Porsche salvage business handy you could do what I did. Or buy a set of take offs from someone who's gone aftermarket exhaust. 'course, some go aftermarket when the OE exhaust goes bad.

These converters come up for sale every once in a while. Here. Craigslist. eBay. Other Porsche web sites/forums.

Macster

The stop and go driving and increase in coolant temperature is normal.

It varies maybe but my observation with my Boxster is when the coolant temperature reaches 212F the fans come on low speed. If the temperature climbs to 216F they switch to high speed.

The fans switch off when the coolant temperature drops to 205F. If driving conditions are right this can happen over and over again, the coolant temp rising to 212F and the fans come on and temp drops to 205F and the fans shut off then a few minutes later the temp is up and the fans are on and so on.

Check the fans that both are running and blowing the same amount of hot air out. Radiator fans have been known to quit running or they still run -- one can hear the motor -- but for some reason the fan doesn't spin as fast as it should -- but the motor current draw can be higher than normal -- and the fan's output is feeble.

Be sure the radiator ducts are free of trash. These can get quite loaded with leaves, plant trash, papers, what have you. They would have to be quite loaded to interfere with the engine's cooling but just in case check and if there is some trash you might have to remove the bumper cover and clean the trash out of the ducts.

And if you let the engine idle if the ambient temperature is warm enough -- roughly in the mid to high 70's at least -- the fans will come on. At some point the engine compartment fan will come on, too.

Schnell Gelb

Clipod,
You mention sluggish acceleration +cat issues.
It is possible that the cat has become partially plugged up. An easy test is to use a cheap IR point-&-shoot thermometer to test the temperature of the cats. The plugged cat will be substantially higher.
http://www.harborfreight.com/infrare...ter-93984.html
Here's a video:
I hope this helps you.

San Rensho

The test for cats is the O2 sensor voltages. Plot before cat voltage on one graph and post cat voltage on another. The pre cat voltage should be a straight line. The post cat voltage should resemble a sine wave. If the post cat voltage approaches a straight line, its a clear sign the cat is bad.

hancock1701

Isn't it the other way around? The pre cat voltage should alternate lean and rich like a sine wave showing the computer is trying to achieve ideal air/fuel ratio, and the post cat should be a straight line showing all the oxygen has been used up for the catalytic conversion process.

Macster

Yes, you are correct.

However, the #2 sensor's voltage curve won't be a flat line. Its voltage curve also traces a sin wave, albeit quite muted compared to the #1 sensor's voltage curve. The amount of voltage change the #2 sensor signals along with its timing compared to the #1's voltage signal is used by the DME to know the converter is operating properly.

hancock1701

I've been having an intermittent P0430, and have been watching the pre and post voltages on that bank. The post voltage oscillates much the the pre voltage during idle, which makes it look like a dead cat, and then it becomes much more muted in higher RPM.

However, when in higher RPM, the post voltage still drops down past 0.1V once every few cycles of the pre voltage. I read that the computer will know when an O2 sensor becomes bad or tired, and trigger a code, so I wonder what that drop in post voltage is? A sign of a dying cat?

Macster

Possibly a dead converter, well, dead in the sense it is unable to store oxygen for use to process/convert exhaust gases into less harmful gases.

The higher voltage level from the #2 sensor is due to an absence of oxygen. The voltage level should remain high -- but vary a bit in time (sort of) with the up and down reading of the #1 sensor -- as this is a sign the oxygen is being consumed in the converter and thus the converter is working ok.

With a lower voltage this is a sign oxygen is just passing through the converter.

I vaguely recall when I was trying to "catch" a suspected bad #2 sensor when I did manage to be monitoring sensor voltages in real time when the sensor was acting up low voltage readings is what I observed.

'course, the DME was logging sensor related error codes, and not logging converter codes.

Later when a bad converter was acting up -- bad from a loose brick in the housing -- while the DME logged P0430 time and time again -- though sometimes separated by weeks or even months -- there was never an O2 sensor error logged.

The factory manual is quite clear on this. If the P0430 (or P0420) error codes are accompanied by aging O2 sensor codes replace the indicated sensors and clear the codes and road test the car. If the P0420/P0430 codes come back replace the indicated converters.