'84 Carrera Loss of Power

[clio09]

Hi I'm new here and this is my first post. I have owned an "84 Carrera for 17 years and it has been a great car. Now pushing 220k miles. My tech died a couple years ago and while there are several well known Porsche shops in my area he took care of my car the best. I am experiencing a loss of power and as an example I do not get good acceleration up a hill and cannot get the car to go more than 100 mph on a straight away. I have had similar issues in the past and on one occasion about 4 years ago my tech replaced the fuel pump and I have gone through two catalytic converters (aftermarket, techs tell me the Porsche cat is hard to get and very costly) in the last 3 years. I was curious if anyone has any suggestions for what might be the issue. I am suspecting fuel pump or cat but I am mostly guessing here.

[917_Langheck]

Welcome,

Your cat is supposed to last the life of the car; they are not supposed to be a disposable wear item. If yours is being consumed in a matter of a year then your fuel mixture is incorrect. Keep an eye out here in the For Sale section for an oem cat; seen at least three in the last few months.

As to power loss, when was the last time your O2 sensor was changed? How about your fuel filter; how many miles on that?

Post up what part of the country you're in, I'm sure there is someone here who could recommend a competent replacement tech for your needs.

Cheers,

Member of the '84 Carrera Club...

[clio09]

I live in Northern CA, Napa County. The whole thing with the cat got going when I failed a smog inspection in 2018. The original cat was replaced at that point with an aftermarket one and that lasted a year. Another aftermarket cat was put on by a pretty reputable tech in the area and that is the one that is on the car now. This same tech performed a 30k service (210k miles) in September of 2019 where the fuel filter was replaced, about 6k miles put on the car since then. Not sure the last time the O2 sensor was replaced. I will look for an OEM cat and look into the O2 sensor. Thanks for the help.

[cabmandone]

I think anyone will be mostly guessing what your problem might be. Since you've had the fuel pump replaced and a relatively new fuel filter, I'd start by checking fuel pressure and performing a test of the fuel pressure regulator to make sure it's functioning properly. I'd check the function of the idle switch and the wide open throttle switch to be sure both are working properly. I'd pull the elbow off of the throttle body and verify that I'm getting full stroke of the butterfly at W.O.T. I'd check exhaust port temps to make sure all cylinders are fairly even. As far as the o2 sensor, you can run the car with it unplugged and it won't make the car act like yours is. A wideband o2 AFR meter with data logging would be helpful in diagnosing as it would help tell you what is going on with the fuel trim at the time the problem occurs.

[GH85Carrera]

On my 1986 El Camino when the cat died, it felt like I was hauling a large trailer behind me. When I took it to a local muffler shop he put it in the air, and all we had to do was hit the cat with a rubber mallet, and the sound of loose "stuff" inside was evident. That happened after nearly 200,000 mils and the car was running rich at the time from the lousy factory carburetor. I replaced it with a throttle body fuel injection system and all is wonderful and the car is at 375,000 miles now.

It is pretty easy to take off the cat if the nuts are not just rusted blobs. If the car is running too rich, the cat will not last as long as it should. They tend to run hotter than designed, and go bad fairly quick. Be sure to get new gaskets.

[pmax]

Is it burning oil ?

[nene]

Clio,

I am in Sonoma if you need a second pair of eyes. I have an 86 so I am familiar with this model.

Serge