majuva33

I've only had my 951 for a few weeks and all along it has been running fairly rich. I've changed the AFM and checked a few other things. So far no luck. So I've booked it in to the local Porsche mechanic, but I can't get the car in until another 1 1/2 weeks.

So my question is, if the car runs rich, will it do any harm to anything in the meantime? I will probably need to drive it about two to three hundred miles before it goes to the mechanic.

The car is fine under revs and boost, only when it's idling it's idling rough and blowing black smoke out of the exhaust. But other than that, it drives very well. Doesn't cough, backfire or anything like that. Your thoughts?

Charlotte944

Besides wasting fuel (and money), over time running rich will clog the CAT and destroy the O2 sensor.

I would start off by checking vacuum to the Fuel Pressure Regulator and Fuel Pressure Damper. If there is no vacuum here the fuel pressure goes to MAX and the DME cannot adjust injector duty cyle enough to keep the engine from running rich.

If you have a digital volt meter you can "back probe" the O2 sensor connector. At idle with the sensor warmed up you should see the meter reading vary across 0.50 volts. An even quicker test is to unplug the sensor while the engine is running. The engine RPM should change. The reason for this is the DME will go to a default rich fuel mixture to prevent a lean run.

majuva33

Thanks for that. My problem is actually having the time to do the checking. I simply don't have it, so I've booked it in to the local Porsche dealer to get it fixed. But it's not going in until another week and a half.

I was just wondering if it's going to stuff something up in the meantime...

Cheers

wi54545

Do what charlotte says, disconnect the o2 sensor at the back of the manifold. The DME will revert to preset fuel maps. This is how I run my car until I can get a new o2 sensor. Also, you might have a large vacuum leak somewhere. Are the lines connected to the FPR and fuel damper? Look for anything obvious.

Got Me a Porsha

Do you have an Autometer narrowband a/f ratio lightshow...errr I mean gauge? If so, disconnect it and see if it cleans up.

I've seen this happen more than once.

Eyal 951

If ifs extremely rich, you can get to the point of washing the cylinder walls clean which is nad on the piston rings.

majuva33

Okay. I've disconnected the O2 sensor. The problem seems to be that.

Next question, can I drive it around for the next 300-400 miles with the O2 sensor disconnected?

Cheers

wi54545

Go for it! The Europeans do it every day! If you have emissions testing, you might need to replace it. Its easy to do.

majuva33

No, we don't have emissions testing.

So do you mean that I don't need to replace it at all? Just disconnect it?

It's $270AUD here, which is about $190 USD. If I don't HAVE TO buy it, I rather wouldn't!

Cheers

wi54545

If you really want to replace it, Paragon has a universal 3 wire for around 40 bucks. You just have to splice it into the original wiring. I don't think that the euro cars use one, so I would assume that you don't need it that much. It works for me now.

hally

Time to stop paying the porsche tax here in Aus majuva, you will be amazed how many kilos of goodies you can airmail here for $US30, all hail usps.com.
The trick is to batch a few things together, you must need some brake pads etc soon right! paragon products are great to do business with.

majuva33

Paragon!

Sounds good to me! Thanks for this. Another invaluable advise that'll save me some hard earned Aussie dollars