When was the last time you changed your fuel filter. another 3.2 posted that a clogged filter was his culprit.

^ that's very awesome information, and worthy of a sticky for us DIYers.

Duh. Forgot about the rings and exhaust valves. Guess I need to up my dose of ginkoboloba ;)

Thanks, db, for the elegant solution and additional information.

Yes,..that's good stuff!!!!!!

THANKS!

Doyle

Your welcome SmileWavy

"The first step in an engine driveablity problem..right out of the fuel injection manual...check for air leaks..if you don't, your just guessing."

Very, very few 911 3.2s have major air leak problems and they don't manifest
themselves as described in this thread. So, if there's a possible air leak,
enough of the hyperbole about air leaks and let's LIST the possible sources
and fully describe to the thread starter EXACTLY how they'll affect a 911 3.2
and not about BMW air leak hyperbole. Most of the info presented in this
thread appears to be paraphrased from a Bentley's type of mis-guided info.

Bottom line: Let's provide some very specific areas to focus on and useful help.

You're right, Loren. We did get a bit OT in this thread, and it does certainly seem that the car is running rich.

I would be interested in knowing the fuel pressure, and would probably verify with a Air Fuel Gauge, such as a LM-1 with a wideband O2 sensor. I installed a second bung in a cat bypass test pipe just for that purpose, and I can see what the DME O2 sensor is doing, and I can watch it literally start closed loop operation. You can watch the mixture go rich when you disconnect the fuel pressure regulator, and the DME compensates back to .99 to 1.01 lambda. Same with the oil tank cap except you can watch the mixture go lean, then compensate back to spec. No guessing. Something like this tool would be a great help to the OP.

If the fuel pressure is too high, that would cause the mixture to be too rich.

Also, I traced rich running back to a faulty O2 sensor wire several years ago, and actually fixed the wire and kept the sensor. It has passed smog and run beautifully ever since.

"A more modern software package (EPA Paranoid 2.1 from Porsche is the base software) for the DME will address that"

- db_cooper -

Really? And more hyperbole to confusion the issue & thread starter.
Sounds like the marketing 'hook' caught another one!

"If the fuel pressure is too high, that would cause the mixture to be too rich."

- rusnak -

That's a good start, i.e. a simple test to eliminate one unknown.

Poor thread starter, the guy probably has started having nightly dreams about
air leaks, as there are over 8 posts that mention that.

Just to be clear..

Air leaks do not automatically make the engine run rich

Trying to "repair" an engine with an air leak without first diagnosing the problem will....make the engine run rich..because..what else can be done if you don't know?

All sorts of wild dodgy things, including wildly over enriching the base CO adjustment, have been done without the owners knowledge to increase the amount of fuel available to the engine. My example of AFM being opened and tampered with only being one. Fuel pressure regulators being squeezed with a vice with sockets to increase the fuel pressure, or a BB in the vacuum line to the FPR..trying to run the engine richer.

So, for example, if you check your fuel pressures first and find them too high..and fit a new fuel pressure regulator..and now the 911 still won't run well..because you skipped step one.

Best find out you have no air leaks, step one..go to step two..three...four

So..when starting to run your steps for repair..begin at the beginning..

The exception might be if you are the owner the 911 from new and did the service on the machine yourself..and know for a fact what the service history is from day one and you were driving the car and it suddenly went rich for no reason........Not a likely scenario.

When someone gives a shout for help on this forum, in offering advice..I take the same approach as a new friend with a problem 911 that just called on the phone..start your fuel injection diagnostics at the beginning..and fix the car..don't treat the symptoms.. I don't know the car or its real history..and don't know if the owner can say for sure too. It may have been "repaired" and too rich for a long time without our friends knowledge, finally saturated the O2 sensor or whatever and now won't run correctly..who knows?

Begin at the beginning...

"Trying to "repair" an engine with an air leak without first diagnosing the problem will....make the engine run rich..because..what else can be done if you don't know?"

So! Which can be said about any source of an engine problem.
Then why make a single assumption, i.e. air leak, without doing
ALL the diagnostics basics. The statement is contradictory.

Loren..are we talking about an engine with a rich running condition without some visible issue ??

3.2s will suck the intake gaskets and there is a handful of suspects behind the throttle body. Plenty of opportunities.

Begin at the beginning..its a good place to start.

"are we talking about an engine with a rich running condition without some visible issue ??"

Again, so! If it's running rich, assume an air leak? Don't think so.

"3.2s will suck the intake gaskets and there is a handful of suspects behind the throttle body."

Basically just affects the idle conditions.

Key Point: The thread starter indicates that the engine runs & drives better with the oil
cap off, i.e. more intake air.

Not to quarrel but...If you don't know....begin at the beginning, its a good place to start.

When the intake gaskets start going..and the idle CO is jacked up to compensate..some intake gaskets may be intact and others not..uneven fuel/air ratio between cylinders..and the engine will give the symptoms of being rich..because it is..on a number of pots after the CO is jacked up. O

Our friend would notice the "rich" issues at idle..because he is back there with the engine.

Off idle and at cruising speed... things will change as the air leaks are less a contributor to the over all F/A volume and maybe the O2 sensor can get it close...or maybe not...but our friend is in the car driving and not watching the tailpipe.

First step..the integrity of the intake/air leaks.....begin at the beginning, its a good place to start

I have been chasing this also.
First thing I did was remove the heater fan and redo the throttle linkage.
I removed the Thottle body and cleaned it, then reset the idle micro switch.
Re-torqued the intake bolts (all loose)
Removed, cleaned and replaced all the intake vacuum lines.
removed and cleaned the ICV...seems to move freely...but its on my list.

I still have the issue of cycling idle only when hot.
I am going to replace the O2 sensor this weekend to see if it had previously gotten so dirty that its giving false readings...I have a new one on hand.

I am figuring O2 sensor then ICV, then CHT...
We shall see.
After cleaning I could get the idle to settle down if I revved it at a stop light.
Then once it got really hot/warmed up...that no longer works.

Rich

idle
 

Everybody that works in the Porsche industry knows that at each and every service, part of that service is torque down the intake manifolds. WD-40 does not detect air leaks, starting fluid should be used.

Yep..they get loose and the gaskets can become a memory.

WD40 leaves a residue. Starting fluid/ether dissipates as does propane.