C4inLA

Diagnostics UDT999 Interpretation

Ran my UDT999 diagnostics this morning, would like to see others who care to share for comparison. I don't think car was up to temp quite yet before turning off.... Pungent smell from exhaust... No faults on Motec or PDAS...

Trying to understand Motec Actual values screen.

Was playing with PDAS screen, used to bleed locks before, but today just clicked on locks START and noted the impulse counts for doing a physical wheel spin test per impulse, kind of cool. Assume all wheels off the ground for lock spin tests.

Few questions for those familar running diagnostics on hammer or PDT/UDT;

What is CAT status Closed mean? I did major engine bay cleaning and removed entire manifold, cleaned reinstalled earlier in year.

Added new O2 Lambda sensor in CAT and have not yet driven or adapted. Took a screen print, not warmed up completely as exhaust smell is pungent (Why is that) !!! The Oxygen sensor is bouncing all over, .01 to .48 ? Turn off car and for 30 seconds or longer a spill of whitish smoke like off the tip of a cigarette continues to spill from tail pipe? I should have no issues with CAT? Normally we drive and don't run car in garage and stare at tail pipe, makes one paranoid How long before CAT does it's job? Minutes after startup? Should tailpipe smell be more neutral if CAT is doing its job? Thoughts?

Click below screenshot, Cheers!

Diag112715.doc

Laurence Gibbs

CAT closed , likely to mean running in closed loop. As opposed to open loop. i.e. cat is trying to maintain lambda. My hopefully correct understanding is that closed loop only works around idle a, anything above and it will go into open loop mode.

-nick

Are your temperatures in Fahrenheit or Celsius? You said you were warming up, so engine temp of 109C wouldn't make sense, but ambient temp of 21.9F in SoCal would surprise me too. That will change the diagnosis dramatically!

C4inLA

It was just running few minutes.... I am hoping someone will share what a well tuned aspirating 964 reads on all actual values for what my targets sould be... I know your out there peeps... I am wondering what a well warmed ETemp and Atemp in Fahrenheit should be? Also, wonder where Atemp sensor is located? Is it the coil thing inside air blower tube driver side engine bay?

Duck

Air temp is located inside the AFM.

C4inLA

Thanks. ETemp cyl #3, correct?

Duck

Yes, the engine temp sensor is on side of cylinder 3. I have a new one to install when my engine gets back from being rebuilt.

-nick

Just looked at the LA temperature forecast, lows in the high 40's F. So readings are obviously in Celsius.

Injector pulsewidth looks normal for idle and warm. Your o2 voltages should be bouncing between ~ 0.1-0.9 volts, and averaging about 0.5v. Averaging higher than 0.5v means that you're rich, averaging lower is lean. So o2 says lean, inj pulse (labeled as load) says normal. Your afm (incorrectly labeled maf) voltage looks very low. Should be around 1.3v at warm idle. Could just be that your scantool is setup for 993 and is using an incorrect conversion.

If you suspect that it's lean, then pull a plug and look at it.

Strong exhaust smell at warmup is normal in my experience. You are getting air:fuel from the chip settings (open loop) below engine temp of 70C or at wide open throttle. Open loop programming is very rich in both situations. Any other time, you're in closed loop and the o2 sensor feedback will put thr air:fuel to stoic, 14.7:1. The nature of the o2 sensor, air:fuel will bounce between about 14.2 to 15.1.

If the engine was really just running for a minute, then possibly your cht sensor has a slight short and is reading too low a resistance. Low resistance = high temperature = leaner mix. Testing the cht is very easy. A quick search will give you the procedure.

C4inLA

Really appreciate the info...

Found a great article referencing the Lambda, AFR, O2, Stoic ratios you mention...

http://www.jmgporsche.co.uk/index.ph...osis-emissions


Thx, Matthew.