90 S-4

See attached, (90 S4 a/t 55,666 mi )
recent tuneup & shark tuned
he said everything was good but the cats didn't get
hot enough prior to testing.
How do you guys get the cats extra hot for a test ?
Thanks for any suggestions, I'm going back for a
retest tomorrow at 11:30

jthwan22

No shutting down while waiting in line?

BC

Joe - Your NO is really fine, so two things (and I have personally passed some VERY subpar 928s)

1) Drive it like you stole it, have him ready on the wheels when you pull in with the test.

That may do it.

2) Fill up with 30-50% e85 (there is a station near you). That will pass especially since its high HC. Simply much less HC in ethanol.

BC

http://e85vehicles.com/e85/index.php?topic=2958.10;wap2

928porschemangreg

I just passed CT Emissions today with a HC of 100, Max is 100. It was higher then 2 years ago when it passed at 60. This year, I had some old fuel from the winter storage, and Marvel mystery oil mixed in it. Suggest having high octane fresh fuel only and what BC says.

Mongo

Same issue as mine. Smog guy told me to go for a drive, then come back and dyno it hot. It passed.

928 at last

Yep.
Drive it until it's thoroughly warmed up (I mean not just until the gauge reads hot, but give it time to get to full operating temperature. Don't shut down or wait in line and test.

Mongo

Shutting off is what causes these failures since the cats will cool down.

Jhoffmann

Drive it for 25-30 minutes on the freeway in third gear. Drive straight to the test place and do not shut off the engine - get it tested as quickly as you can following the drive.

90 S-4

All good info ! looks like I screwed it up by shutting it down while I waited, wont
do that twice ..
It's already full of gas so can't try the e85 trick this time but sure will next time .
I'll report back tomorrow -- Thank You !

Speedtoys

But..that doesnt mean that the LH wont stuff in MORE fuel to compensate..right?

BC

It will put in more, but the HC will be inherently lower, as it does not have as much HC when burned.

Mark Anderson

Not saying this is it but the shop I use has never failed a 928. Call me Monday if u want the info

Bill Ball

You have very high O2 (excess air) and high HC (unburned fuel). Seems like you have a miss - bad spark plug or plug wire perhaps. Could be cap and rotor too.

dr bob

What Bill said--

HC is unburned fuel, so the things you go after for that start with ignition pieces. There are other telltales like low CO that point to air leaks, but that's a usable symptom only if the sample is taken BEFORE the cat. The telltale for too lean is nigher NOx. So I'm thinking that ignition components are the starting point. Might be as easy as a set of fresh plugs, inspect wires/cap/rotors.