Hello Donald,

I have no idea what "dilution" is or how it pertains to the emission report.

However I am picking up a few things here.

 

might I suggest installing an air fuel meter inside the car run off the O2 sensor, that way you can see if it is running rich

 

Under the assumption that 'dilution' is in fact the air-fuel ratio - the values should be closer to 14.7 assuming that the engine was warm and that the 40km/hr test was at steady part-throttle. The ideal emissions value is 14.7. Ideal fuel-economy is 15.4 but, Cats of that day were not able to clean the NOx out of that lean a mixture. 12.6 is a max-power ratio that I've only seen at WOT at above 3-4k rpms. (I've seen a dozen or more 928s on dynos with EGAs. Most of them - that I've seen - don't get below 13 on a full-power run.)

 

I just bought my (1985) 928. I haven't had an emissions test done but it smells like it's running rich on fuel. I suspect the O2 sensor but I was looking at the Mass Air sensor and it looks as though it may be in backwards. Is there a right and wrong way put it in? Would it cause problems if someone had put it back in backward? What is the correct way?

 

mass air sensor

Marc
DEVEK

 

Watercooler,
By adding the O2 sensor, seems as if all the basics will have been covered.
There is an excellent 928 specialist in the NWest zone of TO (owner/operator) - he has tweaked numerous 928's into passing the Ont. emissions tests: some of these included Euro S4's without cats/O2 sensors.
If you wish a name/#/intro/etc., feel free to PM.

 

Garth, sent you a PM.

Hello Marc,

I know there are no crystal ***** (except at -20 putting up my Christmas lights), but is your suggestion of the MAS consistent with my readings, or do you think it is the next thing to replace? BTW I would like to put a link (with image) to DEVEK on my web site, is there a DEVEK image out there anywhere?

Merry Christmas,
WC

 

When making a list of tune-up parts, don't forget the smog pump (air pump) filter.