Posting this to see if someone has any suggestions...
I have a 1984 944 that failed the Texas emissions test (low speed).

The first time
2500 RPM 960 RPM
HC(ppm) 36 (pass) 292 (fail)
CO(%) 0.10 (pass) 3.37 (fail)
CO2(%) 15.0 13.1
O2(%) 0.2 0.0
DILUTION 15.1 (pass) 16.47 (pass)

Idle was rough.
after changing O2 sensor, Fuel Injectors (one old one leaking slightly), sparkplugs.
Now Idles perfect. Feels much stronger. Improved , but still failed.

2500 RPM 831 RPM Thres
HC(ppm) 21 (pass) 253 (fail) 220
CO(%) 0.01 (pass) 1.70 (fail) 1.20
CO2(%) 15.0 14.1
O2(%) 0.2 0.0
DILUTION 15.1 (pass) 15.8 (pass) >6


The car has 193,000 miles. I rebuilt it at 175,000 (rings, seals, bearings). Valve guides within limits, so didnt replace. original Cat, plug wires and Dist cap replaced.

got any ideas whaty else can be checked?



Gerald
84 944
90 C2