B&W

Just brought my stock '94 964 turbo (20k) in for emissions testing and it failed on carbon monoxide at the higher rpm range. My '90 944 turbo (35k) always has problems passing the first time too. I spent $800 at the mechanic two years ago to get it to pass. I did drive it on the highway for about 20 minutes before I brought it in. I've tried the fuel additives from Canadian Tire but they didn't make a difference. I feel like I'm back in school holding my breath waiting for my exam scores whenever I have to bring these cars in for emissions. Any advice would be appreciated.

boman993

I was under the impression that the new etests are OBD scans not sniffers??...

theiceman

only 96 and on have obd 2. others are still sniffers

do you always do an oil change before hand and have fresh correct octane gas ?
if you are running high octane in a car that is incapable of burning it your emmisions will increase

993GT

its actually '98 AND newer that get the sniffer test, '97 AND older get a sniffer test but the dyno is gone, '87 AND older have no etest
For your '94 3.6T, try to adjust the CIS fuel head slightly to run slightly leaner to pass the CO part of the test and/or see if someone else has a catalyst that you can try to verify results(only if H/C. CO, and NOX are all high values)

997ajk

You have the report? Are you able to share the numbers reported?

wc11

I was told to drive for 30-45 minutes before bringing it in and have a full tank.

initial

Driving it for 30-45 minutes prior to the etest is all well and good, but if it sits parked with the cat cooling down, you won't have gained much from your drive. If you can work it that they take you for the etest as you show up after your drive, you may have better luck with the results.

I do have my rituals when driving my 95 993 and followed the same regiment with my previous 89 911.
1. I don't take it for short haul trips such as the corner store.
2. I won't go over 4000 rpm until the engine oil is fully warmed up
3. Do hit the red line at least once during the trip.

theiceman

Rob many 96 cars have OBD2 . I am really surprised to hear if you have OBD2 they will still give you the sniffer test, but good to hear though as the OBD2 test is a huge PITA .

a 94 is certainly not CIS unless we are talking about 2 totally fifferent things. CIS stopped in 84. His mixture is electronically controlled and if anything i would be thinking O2 sensor, this will have more effect than anything with trimming out mixture.

993GT

Reason behind '98 and newer doing OBD2 test is that some cars took a while to integrate the systems...
all 911 Turbo's used CIS until the 1995 993TT came out, Carrera's started using EFI-Motronic from 1984 on as you stated

theiceman

wow thats great info .. cant belive something as new as 94 using CIS .. yup then can definitely lean it out a little. Just need an LM-1 , lean it out then put it back after complete.

993GT

ya its pretty crazy they were still using CIS so long, esp. considering it was on the turbo cars and not the n/a ones
also, no air-cooled turbo ever came with twin-plug ignition

997ajk

See below