coltj

I have a ’96 C4, 6-speed, 68+K miles. Top end rebuild at 48K about 4 years ago.

First, the disclaimers:

1. Past performance does not guarantee future returns.
2. Your results may vary.
d. Consider the source

About 7 months ago my car “threw” a CEL. Code was P0410(Secondary Air Injection Malfunction). I reset the CEL, which of course “unset” all of the readiness codes.

Fast forward to Dec ’08, after having driven about 3000 miles. Car was due for inspection so I checked the Readiness Codes; NONE of them had reset. No reoccurrence of the CEL during that time.

While I have had success in the past setting Readiness codes by completing the “driving cycle”, I did not have the time, inclination or co-pilot to attempt to complete the cycle in one continuous session. Here’s the link describing my successful attempt:

https://rennlist.com/forums/993-foru...des-ready.html

Here’s the cycle I use.

1) Start cold engine and idle for approximately 2 minutes, 10 seconds. This checks secondary air injection and evaporative leak detection systems.
2) Accelerate to 20-30 MPH and maintain steady speed for 3 minutes, 15 seconds. This establishes closed loop oxy-sensor operations, response times & switching times.
3) Accelerate to 40-60 MPH and maintain steady speed for 15-20 minutes. This evaluates catalytic converters while oxy-sensor response and switching times are checked.
4) De-accelerate and come to a stop. Idle in gear for 5-6 minutes. This checks evaporative leak detection system.
Remember:
The diagnostic checks above will be discontinued if:
1) Engine speeds exceed 3000 RPM
2) Large fluctuations in throttle position
3) Road speeds exceed 60 MPH

Here's the description of what I did:

1. Left the office late one night. From a COLD start, idled the car for 2 minutes 10 seconds.
2. Drove <30 mph for 3 minutes, 15 seconds, without exceeding 3000rpms. To complete this step I drove around the sparsely populated industrial park where I work. I did this late at night and was able to complete this step without stopping the car.
3. Exited the park and traveled about 4 miles to make my way to Rte 128. Had to stop at several traffic lights. During this stage I did not exceed 30 mph or 3000 rpms.
4. Drove on Rte 128 for about 9 miles, again keeping under 3000 rpms and speed less than 60 mph. This step took much less than the prescribed 15-20 minutes.
5. Exited Rte 128 to secondary roads; had to stop at 6 or 7 lights in traveling about 5 miles to get home.
6. Idled in driveway for 5 minutes, car in gear, clutch in as prescribed in the drive cycle instructions. Yes I know a lot of people are concerned about this step and leaving the clutch in for so long.
7. Left my laptop at work so I couldn’t check the status of the codes.
8. Next morning, started car and idled for 2 minutes, 10 seconds again.
9. Drove the 5 or so miles to Rte 128. Had to stop several times, but kept under 3000 rpms and 30 mph.
10. Drove the 9 miles on Rte 128 again keeping rmps under 3000 and speed under 60 mph.
11. Parked the car and shut it down.
12. Retrieved my laptop from the office; ALL Readiness codes were set.


So in the end, I completed all the steps, and repeated a few of them, within a 12 hour period. I did stop the car several times during some of the steps, but never exceed 3000 rpms or the indicated speeds for steps 2 and 3.

Have at it!!!

Slow Guy

Sounds like the procedure sometimes called the "BMW OBDII Drive Cycles/Readiness Codes". Has worked for me several times without a hitch.

Glad it worked for you.

coltj

Yes, it is the "BMW" cycle.

Slow Guy

BTW, I think we've come to the consensus that the idle in neutral part is intended for auto trans vehicles, I've never left the clutch depressed during this time myself.

coltj

Thanks Bill, that's good to know for the next time.

superpat

Apologies for resurrecting this thread, but in a good cause :-)

My '96 Carrera 4 Cab failed smog, on readiness codes ('failed functional check'), the other day. I had to jump start it after the battery went flat when it was left for a few weeks over Christmas, and 7 months of regular driving had only set the 'M', 'F' and 'CC' codes, leaving 'C', 'EV', '2A', 'O' and 'OH' unset (according to my Equus Innova 3100 OBD2 tool).

I called my 'Porsche guy', Don Wise at Don's Autowerks in Campbell, CA, and he recommended Accurate Smog Check on Curtner in San Jose. I called them and they said to take it to the BAR referee at Evergreen Valley College in San Jose, so I called (1 800 622 7733), made an appointment, and showed up there today with my registration, failed smog receipt and $8.25 in cash.

The tech there (Terrence, iirc) was efficient and knowledgeable. He knew all about the 993 and said that, if all else checked out, readiness codes would not be an issue. I showed him my printout of the BMW driving cycle and his response was 'good luck with that'

About 20 minutes later I was the proud possessor of a referee override certificate.

Bottom line - at least in CA - if your car fails smog on the functional check due to unset readiness codes, don't panic, just call BAR at 1 800 622 7733, make an appointment and you'll be fine. The net cost is zero, since they just charge you the $8.25 certificate fee that you didn't pay to the smog test center, and it's quicker and easier than trying to do the drive cycle :-)

1pcarnut

Thanks, that's good to know, just got my renewal, smog test needed, went to take the car for a drive, dead battery. So now I've get to worry about the codes or at least go to two different locations to deal with it.

97Targa

I went the BAR route yesterday. Failed and was told by the official, "drive the car and they should reset". Next up, BMW driving sequence procedure. BTW, I was quoted $375 by the local stealer, for them to reset the flags. Yeah, no thanks.

97Targa

I am very happy to say mission accomplished! I followed a similar course. However, I only had 5 hours of cool down. So I was able to do it durring my lunch hour. IMHO, it's all about the route that you choose. Being as smooth as possible. Treating the times as minimums. And the speeds as the absolute maximums. It's still pretty tough to do. But it can be done. Much thanks to mac993 and Joe Vampola for their encouragement.

600RR

Superpat: Many thanks for the heads up on the BAR at EVC. While I don't have a current problem, it is good to know that there is an option in the South Bay Area.