OBDII drive cycle explained/smogging

[TomCooper]

Had similar problems ,, LONG DRIVE (100+ miles) fixed the problem

[BadRhino]

Hi JClausen,

I realize this thread is pretty old kind of hoping you can help me?

I have a 2001 Land Rover Discovery 2, I have been told that the Discovery 2 D2 ECU is same generation as several of the BMW's (BMW owned LR from 95-04 ish)

Here's what I've done so far.

I looked up any active DTC's. I had (2)1. rough road and 2.theft deterrent circuit fault. I cleared those and did the "D" drive cycle. It was pretty easy late at night. The last parameter is to let the vehicle idle for 2 minutes. I then turned the engine off (didn't need to do this) and pulled up the Cat Conv and o2 sensor tests. They both came up n/a!! Leaving the reader on I started the engine and ran the tests again this time both modules came up as complete.

I took it to get it rechecked at the smog test station. They told me the evap wasn't ready. It's interesting prior to resetting the DTC codes my evap was complete O2 sensors were complete just the cat conv was incomplete. The question is would the ABS rough road DTC cause the drive cycle to not complete? Also my icarsoft d2 reader shows my evap as active?

Do you know the drive cycle to complete the evap module?

Any help is much appreciated.

Hugh

[mrgizmo04]

I believe evap is evaluated on cold start, but gas tank has to be nearly full. Abs dtc should not interfere with your drive cycle monitors not setting, but if you clear the code, it will reset all monitors and you will need to do the cycle again to set them all to ready again.

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[BadRhino]

I believe evap is evaluated on cold start, but gas tank has to be nearly full. Abs dtc should not interfere with your drive cycle monitors not setting, but if you clear the code, it will reset all monitors and you will need to do the cycle again to set them all to ready again.

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I really appreciate this response. It pretty much confirms what I was thinking an ABS DTC has nothing to do with engine management or emission control So about my thinking shouldn't stop the drive cycle.

I just filled the tank and will let it sit overnight, then do drive cycle A & E which as you say need to be done on a cold start.

[BadRhino]

Update:

These findings that I'm posting are related to a 2001 Discovery 2 which I believe was owned by BMW so the ECUs were the same The years were 1995-2004.

Thanks to mrgizmo04 for the DTC code/ drivecycle info.

I wanted to do an update on all the threads that I participated on this forum related to passing smog in California. My intent is to give my findings based on my circumstances that may or may not help others in the future. When I started I had just purchased a D2 and knew nothing about this specific issue. I want to make a caveat ymmv specifically that I had no faulty emission control devices. Obviously, If you have a DTC specific to the emission system you need to fix that component. How do you do that get a hold of a diagnostic OBD2 and start learning about the emissions system specifically how the ECU uses each device like the upstream and downstream O2 sensors.

I drove 300 mi and was unable to get the catalytic converter monitor up. The mechanic I spoke to started throwing things like it could be the O2 sensor It could be the catalytic converter but these were all speculations. The smog guy was like go drive the vehicle and come back and we'll test it.

I got really frustrated not having a diagnostic tool to look at. So rather than looking over somebody's shoulder I went out and purchased one from Amazon. Somewhere in this forum somebody recommended the icarsoft D2 obdII reader. Great reader so far as I can tell at this moment in time.

Next, I scoured this forum for information on specific drive cycles for the D2. I was tired of being in the dark information wise, so I found this thread. [url]https://landroverforums.com/forum/discovery-ii-18/drive-cycle-info-needed-36364/I[/url there is another thread that actually had a link to a PDF file that you could print out but this is the easiest one for me to find. I printed out the drive cycles and got to work.

When I started this I had seven of the eight IM (inspection maintenance) monitors up. I did that simply by just driving a lot. As I stated above I had all seven except for the catalytic conv monitor up. A neighbor suggested I reset the ECU by clearing all the DTCs. I did this but in retrospect It wasn't necessary. My findings were as long as you don't have a DTC that is associated with the engine management part of the ECU as in my case the ABS DTC was active, It will not stop any of the drive cycles. After doing drive cycles c&d my catalytic monitor came up (I live in southern California so I did my drive cycles at night It made it much easier) but my evap monitor didn't. It was at this point that I started to doubt myself and whether or not the DTC I had active was causing it not to complete the drive cycle. I went to the bimmer forum and somebody there assured me that an ABS DTC would not stop the drive cycle, I forged on and made sure my gas tank was between 3/4 and 1/4 full and did drive cycle A and E which I believe are specifically tailored to the evap as you need to do cold starts. I tried drive cycle A&E a couple times after a full fill up It did not work. As soon as my gas tank reached 3/4 boom!! my 8th monitor came up. The next morning I took it to the smog guy and I passed.

I'm going to post this on a couple other threads that were related to this so this might become redundant but hopefully I can save the next guy some time. THE DRIVE CYCLES WORK!!