Originally Posted by OUScooby

Also wondering what is the timeframe to complete these drive cycles. Is there a certain amount of minutes I have from when starting the car to completing the drive cycle conditions? What about time between different drive cycles or different steps in the drive cycle?

Originally Posted by Don B

As far as I know, there is no time limit for completing a drive cycle. Off the top of my head, I think for some models some of the drive cycles may have to begin with a cold engine, so that would be a limiting factor if you did another cycle first, but I can't recall whether this is true for the AJ26/AJ27.

When you tested your alternator, was it just for voltage output, or did you also test for AC ripple and for voltage regulation loaded and unloaded?

Originally Posted by Don B

Hi OUScooby,

Sorry to join your thread late. First of all, there is not one drive cycle. There are several, one for each diagnostic readiness monitor.

I'm attaching a few documents that may be helpful. The first is the Powertrain DTC Summaries for the 2000 model year. The second is the same guide except for the 2001 model year, which I am including because page 3 explains a bit about drive cycles and monitoring conditions for each DTC. By finding DTCs relevant to your monitors that will not reset you may find specific drive cycle info that may help you reset those monitors or trigger the DTC by replicating the monitoring conditions. For example, for your heated catalyst monitor, look at DTCs like P0420 and P0430. For your oxygen sensor monitor, look at DTCs from P0131 to P0161. For your EGR monitor, look at DTCs P0400 to P0406.

The third and fourth documents are also Powertrain DTC Summaries manual but from 2004 and 2005. They contain very detailed drive cycles for all of the diagnostic monitors available in the 2004 / 2005 4.2L models, which had the Denso 32-bit engine management system. But since your AJ27 uses the Denso 16-bit EMS, it's possible the same drive cycles may work on your car.

Monitor your Short Term and Long Term Fuel Trims (STFT & LTFT). These should be close to zero, but no higher than 10 or lower than -10, which would indicate that your engine is running overly lean or rich, which will prevent several diagnostic monitors from resetting.

If you can get any DTCs to trigger, do not clear them immediately, because clearing them may reset some or all of your diagnostic readiness monitors, and DTCs will help you figure out why the monitors aren't resetting on their own.

One other thought is that low battery voltage can prevent diagnostic monitors from resetting, so you might have your battery and charging system tested by a good analyzer that can detect whether the battery can no longer provide its rated CCA or can no longer hold a 12.6 volt state of charge, or an alternator with excessive AC ripple, poor voltage regulation, etc.

Sorry I can't be more specific, but hopefully you can try some of the cycles in these documents and at the very least, hopefully you will trigger some DTCs that will tell you why your monitors won't reset.

Cheers,

Don

Originally Posted by Highhorse

Are you only 30-70% full of fuel? Some tests won't perform if too low or if full. Be sure your voltages are good on the battery and from the alternator as Don stated.
Good idea to wait overnight for the vehicle to start at ambient temp below 90F.

Originally Posted by OUScooby

Out of hopefulness I'm going to believe the new app and concentrate on the O2 and EGR systems, I wonder if it would be work cleaning or replacing the o2 sensors and egr? If so which O2 sensor should I be looking at? Also can someone explain to me what system "Components" components is referring to so I can find the appropriate drive cycle for that?

Originally Posted by Highhorse

Don probably knows different, ...but like your other app, the O2 (which I think is the aft CAT ones) and the EGR not passing, ...its not going closed loop. O2 sensors are fickle and I'm in the house you have a failing or failed one. Of course I have been kicked out of the house before.

Originally Posted by Don B

I think it must be one or both of the upstream oxygen sensors (before the catalytic converters) where the problem lies, because if a downstream/after cat O2S had a problem your catalyst monitor could not have reset. If your scan app can show you Live Data, watch your O2S signals and see if both of the upstream sensor signals are not behaving in essentially the same way. Cleaning O2 sensors rarely works, so if one of your sensors is misbehaving it's best to just replace it. Cleaning an EGR valve and its associated pipes can sometimes work (if your car actually has one - I just realized I have no idea what year and model your Jag is - can you please add that info to your signature so it shows up in all of your posts?).

The Comprehensive Component Monitor relates to the combined Engine Management System/Transmission Control performance, to confirm the correct gear ratios are resulting from computer commands, gear shifts are being orchestrated properly, etc. I think there are drive cycles for this in the 2004-2005 DTC Summaries manuals I attached to my earlier post.

Cheers,

Don

Originally Posted by OUScooby

the old app also lists A/C refrigerant, secondary air system, and heated catalyst as not ready

Originally Posted by OUScooby

EDIT: Additionally I'm also if it is a bad o2 sensor, why would it not simply throw a DTC and a check engine light?

Originally Posted by JagV8

Once various monitors are unset it doesn't know what can be trusted and thus it also cannot work out which of many codes to flag.

This is one of the reasons why it can be very bad to do anything that unsets monitors (such as clearing codes or disconnecting the battery).

There's a much more detailed doc about this stuff if you want to read a lot...

Originally Posted by JagV8

Once various monitors are unset it doesn't know what can be trusted and thus it also cannot work out which of many codes to flag.

This is one of the reasons why it can be very bad to do anything that unsets monitors (such as clearing codes or disconnecting the battery).

There's a much more detailed doc about this stuff if you want to read a lot...

Originally Posted by Aarcuda

sadly I do. I am having trouble getting mine to complete but it may be me missing a parameter.

Originally Posted by OUScooby

Do you know what parameters you need to get readiness for? It's incredible frustrating with these cars. I don't know why it needs to be this way, any other car you just do a nominal amount of normal driving and everything is fine, but with these stupid cars you must do a complex and exact set of instructions that seem arbitrary to the layman and yet are consequential to being able to pass the local emission testing that are required for you to legally use your car. I'd love to meet one of the engineers responsible for the design of the ecu emissions or evap systems on these cars so I can give the a swift kick in the *****!

Originally Posted by Don B

Dittos on JagV8's advice. There is really nothing unique about the Jaguar engine management system. It's made by Denso, the former division of Toyota, so the engineers you want to kick probably live in Japan. Your Jag is telling you something is wrong, it just isn't telling you exactly what is wrong. No other make of car will reset a readiness monitor if there is a fault in a system. You've just run into one of those situations that is going to require advanced diagnosis. It might expedite things to visit a good independent mechanic who works on Jags or other European cars and is adept at diagnosing malfunctions in the absence of codes.

Originally Posted by OUScooby

Ever other car I've owned in the past will trip a CEL if something is wrong, and even if the readiness monitors have been reset. I've reconnected a battery after working on the car to see CEL pop up pretty quickly, including codes for o2 sensors. After almost 200 miles of driving on this car, if it thinks there is a fault with the o2 sensor of some other system why would it not just throw a CEL?