drive cycle clarification question
#21
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?
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#22
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?
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?
#23
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
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
#25
So out of curiosity I downloaded a different obdii scanner app and used that to check emissions testing, this app showed a different set of systems as not ready, EGR, 02 sensor and Components which is old app was showing as not ready in the right column, but in that same column the old app also lists A/C refrigerant, secondary air system, and heated catalyst as not ready, which this new app say is ready. The left column of the old app has nothing matching this new app.
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?
#26
Fuel was at about 3/4 tank when I left, at about 1/2 tank now, I'll check the alternator as Don suggested, but the battery is new so I'm confident that is good.
#27
#28
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?
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
Last edited by Don B; 04-27-2020 at 09:26 PM.
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#29
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.
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
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
As for the component system I took a look at the 04/05 procedure, hopefully that will be the same as on my car, it seems straight forward enough to do, just wondering how long I can take between steps 13/14 (driving at 40mph) and step 15 (driving at 50-80mph) cause 13 and 14 I can do on surface streets, step 15 will require me to get to a freeway.
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?
Last edited by OUScooby; 04-27-2020 at 10:11 PM.
#30
It was showing them as not available, due to the car not having them, thus also not ready. It's a confusing way to show them but just ignore those that are not available.
#31
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...
#32
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...
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...
#33
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...
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...
#34
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 *****!
#35
That won't work when the car has a fault. Figuring out what the fault is can be tough once it's in this state, but Jaguar are just following the law as regards monitors.
You can see grief with other car makes if you care to search the net...
Bear in mind some US states have very nasty laws, some don't, and some allow a pass once a serious attempt at a fix can be evidenced.
You can see grief with other car makes if you care to search the net...
Bear in mind some US states have very nasty laws, some don't, and some allow a pass once a serious attempt at a fix can be evidenced.
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#36
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 *****!
Last edited by Don B; 04-28-2020 at 12:24 PM.
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#37
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.
#39
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?
It was somewhat similar with a O2 sensor and of course it was the biggest PITA to get to under the passenger side manifold. Thank God that wasn't so common.
I used to drive 60-70k a year when this was happening, so knowing exactly what to go to fix it was rather in my interest.