After replacing O2 sensor and erasing old code P1401, took the car for its bi-annual smog certification. Emissions were all fine but CA dmv computer would not read car because it was not ready for testing. Was told to drive the car about 100 miles and come back. Drove 200 miles and problem still persists. No pending or stored codes but “Catalyst Monitor incomplete” still showing (photo attached) and preventing test. Is there a special way to deal with this or do I have to keep driving and testing until it is “complete” and can hook up to the dmv computer?
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ECU question
- Thread starter bboxer
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My service manual is locked up in my NSX which is locked up in winter storage - so I am winging this a bit and also using some generic info from my son's OBDII scanner manual.
The first three Readiness Monitors which are OK run continuously on the ECU so you can usually set them in a single relatively short trip. My recollection is that the Catalyst Monitor only runs once in a trip and needs to go through at least two complete drive cycles before it will flag as OK / complete. So, if you fixed the O2 sensor and then drove 200 miles (or a 1000 miles) in one go you did not satisfy the 2 or more drive cycle requirement. If you do a web search using the terms OBD II Trip Drive Cycle or OBD II Readiness Drive Cycle you can find more details on what constitutes a drive cycle. One important thing to note is that you can't drive the car around, shut it off and then start up and drive around some more to complete 2 cycles. Each drive cycle has to start with an engine close to ambient temperature.
As I mentioned, I don't know whether the Honda readiness monitor sets in 2 cycles or requires more than 2 drive cycles or whether the Honda drive cycle has some quirky specifics (I doubt it). You may be able to find Honda specific drive cycle information on the web. You can leave your code reader attached to the OBD II port while driving and it will tell you when the readiness monitor for the catalyst has been set. Chances are that if you have driven the car a couple of times since the test was attempted the monitor will now come up as OK (assuming the repairs worked),
The first three Readiness Monitors which are OK run continuously on the ECU so you can usually set them in a single relatively short trip. My recollection is that the Catalyst Monitor only runs once in a trip and needs to go through at least two complete drive cycles before it will flag as OK / complete. So, if you fixed the O2 sensor and then drove 200 miles (or a 1000 miles) in one go you did not satisfy the 2 or more drive cycle requirement. If you do a web search using the terms OBD II Trip Drive Cycle or OBD II Readiness Drive Cycle you can find more details on what constitutes a drive cycle. One important thing to note is that you can't drive the car around, shut it off and then start up and drive around some more to complete 2 cycles. Each drive cycle has to start with an engine close to ambient temperature.
As I mentioned, I don't know whether the Honda readiness monitor sets in 2 cycles or requires more than 2 drive cycles or whether the Honda drive cycle has some quirky specifics (I doubt it). You may be able to find Honda specific drive cycle information on the web. You can leave your code reader attached to the OBD II port while driving and it will tell you when the readiness monitor for the catalyst has been set. Chances are that if you have driven the car a couple of times since the test was attempted the monitor will now come up as OK (assuming the repairs worked),
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Thank you Old Guy. I did drive out 3 or 4 times but certainly did not follow some of the procedure I have now read on the web after your advice. The Drive Cycle is quite different from one site to the other even when they refer to Honda/Acura.
I will try a combination of what I read with tester plugged in and see if I am successful this time. I just discovered I misplaced my 97 NSX complete shop manuals. (Right when I needed them!).
I will try a combination of what I read with tester plugged in and see if I am successful this time. I just discovered I misplaced my 97 NSX complete shop manuals. (Right when I needed them!).
When all else fails, perhaps check the owner's manual (mine is also locked up in the car). The owner's manual might provide a description of the drive cycle.
Spent an hour on the road, tried hard to replicate the Honda/Acura Driving Cycle procedure posted on one of the random website. Didn’t help. Still showing incomplete (Catalyst Monitor and Evap. monitor). I have a feeling it was not the right procedure.
Looks like I have permanently misplaced my old 97 service manuals. Does anyone at all have the correct 97 (or any other year) Driving Cycle (to reset the ECU after deleting a code) details? Thanks!
Looks like I have permanently misplaced my old 97 service manuals. Does anyone at all have the correct 97 (or any other year) Driving Cycle (to reset the ECU after deleting a code) details? Thanks!
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I have a printed 97 Service Manual. Where should I be looking for this for you?
Thank you! I am not sure but I guess in any chapter that deals with MIL, faults, codes, resetting ECU. The actual item I am looking for is known as “Drive Cycle” in both government (OBD2) as well as OEM jargon.
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From my old memory getting rid of this readiness code has nothing to do with number of starts or miles driven. The procedure is while in neutral rev the car to X rpm with the ac on for 3 minutes. What I’m not exactly sure of is the rpm. It was something like 2500 rpm. HTH
On your OBD code reader, is there another page displaying the status of more monitors? The reason I ask is that OBDII usually includes other non continuous monitors such as O2 sensor monitor, O2 heater monitor, EGR system monitor, Evap monitor ....... From the limited info that I extracted from the scanner manual, these monitors have to be set before the catalyst monitor will go through its routine. The catalyst monitor seems to require that everything else be 'set' before it can be set.
As far as I have been able to determine, the catalyst monitor routine looks at the difference in the voltages between the front end and back end O2 sensors. The front end should have a varying voltage signal and the back end should have a steady signal indicating that the excess O2 coming in the front end is being used up by the catalyst in the conversion of CO to CO2. My 'take' is that successful completion of the monitor function merely indicates that the catalyst is doing something, not necessarily that the catalytic converter is meeting emission standards. If the O2 sensor monitor or O2 heater monitors are not set the ECU will not carry out the catalyst monitor - so see if your scanner can check to confirm that those monitors have been set. You said you erased the P1401 code. Check to make sure that you have not generated any pending codes since replacing the O2 sensor. A pending code can prevent the ECU from executing the catalytic monitor function.
One last Hail Mary. I am guessing CT car in your signature means supercharger? If so, the ECU may have adjusted the fuel trims for operation with the supercharger. Can your code scanner read the long term and short term fuel trims stored in the ECU? Some of the OBDII drive cycle guides indicate that if the fuel trims are high, they can prevent the ECU from completing the catalyst monitor function. When you erased your error code, did you do it with the scanner or did you do a complete ECU reset with the clock fuse? I am a little unclear as to what the scanner clear functions do (different vendors have different descriptions). The clock fuse reset clearly wipes all stored data including fuel trims. If you are running with high trims a complete ECU reset would zero the trims and might allow successful execution of the catalyst monitor function. If that works, you may definitely need to drive around to re establish those trims otherwise you might fail the actual tail pipe test; but, at least the monitor would be set.
Finally, I am curious about your P1401 error code. The photocopied NSX DTC cheat sheet does not list a P1401 DTC for the NSX. It lists a P0401 DTC which is an EGR problem. Is that a typo or is your scanner misinterpreting something?
As far as I have been able to determine, the catalyst monitor routine looks at the difference in the voltages between the front end and back end O2 sensors. The front end should have a varying voltage signal and the back end should have a steady signal indicating that the excess O2 coming in the front end is being used up by the catalyst in the conversion of CO to CO2. My 'take' is that successful completion of the monitor function merely indicates that the catalyst is doing something, not necessarily that the catalytic converter is meeting emission standards. If the O2 sensor monitor or O2 heater monitors are not set the ECU will not carry out the catalyst monitor - so see if your scanner can check to confirm that those monitors have been set. You said you erased the P1401 code. Check to make sure that you have not generated any pending codes since replacing the O2 sensor. A pending code can prevent the ECU from executing the catalytic monitor function.
One last Hail Mary. I am guessing CT car in your signature means supercharger? If so, the ECU may have adjusted the fuel trims for operation with the supercharger. Can your code scanner read the long term and short term fuel trims stored in the ECU? Some of the OBDII drive cycle guides indicate that if the fuel trims are high, they can prevent the ECU from completing the catalyst monitor function. When you erased your error code, did you do it with the scanner or did you do a complete ECU reset with the clock fuse? I am a little unclear as to what the scanner clear functions do (different vendors have different descriptions). The clock fuse reset clearly wipes all stored data including fuel trims. If you are running with high trims a complete ECU reset would zero the trims and might allow successful execution of the catalyst monitor function. If that works, you may definitely need to drive around to re establish those trims otherwise you might fail the actual tail pipe test; but, at least the monitor would be set.
Finally, I am curious about your P1401 error code. The photocopied NSX DTC cheat sheet does not list a P1401 DTC for the NSX. It lists a P0401 DTC which is an EGR problem. Is that a typo or is your scanner misinterpreting something?
Thanks. Great info.
Yes I discovered a “page 2” on my tester last night and yes my Evap Monitor is also not complete! I just went for a new drive cycle, this time based on yet another web sourced Acura protocol (sic). Just checked again. Cat and Evap monitors still incomplete!!!
No pending and no stored codes. No MIL either.
You were right about the code number. It was a typo or a brain fart. The code I had was P0141 (bank 1, sensor 2). The O2 sensor was replaced and the code erased (with the scanner), a good 200 miles ago.
PS. Yes the car is a S/C Comptech car from new. My sniff test was actually all good. The CA dmv computer did not hookup because of the lack of “readiness” of my ECU
Yes I discovered a “page 2” on my tester last night and yes my Evap Monitor is also not complete! I just went for a new drive cycle, this time based on yet another web sourced Acura protocol (sic). Just checked again. Cat and Evap monitors still incomplete!!!
No pending and no stored codes. No MIL either.
You were right about the code number. It was a typo or a brain fart. The code I had was P0141 (bank 1, sensor 2). The O2 sensor was replaced and the code erased (with the scanner), a good 200 miles ago.
PS. Yes the car is a S/C Comptech car from new. My sniff test was actually all good. The CA dmv computer did not hookup because of the lack of “readiness” of my ECU
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You probably need to figure out why the Evap monitor is not setting. Once that is fixed the catalyst monitor may fix itself. I seem to recall that the Evap monitor needs a near full tank of gas to set. Might want to make sure that you have checked that box.
The web sourced protocols are interesting. There is an oft repeated 'Honda' protocol that is attributed to the Honda Odyssey. The protocol is elaborate and borderline bizarre (in my opinion) as to the number of steps you have to go through. The only thing that seems to be missing from the protocol is sacrificing a chicken over the car at midnight while hopping on one foot. I am not so sure what is so odd about the Odyssey that it requires such an elaborate driving sequence.
The web sourced protocols are interesting. There is an oft repeated 'Honda' protocol that is attributed to the Honda Odyssey. The protocol is elaborate and borderline bizarre (in my opinion) as to the number of steps you have to go through. The only thing that seems to be missing from the protocol is sacrificing a chicken over the car at midnight while hopping on one foot. I am not so sure what is so odd about the Odyssey that it requires such an elaborate driving sequence.
Thanks again. Yes I tried with full tank, 3/4, 1/2, 1/4 to no avail. Fuel cap seems to be OK but without my books i dont know what else is in the evap system.
Yes some of the websites description of Drive Cycles are almost funny. I just cant fathom the idea that anyone who replaces an O2 sensor has to go thru this mini nightmare.....
In the meantime I am hoping someeone will have the 97 books and look for a specific drive cycle for our cars.
Thanks
Yes some of the websites description of Drive Cycles are almost funny. I just cant fathom the idea that anyone who replaces an O2 sensor has to go thru this mini nightmare.....
In the meantime I am hoping someeone will have the 97 books and look for a specific drive cycle for our cars.
Thanks
All I could find on page 11-60 is the following: I shall continue the hunt for you tonight when I get home.
I had this problem in 2008 on my 97 NSX. Not that I found this in the service manual, but I found this and it worked for me back in 1998 when my readiness tests weren't complete: hope this helps. Try the A/C thing, that is what I did.
http://www.nsxprime.com/forum/archive/index.php/t-105894.html
http://www.nsxprime.com/forum/archive/index.php/t-105894.html
Thanks. I did the A/C trick but only for 3 minutes per another discussion. I may give the longer idle idea a try. I am also trying to take it out for a couple more long drives. I think Old Guy’s explanation about the EVAP system being at fault is the most probable. Acura dealership did not have any clue as to what the Driving Cycle is.
Have a look at this.
http://www.nysada.com/portals/0/webinar_archives/2012_webinars/obdii_inspections.pdf
It provides some useful explanations of the various monitor functions andwhat can trip them up rather than just the typical drive around and hopeadvice. The comments about starting and operating enginetemperature are particularly useful. If your thermostat is leakycausing a slightly low coolant temperature or your engine temperaturesensor is slightly off, you may never get the temperatures as read by the ECUinto the range where the monitor can be set regardless of what bizarre drivecycles you attempt. It might be useful to hook up your scanner andread the engine's starting and operating coolant and intake temperatures tomake sure that they meet the requirements.
Finally, back to another form of the Hail Mary. Since you are fromCalifornia, I recall comments that Ca would pass the car if one or two of themonitors were not set; but, the car tested out within CO, NO and HClimits. It might be useful to check with the CARB to see if thatrequirement has changed. Chances are that if your testing station issome private sector grunt they may not be particularly up on the details of therequirements and may just operate on the all monitors need to be set -gets them some repeat business?<o
></o>
http://www.nysada.com/portals/0/webinar_archives/2012_webinars/obdii_inspections.pdf
It provides some useful explanations of the various monitor functions andwhat can trip them up rather than just the typical drive around and hopeadvice. The comments about starting and operating enginetemperature are particularly useful. If your thermostat is leakycausing a slightly low coolant temperature or your engine temperaturesensor is slightly off, you may never get the temperatures as read by the ECUinto the range where the monitor can be set regardless of what bizarre drivecycles you attempt. It might be useful to hook up your scanner andread the engine's starting and operating coolant and intake temperatures tomake sure that they meet the requirements.
Finally, back to another form of the Hail Mary. Since you are fromCalifornia, I recall comments that Ca would pass the car if one or two of themonitors were not set; but, the car tested out within CO, NO and HClimits. It might be useful to check with the CARB to see if thatrequirement has changed. Chances are that if your testing station issome private sector grunt they may not be particularly up on the details of therequirements and may just operate on the all monitors need to be set -gets them some repeat business?<o
></o>Thanks. The NY monitor readiness exceptions are different from those here in CA. Perhaps a call to CARB will help.
Someone told me the Driving Cycle should be performed with no interruption which really is ridiculous. Since you have to start cold and after the idle part, accelerate to 55mph, you would have to spend the night in your car, parked on a freeway ramp LOL. If it is true, the only way to do it would be on a dyno!
Anyway, I drove another 200 miles today with three starts (one cold) and tried every variation, and the darn EVAP and CAT monitors are still incomplete! Grrrr
Someone told me the Driving Cycle should be performed with no interruption which really is ridiculous. Since you have to start cold and after the idle part, accelerate to 55mph, you would have to spend the night in your car, parked on a freeway ramp LOL. If it is true, the only way to do it would be on a dyno!
Anyway, I drove another 200 miles today with three starts (one cold) and tried every variation, and the darn EVAP and CAT monitors are still incomplete! Grrrr
Take a look at this diagnosis process for a similar issue
https://www.youtube.com/watch?v=irIR2NrLSUI
https://www.youtube.com/watch?v=irIR2NrLSUI
Thanks. Update. three days and 800 effin total miles and both moniitors (Catalyst amd Evap) are incomplete. Did a bunch of recommended drive cycles including a “sure” one recommended by Ramon at Niguel Motors. No success! All parameters including O2 sensors voltage normal. Not sure what to do next, except park the dinosaur!
Funniest part is the recommended drive cycles (highway and city) sent to me by a helpful employee at CARB/BAR. Impossible to follow on the road without interruption and not doable on a lift because of no-load).Have a look.
Funniest part is the recommended drive cycles (highway and city) sent to me by a helpful employee at CARB/BAR. Impossible to follow on the road without interruption and not doable on a lift because of no-load).Have a look.
Attachments
You should be able to run this across a referee. They will inspect your car and may pass you.
Also, you can get a two-year exemption. This will give you extra time to diagnose and repair the problem. (at the end of the exemption you will have to remove the car from the State or destroy it if you cannot get it to pass inspection).
I suspect you are going to have to get a high speed detailed logging system and an ECU extension harness to see what is going on. My guess is you have some noise that is being smoothed out by the scanner that you are using.
Also, you can get a two-year exemption. This will give you extra time to diagnose and repair the problem. (at the end of the exemption you will have to remove the car from the State or destroy it if you cannot get it to pass inspection).
I suspect you are going to have to get a high speed detailed logging system and an ECU extension harness to see what is going on. My guess is you have some noise that is being smoothed out by the scanner that you are using.
The drive cycles are entertaining. I think some of them have been created by two copy writers sitting in a bar and saying to each other, 'OK, now lets tell them to do this'. You really would need a test track or some section of remote road late at night with no other traffic around to execute them to the letter - no wait, that doesn't work because you are supposed to start the cycle immediately after the temp comes up to 1/4 scale. So I guess you have to camp out overnight at the test track with the car (engine off for 8 hours) so that you can start your cycle the next morning without interruption (the copy writers are snorting beer out their noses laughing over that one).
For what it is worth I found a .pdf of the 2001 NSX owners manual and this is the official 'NSX' drive cycle from the manual.
I really do think you have to try the sacrificial chicken at midnight / full moon thing.
Good luck with it. You have my sympathies. I hope you don't get pulled over by the Highway Patrol for displaying erratic driving behaviour.
For what it is worth I found a .pdf of the 2001 NSX owners manual and this is the official 'NSX' drive cycle from the manual.
- Make sure the gas tank is nearly,but not completely, full (around3/4).
- Make sure the vehicle has beenparked with the engine off for 8hours or more.Make sure the ambienttemperature is between 20° and95° F.
- Without touching the acceleratorpedal, start the engine and let itidle for 20 seconds.
- Keep the vehicle in Park(automatic transmission) orNeutral (manual transmission).Increase the engine speed to 2,000 rpm and hold it there until thetemperature gauge rises to at least1/4 of the scale (approximately 3minutes).
- Select a nearby lightly traveledmajor highway where you can maintain a speed of 50 to 60 mph(80 to 97 km/h) for at least 20minutes. Drive on the highway inD (A/T) or 6th (M/T). Do not usethe cruise control. When trafficallows, drive for 90 secondswithout moving the acceleratorpedal. (Vehicle speed may varyslightly; this is okay.) If you cannotdo this for a continuous 90seconds because of trafficconditions, drive for at least 30seconds, then repeat it two moretimes (for a total of 90 seconds).
- Then drive in city/suburbantraffic for at least 10 minutes.When traffic conditions allow, letthe vehicle coast for several seconds without using theaccelerator pedal or the brake pedal.
- If the testing facility determines thereadiness codes are still not set, seeyour Acura dealer.
I really do think you have to try the sacrificial chicken at midnight / full moon thing.
Good luck with it. You have my sympathies. I hope you don't get pulled over by the Highway Patrol for displaying erratic driving behaviour.
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Could you please delete this thread
http://www.nsxprime.com/forum/<wbr>showthread.php/200533-1991-<wbr>NSX-coupe-Black-Black-<wbr>Automatic-29-000-<wbr>JH4NA1150MT001777
http://www.nsxprime.com/forum/<wbr>showthread.php/200533-1991-<wbr>NSX-coupe-Black-Black-<wbr>Automatic-29-000-<wbr>JH4NA1150MT001777
TINO!!!!
What's curious is that the ECU is not attempting to do the test. The monitors are there to indicate that there are no problems - but that the ECU has not run certain tests. In your case this is cat efficiency and evap. Mind you, if the ECU runs either one the result will be that the monitor goes off (test was run successfully). Now, you could have the monitor light off - but a CEL if that particular test failed. In your case -clearly the test is not running.... which is curious.
Focusing first on Cat Efficiency, my experience is that the car has to be fully warm and the car wants steady state cruising at different speeds, AND clutch-out decels. Is your temp sensor/thermostat all stock and working OK? (The car really needs to believe that the conditions are right for the test to initiate.) Too low of a temp may cause the test not to start. How about your battery voltage and alternator. Is all of that perfectly OEM spec? It seems like you have driven more than enough - now it is time to look at why the test may not want to begin. Low (or high) coolant temp and/or battery voltage may be a plausible reason why the test won't initiate. In theory, the condition of your O2 sensors shouldn't be part of this equation. Now that the weather has warmed up a bit, maybe you will have better luck. Constant 30-35 miles speed, followed my constant 45mph speed, and then 55 mph speed with full stops in between. Remember to let car decel in gear as far as possible before depressing clutch.
As for evap, this test often needs to involve an overnight cool-down. Fundamentally , the ECU is looking for ambient temperature differences and then it will look to see if there's a pressure differential in the (sealed) fuel system. It should be able to "see" a difference in pressure in which case you will pass. If gas cap is loose (or other fuel system leak), the fuel system will not see a pressure differential.
Oh, and each time you clear (or attempt to clear) any codes using an OBD2 scanner, you will reset all of the monitors and be right back to square one.
What's curious is that the ECU is not attempting to do the test. The monitors are there to indicate that there are no problems - but that the ECU has not run certain tests. In your case this is cat efficiency and evap. Mind you, if the ECU runs either one the result will be that the monitor goes off (test was run successfully). Now, you could have the monitor light off - but a CEL if that particular test failed. In your case -clearly the test is not running.... which is curious.
Focusing first on Cat Efficiency, my experience is that the car has to be fully warm and the car wants steady state cruising at different speeds, AND clutch-out decels. Is your temp sensor/thermostat all stock and working OK? (The car really needs to believe that the conditions are right for the test to initiate.) Too low of a temp may cause the test not to start. How about your battery voltage and alternator. Is all of that perfectly OEM spec? It seems like you have driven more than enough - now it is time to look at why the test may not want to begin. Low (or high) coolant temp and/or battery voltage may be a plausible reason why the test won't initiate. In theory, the condition of your O2 sensors shouldn't be part of this equation. Now that the weather has warmed up a bit, maybe you will have better luck. Constant 30-35 miles speed, followed my constant 45mph speed, and then 55 mph speed with full stops in between. Remember to let car decel in gear as far as possible before depressing clutch.
As for evap, this test often needs to involve an overnight cool-down. Fundamentally , the ECU is looking for ambient temperature differences and then it will look to see if there's a pressure differential in the (sealed) fuel system. It should be able to "see" a difference in pressure in which case you will pass. If gas cap is loose (or other fuel system leak), the fuel system will not see a pressure differential.
Oh, and each time you clear (or attempt to clear) any codes using an OBD2 scanner, you will reset all of the monitors and be right back to square one.
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