Help! OBD II communication fail?
- Thread starter golkhl
- Start date
TexasBlownV8
Formerly TexasBlownV6
There's 3 potential things going on here.
1) communications issues: if there is an issue, that has to get resolved. Plug in your tuner and read DTCs; if you read successfully, no DTCs or you found some, then communications is working.
2) readiness and drive cycles: this is far simpler than people make it out to be, but you really need to learn how to get it done on your car. For my Mustangs, I can get them in a ready-enough state within 2 drive cycles, each cycle lasting 6-10 minutes.
(a) reset/clear pcm, load tune, etc. No monitors are ready at this point.
(b) take first drive cycle; I drive 6-10 minutes at varying steady speeds of 45, 55, and 65, steady throttle during these times. This gets most of the monitors ready.
(c) let the car sit for at least 6 hours; this is required for evap tests to be run on the next drive cycle.
(d) do another drive cycle, varying the speeds as above; for me, this is driving to the inspection shop, 10 minutes away; by the time I get there, things are ready (I check before going into the shop to make sure I'll pass).
3) if you are getting multiple O2 not ready's for multiple systems, the rear cats are turned off in the tune, and no matter how many cycles you do, it wont pass.
1) communications issues: if there is an issue, that has to get resolved. Plug in your tuner and read DTCs; if you read successfully, no DTCs or you found some, then communications is working.
2) readiness and drive cycles: this is far simpler than people make it out to be, but you really need to learn how to get it done on your car. For my Mustangs, I can get them in a ready-enough state within 2 drive cycles, each cycle lasting 6-10 minutes.
(a) reset/clear pcm, load tune, etc. No monitors are ready at this point.
(b) take first drive cycle; I drive 6-10 minutes at varying steady speeds of 45, 55, and 65, steady throttle during these times. This gets most of the monitors ready.
(c) let the car sit for at least 6 hours; this is required for evap tests to be run on the next drive cycle.
(d) do another drive cycle, varying the speeds as above; for me, this is driving to the inspection shop, 10 minutes away; by the time I get there, things are ready (I check before going into the shop to make sure I'll pass).
3) if you are getting multiple O2 not ready's for multiple systems, the rear cats are turned off in the tune, and no matter how many cycles you do, it wont pass.
I am still waiting on confirmation from my tuner that nothing is turned off like the rear O2s... which I doubt is the case since my exhaust is stock.
No issues communicating with the tuner as I already performed a tune reload, checked for DTCs with both my tuner and scanner with none identified. I used the very detailed drive cycle that was in post #24 twice yesterday with 8 hours in between.
And my scanner still shows only 2 monitors ready. Not sure if the communication would still show up as that could have just been a fluke with the emissions test I assume I very few, if any, monitors ready... but there was no way to tell since it failed with non-communication error.
I plan to take the car into a parts store tomorrow to confirm monitor status tomorrow, followed by a trip to another emissions station.
Thanks for the feedback. But I am still concerned as to why only 2 monitors show up as ready with nothing changed after both very long drive cycles (Fuel and Comp).
No issues communicating with the tuner as I already performed a tune reload, checked for DTCs with both my tuner and scanner with none identified. I used the very detailed drive cycle that was in post #24 twice yesterday with 8 hours in between.
And my scanner still shows only 2 monitors ready. Not sure if the communication would still show up as that could have just been a fluke with the emissions test I assume I very few, if any, monitors ready... but there was no way to tell since it failed with non-communication error.
I plan to take the car into a parts store tomorrow to confirm monitor status tomorrow, followed by a trip to another emissions station.
Thanks for the feedback. But I am still concerned as to why only 2 monitors show up as ready with nothing changed after both very long drive cycles (Fuel and Comp).
FYI. SCT base files have rear O2 default to off.
TexasBlownV8
Formerly TexasBlownV6
Nice to know. Also FYI: those of you with F/I and higher IATs may have some challenges getting monitors 'ready'.
Hoping this mild weather right now will keep IAT's out of the picture as it is typically staying under 100. So does it just take more drive cycles to get past higher IATs or is there another means to get this done?
Timing is everything as I always had a year plus after past tune updates with the E-force before emissions was required, but I have been dealing with a shifting issue since doing the trans swap and of course the most recent one was updated last month... right after I took the car out of winter storage.
Timing is everything as I always had a year plus after past tune updates with the E-force before emissions was required, but I have been dealing with a shifting issue since doing the trans swap and of course the most recent one was updated last month... right after I took the car out of winter storage.
TexasBlownV8
Formerly TexasBlownV6
A tuner can help out on this; or, if you have a relocated IAT, a temporary 'fix' can be made that will keep the IAT below 100*. Running the car more wont usually help, unless the air is very cool and your engine does not get warm from the underhood heat.
BadHabit2Break
Senior Member
I believe some of the test have to be done between certain temps on the IAT, 40-100 degrees.
I can get mine to complete in 66 miles.
sportinawoody
!@#$%^&*(
got mine in 10 miles, 1st trip but not including evap. that is a 2 trip detection and requires a coolant temp below 80 I believe. no matter though, main thing is throttle easy on , easy off, no sudden stabs or releases of the throttle, stay between 50-60 for 5 miles, stop , turn engine off, wait for 30 seconds to 2 minutes, start it back up and let it fully heat up and cycle fans. DO NOT RUN THE A/C DURING THIS PERIOD !!! it runs the fan which cools lots of things off including cat temps. you want the heat for the 02's and the catalyst, then repeat driving cycle. also monitor your coolant temp. i've seen issues with this from stuck open thermostats. if you monitor temps and it goes above 180, you should be setting the monitors eventually. If not, your staying in open loop and its not going to pass. can't say about iat's as they've never been an issue on my car. this always works for me on my car and customer cars
Last edited:
Progress... finally received a response from my tuner and found out most of the emissions monitors were turned off in the tune 
I just loaded his update and seeing progress as 7 monitors now show up with 4 incomplete (Catalyst, EVAP, O2 sensor & O2 heater) and 3 ready (misfire, fuel and comp).
Now the drive cycles start and I can hopefully get this wrapped up tonight or first thing tomorrow.
Thanks for all the feedback!!
I just loaded his update and seeing progress as 7 monitors now show up with 4 incomplete (Catalyst, EVAP, O2 sensor & O2 heater) and 3 ready (misfire, fuel and comp).
Now the drive cycles start and I can hopefully get this wrapped up tonight or first thing tomorrow.
Thanks for all the feedback!!
Last edited:
golkhl
Senior Member
Doug: if the o2 sensor and o2 heater are showing not ready, that means they are still turned off in the tune. That is the problem I ran into with mine. I had vmp turn them back on, and then I did two drive cycles to ready the catalyst and Evap.
golkhl
Senior Member
I feel your pain, I just got mine done today after two weeks of retunes and drive cycles.
At least I am making progress now as I was totally lost until my tuner responded. Worse case I have to buy the $8, 30 day temp tag if this does not get resolved by tomorrow. And then I can leisure approach to getting it ready.
Last edited:
My tuner confirmed the O2s are on and stated they would show as unavailable if not on... Recommended I check the O2s and potential exhaust leaks, which I find hard to believe could be an issue the car has very low miles and was fine until they completed the auto swap and new tune, with nothing else being touched since. Not sure what else to do now other than drive through some additional cycles and see what happens.
Can someone else confirm if this is possible??? Do the O2s need some additional drive cycles? I don't doubt golkhl's car responded quickly after the O2s were turned on, but this is going well beyond my knowledge.
Can someone else confirm if this is possible??? Do the O2s need some additional drive cycles? I don't doubt golkhl's car responded quickly after the O2s were turned on, but this is going well beyond my knowledge.
Last edited:
TexasBlownV8
Formerly TexasBlownV6
BS. My rear o2's get ready on the first drive cycle. Although if IATs are too high, you wont get them ready. Put a 33k-ohm resistor across your iat sensor (instead of using the sensor),but drive carefully (i.e., no wot).
golkhl
Senior Member
When my rear o2's we're turned off they showed as not ready, not unavailable like your tuner is suggesting. As soon as vmp turned them on in the tune, they showed as ready.
Even with the warm weather right now, my IATs peaked at 102 via my Aeroforce gauge. I am not very confident with my tuner so I may end up up with basic email tune from someone else just to confirm. And with E-force there was no IAT sensor relocation.
BadHabit2Break
Senior Member
If they show incomplete, then they are on as your tuner has said.
Your going to have to keep trying the drive cycles to get them complete.
Do you have a way to monitor them as you drive, like an app on your phone or tablet.
Your going to have to keep trying the drive cycles to get them complete.
Do you have a way to monitor them as you drive, like an app on your phone or tablet.
Similar threads
Support us!
Support Us - Become A Supporting Member Today!
Click Here For Details