Failed Emissions Today

[Prodigal]

I don’t have to deal with inspections thankfully but having to drive for 70+ miles to get things ready to be checked just seems insane to me. I get that it needs to be at operating temperature but what’s the magic that happens between mile 5 and mile 70 that suddenly makes things ready??

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[rwp50]

Experienced the same problem on our 2015 C7. Put about 100 miles on it and still failed after a battery change.
Was told it was more of a hourly/day time frame. Since it was spring and really not driving it regularly waited about 4 days and passed no problem.

just my 2cents.

 

[KingKona]

I don’t have to deal with inspections thankfully but having to drive for 70+ miles to get things ready to be checked just seems insane to me. I get that it needs to be at operating temperature but what’s the magic that happens between mile 5 and mile 70 that suddenly makes things ready??

The ECU is a learning computer. When you disconnect the battery, it wipes all the information the ECU has stored that it uses to adjust the parameters of the engine.

So, you have to drive the car to let it learn again, let it re-gather the data.

 

[rwp50]

The ECU is a learning computer. When you disconnect the battery, it wipes all the information the ECU has stored that it uses to adjust the parameters of the engine.

So, you have to drive the car to let it learn again, let it re-gather the data.

Thanks!

 

[Prodigal]

The ECU is a learning computer. When you disconnect the battery, it wipes all the information the ECU has stored that it uses to adjust the parameters of the engine.

So, you have to drive the car to let it learn again, let it re-gather the data.

Ok thanks for the clarification. the long drive is unique to this particular situation because the owner disconnected the battery. Got it. I thought it meant long drives where required for all prior to emissions testing.

 

[KingKona]

About 70 miles or so. Guess I have more driving to do. Not the worst thing in the world since I love driving the car lol. But I'm wondering if it's just driving or if I really need to nail those drive cycles, which can be a pain out in the street. It's not always possible to accelerate from 0-65, coast down to 40, then back up to 65, coast down to 40 etc, and do all that 5 times.

I'm also getting suspicious of the tune now with all the talk of the O2 sensors, and it just so happens to be those couple things that remain not ready when everything else is good to go.

Just drive. You're probably very close.

 

[BlueThunder16]

Just drive. You're probably very close.

Yea hopefully. No response from my tuner yet. I drove it again just now quickly to go to the store and still no good. But tomorrow morning I'm going to take it out for another long drive and see where I'm at.

 

[Dave2013M3]

Hi all. I disconnected my battery the other day to swap steering wheels, and it didn't dawn on me today when I took it in for an inspection that I should have driven it a while beforehand. Does anyone know how many miles I will have to put on it before bringing it back in? And is it miles or actually drive cycles that I have to go through? I've never failed an inspection for anything before so I've never had to think about this stuff.

Also, even though my 93 tune doesn't affect emissions (reconfirmed with tuner today), he suggested I flash it back to stock before bringing it back just in case. I suppose it can't hurt, but is that really necessary, or can I just put miles on it?

I was able to get all my readiness codes to go green in a few days and about 50 miles. For the EVAP you have to have between 1/4 and 3/4 of a tank. If it is above 3/4 of a tank it won't let the EVAP readiness code go green. Also, get the car out on the freeway late at night. No large throttle inputs and keep the speed in the 50mph range. You probably need to do this for 15-30minutes for the fuel trims.

 

[BlueThunder16]

Another drive, another fail. I'm starting to really lean towards it being the tune. Hopefully I'm wrong. I'd say I'm about 120 miles since disconnecting the battery. So I feel like it's either two things: the amount of miles driven is irrelevant and I actually have to complete the drive cycles, or it's the tune. My tuner never got back to me when I asked him to double check the file, but in his first response to me, he suggested always flashing back to stock before an inspection because the tune can sometimes make the monitors work harder to go into a ready state. I don't understand that...if emissions weren't touched in my tune, then they shouldn't be affected, but what do I know. And, if I do flash to stock, would I then have to drive a bunch of miles again afterwards? Because if that's the case, it's not really practical. I can sometimes take months for me to put a couple hundred miles on this car, especially if it's winter. So that would mean I'd have to flash the stock file 4-5 months prior to an inspection every year. What's the point of having it tuned if I have to drive around with the stock tune almost half the year?
... getting frustrated at this point.

 

[WildHorse]

All that driving and still no rear o2 means he shut em off.
I can throw in a tune I have with the rear o2 on and I'll get a CEL
within a few miles.

 

[PoCoBob]

I've been following this thread with some interest. I admit I know nothing about the computer systems in these cars but thought some of what's posted seems a bit over the top. So I looked in my (2019) owners manual and it says after changing the battery let the car idle for at least 1 minute and then drive it for at least 10 miles to allow the computer to relearn the fuel strategies. It sounds like you've invested a couple tanks of gas already, there has to be something else going on here. I would reflash the tune and try that.

And I'm curious about your testing. Do they still put a tube into the exhaust and analyse it that way? In B.C. they stopped testing years ago but when they were testing they started with the tube in the exhaust but by the end they just plugged into the data port under the dash. They put the car on a rolling road and tester would drive the car following a preprogramed video that was shown on a screen in front of the car. Basically he/she needed to match the speed of the wheels to a green portion of the video screen, speed up, slow down etc. Their computer just confirmed all the sensors in the car remained within spec.

 

[MidwayJ]

After disconnecting the battery, I once had to drive our Honda CR-V about 50 miles in order for the sensors to be ready. No experience with my Mustang, but you seem to have driven it plenty. I understand why you suspect the tune at this point.

 

[WildHorse]

In B.C.

Here in Manitoba we never had emissions testing. Only time you might get dinged if a cop happens to see you missing yer CATs. They're more concerned with mufflers/tint.

 

[BlueThunder16]

After disconnecting the battery, I once had to drive our Honda CR-V about 50 miles in order for the sensors to be ready. No experience with my Mustang, but you seem to have driven it plenty. I understand why you suspect the tune at this point.

Agreed. I just don't get it because I don't have much work done to the car at all. It's basically a stock car with a standard 93 tune, which I was initially told would not alter anything having to do with emissions.

 

[BlueThunder16]

I've passed emissions on a 93 tune for years, it's not a problem.

Just go for a nice drive, maybe an hour or so, it will pass.

Just curious, which 93 tune do you have, and are you stock other than the tune? Thanks.

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