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Discussion Starter #1
Hi guys.

My question is how long do our (older - 2010) ECM's store data history reading's? Does it rewrite over old data like after 6 months or does it actually save old data from years ago? Forever ??

I recently moved from AR to CA to be close to my son and grandson so now I have to get my 2010 Challenger R/T Classic smog tested and take the info to DMV to get a CA registration and a set of CA license plates.

Knowing years ago this was going to happen I never added headers or cams or anything fun to my 5.7 because CA does not allow fun of any kind !!

So I bought and installed a Diablo race tune when I bought the car in 2014 and have always used a 1/2 quart of Torco to up my octane from 93 to 95 or better. The car has run outstanding and very much quicker than stock. So now in CA I can only get 91 octane so I upped the Torco to one full quart per fill up and have no problem with the tune here in CA.

Now CA smog shops will do an OBD II reading and may also do a sniffer test and can even check under the car for any illegal mods such as non-factory cats, headers and anything else that CA does not allow. And of course they will want to see stock data readings from the OBD II.

So after removing my tune and restoring the factory tune I have waited 4 months so far and went through maybe 10 tanks of fuel and put on 1,500 miles as required in my own mind to allow my ECM to record enough data from the reinstalled factory tune to allow me to pass the smog test without showing the tester the way different data info from the racing tune I removed.

I'm hoping maybe one of you guys that works for a MOPAR dealership shop might chime in with helpful info here.

For everyone reading this post: I am not trying to lie, cheat or deceive any smog laws in CA. I'm just trying to find out what it takes to show a reasonable length of legal readings to successfully pass a CA smog test.
 

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I do not have any intimate details about how the CA smog tests interrogate the car’s PCM in order to decide a pass/fail, but I can venture an educated guess about what goes on (and what cannot go on), based upon my knowledge of the car’s PCM and the data you reference.

In a nutshell, you’re good. In fact, I believe you are being overly cautious and can dial back your efforts to proactively comply quite a bit.

Your PCM does not store any sizable amount of historic data about how the engine has been operated in the past. There is a very small window of PIDs’ data stored and continually overwritten for the scenario of accident investigation I do believe, but we’re talking on the order of less than a minute I think, certainly no more than a few minutes.

I doubt the smog tests can access that data anyway, but that’s beside the point. What their access does likely provide is simply to retrieve the readiness status of several emissions monitors, returning “Ready/Pass”, “Ready/Fail”, or “Not Ready.”

If all are “Ready/Pass”, the system likely checks for any stored DTCs related to the emissions system and goes from there.

If any are “Ready/Fail”, you fail.

If any are “Not Ready”, you are either failed or told to come back later when they can be tested again and hopefully have a “Ready” status finally.

There are other aspects to the test I’m sure, like the sniffer and visual inspection you mentioned, but again that’s all outside the scope of this answer.

There is just no way that I know of for them to view the historical PID output from your PCM, simply because it does not store any real amount of that data for subsequent retrieval.

Nuke
 

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I believe that, unlike Dodge for warranty purposes, a CA smog check is looking to see if the car passes the emissions test. Not what you may have done to the tune previously, but what the tune is now. As long as all the readiness monitors show as ready, I think you'll be fine

A Guy
 

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OK I'm learning a lot here. I have envisioned how a smog reading is taken the wrong way so hopefully I have Ready/Pass all the way through.

Let me just ask one other question also regarding how the computer stores operating history.

I have been considering a newer Challenger that would still have 2 years of factory warranty left. I believe that installing a performance tune would void the drivetrain warranty.

Others tell me no, just reinstall the factory tune and drive the car for a few weeks to allow the computer to receive and store current readings and then take it in and the performance tune you had wont show up in the history.

Others tell me it takes 6 months of daily driving.

Others tell me I would be screwed. The tune tampering is permanently logged.

What are the true facts regarding adding an aftermarket performance tunes?

I would not want to throw my drivetrain warranty coverage away.

Isn't the use of nitrous the same..........permanently logged?

Before I buy another used Challenger I would like to be reassured that if I had the OBD II accessed and read that the reading would show these things were used in the cars past.

I want to stay away from any car that has had nitrous run through it.

From what I read online many new Challengers end up going in for custom dyno tunes right after they have break-in miles on them. Would this not void their drivetrain warranty right away?

My worry is, I buy one of these cars one year old after the factory tune was reinstalled and don't know I'm screwed until I have a problem that warrants taking the car into a dealer for repairs.

Will they tell me: "sorry dude your car has had unauthorized tunes installed and or nitrous use from what we see on your readout/history so you are not covered". ?

Happy Holidays !!!
 

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If the car has had a tune, or had a PCM swapped, it would be saved permanently in at least one other place than the PCM. If the dealer wants to know, they can tell.

A tune would not automatically mean that part of the warranty would be voided...but they definitely can.

Using nitrous in and of itself would not be something that would be logged UNLESS there was a tune done to accompany it.

My understanding is, if you have had a custom tune they can tell, and they could certainly use that to void the warranty on certain items.

Whether they would use that as an excuse to not change a bad water pump? Or an oil pressure sensor?

A Guy
 

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if the tune doesn't disable any of the monitored systems = all have ready status you should pass the OBD-II inspection test.

In CA, any modifications (visual) that don't have C.A.R.B. exemption / approval, you'll have issues.

There's been visual inspections for years my '92 Chevy (OBD-I) they'd check air injection, exhaust and even check electrical power to the digital EGR valve. The funny thing was since most models were A4, they had belt drive A.I.R. pumps - they techs would get all worked up as if I had removed emissions equipment.

- mine was an M5 and had an electric A.I.R. pump and I'd point out the VECI label that diagrammed and noted the system for the M5 application.

Due to people messing with emissions equipment over decades, its brought things to this.

Periodic emissions testing got going in the early 90s, and has become more intensive as the years have gone by. Even in the 70s, you had to get emissions tests to transfer title to a vehicle back then. I lived in the state from '74 to '07.
 

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OK I'm learning a lot here. I have envisioned how a smog reading is taken the wrong way so hopefully I have Ready/Pass all the way through.

Let me just ask one other question also regarding how the computer stores operating history.

I have been considering a newer Challenger that would still have 2 years of factory warranty left. I believe that installing a performance tune would void the drivetrain warranty.

Others tell me no, just reinstall the factory tune and drive the car for a few weeks to allow the computer to receive and store current readings and then take it in and the performance tune you had wont show up in the history.

Others tell me it takes 6 months of daily driving.

Others tell me I would be screwed. The tune tampering is permanently logged.

What are the true facts regarding adding an aftermarket performance tunes?
On a pre-2015, there would likely be no way for the PCM’s non-stock tune history to be ascertained. Whether it had been altered or not wouldn’t be something they could tell, only what the status of the current tune was - stock versus non-stock.

Now if all the emissions monitors were in the not ready state, that would be a clue that the tune had been recently restored, but not necessarily evidence of tune alteration, as simply unhooking the battery would cause the same thing.

Post-2014 PCMs will set a code in memory that indicates the stock tune has been altered or replaced at some point. Restoring the stock tune doesn’t unset this code either, it’s there until it is cleared by a dealership, if it can even be cleared. It may be set for the life of the PCM once turned on, I’m not sure on that one.

I would not want to throw my drivetrain warranty coverage away.
The warranty remains in tact until something that would prevent warranty claims on that system is declared to have taken place. So you would be oKay until something that could conceivably be caused by the non-stock tune was declared to be the cause of the warranty-claim target‘s failure/malfunction. If that never happens, the warranty remains intact.

Isn’t the use of nitrous the same..........permanently logged?

Before I buy another used Challenger I would like to be reassured that if I had the OBD II accessed and read that the reading would show these things were used in the cars past.

I want to stay away from any car that has had nitrous run through it.
No. Nitrous just means the CCs get oxygen in a different format. The PCM doesn’t know or care what form the oxygen takes when introduced into the CC, except for the modified tune that it needs to handle the forced induction.

So the fact that a modified tune had been loaded to handle to nitrous may be visible, but only on 2015+ cars. What that tune did or why it was loaded would remain a mystery though.

From what I read online many new Challengers end up going in for custom dyno tunes right after they have break-in miles on them. Would this not void their drivetrain warranty right away?

My worry is, I buy one of these cars one year old after the factory tune was reinstalled and don't know I'm screwed until I have a problem that warrants taking the car into a dealer for repairs.

Will they tell me: "sorry dude your car has had unauthorized tunes installed and or nitrous use from what we see on your readout/history so you are not covered". ?

Happy Holidays !!!
No, see previous answer above.

Its natural to worry about what has been done to a used car, but knowing in such great detail is not going to be possible in most cases. The previous owner could fill in the blanks if you could talk to them personally I suppose, but that’s not likely to happen on most used car purchases obviously.

Nuke


NOTE: using 2014/2015 as the delineated line for the PCM stuff was all just a guess on my part. I know that behavior exists now, but I’m not certain they started it in 2015. There was a body and functionality refresh in 2015, so I assumed the PCM changes were the same. That may only be a thing to worry about for 2018+ cars, I just don’t know for sure. The info exists over on the DiabloSport forum though.

If you truly needed to know, DS’s website/user forums could provide the answer to the question, “what years can they tell for sure when you’ve accessed and altered the tune?
 

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"My question is how long do our (older - 2010) ECM's store data history reading's? Does it rewrite over old data like after 6 months or does it actually save old data from years ago? Forever ??"

Engine telemetry has a very short life span. The engine controller constantly monitors various things and calculates among other things fuel trims. If the short term fuel trims get too far into the rich or lean zone the long term fuel trims are adjusted by this amount and the short term trims are set back to zero.

One can clear, reset to their factory defaults, the long term fuel trims (and other learned behavior) and reset the readiness monitors back to the their incomplete state by doing a clear DTC operation. There does not even need to be a real/active error code for this operation to act upon.

After doing this DTC clear opeation the car must be driven in such a manner to give the ECU the opportunity to run through all its diagnostics and among other things set the readiness monitors to complete provided they are operating correctly.

For safety systems some history is recorded, so in the event of an accident various info is available but my info is this requires a factory diagnostic computer to access. The info is speed, seat belt use, and other data, some few seconds of "historical" data to try to get a picture of how the car was being operated before the event.

This data is constantly being overwritten and has a very short lifespan.

"Now CA smog shops will do an OBD II reading and may also do a sniffer test and can even check under the car for any illegal mods such as non-factory cats, headers and anything else that CA does not allow. And of course they will want to see stock data readings from the OBD II."

AFAIK -- it has been since sometime in 2017 when I last had to have a car smogged -- there is no snifter test.

A computer is connected to the car and it obtains various info and from this decides if the engine is smog compliant.

Believe it or not I wrote a smog test application for a plug in device some years ago.

The device queried the ECU for any active, pending, or permanent DTCs. It queried for readiness monitor status. From memory: Run time since engine start. Distance traveled with MIL on. Number of engine warm ups since DTC clear. Distance traveled since DTCs cleared. Time since DTCs cleared.

It asked for VIN. Calibration ID. Various calibration verification numbers. Calibration verification numbers for messages of various PIDs (somewhat dependent upon the OBD2 protocol).

This was collected -- took less than 30 seconds -- then stored for processing later. I do not know the algorithms used to process the data and decide if the vehicle passed smog.

"For everyone reading this post: I am not trying to lie, cheat or deceive any smog laws in CA. I'm just trying to find out what it takes to show a reasonable length of legal readings to successfully pass a CA smog test."

The smog techs never really bothered to inspect my vehicles. But both were Porsche cars and had no outward sign of any mods. The exhaust was stock which probably was a big reason the techs never bothered with any real inspection.

The Boxster engine was never exposed. This is a rather involved process. The Turbo engine compartment lid was opened and the tech gave the engine a quick glance but it was clear the engine was factory stock. For example all the visible fasteners still had the factory paint dabs intact which indicated there had been no wrenching done.

About all you can do is drive the car normally and with an OBD2 tool query the car for any active, pending, permanent DTCs. If none and if all the readiness monitors are set to complete that's a pretty good sign the engine will pass smog.

However, I do not know what kind of check there is to try to determine if the engine controller program/data table images have been "tampered" with that is changed by a "tune". If there is some test for a change in these images -- and based on my experience with writing firmware for embedded microprocessors there are ways to know an image has been tampered with, or replaced -- the car could fail smog due to this evidence of tampering.
 

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A Guy
 

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A Guy, wow just finished reading the post you referred to me here. What a nightmare !!! I hope I don't get caught up in this scenario. I have not taken the car in to the shop for the smog cert. yet. I'll definitely post again after I do take it in.

I get the check engine light every now and then usually 4 to 6 months apart. It will occur for maybe 2 to 3 trips just driving local and then it's gone for months again. I'll use my sons OBD II reader to see what shows up that may not be triggering the check engine light at this time.

I do know that the shop I'm using is known for a "relaxed" environment so I'll see what happens.

Thanks for linking this other post for me.
 

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If you are trying to get your emissions monitors to show up as complete, you need to run through drive cycles which you can find in the chiltons online manual.


BUT if you have had modifications to your tune such as disabling DTC or if the rear O2 sensors are set so the will never read you will never get the monitors to complete.

For example, I was fighting to get my cat and O2 to complete only to find out rear O2 was disabled by raise the temp at which its readings kick in and there were quite a few DTCs disabled in the tune. Once I got the tune addressed it took several drive cycle attempts to get the monitors to kick in.
983756
 

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It passed, no snags.
That’s strange, I called them and told them to be on the lookout for a NoGoodNick driving a Challenger and that it had been so heavily modified it was singlehandedly responsible for the death of at least 5 polar bears and 2 blue whales, and that’s just in the last two weeks!

I bet I know what happened...Those dullards running the show over there don’t know their Chargers from their Challengers and were probably looking for a Dodge with FOUR doors...SMH

Oh well, you bested them this time, but they’ll get you sooner or later!!

😛
 

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I knew there was a smog spy on this forum !🕵️‍♂️
I didn’t have any choice. They make me turn smog rat!

I was caught on a public highway running octane booster clearly labeled for off-road use only. What was I supposed to do?
 
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