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I took my car to smog check after a tune up. All is good except I need to do a "Drive Cycle". 30 years of driving and I don't know there is such a thing. Shop owner said it's because battery was replaced and computer lost all data; the drive cycle will put data back to the computer for the smog check to pass.
I looked up the drive cycle process for my vehicle. It is dotted with many abbreviations. I really wonder how others get by this process. DTC, PCM, PID, ECT, EVAPDC, FLI, TP -- these are just the abbreviations from step 1 of 14. I googled ECT for example and it returned some medical explanation...
1. Any one can help with these abbreviations? Is there a site that lists all the definitions?
2. Also, how closely do I have to follow the instruction to pass? Again I can hardly imagine more than 5% of the people following precisely these instructions...
3. Finally, I need to drive the vehicle to pass the smog check, but on the other hand I I need a smog check to drive the vehicle. How does this work? Shop owner said "I'm not the local police"...
I took my car to smog check after a tune up. All is good except I need to do a "Drive Cycle". 30 years of driving and I don't know there is such a thing. Shop owner said it's because battery was replaced and computer lost all data; the drive cycle will put data back to the computer for the smog check to pass.
I looked up the drive cycle process for my vehicle. It is dotted with many abbreviations. I really wonder how others get by this process. DTC, PCM, PID, ECT, EVAPDC, FLI, TP -- these are just the abbreviations from step 1 of 14. I googled ECT for example and it returned some medical explanation...
1. Any one can help with these abbreviations? Is there a site that lists all the definitions?
2. Also, how closely do I have to follow the instruction to pass? Again I can hardly imagine more than 5% of the people following precisely these instructions...
3. Finally, I need to drive the vehicle to pass the smog check, but on the other hand I I need a smog check to drive the vehicle. How does this work? Shop owner said "I'm not the local police"...
A drive cycle is making a trip, usually of a certain distance. Start, drive, stop. But, that's a VERY misleading answer.
DTC = Diagnostic Trouble Code
PCM = Powertrain Control Module (Also often just called "The Computer")
PID = Program ID or similar.. Basically you have addresses in the computer, they're called PIDs, that are specific to various things. Thermostat temp, etc. I'm wrong on this one, but right in a very general sense.
ECT - Well, I would say Engine Coolant Temp, but.. That doesn't seem right
EVAP - Evaporative emissions system. Not sure about the DC.. Perhaps Diagnostic Code?
FLI - Not ringing a bell.. Oh, crap.. Fuel Level Indicator. So.. Yeah.. That means ECT is likely Engine Coolant Temp. and below is likely throttle position. You were missing a little context on the questions there. You must be looking at live data?
TP - Throttle Position?
but.. Let's go back to the drive cycle. Many tests ("monitors") are run by the PCM.. Some of them require specific parameters to be met. Some run as soon as you turn the key to "on" without even cranking.
The ones that require certain parameters.. They're all different.. Between manufacturers and even models.
The one that ALWAYS takes the longest to run is the EVAP. It has a list of parameters that have to be met.. A common one that can be hard to hit is that normally, the engine has to warm up to operating temperature, has to run for a specific amount of time, at least, and one of the real PITA ones, the gas tank has to be between 25% and 75%. So, literally, your EVAP tests may never complete if you're like my grandma who wouldn't let her car get below 3/4 a tank. Of course, she drove a 1978 Oldsmobile, so, not really a problem for her.
But, then, it has to hit those parameters and pass at least THREE times for the EVAP monitor to pass.
This page gives some of the parameters for the monitor to run and pass.
Once you clear the computer or remove the battery, all those monitors reset to 'untested' and have to run before they get to a 'pass' condition (Or Fail if you have a problem) Some of them, like Ignition.. They pass as soon as you start the car pretty much.. Others, like EVAP.. Whew.. They can take a while.
FWIW.. Most people just in normal driving get the monitors set. Takes longer for some than others. But.. As long as you're not the type that puts $5 of gas in your car and drives to the next station.. Just drive normally. They'll set in a few days, a week at most. Though paying attention to your fuel level and keeping it between 1/4 and 3/4 will help set the EVAP sooner.
A drive cycle is making a trip, usually of a certain distance. Start, drive, stop. But, that's a VERY misleading answer.
DTC = Diagnostic Trouble Code
PCM = Powertrain Control Module (Also often just called "The Computer")
PID = Program ID or similar.. Basically you have addresses in the computer, they're called PIDs, that are specific to various things. Thermostat temp, etc. I'm wrong on this one, but right in a very general sense.
ECT - Well, I would say Engine Coolant Temp, but.. That doesn't seem right
EVAP - Evaporative emissions system. Not sure about the DC.. Perhaps Diagnostic Code?
FLI - Not ringing a bell.. Oh, crap.. Fuel Level Indicator. So.. Yeah.. That means ECT is likely Engine Coolant Temp. and below is likely throttle position. You were missing a little context on the questions there. You must be looking at live data?
TP - Throttle Position?
but.. Let's go back to the drive cycle. Many tests ("monitors") are run by the PCM.. Some of them require specific parameters to be met. Some run as soon as you turn the key to "on" without even cranking.
The ones that require certain parameters.. They're all different.. Between manufacturers and even models.
The one that ALWAYS takes the longest to run is the EVAP. It has a list of parameters that have to be met.. A common one that can be hard to hit is that normally, the engine has to warm up to operating temperature, has to run for a specific amount of time, at least, and one of the real PITA ones, the gas tank has to be between 25% and 75%. So, literally, your EVAP tests may never complete if you're like my grandma who wouldn't let her car get below 3/4 a tank. Of course, she drove a 1978 Oldsmobile, so, not really a problem for her.
But, then, it has to hit those parameters and pass at least THREE times for the EVAP monitor to pass.
This page gives some of the parameters for the monitor to run and pass.
Once you clear the computer or remove the battery, all those monitors reset to 'untested' and have to run before they get to a 'pass' condition (Or Fail if you have a problem) Some of them, like Ignition.. They pass as soon as you start the car pretty much.. Others, like EVAP.. Whew.. They can take a while.
FWIW.. Most people just in normal driving get the monitors set. Takes longer for some than others. But.. As long as you're not the type that puts $5 of gas in your car and drives to the next station.. Just drive normally. They'll set in a few days, a week at most. Though paying attention to your fuel level and keeping it between 1/4 and 3/4 will help set the EVAP sooner.
Thank you. I think I am going in to DMV to get those "one-day permission" that they issue for taking the car to do smog check, and use that to do this drive cycle exercise.
I thought about just taking the car on to the freeway, but was afraid the highway patrol will not be so understanding.
Location: East of Seattle since 1992, 615' Elevation, Zone 8b - originally from SF Bay Area
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This is a rare problem, because repair shops are able to keep power to the computers with an alternate power source while changing the better, so none of the data is lost. T
This is a rare problem, because repair shops are able to keep power to the computers with an alternate power source while changing the better, so none of the data is lost. T
This is a rare problem, because repair shops are able to keep power to the computers with an alternate power source while changing the better, so none of the data is lost. T
True, but, unless you're going in there for the inspection, they usually don't do it. Body shops, I haven't seen a one that does it.
And, of course, if your battery dies.. Well.. The old saying of closing the barn door after the horse got out applies.
Code readers, even ones that can check the monitors, are pretty dirt cheap now and everyone should probably have one. The biggest problem I see is used car dealers (shocker)..
My nephew was looking for a car so I went out to look at several with him.. Here in SC, there is no emissions checks. But, we looked at three different vehicles where the monitors hadn't run.
The first one was an Xterra. Obviously, when you see the monitors not run, questions arise. I started looking deeper and the SECOND red flag was that the engine compartment was spotless. On a vehicle with 250k miles on it.
They had bought it at auction, and it had the standard Nissan transmission cooler inside the radiator, which broke, coolant in the transmission.. Bad transmission. They had replaced the transmission, with a junkyard tranny. No providence on that one. They didn't mention ANYTHING about it until I found it, then said "Oh, there's a warranty on the transmission".. The warranty was 6 months (of which 1 had already passed) or 6000 miles. And, of course, the warranty covered parts only. Ran like hell away from that one.
The others, I found things that just didn't sit right with me on.. Can't say the dealers were shady, although, the fact that they were used car salesmen pretty much means, yep, they're shady. But, the fact that the monitors hadn't run.. Big red flag. Because they likely had codes set and the dealer disconnected the battery or cleared the codes so it wouldn't set until you got 30 miles down the road after buying it.
I took my car to smog check after a tune up. All is good except I need to do a "Drive Cycle". 30 years of driving and I don't know there is such a thing. Shop owner said it's because battery was replaced and computer lost all data; the drive cycle will put data back to the computer for the smog check to pass.
I looked up the drive cycle process for my vehicle. It is dotted with many abbreviations. I really wonder how others get by this process. DTC, PCM, PID, ECT, EVAPDC, FLI, TP -- these are just the abbreviations from step 1 of 14. I googled ECT for example and it returned some medical explanation...
1. Any one can help with these abbreviations? Is there a site that lists all the definitions?
2. Also, how closely do I have to follow the instruction to pass? Again I can hardly imagine more than 5% of the people following precisely these instructions...
3. Finally, I need to drive the vehicle to pass the smog check, but on the other hand I I need a smog check to drive the vehicle. How does this work? Shop owner said "I'm not the local police"...
Word to the wise, good looking up for abbreviations and acronyms use dogpile
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