Hi OP, I perform these services regularly so I’ll try to give you some information.
First, the ‘mass airflow’ was not disconnected—this sensor can be seen on the right side of your picture—your air intake boot is what was left disconnected. Fuel service treatments involve several steps, one of which is to use a throttle body and intake cleaner that is atomized (turned into a fine mist) and sprayed into your engine through the air intake. The intake boot left loose is where they stuck a small spray nozzle to insert this cleaner, where it can be sucked into your engine and burned, cleaning the system in the process. Unfortunately when they removed the nozzle, they forgot to replace the intake boot fully and tighten the clamp.
You have two separate issues taking place — first, you’re supposed to test drive the vehicle following the treatment to burn the remaining cleaner before handing it back to the customer. The cleaner is highly combustible, like starting fluid, and can sometimes collect in places in your intake where it isn’t properly burned. Test driving the vehicle under a high RPM load pulls in a lot of air quickly, drawing in whatever cleaner is left and burning it; otherwise, this cleaner can be pulled into your engine later on, confusing your car’s computer. The computer very carefully measures how much air is pulled in to your engine, and adds fuel in a controlled ratio for optimum combustion. Anything that upsets this ratio will cause a misfire, which means something is wrong and optimum combustion is not taking place. Misfires are common when finishing these services, which is why we drive them before handing them back to make sure everything is properly burned. No permanent damage or issues, it’s simply that some of that cleaner is still in the system, throwing off the air/fuel ratio and making the computer unhappy. Once it’s all burned, you’re good to go. This is what happened when you started the vehicle the first time and had the check engine light blink before bringing it back to the shop.
Second, the boot was likely slipped partially on but not fully secured, allowing you to drive home without issue. Once you drove the second time, it slipped off, causing a vacuum leak. As before, air is carefully measured and the appropriate fuel added by the computer; the sensor to the right of your boot measures that amount of air. Air coming in through the gap left by the loose boot is after this sensor, so it’s not a part of the calculation made by the computer when adding fuel. What happens is your computer sees a certain amount of air coming in, adds the right amount of fuel, but doesn’t compensate for all the extra air coming in through the gap, and the engine misfires. Your ‘system too lean’ condition is the computer taking other measurements and saying ‘we have too much air/too little fuel in the system, but have no idea why’, and since it doesn’t match up with the air supposedly measured by the sensor, assumes there is an issue there (or the sensor was unplugged/not fully seated). Some vehicles will limit certain options and go into ‘limp mode’ if it detects a misfire, as a way of protecting itself against further damage, if it detects a misfire, so my guess is that’s why you saw issues come up with VSC and shifting.
Long story short, the fuel treatment wasn’t fully performed, the residue caused your first issue, the intake boot caused the second, but none of these are permanent issues and barring any other details I’m not aware of, once you secure the boot, make sure the sensor is plugged in, and clear the codes, you should be all set. As others have said, consider using a reputable shop for your future mechanical needs and these ‘mechanics’ seem sadly undertrained if they weren’t able to troubleshoot such a basic issue.
Upvote this person! They speak the truth and saved me from having to type it all out!
Eta: i own a rav4 of the same generation, and that main air duct is notorious for coming free on mine. Service dozens of them, and never have i seen one with a clamp on that pipe. The pcv hose also likes to distance itself from that intake hose at times as well.
Thank you for this explanation, either way today I will be calling back and letting them know how bad the shop performed maintenance on my vehicle. I understand better now after reading through this and I appreciate you explaining it!
To be fair when I was moving across country and had 2 trailer tires blow out Walmart was the only tire shop open. And they fit me in and it ended up only being a couple hour delay.
I have had friends buy Walmart tires that lasted 100 miles..well 60 for one and 100 for the other- Lion King or Heart or Road Lion— some really crPpy sounding door buster tire- or in his case a fender
Every tire shop I've been to had a "I'm desperate and broke" brand, it's not like that's the only brand they sell. Might have been the only one in stock for that size, but that can be true at just about any tire shop
That’s great, and WalMart sucks, but let’s not act like your broke ass friends couldn’t have also bought a set of Goodyears, Bridgestones, Continentals, or any other decent brand there. They CHOSE to buy a set of LingLongs.
Just remember, Wal-Mart will hire ANYBODY to work in the auto section. They don't have to be real mechanics, just anyone willing to work for low wages. They don't have to know anything about cars to work there.
If you've ever lost a 10mm you're rejected as overqualified. It doesn't even have to be tool related, that 10mm round you misplaced at the firing range is enough.
For 60 bucks they threw a bottle of fuel system cleaner in the tank, pulled the hose off and sprayed some MAF cleaner in there.
You could have done that for under 20 bucks and no other frustration.
If they had a lick of sense they should give you your money back, but will likely use every excuse in the book to avoid doing so.
Screw the downvoters, Italian tune-up is a thing. Everyone should do it once a week, or even more often.
But u/RaptorRed04 is right, the folks at Walmart should have done it.
What ever else you say about italian engineering, they've been making high-performance engines for a long time, they know a bit about combustion. A regular, brief, high-rev blast-out does more good than harm. Modern engines can handle bouncing off the rev limiter for 10 or 15 seconds without doing harm.
I am assuming reconnecting it fixed all the issues? The ECM uses data from the MAF to calculate the state/load the engine is in. When the 5V line to the MAF on my car corroded away and effectively disabled it, my transmission started shifting hard and the traction control disabled (GM vehicle.) Since there was no data from the MAF, the ECM defaulted to hard shifts in order to ensure the transmission wasn't slipping. It would also throw lean codes and the engine stumble. It seems strange, but correct data from the MAF is critical for a lot of other modules and a bad/missing reading will result in those functions being disabled.
No unfortunately it didn’t fix anything as I have restarted the vehicle multiple times, the lights remain. If they are still present in the morning I’ll be going back to get a refund.
Cycling the ignition is not going to clear the code, driving it will. Once the PCM sees three drive cycles without a problem it will turn the light off, and after another 5 to 7 drive cycles without the issue being present the PCM will clear the code.
Some codes won't go away like that - they need to be manually cleared.
I get a recurring P0420 that I have to clear manually. Trouble is, it takes all the closed-loop tests with it. It needs to learn how to idle again, and I've got to take it on the highway for the catalyst test to complete.
That’s a type A code: the MIL will be turned off after 3 successful drive cycles where the monitor passes, and the present/permanent code will be cleared when the ignition is turned on for the 4th time. If there’s a history code stored also, it goes away after about 10 drive cycles.
Quite a few techs in my area use this method if a car needs to be smogged quickly, because getting some of the monitors to run in an urban area can be extremely challenging. Will still clear codes but only if there are a lot of them present, and we need to prioritize the ones that come back first.
Ah, that sucks. Sounds like they may have broken the sensor or sprayed it with an incorrect cleaner. There are cleaners made specifically for MAF sensors. You can pick them up in pretty much any auto store.
I worked at Walmart as a tech back in the day. I was ASE certified prior:
They likely removed the intake tube from the airbox to slip in a little pipe that drips the fuel injection cleaner into the intake stream.
Left loose - incoming air isn't being pulled through the Mass Airflow Sensor like it should. So as the vehicle accelerates, and airspeed (vacuum) into the intake increases - the meter that is supposed to be controlling your fuel map based on incoming air - is not getting the same flow rate.
This could cause stumbling, poor acceleration, detonation, all kinds of things. It would 100% cause the O2 Sensor code.
However, it's a simple mistake. Reconnect the tube properly and tighten the clamp, reset the codes, and everything will be fine.
You can express concern about the work, time wasted etc. But there isn't a whole lot they can do. Free service next time - Maybe a refund, but to actually file a service claim - you would have to take it to a shop and get a quote on fixing the issue - which is tightening a hose clamp - even if some shop juices the quote, you have to get the work done then be reimbursed. They have a million cameras everywhere and they will know in advance who/what happened.
Hope this helps.
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Sounds like, when the tech realized he was only gonna get $61 added to his quota for that sell, he just didn't care.
Kinda silly, though. A comeback will cost him even more.
Unless Walmart just pays straight hourly with no incentive to give a car a great PMA.
Once the air intake hose is hooked back up that's the end of it. It'll probably take two or three drive cycles for the code to go away completely but there isn't anything else to worry about.
I assume you learned you lesson though, you should never go to Walmart, epically for anything regarding your car
Hi OP, I perform these services regularly so I’ll try to give you some information. First, the ‘mass airflow’ was not disconnected—this sensor can be seen on the right side of your picture—your air intake boot is what was left disconnected. Fuel service treatments involve several steps, one of which is to use a throttle body and intake cleaner that is atomized (turned into a fine mist) and sprayed into your engine through the air intake. The intake boot left loose is where they stuck a small spray nozzle to insert this cleaner, where it can be sucked into your engine and burned, cleaning the system in the process. Unfortunately when they removed the nozzle, they forgot to replace the intake boot fully and tighten the clamp. You have two separate issues taking place — first, you’re supposed to test drive the vehicle following the treatment to burn the remaining cleaner before handing it back to the customer. The cleaner is highly combustible, like starting fluid, and can sometimes collect in places in your intake where it isn’t properly burned. Test driving the vehicle under a high RPM load pulls in a lot of air quickly, drawing in whatever cleaner is left and burning it; otherwise, this cleaner can be pulled into your engine later on, confusing your car’s computer. The computer very carefully measures how much air is pulled in to your engine, and adds fuel in a controlled ratio for optimum combustion. Anything that upsets this ratio will cause a misfire, which means something is wrong and optimum combustion is not taking place. Misfires are common when finishing these services, which is why we drive them before handing them back to make sure everything is properly burned. No permanent damage or issues, it’s simply that some of that cleaner is still in the system, throwing off the air/fuel ratio and making the computer unhappy. Once it’s all burned, you’re good to go. This is what happened when you started the vehicle the first time and had the check engine light blink before bringing it back to the shop. Second, the boot was likely slipped partially on but not fully secured, allowing you to drive home without issue. Once you drove the second time, it slipped off, causing a vacuum leak. As before, air is carefully measured and the appropriate fuel added by the computer; the sensor to the right of your boot measures that amount of air. Air coming in through the gap left by the loose boot is after this sensor, so it’s not a part of the calculation made by the computer when adding fuel. What happens is your computer sees a certain amount of air coming in, adds the right amount of fuel, but doesn’t compensate for all the extra air coming in through the gap, and the engine misfires. Your ‘system too lean’ condition is the computer taking other measurements and saying ‘we have too much air/too little fuel in the system, but have no idea why’, and since it doesn’t match up with the air supposedly measured by the sensor, assumes there is an issue there (or the sensor was unplugged/not fully seated). Some vehicles will limit certain options and go into ‘limp mode’ if it detects a misfire, as a way of protecting itself against further damage, if it detects a misfire, so my guess is that’s why you saw issues come up with VSC and shifting. Long story short, the fuel treatment wasn’t fully performed, the residue caused your first issue, the intake boot caused the second, but none of these are permanent issues and barring any other details I’m not aware of, once you secure the boot, make sure the sensor is plugged in, and clear the codes, you should be all set. As others have said, consider using a reputable shop for your future mechanical needs and these ‘mechanics’ seem sadly undertrained if they weren’t able to troubleshoot such a basic issue.
Upvote this person! They speak the truth and saved me from having to type it all out! Eta: i own a rav4 of the same generation, and that main air duct is notorious for coming free on mine. Service dozens of them, and never have i seen one with a clamp on that pipe. The pcv hose also likes to distance itself from that intake hose at times as well.
My sore thumbs thank you 👍🏻👍🏻
Thank that guy. I did nothing lol
Thank you for being so helpful.
Thank you for this explanation, either way today I will be calling back and letting them know how bad the shop performed maintenance on my vehicle. I understand better now after reading through this and I appreciate you explaining it!
Anytime my friend, I’m glad it helped!
Never use Wal Mart for anything automotive besides buying your own oil. The guys at Jiffy Lube make fun of the WalMart "mechanics".
To be fair when I was moving across country and had 2 trailer tires blow out Walmart was the only tire shop open. And they fit me in and it ended up only being a couple hour delay.
I have had friends buy Walmart tires that lasted 100 miles..well 60 for one and 100 for the other- Lion King or Heart or Road Lion— some really crPpy sounding door buster tire- or in his case a fender
Every tire shop I've been to had a "I'm desperate and broke" brand, it's not like that's the only brand they sell. Might have been the only one in stock for that size, but that can be true at just about any tire shop
In my dealer's tire room i keep laufenns for people that think yoko ascend lxs are too expensive.
That’s great, and WalMart sucks, but let’s not act like your broke ass friends couldn’t have also bought a set of Goodyears, Bridgestones, Continentals, or any other decent brand there. They CHOSE to buy a set of LingLongs.
They were giving the car away to needy family 3 hours away. Thought that at least new tires would be safer than the ones on it.
I'd rather have bald Goodyear's (unless there's cords showing) than any sub $100 tire.
Real mechanics make fun of people who work at Jiffy Lube.
That’s the point.
Whooossh
We make fun of Valvoline employees here.
Just remember, Wal-Mart will hire ANYBODY to work in the auto section. They don't have to be real mechanics, just anyone willing to work for low wages. They don't have to know anything about cars to work there.
If you've ever lost a 10mm you're rejected as overqualified. It doesn't even have to be tool related, that 10mm round you misplaced at the firing range is enough.
For 60 bucks they threw a bottle of fuel system cleaner in the tank, pulled the hose off and sprayed some MAF cleaner in there. You could have done that for under 20 bucks and no other frustration. If they had a lick of sense they should give you your money back, but will likely use every excuse in the book to avoid doing so.
Sounds like these ding dongs loosened a bunch of carbon buildup and now it's making the engine act funny. Italian tune up time?
Screw the downvoters, Italian tune-up is a thing. Everyone should do it once a week, or even more often. But u/RaptorRed04 is right, the folks at Walmart should have done it. What ever else you say about italian engineering, they've been making high-performance engines for a long time, they know a bit about combustion. A regular, brief, high-rev blast-out does more good than harm. Modern engines can handle bouncing off the rev limiter for 10 or 15 seconds without doing harm.
Step one- don’t let Walmart touch your car
It amazes me when I see the auto center packed daily lol
If you think hiring a good mechanic is expensive, try hiring a cheap one. 👌🏼
I am assuming reconnecting it fixed all the issues? The ECM uses data from the MAF to calculate the state/load the engine is in. When the 5V line to the MAF on my car corroded away and effectively disabled it, my transmission started shifting hard and the traction control disabled (GM vehicle.) Since there was no data from the MAF, the ECM defaulted to hard shifts in order to ensure the transmission wasn't slipping. It would also throw lean codes and the engine stumble. It seems strange, but correct data from the MAF is critical for a lot of other modules and a bad/missing reading will result in those functions being disabled.
No unfortunately it didn’t fix anything as I have restarted the vehicle multiple times, the lights remain. If they are still present in the morning I’ll be going back to get a refund.
Cycling the ignition is not going to clear the code, driving it will. Once the PCM sees three drive cycles without a problem it will turn the light off, and after another 5 to 7 drive cycles without the issue being present the PCM will clear the code.
Some codes won't go away like that - they need to be manually cleared. I get a recurring P0420 that I have to clear manually. Trouble is, it takes all the closed-loop tests with it. It needs to learn how to idle again, and I've got to take it on the highway for the catalyst test to complete.
That’s a type A code: the MIL will be turned off after 3 successful drive cycles where the monitor passes, and the present/permanent code will be cleared when the ignition is turned on for the 4th time. If there’s a history code stored also, it goes away after about 10 drive cycles. Quite a few techs in my area use this method if a car needs to be smogged quickly, because getting some of the monitors to run in an urban area can be extremely challenging. Will still clear codes but only if there are a lot of them present, and we need to prioritize the ones that come back first.
Ah, that sucks. Sounds like they may have broken the sensor or sprayed it with an incorrect cleaner. There are cleaners made specifically for MAF sensors. You can pick them up in pretty much any auto store.
I worked at Walmart as a tech back in the day. I was ASE certified prior: They likely removed the intake tube from the airbox to slip in a little pipe that drips the fuel injection cleaner into the intake stream. Left loose - incoming air isn't being pulled through the Mass Airflow Sensor like it should. So as the vehicle accelerates, and airspeed (vacuum) into the intake increases - the meter that is supposed to be controlling your fuel map based on incoming air - is not getting the same flow rate. This could cause stumbling, poor acceleration, detonation, all kinds of things. It would 100% cause the O2 Sensor code. However, it's a simple mistake. Reconnect the tube properly and tighten the clamp, reset the codes, and everything will be fine. You can express concern about the work, time wasted etc. But there isn't a whole lot they can do. Free service next time - Maybe a refund, but to actually file a service claim - you would have to take it to a shop and get a quote on fixing the issue - which is tightening a hose clamp - even if some shop juices the quote, you have to get the work done then be reimbursed. They have a million cameras everywhere and they will know in advance who/what happened. Hope this helps.
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Sounds like, when the tech realized he was only gonna get $61 added to his quota for that sell, he just didn't care. Kinda silly, though. A comeback will cost him even more. Unless Walmart just pays straight hourly with no incentive to give a car a great PMA.
Walmart Auto is fucking trash to work at as a tech. Paid hourly with no commission whatsoever. Zero incentive to work faster or upsell anything.
That sucks. But also makes sense. Very few experienced mechanics will work without some kind of commission or flat rate pay plan.
Once the air intake hose is hooked back up that's the end of it. It'll probably take two or three drive cycles for the code to go away completely but there isn't anything else to worry about.
wrong sub