# Emissions failure after I changed my air filter



## plano-doug (Jul 1, 2015)

Barry Allen said:


> Yesterday I changed the air filter at about 42,000 miles.
> <snip>
> A quick trip to the local dealer revealed that an o-ring around the MAF sensor had been squished out of place
> <snip>
> When you are man-handling (or woman-handling, ladies  that filter housing out of the way to jam a new filter inside it, be careful with the connector for the MAF sensor.


I haven't done one on a gen2 Cruze, but it looks like a wrestling match in the Youtube video I just watched.

It's definitely a PITA on my gen1 Cruzes, and also on my Impalas.

In all cases, one must apply substantial stress to the components in the air path. It's easy to damage something.

It's frustrating that the factory engineers can't come up with something easier and less prone to damage.

My paradigm may be old fashioned, but it's surely a no-brainer !

Doug










.


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## Barry Allen (Apr 18, 2018)

plano-doug said:


> My paradigm may be old fashioned, but it's surely a no-brainer !


Meh. The downside to that is you get hot air going into your intake after it's passed through the AC condenser and radiator, unless you have an "Air Grabber" hood on some muscle cars.

The absolute worse air intake design I ever saw that I had to help fix was a 2003 Dodge Ram 2500 with the 8.0 V-10 engine. The prior generation of that pickup ran with the V-10 and did just fine with fuel economy, comparatively speaking. The BR/BE generation had the air intake box on the driver side and the clean, cold air would flow right into the intake manifold on the driver side. For the DR generation the air intake got switched to the passenger side. PROBLEM: the intake manifold on the V-10 couldn't be swapped side-to-side because it wouldn't clear the brake booster and master cylinder, even with a smaller version. Chrysler didn't want to spend money to redesign the intake manifold so their solution was to run a clean air tube across the top of the gap between the radiator and intake manifold, then made a u-turn to flow into the throttle body. That air tube would soak up lots of heat during high ambient temperatures and heavy duty towing. A friend of mine owned one of those trucks and was getting horrible fuel economy while towing (like, 6-8 mpg when 12-15 would be expected). The air intake temperatures were causing the ECU to run the fuel mixture really rich to prevent detonation, even when he was running mid-grade or premium when regular was the spec for the engine. You could accelerate just fine but that truck could not pass a gas station while towing heavy loads.

Our solution was to totally ******* butcher a hood from the junkyard. We put a cone-type air filter directly on the throttle body, cut a hole in the hood in the right spot, and then welded some baffles under the hood to somewhat "corral" the air filter. Then, we welded up a homemade hood scoop and used Rust-Oleum to spray it all in the closest color silver as could match the factory color. Fixing that to get some relative cool air flowing into the air intake brought his fuel economy back up to where it should have been.


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## Barry Allen (Apr 18, 2018)

plano-doug said:


> I haven't done one on a gen2 Cruze, but it looks like a wrestling match in the Youtube video I just watched.


My problem was that I disconnected nothing. I took the little short tube out (the one that funnels air from the top of the front grill into the air box) and then unscrewed the 4 Phillips screws to open the air box. I pulled the top of the air box back enough to yank out the old filter, wedged the new filter in there, and buttoned it up.

Without unplugging that MAF connection on top of the tube after the filter box (looks like the crankcase ventilation flows into that valve/sensor), I probably did that damage to the o-ring where it was popped out of place.


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## BodhiBenz1987 (Jan 13, 2018)

Barry Allen said:


> My problem was that I disconnected nothing. I took the little short tube out (the one that funnels air from the top of the front grill into the air box) and then unscrewed the 4 Phillips screws to open the air box. I pulled the top of the air box back enough to yank out the old filter, wedged the new filter in there, and buttoned it up.
> 
> Without unplugging that MAF connection on top of the tube after the filter box (looks like the crankcase ventilation flows into that valve/sensor), I probably did that damage to the o-ring where it was popped out of place.


Was it the connection around the MAF sensor that leaked, or the connection where the breather tube comes in (I think that is a heater, based on AllDataDIY?)? Curiously mine is awaiting a replacement for that flexible rubber pipe where the breather tube comes in, because apparently they found a leak there after they noticed MAF values on the high side of "in range" at idle. They don't think the leak is related to my regen problem (wouldn't make sense since previous MAF values were much lower/normal while this was ongoing for ages) but I'm hoping it could be why I have seen reduced fuel economy only recently. They need to replace it as a rule-out before they can do any more diagnostics but hopefully it will help in some way. When I did my air filter (in March ircc) I did remove that pipe as carefully as possible, and unplugged the MAF harness, but even so you need to squish things around to get things in and out. I never had any codes (of course) so I have no idea when mine started to leak or if it is even an issue at all. It's also possible my MAF values are high for other reasons (electrical). We'll see. I wouldn't think a leak on the negative side of the turbo would be that big a deal, but I guess the MAF values are so important that if they are off it would really effect how the engine runs.

I like the air cleaner design on my 87 Mercedes ... just four nuts and remove the lid. The air is routed in from behind the fender and actually comes in holes at the back of the fender in the door jamb (changed in the 90s to a louvered fender).


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## TDCruze (Sep 26, 2014)

Thanks for the heads up. I could easily see things getting damaged or knocked out of place, these air filters are a pain to change. First gen was much easier.


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## Barry Allen (Apr 18, 2018)

BodhiBenz1987 said:


> Was it the connection around the MAF sensor that leaked, or the connection where the breather tube comes in (I think that is a heater, based on AllDataDIY?)


The whatever that part is that plugs into the air intake and has what appears to be a breather tub coming from the valve cover, that's where the o-ring was out of place. It probably was twisted when I was pulling the cover back to change the air filter.


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## Barry Allen (Apr 18, 2018)

BodhiBenz1987 said:


> I guess the MAF values are so important that if they are off it would really effect how the engine runs.


During the day that I was driving the car around, fuel economy was plunging very low. The dash display was dropping into the 20s, but I thought that had a lot to do with running the AC on MAX and a regen cycle that I noticed was occurring.

Or it could have been bad MAF values screwing up fueling.


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## Snipesy (Dec 7, 2015)

The leak would have to directly blow onto the sensor to really mess it up. A small air leak doesnt really do much pre turbo. I dont know how the new GM Maf sensors are arranged but definitely possible for it to really mess it up.


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## Barry Allen (Apr 18, 2018)

Snipesy said:


> The leak would have to directly blow onto the sensor to really mess it up. A small air leak doesnt really do much pre turbo. I dont know how the new GM Maf sensors are arranged but definitely possible for it to really mess it up.


This was messed up enough to give me an intermittent warning message that it was going into limp mode: 175 miles until speed restrictions kick in.


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## Barry Allen (Apr 18, 2018)

I'm still a little confused about the differences between the stock air filter and the replacement. 

This is what I bought: https://www.autozone.com/external-engine/air-filter/stp-air-filter-sa12112/737928_0_0

The photo here IS NOT what came in the box. The clip on the top of it was replaced with a large "bump out" of foam rubber to where the filter just fit onto the lip of the air intake inside the air box and the foam rubber just wedged it into place.

The stock filter was more oval shaped and the replacement was round. Also, inside the stock air filter was a plastic mesh spaced deeper inside the filter that appeared to be something like a "flow straightener." Anyone who remembers the VW Dieselgate scandal might know about that. As part of repairs for millions of vehicles in Europe, VW upgraded the engine control software and installed a plastic air intake "flow straightener" that was basically a long tube mesh that would stop the turbulence inside the intake pipe and smooth it out. VW discovered through computer modeling not available at the time the engine was designed that emissions could be reduced by smoothing air flow into the MAF for more accurate readings by the ECU.

So, this filter seems to have less filter media, doesn't have a plastic clip to hold it in place in the air box, and doesn't have an internal flow straightener built into it.


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## BodhiBenz1987 (Jan 13, 2018)

Barry Allen said:


> The whatever that part is that plugs into the air intake and has what appears to be a breather tub coming from the valve cover, that's where the o-ring was out of place. It probably was twisted when I was pulling the cover back to change the air filter.


That's where mine is too I'm told. Weird coincidence. Though in my case they said it was small enough they doubt it is making a difference, but have to fix it as a rule-out (plus I wouldn't want a leak even if it wasn't causing trouble yet). What I don't really understand is how something relatively far away from the MAF sensor would change the flow over it so much. Maybe by pulling in a lot of air at that seal, it was pulling less from the air box, and less across the MAF sensor, which could have caused your issues. In my case the readings seem to be the opposite of that (high) so I'm thinking mine is another issue.


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## Barry Allen (Apr 18, 2018)

BodhiBenz1987 said:


> That's where mine is too I'm told.


This part was where the o-ring was bulging out and out of place.


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## BodhiBenz1987 (Jan 13, 2018)

Barry Allen said:


> This part was where the o-ring was bulging out and out of place.
> 
> View attachment 287614


Thanks, from the dealer's description that is where mine is leaking too. Looking at the parts catalog its apparently a heater.


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## TDCruze (Sep 26, 2014)

BodhiBenz1987 said:


> Thanks, from the dealer's description that is where mine is leaking too. Looking at the parts catalog its apparently a heater.


Cable is to small for it to be a heater. I think it is an electronically controlled PCV solenoid or something like that.

I used the AC Delco replacement air filter and it was the same as original. Still it is a pain to change with fragile plastic clips.


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## Snipesy (Dec 7, 2015)

TDCruze said:


> Cable is to small for it to be a heater. I think it is an electronically controlled PCV solenoid or something like that.
> 
> I used the AC Delco replacement air filter and it was the same as original. Still it is a pain to change with fragile plastic clips.


It is does in fact have a heater.

As for why idk but there you have it. Maybe fight off freezing water due to vacuum idk.


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## Barry Allen (Apr 18, 2018)

Snipesy said:


> It is does in fact have a heater.
> 
> As for why idk but there you have it. Maybe fight off freezing water due to vacuum idk.


It looks like a vent hose from the valve cover to the intake, so it's circulating crankcase gases back into the intake. With all the moisture the heater is probably to keep it from freezing up in winter.


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## Barry Allen (Apr 18, 2018)

SimonJones87EsJ said:


> harmful substances which are consisting in the air like CO2 get into your car


CO2 is about 400 ppm of atmosphere and it is inert. It doesn't affect anything and it passes right through the engine with no effect.


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## Snipesy (Dec 7, 2015)

Barry Allen said:


> CO2 is about 400 ppm of atmosphere and it is inert. It doesn't affect anything and it passes right through the engine with no effect.


It’s a bot. Google “markov chain” and it’ll make sense why it doesn’t make any sense.


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## Barry Allen (Apr 18, 2018)

Snipesy said:


> It’s a bot. Google “markov chain” and it’ll make sense why it doesn’t make any sense.


I suspected as much. HELLO PERSON WITH AN ACCOUNT CREATED 2 DAYS AGO AND THIS IS YOUR FIRST POST! I still wanted to reply with at least one basic fact.


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## Snipesy (Dec 7, 2015)

Barry Allen said:


> I suspected as much. HELLO PERSON WITH AN ACCOUNT CREATED 2 DAYS AGO AND THIS IS YOUR FIRST POST! I still wanted to reply with at least one basic fact.


Yes. Unfortunately the open AI project released GPT2 (basically a more complicated markov chain with learning). This happen about a year ago.

Sadly some not so good people are incorporating this for spam. The text looks right. Feels right. But that’s about it.


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## oregon_rider (Jul 21, 2017)

I flagged this post as spam to the moderator a few days ago...

jeff


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