I put a cone air filter on my SS 2.0l and now I'm getting this code the same day. Then the light went out for a week and today on the way to work it came back on. Why would a cone filter do this? Or is it a different problem? Should I put the original filter back in when I take it to the dealer for warranty works? Thanks

P0171 Fuel Trim System Lean -PCM

What type of cone filter? Is it a kit from somewhere? Or something you made yourself?

That code in simple terms means that the computer detected that there was more oxygen, and attempted to add more fuel to compensate, but it has added as much as it can, and it still sees that there's more air than fuel, so it set the code.

It's not likely that you're actually getting that much more air because of a filter. It's more likely that either (a) something in the filter setup has 'fooled' the computer into thinking there is (usually something to do with how the air flows over the MAF sensor, which is why I asked what your setup was), or (b) you have a vacuum leak somewhere that's letting a bit of unmetered air in and causing the lean condition. That would probably be the first thing I'd check - listen for hissing/air leaks, check all your seals, make sure everything's tight.

I just put a Ractive cone air filter in place of the stock filter. Never touched anything else. The cars only got 1200 MIles on it right now.

I just put a Ractive cone air filter in place of the stock filter. Never touched anything else. The cars only got 1200 MIles on it right now.
Then I bet it's a vac leak somewhere from where you took it apart to put the new filter in. Just go over everything - take it apart and put it all back together very carefully, make sure everything's sealed up well. It's possible during the process you bumped the plastic intake plumbing up by the throttle body too, so I'd check all the way up there. Just make sure she's all tightened up.

Oh and remember to either pull the battery or have someone clear the code when your finished. Once the ECM is reset, it takes a fair bit of driving for that code to pop back, so drive it for a couple days and see where you stand.

I had the same problem (code) with mine...The dealer thought it was the K&N (E-1009) but I said there is no way a filter will do that. The code came on once before I had the K&N and after 2-3weeks it came on with the K&N. The other guy on this board said it being either a vacuum leak or a MAF problem. Your getting unmetered air into the system...Colin :cssNET:

So if i have no vacuum leaks then what do I have to do?

could be oil from the filter on the MAF causing it to see less air than it's getting. did you just put a new filter in the stock airbox, or have you changed the tubing?

I didn't change the tube, all I did was take out the stock one. Then I put the cone filter on where the stock one sealed up at the top and drilled a hole so I could clamp it. The hole I drilled isn't a problem either if you're wondering.

Thanks

I put a cone air filter on my SS 2.0l and now I'm getting this code the same day. Then the light went out for a week and today on the way to work it came back on. Why would a cone filter do this? Or is it a different problem? Should I put the original filter back in when I take it to the dealer for warranty works? Thanks

P0171 Fuel Trim System Lean -PCM

It's more than likely set because now your engine is running lean because it's getting more air than it is used to. The pcm keeps an average of the fuel usage and if it suddenly gets outside than range then it can trip that code. I think you can reset that average but I am not sure how without the right GM scan tool.

Thats just a short blurb from the manual. I am not a mechanic or anything, so I could be wrong :)

It's more than likely set because now your engine is running lean because it's getting more air than it is used to. The pcm keeps an average of the fuel usage and if it suddenly gets outside than range then it can trip that code. I think you can reset that average but I am not sure how without .

Thats just a short blurb from the manual. I am not a mechanic or anything, so I could be wrong :)

Disconnect the Negative Batter Cable from the battery and reconnect it within 5 to 10 minutes elapsed time, as it should reset the ECU, to relearn the modification you added to your vehicle. This is usually normal for a Code to set and get a SES light to come on.

FWIW, Always disconnect the Negative Battery Cable from the battery, when attempting to change, or convert the present Air Intake System or making any changes under the hood to the electrical system etc. Hope this helps, as the ECU is confused, without performing this simple procedure. :cssNET:

also good to depress the brake so as to drain the system of any electrical charge. something i've always done.

I just jumped in the car to go for a drive and now the light is out. We checked the codes again with the code reader and it is still there but no light. Should I worry about it? Or should I unhook the battery like said above?

Yah i had that problem about 2 or 3 weeks ago....i have a K&N filter....the guy from the dealership then just overrided the problem and now the light isnt on anymore

How did the dealership over-ride the problem? Did they disconnect the battery for 5-10 mins? Please let us know...

PS- Thanx for all the help you guys. It is very appreciated....Colin

You can reset the long term fuel trim levels with the GM scan tools...

same thing i had wrong, i had a k&n filter, and i took it off and put the stock back on and they said it was a bad 02 sensor.

So can I take it back to the dealer with the cone filter or should I put the stock one in it to take it back?

They light only comes on if the condition is noted twice within a certain time period.

I would clear the code and see if it comes back...

You can reset the long term fuel trim levels with the GM scan tools...

BINGO!

We had a similar problem, make sure to remove the neg cable, so the pcm can learn fresh, the trims are all over on this car so if the base map is not reset then the map that is in real time is trying to adjust it down or up and it is seeing it is out of the norm, once we did the full reset and some datalogging the trims were still all over but the code has not come back...

\these pcm's in the SS are a lot more touchy than the other pcm's and they seem to be little busy bodies trying to adapt everything... :D

CHECK FOR VAC LEAKS!!!! The ECM does not set that code because it's getting "more air than it used to". It set that code because it's getting more air than it practically should be able to. There's a big difference. If you just unplug the battery, this will go away for a day or two, then come right back. If you pegged the fuel trims once, and you don't correct the condition, you will just peg them again. The computer is not "confused", in fact it knows EXACTLY what's normal, and it's setting the code because it's not seeing what it should. You need to correct the source of the problem.

There's no great mystery here. I think most ppl don't really understand how the ECM works.... there's nothing abnormal. It's not confused, it's not upset because it's used to seeing one filter and now there's another, and it doesnt just need to be reset. It's telling you that there's a problem you need to fix. That;s what it's designed to do. Find the abnormality (vac leak is more than probable, given that you had your intake plumbing apart), correct it, pull battery to clear the code, and you're done.

BluebaltSS, you said you drilled a hole somewhere? Where? Not in the intake tube anywhere downstream of the MAF, I hope? Because if you did, that's your vac leak right there.

The hole I drilled is not anywhere that affects the vacuum. I cant explain where it is exactly. It's right in the side of the airbox, so I could tighten the clamp. The only air that gets into the engine is through the filter. I checked the vacuum line on the intake plumbing, there is only one. It is still hooked up and not leaking.

I also forgot to mention, when the car is at idle and if I punch the gas it hesitates for a sec because it revs up. Sometimes the revs go up, then come down, then back up a bit and then back to idle. It's done this eversince I bought the car last week. But the light never came on untill 30 minutes after I put the cone filter in the stock air box.

The hole I drilled is not anywhere that affects the vacuum. I cant explain where it is exactly. It's right in the side of the airbox, so I could tighten the clamp. The only air that gets into the engine is through the filter. I checked the vacuum line on the intake plumbing, there is only one. It is still hooked up and not leaking.
Try the soapy water deal. Spray soapy water solution around the seals in the intake plumbing and look for bubbles. If you have a vac leak, it's definitely a very tiny one. Only a tiny vac leak would set this code. A large vac leak (like a hose unplugged) would fail a rationality diagnostic and set a differnet code, not peg a fuel trim like this.

I also forgot to mention, when the car is at idle and if I punch the gas it hesitates for a sec because it revs up. Sometimes the revs go up, then come down, then back up a bit and then back to idle. It's done this eversince I bought the car last week. But the light never came on untill 30 minutes after I put the cone filter in the stock air box.
This doesn't sound like totally abnormal behavior. It should take just a split second to rev up if you step on the gas - this is just the throttle calibration. It's designed to open the blade a bit slower to do away with the sudden influx of air, and then you don't need things like tip-in spark retard and crap like that any more.

Holy hell if you're having this many problems with your fuel running lean from a cone I'd hate to see what would happen to us considering the bolt-on S/C for the 2.2L. Between switching to high-octane and the blower it's prolly gonna have a fit and just refuse to turn on :lol:.

What people are saying is right, resetting the system either via the battery disconnect or the dealer overriding the code should fix it, but this won't guarantee that it won't come back again if you take the second route. I think you really need to reset the system if checking for vaccuum leaks proves a non-issue. I think your dealer could also do a much better job of this for you if you were to take it in. I'm not sure that they'll service it though because you changed the filter but it's worth a shot.

Permafried-

Holy hell if you're having this many problems with your fuel running lean from a cone I'd hate to see what would happen to us considering the bolt-on S/C for the 2.2L.
EXACTLY! This is exactly why I'm saying that something is wrong, a leak or something.

If all this were just because you put on a new filter and the ECM doesn't like that it's flowing just a touch more than stock, then people would be setting codes left right and center when their stock filters got dirty and airflow dropped a bit. Obviously that doesn't happen. The ECM can very easily cope with slightly more or less air IF there's no problem. So clearly there's a problem here. :)

I'd be willing to bet that if you pull the airbox assy all apart, put it back together very carefully, paying great attention to making sure it's all sealed up fine, and then pull the battery for 10 secs, you will not see this again. But hell, what do I know...

I was running lean there too for the longest time. My air intake tube came all the off on me (note: I have not installed any kind of new filter or anything to it), so check and see if all your stuff is tight. BTW I dont know if this contributied to it or not but I had a bad Cam Sensor, which I dont know how that happened.

CHECK FOR VAC LEAKS!!!! The ECM does not set that code because it's getting "more air than it used to". It set that code because it's getting more air than it practically should be able to. There's a big difference. If you just unplug the battery, this will go away for a day or two, then come right back. If you pegged the fuel trims once, and you don't correct the condition, you will just peg them again. The computer is not "confused", in fact it knows EXACTLY what's normal, and it's setting the code because it's not seeing what it should. You need to correct the source of the problem.

There's no great mystery here. I think most ppl don't really understand how the ECM works.... there's nothing abnormal. It's not confused, it's not upset because it's used to seeing one filter and now there's another, and it doesnt just need to be reset. It's telling you that there's a problem you need to fix. That;s what it's designed to do. Find the abnormality (vac leak is more than probable, given that you had your intake plumbing apart), correct it, pull battery to clear the code, and you're done.

BluebaltSS, you said you drilled a hole somewhere? Where? Not in the intake tube anywhere downstream of the MAF, I hope? Because if you did, that's your vac leak right there.

DanM you are correct a vacuum leak could cause that code, but given the current situation of replacing the air filter with a high flow version I think it's reasonable to attribute this code to the fuel trim levels.

I dunno if you have access to the manual but short term trim levels being more than 10% off the long term levels will cause this code.

DanM you are correct a vacuum leak could cause that code, but given the current situation of replacing the air filter with a high flow version I think it's reasonable to attribute this code to the fuel trim levels.

I dunno if you have access to the manual but short term trim levels being more than 10% off the long term levels will cause this code.
Yeah I know what causes the code. I suppose it's possible, but I'd bet good money that this is not just due to a new filter. Like I said above, if that were true, this thing would set codes out the butt when you replace a dirty air filter, and it doesn't.

I hear what you're saying, but if all this guy did was replace the paper filter with some other brand, and locked it back inside the stock airbox, theres no way the airflow is that much different. ESPECIALLY when he's only had the car for a week, and the LTFTs probably aren't even in equilibrium yet! Not even Ractive filters are that special. :) I still say small vac leak.

All other discussion aside.... why WOULDN'T you take the 10 minutes to take the tubes off, and put them back on just to be safe? You'd rather drive around with (possibly) a vac leak and leaner than normal condition just because you're too lazy to check?? Just take the tubes off, put em back together carefully, and clear the code. It takes 20 minutes man.

EXACTLY! This is exactly why I'm saying that something is wrong, a leak or something.

If all this were just because you put on a new filter and the ECM doesn't like that it's flowing just a touch more than stock, then people would be setting codes left right and center when their stock filters got dirty and airflow dropped a bit. Obviously that doesn't happen. The ECM can very easily cope with slightly more or less air IF there's no problem. So clearly there's a problem here. :)

I'd be willing to bet that if you pull the airbox assy all apart, put it back together very carefully, paying great attention to making sure it's all sealed up fine, and then pull the battery for 10 secs, you will not see this again. But hell, what do I know...

Dan, there really is no way to have a vac leak, there is only 1 connector to the TB pipe and it is rubberized, the PCM is seeing a LOT more airflow that is pushing it outside its realm of compensating. We datalogged it, the MAF readings went WAY up real fast compared to stock. sorry to say Vac leak in 1 connector, not likely....to easy to say, the airbox and up pipe are 1 piece, ther is only 1 clamp that connects the up pipe from the airbox to the tb pipe. :cool:

I hear what you're saying, but if all this guy did was replace the paper filter with some other brand, and locked it back inside the stock airbox, theres no way the airflow is that much different. ESPECIALLY when he's only had the car for a week, and the LTFTs probably aren't even in equilibrium yet! Not even Ractive filters are that special. :) I still say small vac leak.



Bingo, Mr Goodwrench...this is not a high flow filter in the stock canister, it is a conical air filter attached to the stock box with the bottom left off....

So the airflow is a LOT different, you do read that we datalogged both and found a lot of difference not to mention S/C pressure is up .5 lbs and spools(funny to say, I know it doesnt spool but with the bypass it does in a way) WAAAAY faster, you can flash full bosst I'd say a great deal faster than stock...not trying to be smart just clarifying
oh and trust me we checked the reinstallation well :) :nuts: :cssNET:

OK, I'll take the hose off the TB and take off the other end too and recheck everything. I have already checked the connection for the MAF and made sure everything was tight down below. So say if this doesn't fix my problem. Does that means it's my Fuel Trim? Do I have to get the dealer to fix that or unhook the battery? And if the dealer does it will they void the warranty cuz of the filter?

Thanks alot for all the help!
Dave

Fair enough, thought he said he just put a new filter in the stock box. Good luck, hope it doesn't come back on you!

I got the dealer checking mine too...I disconnected the battery and the code came back on. I got them too check for vacuum leaks, MAF and fuel trim levels...What is going too happen when we order our CAI like K&N Typoon and AEM...How do we fix this problem? Colin

Okee dokee.

I am just gonna interject with a little bit of sanity here.

Recheck all of your air intake connections, make sure the the clamps are secure and the pipings is seated properly.

There are lots of things that can cause a P0171 it may just be coincidence that it occured so close to the installation of the filter..

Make sure all of the pleats of the filter are even spaced, an irregurlarly shaped filter will disrupt airflow and cause false DTC's.

Make sure your ENGINE OIL DIPSTICK is fully seated in the tube and its seals are okay.

Make sure your ENGINE OIL CAP is properly installed and seal is ok.

Make sure all of the vacuum & emissions hoses are in good condition and properly secure at their connections

Chnage your fuel station, small amounts of water in your gasoline will cause this code

High levels of alcohol contamination in your fuel will cause this code(or mistaken use of E10, E15, or E85 fuel)

A clogged or mechanically failing injector will cause this code.

This condition could be present during high fuel demand due to a fuel pump that does not pump enough fuel, a plugged fuel filter, or a restricted fuel pipe.

Loose or leaking exhaust sytem pieces can cause this code.

Leaking intake manifold gaskets.

Leaking supercharger gaskets or supercharger housing.


The best course of action is to take the car to a competent mechanic skilled in the operation, diagnosis and repair of this vehicle and its engine and emissions control management systems.

Ok guys well I just got back from the GM dealership they diagnostic the car most of the day and found out it was a bad O2 sensor....Even with the stock filter it was throwing that lean code. So they ordered a new O2 it will be in on Tuesday...Hope this helps guys.....Colin :-D

Hey guys, I checked the stuff you told me to and it all looks ok. I'll take it back to the dealer and see what happens. Should I put the stock filter back in or will they even notice?

Hey guys, I checked the stuff you told me to and it all looks ok. I'll take it back to the dealer and see what happens. Should I put the stock filter back in or will they even notice?

Yes put it back to stock or they will blame your filter. I am sure they will look there.

OK, I put my old filter back in and since then my CEL hasn't come on since. It might in a bit of time, not too sure. Got an apointment at the dealer tommorow so we will see whats going on with this. I'll keep ya posted.

MAF sensor and K+N filter oil do not go together......the oil will contaminate the MAF wire causing it to read incorrectly.....this is very commong on all MAF cars using a K+N filter...............easy fix as all you have to do is clean the MAF wire using a Q-tip and alchohol