P0111 code
 

So i did some air box modifications today which ultimately i left out the first screen and horn. The 2nd screen is in place still... and my car idles acceptably still ( a little "rougher" more of a chuckle) but seems of no threat to kill the car at idle. However i did kick a P0111. When i took it for a hard run to test the new intake mods it ran perfectly fine except when i dumped on 3rd at 7k rpm it had a solid 1 second hesitation then took off like nothing happened which I'm assuming this is what caused the code to show up cuz it was not there before the run.

My only guess is that removing the horn and 1st screen is the cause of the code.
The only real question i have is: Will this cause any actual problems with the car? Or can i just run it as it is and if the hesitation returns or the MPG takes a big drop put the horn back in at that time?

I did read through the other threads on this code and most are saying bad sensor, bad harness or PCM is dying. i know my PCM is good still and the sensor was perfectly fine before I took out the horn. I have no issue with codes if they aren't going to cause any actual problems. I can just get out my tuner and stop the ECU from scanning for them if i want to get rid of the CEL.

The screens and horn are there to straighten the airflow for the MAF. If the airflow is turbulent, the MAF will not read accurately. The computer may be able to adapt, but the P0111 points to the IAT which is in the MAF not reading correctly.

So how about putting everything back as it was, and see if the problem goes away? There is no good reason to modify the airbox anyway.

Without knowing your fuel trims (which you can get via OBD), hard to tell if the computer is fully able to compensate for the problem you're creating for it. Hesitation sounds like bad news though. What problem are you actually trying to solve?

My car hasn't been getting enough air through and sending unburnt fuel through the exhaust. I checked all my afr tables, ignition system, and changed out my filter for a new oem paper filter and still having the issue. When I did this I didn't get any unburnt fuel in my exhaust like before so it did solve that issue but seems to have created another one. I may have to just save up for a good aem Cai to solve this right.

I have hi flow exhaust and a tune on the car which all ran fine for quite a while. Just recently this issue started. Really hope it's nothing further down the intake line. All my valves are still good. I reached in and checked the actuators for wear and all are still nice and snug.

Not getting enough air is not a thing. If you were running rich, you really ought to look at your fuel trims and see what is actually happening. It could have been a vacuum leak that you accidentally repaired by taking the intake apart.

Also failing ignition coils could produce a similar effect. Get data. AFR, MAF airflow and long term, short term fuel trims on a warm idle will help you fix this properly/avoid knock-on problems.

I'll have to look at those. Won't be until the weekend probably since I live on the road during the week with a company vehicle.

I did drive it an hour this morning and got on it hard trying to get it to hesitate or kick code again and I couldn't do it no matter what I tried. Maybe it a fluke on that one since I had alot of the vacuum lines apart when I was messing in the air box. I had it just idling to warm up then took it out and it had it's fit on the first hard pull but hasn't since.

Ultimately I plan to get a good Cai put in it. From what I have read AEM is the best out for our car. And really the only one that actually helps power the knock offs all seem to cause us to lose power.

The stock intake is already cold and even the AEM offers marginal improvements, if any. That's also why modifying the airbox accomplishes very little. There are better ways to spend a few hundred than replacing the intake, but it's your car and your money.


If you had unplugged the battery while doing this work, that might be one reason it behaved strangely on first start. Needs time to learn.

thats why I haven't gone out and blown a whole lot on parts. I got better stuff to spend my money on right now. Most of what I have done is easily reversible and what isn't is cheap to replace.

I'll check my fuel trims and maf this weekend if everything checks out ok I may just leave it as is to see if the code ever comes back and try to catch the cause of it.

My next upgrade will be the BHR ignition system which will help tons on my AFR usage. I haven't noticed any decline in my stock coils but I'm at 82k so I'm betting there time will be ending soon. Better to replace sooner than wait til I'm dead on the road.

How did you diagnose this?

The thing about OEM coils is when you have symptoms, it's too late and other, more expensive parts may need replacement (like the cat). They die silently and depending on which one has degraded (die is the wrong word), the engine could continue to operate normally. So yeah definitely better sooner than later.

Have you tried resetting the NVRAM?

Disconnect the battery, wait for a minute, and press on the brake once. That should reset the existing fuel trim and make the system relearn.

And yeah, AEM intake doesn't really have much of an improvement... OEM intake in this car is already really good.

Exhaust sniffer test showed unburnt fuel and I opened a gauge on maf which showed low flow.

I took out the stock cat already. But I want to avoid any other issues that coil failure would cause.

No I have not. Honestly never heard of that. Will it mess up my performance tune?

Won't affect your tune, but now I'm curious what tune you have.

Low MAF flow + rich condition =vacuum leak. Air is getting in somewhere where the amount of air is not measured. And/or messing with the airbox is throwing off the MAF reading, I'm not sure if we're talking about before or after that. Start searching. Commonly missed one is the VFAD line from under the throttle body to front of the airbox.

But if you no cat, I don't think the sniffer test is valid. Of course it's rich for a sniffer, you've removed the thing that cleans up the exhaust. Would help to know what actual values you had for MAF airflow and AFR.

The actual afr was 0.56 and air flow was 179gps
the demanded was 0.78 AFR and 286gps
That high rpm WOT... Low load low rpm conditions it was meeting the demand.

And I have the VersaTuner and put the basic performance tune on my car.

I did pull apart like 3 of the connections on the vacuum line so maybe I fixed a vac leak without realizing it.

And the sniffer shows all the different items in the exhaust individually and even catless there shouldn't have been as much raw fuel as I had. Of course all my emmisions were off the charts but in my state there is no need to do yearly tests so I'm not in trouble for that.

Just putting out an update.

I got to come home one night so took my car out for a long run. Took my scanner and logging system with me.

I put about 400 miles on my car I did everything I could to get it to hesitate. Launching, WOT, high speed runs, lugging the engine. I even was shutting the car off and starting it hot,. Letting it sit to cold start it . Spent about 9-10 hours straight on this sorting it out.

So the P0111 code was showing as a "pending" code which is described as being detected but not occuring often/long enough to be considered an actual problem so doesn't actually send a CEL.
This was happening when I first started the engine hot or cold. But never sent back to pending again under drive conditions. Which this lasted about 250 miles, plus the 50 miles I put on it right after I did my mod so 300 miles total. During this time I checked the sensors check history and the IAT was being shown as "incomplete" so it wasn't even getting the sensor checked successfully.

At this time I assume I made a full cycle and it finally ran a check on the sensor came back positive and the pending code was gone. Hasn't showed up at all in the last 100 miles. No pending, no hesitations.

I will keep an eye on it for a while longer yet but at this time it seems that when I unhooked all the sensors and lines the ECU lost connection with them and took some time to get back in synch with them and get everything back in check.

Want to thank everyone that posted here to help me on this, I learned alot from everyone.

Ok, glad it's running better, but the numbers still concern me a little. Now that it is stable, it might be good to retake that data one more time (at idle this time).

0.56 (lambda?) is off the scale rich, like ~5 AFR. I don't think the O2 sensor can even measure that rich. 179 grams per second airflow really depends on rpm. "high rpm" is not a number. We're really not looking for transient high rpm data here, you want the car in a stable idle and fully warmed up.

I've not heard of 'demanded airflow', but the demanded 0.78 lambda (11.5AFR) is rich but at least on the scale. Normal tunes aren't supposed to drop to 11's AFR, there's no power there.

Grab the LTFT and STFT (fuel trims) if you pull the data again (at idle). They should be near zero. If they're not, there's still an issue.

High rpm I'm talking about 7-9k range but yeah I will pull the FTs next chance I get.

My program shows a demanded set of info which is based on the charts and throttle position to determine what it should be getting if all conditions are perfect and then shows what it is actually getting on the actual charts.

Btw do you guys normally measure air flow in lb/min or gps?

You are correct the factory intake is very good,I do have a Racing Beat cold air box and ram air intake I think it is a little better than the factory intake.