califcarm

2 X in three months. Only happens with long drives with AC on. Less than 1 hour commute to work with AC on is ok for months. Then I make a two hour trip and if I turn on AC the code comes in about 20-30 min.

I replaced purge solenoid and valve after 1st time and thought it was fixed until a few months later (this weekend) I got it again.

Any ideas?

Henry3959

P0221 is your pedal position sensor in side the car... nothing to do with the purge solenoid.

ForceFedDork

P0221 = Throttle Position (TP) Sensor 2 Performance
it is NOT a pedal diagnostic.

i would start by checking your wiring between the throttle and the ECM. Next i'd replace the throttle.

califcarm

Thank you. Yes, it is a code from the actual throttle plate position being too far from the expected position as I under stand it.

The strange part is that it is only on extended drives at highway speed where the AC is turned on. Seems if it were a wiring or harness issue or the TB was bad it would manifest itself at other times also.

Anyone have ideas why it would be only on long extended drives where the AC is on to trip the code? I can drive for months on shorter drives with the AC on or off and not get it. It seems solidly connected to having the AC on, and only if I am at highway speeds for lets say over 1 to 1.5 hours constantly. But 1.5 hours or more long haul constant without AC on does not yield any problems or codes. Car runs fine in all other ways except this situation with this code.

My guess is it is somehow related to the additional load the AC puts on the engine and how it might respond to that. I know at idle all engines compensate for the addional AC load on it. Older engines would normally open an additional air source post throttle body to keep the idle from dropping too much. With drive by wire I am not sure how the LNF does this at idle, as it could adjust only the throttle plate position if engineers decided to do it that way.

And no idea if there would be any compensation for the additional load beyond idle range or not.

Any additional ideas are welcome.

Henry3959

I should have looked it up... Memory sucks

jdbaugh1

iTrader: (1)

Shot in the dark but maybe you have more problems with your TB with the AC and longer drives because of the additional heat in the engine bay causing all the components to get hotter than other driving conditions.

califcarm

Might be. I will keep that in mind. Maybe just need to change the TB out as it might be sensitive to heat saturation on the sensors.

ECaulk

iTrader: (6)

I don't think that the added heat from the ac and long drive is the issue.

It's potentially something between your DAL tables and optimum spark or torque tables, try logging where the load cells are for that condition and make an adjustment

Kickbutts228

That's crazy I am literally having the same problem but in the city and my clutch locks me out of every gear like no fluid is pushing the slave cylinder the pedal feels empty but only with A/C on

califcarm

I was thinking it might be something between them. But my DAL is stock at anything less than 60% of max load. Optimum spark is close to stock (1.1X Main spark - optimum spark). My optimum torque tables are completely stock. I really only modified high load areas of any controlling tables and blended them back to stock.

If I was logging, what parameters would I be most interested in and watching? I am guessing something to do with ETC desired vs actual? Or some others?

ECaulk

iTrader: (6)

I'd watch VE vs MAF also just to see if there is a significant difference between the two, not sure if they can cause a throttle position code but you want them to be close to each other for cruising. I still would recommend tweeking the DALs a bit in the cruise area you can def smooth things out and help with fuel mileage

ForceFedDork

Let me try this again.

Throttle is safety critical, therefore there are 2 separate sensor that read the same throttle position (for redundancy). Usually, one sensor starts at a low value (voltage) and increases as the throttle opens and the second sensor starts at a high value (voltage) and decreases as the throttle opens. These 2 sensors are rationalized against each other. If they do not agree with their expected value within a certain tolerance then this code sets. I just read through the service manual and there is a second way this diagnostic could set: the throttle position is rationalized against the MAF sensor. If your tune messed up the MAF calibrations bad enough, i guess this could set.

So, your connection with the AC is because you need more power to cruise on the highway with AC, therefore the throttle is opened further, it might be that the throttle sensors have a bad spot at a certain angle that you hit for long enough to set the code while on the highway. OR, could be that the extra power consumed by the AC (therefore more air flow) puts you in a spot where your MAF calibrations were "tuned" wrong and the rationality doesn't make sense to the computer.

Here are the conditions for setting that code:
P0221
•The TP sensor 1 disagrees more than 6.3 percent from TP sensor 2 for over 140 ms.
•The TP sensor 2 disagrees more than 9 percent from the throttle position calculated from mass air flow (MAF) signal for over 280 ms.

Could be that your throttle sensors are on their way out and it will get worst with time and it will be more evident. It is also possible that the "tune" managed to break the diagnostic by messing with the MAF calibration incorrectly.

Tell us more about your tune, (or post it up here if you're comfortable with that) and we can rule that out, or start a very long pi$$ing contest about tuning opinions.

ForceFedDork

if you have the capability to log data.
Collect:
MAF in Hz AND air mass
STFT AND LTFT
VE vs MAF like ECaulk said.
frankly you should already have all these signals in your configuration.

But im guessing if you go cruising on the freeway with AC, be very smooth (keeping the engine in steady state) and very slowly and smoothly vary speed and throttle. i'm guessing you'll find that there's a bad spot in your MAF calibration (assuming you messed with that in the tune or you have some aftermarket intake and aren't tuned for it properly) and this will be visible in the STFT+LTFT will drift away in a certain spot.

ECaulk

iTrader: (6)

^ this, its likely a MAF calibration issue or some of the tables not playing nice. Not sure if the OP has tweeked the cam tables but any adjustments made need to be smoothed out.

I've had surging before when on cruise control due to my opt spark tables being not as smooth as they should be. Surging as in building 3-5psi and then to -5inHg and back and forth.

califcarm

Great thoughts guys.
And great info on what sets that code.

I think you might be on to something with the MAF calibration. I am completely stock mechanically except for a ZZP upper charge pipe and IC (both stock plastic ones exploded at separate times at 23-24psi). And and drop in KN filter.

For the MAF it did calibrate it as my LTFT from the factory GMS1 tune I got the car with sat around -7 to -8. I know there are a couple of techniques to do this. I wanted to keep the MAF curve smooth, so I used only a pure offset of the factory curve for "rough" tuning of it. Then I tuned the MAF table for the individual cells that were out (iterations to get there). Seemed good for WOT as my LTFT+STFT at WOT through full pull was near zero. And my LTFT since I tuned the MAF has sat between -3 and +3 depending on the time of year and weather conditions (warm/wet tends a little negative, cold/dry tends a little positive, over each summer or winter season).

I could see a few cells in that table being off enough that holding near steady state driving on the highway might stay in a bad cell just enough error to throw the code. Where commuting stop and go traffic I do most of time passes through the cell so quickly it does not trip it. I could put the factory MAF curve and correction table back in my overall tune on my next road trip and see what happens.

My tune is attached if you want to review it. Mostly stock in low load and daily driving, tuning primarily high load areas of the maps, blended back into stock by about 50% load.

ECaulk

iTrader: (6)

I'll take a look later, you might consider cleaning the maf sensor given you have a K&N drop in. Then for logging adjustments for the MAF is usually suggest (from experimenting with what some of those over on the hptuners forum said) unplugging the evap initially to get the trims dialed in, then plug it back in and make sure nothing changes significantly.

califcarm

Good ideas. I did just clean the maf (but after the long trip and code was thrown). I did unplug the evap during the MAF tuning process when I did that which was about year ago.

I use a blue tooth adapter with my smart phone to watch the fuel trims regularly (a few times a week at least) to make sure they are not wandering.

ForceFedDork

my comments on your tune:
MAF cals: the way i read about tuning the MAF, and the way i did it, was to set the MAF Correction Base table to all 1, then log multiple files (smooth throttle input, keep the engine in steady state, collect a lot of data) averaged fuel trims of all the files on the Hz axis, then multiplied that to the MAF Airflow vs Freq. table. THEN, i have very small corrections to the MAF Correction table, and only in the low load region (2 left most columns). The way you did it, you have a lot of changes in the MAF Correction table and it's very jumpy, the zig zagging in the MAF Correction table is probably what's causing you problems. the spikes in the 3500 and 4000 rpm, those could causing you problems, you definitely want smooth lines in those tables.

some other random remarks that are just my opinion:
I think you DAL tables are higher than they need to be, it can be done with lower DAL values, somewhat irrelevant though.
If you still have a cat, which i think you do, i think you took too much fuel out of the COT component protection table, you could melt your cat if you run the car hard at full throttle (like a track day).

you are running quite a bit more spark than me at WOT, i guess if you can get away with it without knock, good for you, i can't. i even knock at 12.5 deg advance at 5500rpm.

and just as an FYI, you can control your boost spike with the MALT, then you dont have to do the weird thing you have in the boost by gear table and in the wastegate Duty Cycle Corr table, but that's a long conversation for a different time. just send me an PM if you want to discuss that.

ForceFedDork

i also have a stock airbox with a drop in K&N filter, and even if it's not perfect i think you could just run the stock MAF cals to see if your problem goes away.

califcarm

Thanks for all the thoughts. Good stuff.

For the MAF calibration, I figured either your MAF airflow vs frequency curve would be jumpy but have a smooth table, or the frequency curve would be smooth and the table might be a bit more jumpy. I do agree that the table is quite jumpy so I think I will just go back to using the stock table for all loads less than 70%. And smooth any that look too jumpy above that. The KN drop in seems to like some additional air in the high load high rpm areas compared to a brand new stock AC delco paper filter (I tuned them back to back to see the difference). Indicates that the KN does indeed flow better at high air flow rates.

Thanks for tips on the COT protection. It only comes into play if things get pushed hard and heat up so I will add some fuel back in to keep the CAT from possibly melting.

For spark I am just fortunate as on 93 octane I don't get any knock on the tune. I know some people run a bit more spark at 3500 rpm range than in my tune, but when I did that it often kicked off knock events that lasted through 5000 rpm. When I took out a bit of timing mid range it allowed me to slowly add more back in as rpm climbed. Making more power overall.

I left MALT maxed only because I wanted different responses in each gear, and the momentary overboost in the mid range was different for each gear. The gearXrpm table allowed me to tune each of those gears separate instead of trying for one compromise that worked for all gears. In particular I did not want to slow down or dampen 2nd gear boost onset at all (which MALT would have affected). I know it is a little different than most tune strategies.

Thanks again for all you input and taking the time to look things over.

califcarm

Good idea. Really no harm in trying this. My fuel trims might be a little farther off, but then again that is what they are there for in the first place.

califcarm

Just to post back with final results:

Code came back about 3 days ago (both A and B circuits sensors this time) and began repeating, getting to the point yesterday that it would go into reduced power mode upon start up immediately and could hardly drive at all from bucking even while in reduced power mode.

Changed the TB last night and it now drives perfectly again.