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There are good reasons to turn some codes off, but doing that to mask the fact that the tune is wrong is not one of them.
You installed a new MAF sensor and now the air mass measurement is higher than it was before...high enough to trigger the code...which sounds like you need to have your tuner tune the MAF curve for the new sensor. If the sensor is not OEM then the curve may vary from the stock one. Alternatively the car may have been tuned on your old sensor when it was dirty, which would also affect the curve...either way you changed one piece of the puzzle, so I would focus there.
After fixing the MAF curve, there is a "Calc Airflow" table in the PCM specifically for setting the thresholds for triggering P1514. The flavor text for this table is "Calculated Airflow vs TPS vs RPM - P1514 Error: The VCM uses this table to determine the maximum airflow the Electronic Throttle should be passing at a certain TPS positino and RPM. If the measured airflow exceeds this value then P1514/P0068 is set." RPM and Throttle position are the axes for the table. The field values are grams per cylinder.
I assume that the g/cyl number used in this table is based on whichever air model is currently being used by the motor (MAF vs VE). If that is the case then at higher RPM MAF is in use, which also points back to the change that was introduced.
Typically people raise the table values by a percentage to get the trigger threshold above what you should experience while driving (with some safety margin). I'm sure there are more scientific ways to configure this table (logging g/cyl, RPM, and TPS, creating a histogram, and using that data for example). It is also possible to just max out the values in this table, but there is a safety net for a reason.
That is exactly what I was thinking. This is a safety feature that is there for a reason and should not just be blindly turned off.
I appreciate the debate, but I have some issue with the examples, so lets look at them independently and compare them to the topic at hand and what I originally posted.
Originally Posted by Milan
So do you guys turn your traction control off when making pulls or do you leave that on all the time because of the safety net?
Similar to the next item, pushing the traction control button is a conscious decision that the driver makes. For most people who do not spend all of their time on a drag strip or road course traction control is on most of the time. You have the option, as the driver to selectively disable it or enable competitive driving mode.
If you turn off traction control you use your right foot to maintain or destroy traction at the rear wheels, depending on your intent. You have tactile feedback through the pedals, steering wheel, and seat. You have control of changes to the throttle.
If you turn off the DTC and the MAF curve is bad the first "feel" that you have of trouble may be a loud bang followed by some quality time in the cab of a tow truck. Obviously this is worst case, much like planting your right foot on the floor and driving straight into a tree if the traction control is off.
My whole point is that the change of MAF sensor resulted in the PCM believing that the world around it is different. It thinks more air is entering the motor than it is expecting at certain RPM. That caused it to cross a threshold to trigger the DTC and reduced power mode. There is a right way and a lazy way to ensure that the car doesn't trigger that DTC.
The question he should be asking is "I understand that this DTC means that the car is measuring more incoming air than it is expecting for a given RPM and throttle position...why is that?" When you ask that question it starts you on the path to the right answer.
Originally Posted by Milan
What about CAGS? Is that still on on your cars? All these things are there for a reason, why blindly turn them off?
CAGS is a "feature" installed for fuel economy. It has zero to do with motor or transmission safety (although you can argue that accelerating from a ridiculously low RPM through the bog isn't exactly good for the car).
If that DTC triggering table and MAF curve are properly calibrated the car should never trip that DTC unless something breaks, either sensor swings out of calibration, or you mechanically change the playing field (smaller supercharger pulley, for example).
Disabling CAGS is a conscious, not blind, decision. It directly eliminates the root cause of a perceived issue (I don't like shifting 2 gears and bogging). That is the way to address this. Disabling the P1514 DTC doesn't address the root cause and is very much a blind, knee-jerk sort of reaction. Yes, it ensures that you'll never see that DTC again, but your core problem is still there.
I am fundamentally less concerned about the DTC than I am about the quality of his MAF calibration. The entire purpose of a calibration is to accurately adjust the fuel and air model so that the motor behaves exactly as you tell it to under all conditions.
Originally Posted by Milan
After all as far as P1514 goes, your throttle could get stuck open and you could be too stupid to kill the ignition.
You're missing the point of what the purpose of that code does. It is a safety check to ensure that the combination of throttle position sensor and MAF are working properly by using one value to check against the other for the entire RPM range.
This has nothing to do with whether the throttle is stuck open. Hypothetically, if the throttle is stuck open and the mass of air passing the MAF sensor at any given RPM is within the configured bounds this code would not be set because the combination of MAF and throttle position sensor values for that RPM aren't over the configured threshold. If that does happen, yes you would have to shut the motor down yourself regardless of programming.
If the MAF curve is wrong and he takes it to a tuner to disable the DTC (fixing the symptom) without ever throwing a wideband on it to see what the actual AFR/Lambda is at high RPM, it is possible that the car will be running either rich or lean (most likely rich since the MAF is telling the car that more air is coming in than it saw before, so it is spraying more fuel). A little richer wont hurt anything other than performance unless it goes really rich in case cylinder wash is a possibility, but if at some point in that curve the car is running lean there is a chance that he will have an 8 cylinder paper weight. It isn't likely, but why risk it?
If it were my car, I would do it right...have the tuner put their wideband on the car, check the MAF calibration and adjust as needed. If the MAF calibration does need to be adjusted they may not have to do anything to the DTC trigger table at all, but they should be able to figure that out through logging. Having said that, the tuner will most likely charge more money to do this, so it is up to him to have the conversation and decide whether or not the cost is worth it to him.
At the end of the day its your car and you're welcome to adjust it and tune it how you want. However the majority of the material in this thread was trying to address the symptom (DTC/reduced power mode), not the root cause (MAF was changed and now the system as a whole behaves differently than it did prior to the change). It is important for the OP to have enough information to have a good conversation with their tuner, which is why I posted in the first place.
what i met to say was i installed a Autozone MAF then i had it tuned at the tunner. i was having a surging idle tunner said it was a bad MAF so i replaced it and he didnt hes custom tuner on it. do you think i should get a OEM MAF?
I appreciate the debate, but I have some issue with the examples, so lets look at them independently and compare them to the topic at hand and what I originally posted.
Similar to the next item, pushing the traction control button is a conscious decision that the driver makes. For most people who do not spend all of their time on a drag strip or road course traction control is on most of the time. You have the option, as the driver to selectively disable it or enable competitive driving mode.
If you turn off traction control you use your right foot to maintain or destroy traction at the rear wheels, depending on your intent. You have tactile feedback through the pedals, steering wheel, and seat. You have control of changes to the throttle.
If you turn off the DTC and the MAF curve is bad the first "feel" that you have of trouble may be a loud bang followed by some quality time in the cab of a tow truck. Obviously this is worst case, much like planting your right foot on the floor and driving straight into a tree if the traction control is off.
My whole point is that the change of MAF sensor resulted in the PCM believing that the world around it is different. It thinks more air is entering the motor than it is expecting at certain RPM. That caused it to cross a threshold to trigger the DTC and reduced power mode. There is a right way and a lazy way to ensure that the car doesn't trigger that DTC.
The question he should be asking is "I understand that this DTC means that the car is measuring more incoming air than it is expecting for a given RPM and throttle position...why is that?" When you ask that question it starts you on the path to the right answer.
CAGS is a "feature" installed for fuel economy. It has zero to do with motor or transmission safety (although you can argue that accelerating from a ridiculously low RPM through the bog isn't exactly good for the car).
If that DTC triggering table and MAF curve are properly calibrated the car should never trip that DTC unless something breaks, either sensor swings out of calibration, or you mechanically change the playing field (smaller supercharger pulley, for example).
Disabling CAGS is a conscious, not blind, decision. It directly eliminates the root cause of a perceived issue (I don't like shifting 2 gears and bogging). That is the way to address this. Disabling the P1514 DTC doesn't address the root cause and is very much a blind, knee-jerk sort of reaction. Yes, it ensures that you'll never see that DTC again, but your core problem is still there.
I am fundamentally less concerned about the DTC than I am about the quality of his MAF calibration. The entire purpose of a calibration is to accurately adjust the fuel and air model so that the motor behaves exactly as you tell it to under all conditions.
You're missing the point of what the purpose of that code does. It is a safety check to ensure that the combination of throttle position sensor and MAF are working properly by using one value to check against the other for the entire RPM range.
This has nothing to do with whether the throttle is stuck open. Hypothetically, if the throttle is stuck open and the mass of air passing the MAF sensor at any given RPM is within the configured bounds this code would not be set because the combination of MAF and throttle position sensor values for that RPM aren't over the configured threshold. If that does happen, yes you would have to shut the motor down yourself regardless of programming.
If the MAF curve is wrong and he takes it to a tuner to disable the DTC (fixing the symptom) without ever throwing a wideband on it to see what the actual AFR/Lambda is at high RPM, it is possible that the car will be running either rich or lean (most likely rich since the MAF is telling the car that more air is coming in than it saw before, so it is spraying more fuel). A little richer wont hurt anything other than performance unless it goes really rich in case cylinder wash is a possibility, but if at some point in that curve the car is running lean there is a chance that he will have an 8 cylinder paper weight. It isn't likely, but why risk it?
If it were my car, I would do it right...have the tuner put their wideband on the car, check the MAF calibration and adjust as needed. If the MAF calibration does need to be adjusted they may not have to do anything to the DTC trigger table at all, but they should be able to figure that out through logging. Having said that, the tuner will most likely charge more money to do this, so it is up to him to have the conversation and decide whether or not the cost is worth it to him.
At the end of the day its your car and you're welcome to adjust it and tune it how you want. However the majority of the material in this thread was trying to address the symptom (DTC/reduced power mode), not the root cause (MAF was changed and now the system as a whole behaves differently than it did prior to the change). It is important for the OP to have enough information to have a good conversation with their tuner, which is why I posted in the first place.
I'm glad you typed all that so I don't have to.
The examples given in reply to us saying to not just disable that feature were poor at best and not really comparable.
i start to notice a slight hesitation are about 1500rpm and 2800rpm when i feather the gas pedal. in 1st and 2nd gear. any ideas?? i just ordered a fuel pressure and wide band by AEM.
i start to notice a slight hesitation are about 1500rpm and 2800rpm when i feather the gas pedal. in 1st and 2nd gear. any ideas?? i just ordered a fuel pressure and wide band by AEM.
Yes, you need a wideband. Do you have HP Tuners?
PLX makes a really nice wideband. Not sure about AEM, I've read plenty of good and bad about them so I didn't go that route
i believe he use HP tuners.. i didn't tune it i had a tuner do it for 450.00
I would have expected a more spot on tune for $450, which is about the going rate for a custom tune. Did $450 include the dyno time? I would ask him the questions instead of us, and then reply back with his responses - I'm sure the more knowledgeable members here will be able to determine if he is bs'ing or not.
I would have expected a more spot on tune for $450, which is about the going rate for a custom tune. Did $450 include the dyno time? I would ask him the questions instead of us, and then reply back with his responses - I'm sure the more knowledgeable members here will be able to determine if he is bs'ing or not.
In addition to what was posted above (20 minutes is simply not long enough to tune for drivability, which is by far the hardest part to tune for), the exact questions you posed to us (hesitation, etc). Also, I'm not sure why he chose to tune it without a wide band. One thing that doesn't make sense to me, is why he told you to shift at 6000 rpms, when clearly the dyno chart indicates he upped the rev limiter to 6400-6500. That doesn't make sense.
im from rhode island. i asked him what should be my max shift point. he said about 6000. also i did order a wide band and fuel pressure gauge. from AEM
im from rhode island. i asked him what should be my max shift point. he said about 6000. also i did order a wide band and fuel pressure gauge. from AEM
Why did the dyno graph display all the way to 6400 - 6500 rpms then? Did he mess with the stock rev limiter?
05-22-2015, 12:58 PM
