Scan Tool Review: Offline Repair Info (2)

 We began with the TOPDON ArtiDiag606S in the first installment of this series covering available repair information on various scan tools. The criteria here is information available without connecting to the vehicle. This time we'll cover the Harbor Freight ICON T10. The T10 uses a Android tablet format and is packaged with the TRUEFIX repair information package. 

Choosing the TRUEFIX option will open a webpage where you can enter the specific vehicle information and after that choose your search terms which in this case will be that same P2646 as we covered in the last installment. 

From there we get repair, location and procedural information related to the code and the variable valve timing system. 

Now in case that isn't enough you have yet another option on the T10 because it is Android tablet based. You can choose the Repair Information tab in the Toolbox menu and have an array of online sources of your choosing. You can even add YouTube cat videos if you like. 

Very impressive. 

 

Next up the Autel MaxiSys MS906MAX

Kenny@GGAuto.Repair

Scantool Review: Offline Repair Info (1)

 Way back in 1998 I got a Snap-on Vantage MT2400 and it changed my life. If you aren't familiar the tool was a hybrid of sorts between a graphing digital multimeter and a lab scope which was definitely useful in and of itself but it was also a portable diagnostic database that upped my game. I never understood why it wasn't the most popular tool Snap-on had. You could carry the Vantage out to any car, even a system you weren't familiar with and in a few minutes know exactly how a particular sensor worked, how to test it and do the tests. Game changer. I still have two of them, as well as the kv modules but the display screens succumbed to age and are no longer legible or I would still find uses for them. 

While that tool was a major innovation in 1998 modern scan tools pack a lot of repair information, even those at the lower end of the spectrum. A TOPDON ArtiDiag600S can be had for less than $200. Let's look at one of those and how it handles providing repair information offline, or with no connection to a vehicle. Very useful for getting familiar with a system before the car is even in the shop and planning a best approach pre-emptively. 

. Very recently had a 2008 Acura MDX in for a P2646 so lets use that. Enter the Library. 

DTC Repair Guide

The manufacturer and code.

Get the code description, repair reports and repair steps. 

You can also look for technical service bulletins but they are listed by system and may have to do some scrolling to find if there is a relevant one vs a more precise search. Next up we'll see how the Harbor Freight ICON T10 handles the same repair, as far as sharing information. 

Kenny@GGAuto.Repair

TPMS Article (link)

 TPMS Diagnostic Surprises Andrew Markel Brake & Front End

OBDII Data: Ambient Air Temperature

 There was a time that if your Ambient Air Temperature sensor wasn't working the only noticeable thing was your outside temperature display was incorrect or non functional. These days however the Ambient Air Temperature is factored in to the engine control logic and an integral part of the system. The system monitors the engine coolant temperature, the intake air temperature and the ambient air temperature. Cold air is denser than warm air and that becomes part of the air density calculation of the engine computer. It affects fuel mileage, emissions and performance. The pid for AAT isn't as straightforward as you might think however. You would expect that a vehicle sitting overnight without running would have engine coolant, intake air and ambient air temps all pretty close to each other when looking at the data with key on but that isn't always the case. There are rules of engagement that vary a bit from manufacturer to manufacturer that prevent the AAT pid from showing the current state of the sensor reading. Now the sensor can be working just fine and the sensor resistance has changed to match the current temperature but the number you are seeing with key on usually won't update to current reading until the vehicle is driving under the particular manufacturers rules. Some may update on the starter engagement but others not until the car is driving at some distance, some length of time or some speed. However the engine computer used the current resistance in real time to calculate the conditions at the engine start up. It just isn't showing the current value yet on the scan data. It is a bit like the computer logic that prevents your fuel gauge reacting to the fuel sloshing around in your tank while you are driving. You don't have to see the gauge reacting to that because the sensor data is being filtered and slowed before it reaches the gauge. 

Bearing in mind that the AAT data you are looking at isn't necessarily what the engine control module is currently reacting to, know that the ecm is very capable of noticing a discrepancy that isn't rational if one temperature sensor reading is contrary to what would be logical compared to the others. If you want to see the current readings for your own comparison, you would meet the conditions required for the scan pid to update as the quickest and simplest way. The computer will set a code if it sees illogical temperature data but there are times when a sensor can be incorrect yet acceptable to the computer so it never hurts to check. 

A few things of note, the intake air temperature is measuring under hood temps of air in the air intake tube so not the same as the outside air temperature being monitored by the ambient sensor which is often located near the front grill or in an outside rearview mirror. Also, the rules of engagement for the climate control ambient air pid are not the same as the rules for the engine control even though it is often using the same sensor, so it is not unusual to see different temp readings in HVAC ambient air and Engine ambient air. Temps are also factored in to the computer deciding how long your engine should take to warm up, a P0128 being related. 

Thanks for reading!

Kenny@GGAuto.Repair

OBDII Data: Air Flow Rate

 Let's take a look at the data item  Air Flow rate from the Mass Airflow Sensor. The most straightforward way to look at this pid on a scan is grams per second however in my screen shots I have the tool set to imperial vs metric so we will need to convert. The reason I say it is more straightforward in metric readings is that your expected flow rate in grams per second at idle should be roughly the same as the engine size. Be aware of the caveats to that rule of thumb. The engine should be idling normally and steady, no accessories on and a fully warmed engine. Accessories on, cold engine, erratic idle, all those will affect your base air flow. I had a 2010 F150 in with a 4.6 and when the engine was idling cold the computer had raised the rpms for warmup and I was getting air flow of 0.86 lb per minute, which translates to 6.5 grams per second which, though steady, was significantly higher than the 4.6 expected. 

Once the engine was warm and the idle was slowed due to a warm engine the air flow was 4.0 grams per second and normal. See how closely that is to the 4.6 engine size? Now there was also a Toyota in the shop with a 5.7 engine so let's test that rule of thumb once again. The warm engine, good steady idle and no accessories brought me 0.66 lb per minute, or 5 grams per second. 

On a roll now so I took a look at the air flow on the 2011 GMC 5.3 and found a problem. The truck was here for an oil pressure switch replacement, which was done, but I have just found another problem simply by looking at the air flow pid. The idle speed was correct and stable but my air flow was erratic and varying from 0.86 to 1.06 lb per minute, or 6.5 to 8.0 grams per second. This Mass Airflow Sensor had not set a code but this signal indicated a problem. Being the GMC it would not be unlikely I was looking at a MAF that would soon fail but it was even more likely I was looking at a dirty MAF sensing wire. The sensor is easy to remove and very definitely needed cleaning. 

Once the sensor was cleaned and re-installed I had a steady airflow reading of  0.72 lb per minute, 5.45 grams per second. The sensor had been misreporting air flow by about 20%. So before the cleaning, and because the computer thought the air flow was more than it actually was it would have been adding extra fuel. We have just improved gas mileage and acceleration by providing the computer with an accurate air flow reading. 

Thanks for reading!

Kenny@GGAuto.Repair

OBDII Data: Accelerator Position

 Because there is no throttle cable on a drive by wire system the computer needs to see what position you are placing the accelerator and it determines that by looking at the signal from the Accelerator Pedal Position sensor. Similar to the Throttle Position having redundant sensors, the Accelerator Pedal Position has two outputs that can be monitored in scan data as Accelerator Pedal Position D and Accelerator Pedal Position E. The system is set up that way so that if there is a sensor problem it will be noticed because the two outputs will no longer correlate. A mismatch here would set a P2138 and put the system into a limp in mode, limiting how much throttle can be given. Depending on application the two signals may vary in voltage output but they will always move together in sync as you press the pedal. 

Thanks for reading!

Kenny@GGAuto.Repair. 

OBDII Data: Throttle Position

 Electronic Throttle Bodies or throttle by wire systems have no accelerator cable and are responding to commands from the powertrain control module. Contained in the throttle body are two position sensors that relay the throttle position information back to the powertrain module so that it can "see" the response of the throttle to its commanded actions. Absolute Throttle Position is the data item for the primary sensor monitoring the butterfly valve angle. Absolute Throttle Position B is from a secondary sensor reporting the same information but on a different circuit to the powertrain module. This redundancy is for safety purposes and allows the powertrain module to cross-check and verify the information. Notice in the wiring diagram that the two sensors do share the same reference and return circuits. 

If the computer notices a discrepancy in the two signals it will set a fault code and go into a failsafe or limp-in mode that doesn't allow but a minimum of throttle. P2135 would be a result of that discrepancy. You can monitor and compare the two sensor outputs by looking at Absolute Throttle Position and Absolute Throttle Position B. They should correlate closely as the throttle moves. 

 On this particular application the signals are a mirror image of each other. 

Thanks for reading!

Kenny@GGAuto.Repair