Scanning OBD-II Fuel Trim Parameter

Explains the Fuel Trims PID OBD-2 Scaner Parameter in further detail. Watch our other video on fuel trims. FT is the ECM deviation from base injection timing and it'll let you know if the ECM is adding or subtracting fuel from the base/normal injection pulse width.

Category:

Autos & Vehicles

Tags:

• Scanner
• Automotive
• sensor
• diagnostics
• electrical
• OBD II
• OBD2
• auto repair
• Mandy Concepcion
• fuel-trims
• Fuel Trims
• injector
• base injection
• fuel injection
• LTFT
• STFT
• P0170
• P0171
• P0172
• P0173
• P0174
• P0175
• engine
• software
• technology

[jdubb408]

cant stand this gay computer voice

[ADPTraining]

@jdubb408 Thanks for posting. We thrive to make our videos better all the time, while keeping them free for all. We appreciate your suggestions and thanks again. Keep posting.

[5ohMan]

OMG..can someone shoot this computer voice.... Id rather listen to a guy from India narrate this..sheesh

[ADPTraining]

@5ohMan Hello, thanks for participating and posting. We thrive to give people another perspective on automotive technology. We're also a full fledged auto repair advice and help center. We encourage folks to post and participate. We also have lots of viewer from beautiful India and encourage participation. Our American and English computer narrations are the best solution to this FREE service. So, if you ever have car issues, ask away and let us help you. It's FREE.

[nobleheight]

Is it possible to simulate a condition in the shop/lab where the RPM is increased but the engine load stays the same, and then measure both injector duty cycle and pulse width.

I am thinking that a good way to keep the load the same would be to raise all 4 wheels off the ground using a lift and putting the vehicle in drive and stepping on the gas pedal. Stepping on the gas pedal will increase RPM, and since the car is off the ground, I assume this means there is no load on the engine.

[ADPTraining]

You don't have to raise the vehicle. At Park or Neutral there's no load and it'll work the same for your calculations.

[ADPTraining]

Use an oscilloscope and plot the injector pulse waveform. You'll see that at idle is value A, as you accelerate it widens to break the inertia and provide more power, and at a stable high RPM is goes down to value A. Value A signifies whatever calls for your engine type.

[ADPTraining]

There's always some load at higher RPMs. Effort to suck in outside air, engine parts friction, etc. These questions are probably outside the scope of engine diagnostics and more for engineers, but I applaud your logical reasoning. You can give our comments a shot. Buy an inexpensive DMM, with CD and PW or if you have access to an oscilloscope and try in on your own vehicle. THe problem with using a DMM is that all of them use avaraging circuitry and therefore not won't give an exact mSec value.

[nobleheight]

I am now thinking that even if the car is on a lift, as the RPM is increasing, engine load will increase with RPM due to the inertia inherent in the powertrain. Once the increasing of the RPM has reached a plateau constant value of let 's say 5000 RPM and allowed to stay at that constant level, then engine load will go back down to it's idle level, since the powertrain is no longer accelerating but instead moving at a constant velocity. Is that right? Or even close?

[nobleheight]

If it is impossible to simulate this condition either in the lab/shop or on the road, then I guess you are right about the relationship of RPM and injector PW being difficult to put into perspective.