Dave never said there was combustion while coasting in gear. Just said the plugs still fired.

 

i don't think mine does that.. I Have AN 07, BUT NOW I'M GONNa check tomorrow to see

 

As long as the engine is running there is combustion... but twice he said when there is no throttle the injectors provide no fuel (originally used term not firing but then said save idle - all of which is what I initially was asking for clarification on)... but clearly if there was no fuel thus no combustion the engine wouldn't even run.

My point was; the injectors are working regardless of throttle.

 

It's called engine braking and in post 26 you state that the injectors are delivering fuel when you release the throttle. They are most definitely not delivering fuel when the car is coasting in gear. The engine is most definitely "running", it's just that combustion is not rotating the crank shaft, the car's momentum is. I have not once corrected myself in this thread. Everything I've stated is true. The injectors are not firing because if they were they'd burn themselves up because fuel keeps them lubricated and cool. Only when the rpms drop below a certain level, typically 1,200rpms or so, will the injectors turn back on to keep the engine from stalling. You sometimes can feel this or watch it on the tach.

 

^ So in Slip-Lock when the RPM falls the injectors are off, but when it bounces off the limiter that's the Injectors kicking in?

on 05/06 Driving in D on the highway would be best for MPG since it fully locks up?

 

Off throttle, yes. Rev limiter? I honestly don't know. My 03 has a pretty brutal rev-limiter and it sure feels like the injectors are cutting in and out, but the ECM could also changing cam angles, simply closing the throttle, etc. A lot could be going on.



The only real way to test this would be take 100 mile trip in MM (cruise). Then drive back on the same road in D, same cruise speed. If the results differ by maybe 5%, then there may be it's true. Honestly, I think your tranny is locked while at cruise on the highway in MM, it's just that the lock-up control is release quicker to make the car more responsive.

Have you tried this test in the 75-80mph range so that you're above the stall speed of the TC?

 

Ok I might be a lil green on the subject (which means very green). I'm trying to figure what does all this mean. Does it mean when the car is not accelerating the transmission is not in gauged, which means the rpms are at a lower state. Once the gas is pressed the rpms increase; however, the "speed-O" meter is steady at the speed that the car is moving (momentum). As the transmission is engauged the hold steady and not the speed-O meter moves at the rate of the rmps or at the speed of the rate of gas going into the throttle body.

If I'm wrong let me know, but is what is being discussed a bad thing or something that one should keep and "eye" on that might cause problems in the future?

 

I guess someone needs to data log a coast in gear situation and observe the injector duty cycle

 

^I have an idea that's even more direct.

 

That's nice. Going to illustrate it for everyone here?

 

^Actually I have two ideas... but one requires a rather large oscilloscope, and I don't know if my inverter will power it :/

But yes, I'll post a video (possibly in a new thread) with my findings.

 

I just don't quite understand how your idea is more direct (or simple) than me hooking up my autoenginuity OBDII scanner to my laptop and going out for a drive.

I haven't played around with it for awhile but I do believe I can observe the injector duty cycle in almost real time.

 

^I didn't say simple... I said direct.
There's a big difference in semantics, but I'm not Mike, so I won't bicker about it

You should absolutely take your OBD scanner for a drive. I'd like to see findings from that as well.

 

^ If this is something you can bring to the Run, we can do it on my car to compare. 03/04 to 05/06 coasting in D and MM.

 

The scanner is reading the injector duty cycle. Is that any less direct?