Team-BHP - View Single Post - Hyundai Verna CRDI VGT - Updated at 22k-km, 35k-km & 40k-km, Plus A Minor Crash

sameel · 30th June 2008, 10:35

@rippergo
dude in fourth gear at 40kmph, its absolutely fine[ the duration of injections at high gear in low rpms will be small). when we switch over to 3rd, another set of injections might or might not happen, it can be either the same injection pattern as in 4th or maybe different[ still duration of injections will be more!] . but usually the third gear will be multyplying the toque much more than the fourth gear so, its better to be in 4th gear[ less enery conversion loss compared to 3rd gear] and the verna has got 4th , 5th gear as overdrive that is they wont loose effeciecny even if the car slows down to a speed less than recomended for the specific gear just like in 5th also the car can go in 55+kmph, and for 4th 40kmph is also fine .

the next question.
well there is two ways of realisation for which gear is selected .
one is v\n ratio vehicle speed to engine speed ratio.
and the other is a message from CAN interface from GCU gearbox control unit basically that is an ECU for the gearbox, here the GCU has a sensor which gets the gear as a switch output. and yes in simple terms the GCU is connected to ECU by wire. ok. so technically there should be a connection to ECU indirectly ok.

the v\n works like the following. ( each gear has a defined tolerance band for ratio and a threshold band for the ratio!!)
when the ratio is with in a tolerence band the current normal gear is detected by ecu, when the ratio is in threshold band, then corresponding fast gear is detected .
and reverse gear will have a very unique v\n ratio not similar to any other gear ratio.
hope you guys understand.
so in a verna there should be GCU considering that its a new gen vehicle.
i guess the old cars with just ECU will be using the V/n methd.
so now i hope you guys know how the ECU gets to know which gear is selected and how the ECU differentiates between 2000rpm in 1,2,3,4,5 gears!!
peace out
sameel

30th June 2008, 10:35	#253 (permalink)
sameel BHPian Join Date: Jan 2007 Location: cochin Posts: 181	@rippergo dude in fourth gear at 40kmph, its absolutely fine[ the duration of injections at high gear in low rpms will be small). when we switch over to 3rd, another set of injections might or might not happen, it can be either the same injection pattern as in 4th or maybe different[ still duration of injections will be more!] . but usually the third gear will be multyplying the toque much more than the fourth gear so, its better to be in 4th gear[ less enery conversion loss compared to 3rd gear] and the verna has got 4th , 5th gear as overdrive that is they wont loose effeciecny even if the car slows down to a speed less than recomended for the specific gear just like in 5th also the car can go in 55+kmph, and for 4th 40kmph is also fine . the next question. well there is two ways of realisation for which gear is selected . one is v\n ratio vehicle speed to engine speed ratio. and the other is a message from CAN interface from GCU gearbox control unit basically that is an ECU for the gearbox, here the GCU has a sensor which gets the gear as a switch output. and yes in simple terms the GCU is connected to ECU by wire. ok. so technically there should be a connection to ECU indirectly ok. the v\n works like the following. ( each gear has a defined tolerance band for ratio and a threshold band for the ratio!!) when the ratio is with in a tolerence band the current normal gear is detected by ecu, when the ratio is in threshold band, then corresponding fast gear is detected . and reverse gear will have a very unique v\n ratio not similar to any other gear ratio. hope you guys understand. so in a verna there should be GCU considering that its a new gen vehicle. i guess the old cars with just ECU will be using the V/n methd. so now i hope you guys know how the ECU gets to know which gear is selected and how the ECU differentiates between 2000rpm in 1,2,3,4,5 gears!! peace out sameel Last edited by sameel : 30th June 2008 at 10:37.