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hawairish

Drive-by-wire + AT + 4L = sucks

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I've griped about the AT in the past, but something that's really been bugging me is the drive-by-wire + AT on my 04 when off road, particularly in 4L.  The main issue I have is that the truck doesn't crawl at all...it revs and revs and revs and does nothing, and then lunges forward once there's enough revs.  I completely despise it about my truck.  My offroad outing the other day, and watching the video of it, straight out embarasses me because it looks amateurish, but I know I'm barely even throttling it and you can hear the engine slowly revving up in response.  I keep the trans in "1" when in 4L, so it's not a product of a shift either.

 

My question, however...is this normal for anyone else??  Keeping in mind that 03-04 R50 and I think only 03 QX4 have drive-by-wire, I suspect all the drive-by-cable AT guys don't have this problem.

 

I have no driveability issues otherwise.  The transmission is responsive all other times, including 4H (this might be hard to substantiate because when I'm in 4H, I'm usually not going slow or not needing to ease up to speed from a stop).  I don't suspect issues with the torque converter.  My truck doesn't even idle up my driveway, though which has a very moderate slope.  By comparison, the FJ80 I've been working on for months will storm up my driveway in idle.  The truck accelerates well, and I don't feel any sort of slipping at low or high speeds.

 

Given that, is there something else to consider?  I'm considering crawler gears, but not if it just means I'll have to rev higher to get the same results.  Is there some way to put a low-speed lock on the TC?  Should I crash it into a wall and find an 02 instead?  Is there an issue with the transmission I'm not aware of?  

 

 

 

 

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4 hours ago, hawairish said:

I've griped about the AT in the past, but something that's really been bugging me is the drive-by-wire + AT on my 04 when off road, particularly in 4L.  The main issue I have is that the truck doesn't crawl at all...it revs and revs and revs and does nothing, and then lunges forward once there's enough revs.  I completely despise it about my truck.  My offroad outing the other day, and watching the video of it, straight out embarasses me because it looks amateurish, but I know I'm barely even throttling it and you can hear the engine slowly revving up in response.  I keep the trans in "1" when in 4L, so it's not a product of a shift either.

 

My question, however...is this normal for anyone else??  Keeping in mind that 03-04 R50 and I think only 03 QX4 have drive-by-wire, I suspect all the drive-by-cable AT guys don't have this problem.

 

I have no driveability issues otherwise.  The transmission is responsive all other times, including 4H (this might be hard to substantiate because when I'm in 4H, I'm usually not going slow or not needing to ease up to speed from a stop).  I don't suspect issues with the torque converter.  My truck doesn't even idle up my driveway, though which has a very moderate slope.  By comparison, the FJ80 I've been working on for months will storm up my driveway in idle.  The truck accelerates well, and I don't feel any sort of slipping at low or high speeds.

 

Given that, is there something else to consider?  I'm considering crawler gears, but not if it just means I'll have to rev higher to get the same results.  Is there some way to put a low-speed lock on the TC?  Should I crash it into a wall and find an 02 instead?  Is there an issue with the transmission I'm not aware of?  

 

 

 

 

Interestingly enough, my 1997 JDM QD32TI diesel also has drive by wire! Along with the early 4 mode 4wd.

I have a similar but different criticism. I find that the throttle pedal is extremely sensitive. This leads to good responsiveness on the road, but offroad makes the vehicle very jerky and difficult to drive smoothly. I've got it mastered now, but whenever I let mates drive it they always comment on this. I just wish Nissan had reprogrammed it so that when you put it in low it was less aggressive on the throttle. Would make it much easier to drive.

I've never found it lags. Most of the lag in mine is turbo, but even then that's not actually too bad by 90s diesel standards, because at 3.2 litres it's quite a decent displacement and doesn't rely too much on boost for the low end torque.

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In 4LO there is a significant difference at idle for me. She will basically go imma say up to 6mph without even touching the gas. When i do give it some throttle I feel what you mean. She will rev up with no power response for a few seconds until you get around 1700rpm . I wish it wasnt a pain to convert to a cable throttle. 

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5 hours ago, KiwiTerrano said:

Interestingly enough, my 1997 JDM QD32TI diesel also has drive by wire! Along with the early 4 mode 4wd.

I have a similar but different criticism. I find that the throttle pedal is extremely sensitive. This leads to good responsiveness on the road, but offroad makes the vehicle very jerky and difficult to drive smoothly. I've got it mastered now, but whenever I let mates drive it they always comment on this. I just wish Nissan had reprogrammed it so that when you put it in low it was less aggressive on the throttle. Would make it much easier to drive.

I've never found it lags. Most of the lag in mine is turbo, but even then that's not actually too bad by 90s diesel standards, because at 3.2 litres it's quite a decent displacement and doesn't rely too much on boost for the low end torque.

 

I don't think I've had an issue with pedal sensitivity, though.  The engine revs accordingly to pedal pressure as far as I can tell, but there's just a total lack of a positive connection between engine and transmission.  I'm partially accusing the DBW system of babying my throttle or some weak electrical logic, but mainly accusing the transmission of just not hooking up gradually at lower RPMs.  I'm not an AT kind of person (this was my first AT vehicle actually), so for all I know this is just "normal" (and crappy).  But, I think the fact that the truck largely remains stationary at idle (unless on a totally flat surface, and even then doesn't pull hard at idle) is odd.  Even my Telluride wants to get moving when I take a foot off the brake.

 

2 hours ago, JackFletcher said:

In 4LO there is a significant difference at idle for me. She will basically go imma say up to 6mph without even touching the gas. When i do give it some throttle I feel what you mean. She will rev up with no power response for a few seconds until you get around 1700rpm . I wish it wasnt a pain to convert to a cable throttle. 

 

That sounds like it.  Converting to DBC is basically not possible/practical.  New gas pedal, all the cables, new cruise control system, all wiring and controllers.  I swear the only remnant on the DBC version in ours is the throttle cable bracket on the upper plenum, and no clue why Nissan even left that in when there's nothing attached to it.

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I encountered this somewhat in Missouri: I’d a approach a rock  step slowly, and the engine would just rev and rev and rev, not moving the car onto and over the obstacle, then, once I started moving, I immediately feel the need to slow down. Other times in Idaho there are lunging aspects to the driving style, although I think with my differentials being open-open, my lack of traction might reduce that effect. But even on an obstacle like the one below, which alternately lifts/drops each side of my suspension as I move forward, instead of being able to slog through the obstacle at something of an even speed, I always find myself going over the first step, then braking to stop the lunge, then restarting to take on the next dip/peak on the obstacle. But just about anytime I go over an obstacle, it’s a lunging motion that necessitates a harsh braking, which is about what you have.  Though I suspect your lockers are making the problem more noticeable.

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here’s the view from below. Each dip/step is about 1-3 ft and enough to eliminate traction if I don’t take a really good line.

 

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I have a little experience off-roading in a 03 Rubicon 6sp, but what I did with it wasn’t as trying as what I’ve put the pathfinder through. However, I’ll probably have the opportunity to drive it a lot during Christmas break, and was already planning on some light trail use with it if I can get my hands on it. Now I’m going to be paying a lot closer attention to how it performs.....

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I haven't needed 4low out in the woods on an obsticle yetvso i cant say to its rpm build up as mentioned, because ive only needed to use 4H . Ive only engauged the 4L on flat gravel before though and it had no problem trying to get moving, while not nearly as fast of a roll as 4H, but it was still something. But the not getting up and going until about 1500-1700rpm i havnt had to deal with yet. Ive just gone right up things with 4H and never had problem. I do also have an 03 with manual stick transfer case and AT

 

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From what I've read, a torque converter with too high of a stall speed causes symptoms that sounds an awful lot like the lunging you guys are talking about, but I have no idea how/why an R50 Pathfinder would've ended up with a high-stall converter or where you'd get one with a lower stall speed. The '03 manual says the stock converter should stall between 2,440 and 2,640 rpm, for whatever that's worth. The torque converter lock-up clutch isn't supposed to do anything unless you're cruising in overdrive, so I doubt messing with that would help you crawl. And yeah, doesn't sound like it's the trans itself.

 

I haven't wheeled drive-by-wire, but I remember how laggy it was in my dad's '03. If you've got a scanner/app/whatever that'll draw graphs, I'd be curious to see the throttle position plotted against pedal position to see if the computer's playing silly games with the throttle angle. See if you can catch the computer spiking the throttle when the truck lurches. I've seen adverts for products that supposedly let you modify the behavior of e-throttles in some vehicles, though I'm not sure stacking another nanny on top of the one that's currently causing problems sounds like progress.

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I wonder if theres anything in the throttlebody air intake or anything that needs to be cleaned or a sensor in the throttle body that could use a cleaning to help this problem.
Just a shot in the dark at a fish full barrel

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On 10/31/2019 at 5:30 AM, Slartibartfast said:

From what I've read, a torque converter with too high of a stall speed causes symptoms that sounds an awful lot like the lunging you guys are talking about, but I have no idea how/why an R50 Pathfinder would've ended up with a high-stall converter or where you'd get one with a lower stall speed. The '03 manual says the stock converter should stall between 2,440 and 2,640 rpm, for whatever that's worth. The torque converter lock-up clutch isn't supposed to do anything unless you're cruising in overdrive, so I doubt messing with that would help you crawl. And yeah, doesn't sound like it's the trans itself.

 

I haven't wheeled drive-by-wire, but I remember how laggy it was in my dad's '03. If you've got a scanner/app/whatever that'll draw graphs, I'd be curious to see the throttle position plotted against pedal position to see if the computer's playing silly games with the throttle angle. See if you can catch the computer spiking the throttle when the truck lurches. I've seen adverts for products that supposedly let you modify the behavior of e-throttles in some vehicles, though I'm not sure stacking another nanny on top of the one that's currently causing problems sounds like progress.

 

Good info, thanks.  It gets me wondering if perhaps easing off the throttle a little once it's going is what's causing it to 'dump pressure'.  Like, it builds up revs and eventually stalls, but the slightest throttle drop resets.  You can see in those videos there were several moments where the trucks starts moving up and then rolls back down—that's me trying to limit the build up of revs to prevent the lunging once it's going, where I expect the truck to maintain pace and just crawl up.  Unfortunately, if I don't ease off the throttle over the crest, it looks like I'm gunning it.  If I ease off the throttle, it looks like the truck can't even make the climb.  There's no middle ground.

 

I think my scanner can monitor and record throttle.  I may have to look into that.

 

On 10/31/2019 at 6:44 AM, spicyheckboi said:

I wonder if theres anything in the throttlebody air intake or anything that needs to be cleaned or a sensor in the throttle body that could use a cleaning to help this problem.
Just a shot in the dark at a fish full barrel

 

Throttle body and intake should still be pretty clean, just did all that maybe a year ago.  Notably, my TB is "rebuilt"...I had taken it apart to clean the contacts, even though it is not intended to be serviceable.  My truck has previously thrown codes related to mismatched "A/B" signals, but all that went away when I rebuilt the TB.  I ran diagnostics and re-learn tests on it at the time, so I think the system is behaving correctly.  Previously, the issues would cause the truck to stutter and would cancel cruise control and such...no issues like that since.  

 

In reality, this is probably just going to be something I have to learn to live with.  I do have a small RMS leak, so there's also a decent possibility that I go with crawler gears if I'm going to go through all that work to pull the trans down.  Given the stall speeds above, I would expect this issue to largely cease because the RPMs would be higher, but I'm not sure it really solves the problem completely.

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I’ve had the opportunity to drive both DBW, and DBC back to back, and the biggest difference i’ve noticed is the touchiness of the wire. i’ve never had a problem like what you’re stating and i had been in 4lo plenty of times. though the overall responsiveness with the cable felt much more controllable throughout the pedal while off roading.

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Drive by wire with a manual trans is horrible as well. My 04 golf has that.

 

My Xterra SC has a similar issue but not exactly the same, it is cable driven, but the throttle plate has a much more aggressive opening (to make it feel even faster, I guess). So in 4L on the trail it lunges forward with the smallest application of the throttle. Something I've just had to get used to/live with.

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Seems like the consensus, then, is that the DBW is too sensitive...though, that may be synonymous with "more responsive", and ultimately by-design?  It could be just that my driving sucks, though I'm definitely not a run-and-gun wheeler.

 

Being that I wheel with a lot of D40/N40 guys, I would have expected similar behavior from their trucks, but I've not observed that.  They have a considerably better crawl ratio (33.9:1 for a 5/AT, vs. 26.1:1 in mine), and I wonder if that makes that much of a difference.

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Commenting on DBC / TX14 '02 LEs:

@02_Pathy: A year ago I was spotting for the PNW group at Tahuya. 02_Pathy was able to approach, climb, traverse & descend obstacles with minute precision - a VERY controlled drive.

Myself:  I've mostly used 4Lo just on rough Forest Roads this year, my last trip I was in 4Lo for long time intervals, however, I would note that I definitely have a linear throttle response.

 

 

Edited by RainGoat
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Perhaps we can look at this if we get a group up to washington this spring. Especially comparing myself and @02_Pathy.

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Commenting on DBC / TX14 '02 LEs:
[mention=39493]02_Pathy[/mention]: A year ago I was spotting for the PNW group at Tahuya. 02_Pathy was able to approach, climb, traverse & descend obstacles with minute precision - a VERY controlled drive.
Myself:  I've mostly used 4Lo just on rough Forest Roads this year, my last trip I was in 4Lo for long time intervals, however, I would note that I definitely have a linear throttle response.
 
 
I can say that the drive by cable is very controllable and predictable and in 4lo I can feather the throttle and not lurch forward, I have driven several drive by wire vehicles and the response is definitely not like a drive by cable and in my dad's '19 Trailhawk it is extremely terrible, you keep adding throttle and nothing happens then all of a sudden power comes out of nowhere and you launch

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Commenting on DBC / TX14 '02 LEs:

[mention=39493]02_Pathy[/mention]: A year ago I was spotting for the PNW group at Tahuya. 02_Pathy was able to approach, climb, traverse & descend obstacles with minute precision - a VERY controlled drive.

Myself:  I've mostly used 4Lo just on rough Forest Roads this year, my last trip I was in 4Lo for long time intervals, however, I would note that I definitely have a linear throttle response.

 

Now that I think about it, there was another R50 that was very lurchy on the same obstacles. I chalked it up to inexperience as he was a new off-road driver, however, I do believe he had an ‘03, which would be DBW, so maybe that was really the issue.

 

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Drive by wire does have some difficulty just off idle. I believe I read somewhere, possibly when I was working at the dealership that there was a lot of complaints about aggressive tip-in with the Titans when off road. I think that they had a programing update to change the throttle response when the truck was put into low range. I don't know if anything like that was done for others though. It might be more practical to practice 2 pedaling when crawling. My old 93 uses the old cable throttle but I still find using both pedals at the same time gives better control in some cases where I need more torque, but slow wheel speed. The R50 and most of the D22/WD22's are old enough that the brake signal override is pretty tolerant of applying brake and throttle at the same time.

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So i got to get into 4lo when i went off roading near the beach in south Jersey the other day. I still have smoothness and not expiriancing what you guys are. Im an 03 with the drive by wire, but i also did just change every fluid but diffs and coolant, and i had all od my toolsbin the truck so it was pretty heavy too, maybe the weight makes it work better? Idk why i wouldnt expiriance the same as you guys unless its that or maybe the big aggresive tires ?? But when i am in 4L and gently get on the pedal i get immediate response that isnt lungy or kicking in at a higher rpm like that

 

Idk maybe my r50 is just weird

 

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5 hours ago, spicyheckboi said:

So i got to get into 4lo when i went off roading near the beach in south Jersey the other day. I still have smoothness and not expiriancing what you guys are. Im an 03 with the drive by wire, but i also did just change every fluid but diffs and coolant, and i had all od my toolsbin the truck so it was pretty heavy too, maybe the weight makes it work better? Idk why i wouldnt expiriance the same as you guys unless its that or maybe the big aggresive tires ?? But when i am in 4L and gently get on the pedal i get immediate response that isnt lungy or kicking in at a higher rpm like that

 

Idk maybe my r50 is just weird

 

Not sure we're apples-apples here.  I have no problems driving in 4L on flat or moderate terrain.  I don't think a beach and the desert terrain I'm usually on have much in common except some sand.

 

The specific scenario I'm referring to is when climbing an obstacle, and the throttle build-up that occurs.  At the slightest throttle change, the truck will either lunge forward or completely dump torque and roll back; there's no middle ground where it just "crawls".

 

Comparing to a manual transmission, it'd be like pressing the clutch in when giving it a little gas, or revving up with the clutch at moderate pressure, and then just dumping the clutch pedal, where the vehicle won't stall, but it'll bump forward.  There's no sweet spot where you've got just enough clutch pressure to give it some gas and it'll both move forward and slip just enough.  My '08 Wrangler w/ 6MT was perfect for this, where you could be almost completely off the clutch and in 4L and the truck would just move.

 

Here's the video from my latest trip that really put me at my tipping point.  See specifically:

https://youtu.be/hzffJ3nu-T4?t=230 — lots of rollback trying to avoid lunging up that rock just trying to position the truck.  Around 5:38, I'm having to rev up quickly a few times to get any response and avoid rollback.

https://youtu.be/hzffJ3nu-T4?t=1119 — especially at 18:52 where it just catches and goes.  Spotter thinks I'm trying to kill everyone, but in reality, the revs sounded like they were holding.  Both lockers were engaged and there was no slippage until the 1st lunge, when a boulder broke loose under my left-rear tire.  During that obstacle (and clipped from the video, after I suggested needing a manual transmission) even the spotter said he could hear the truck flare/rev up excessively, not move, then just catch.

https://youtu.be/hzffJ3nu-T4?t=1633 — in particular 27:39 and again 27:42...you can hear me trying to rev up just to move and barely get a response, then it just goes.  Bear in mind I'm on a near 45° decline...how much throttle should I really even need?!  The guys think I was going to launch it, and the whole time I was trying to feather it.

 

For all I know, maybe I suck at driving this truck and should give it all up.  I am absolutely not the type of wheeler who just guns it through obstacles; frankly, I hate those sort of people.  But what irks me the most is looking like some reckless idiot with no regard for his truck, when I'm not even remotely out to damage or destroy my truck (though it is an accepted risk).

 

@Mr_Reverse, admittedly, my two-pedal does need work and it is something I practice on occasion...I'm just never comfortable doing it.  I don't trust my right foot enough.  I'd rather pull the e-brake and throttle up.

@adamzan, I'd totally take that response-and-lunge over this no-response-and-lunge any day.  The throttle response in my truck is quite responsive, but not knowing when it's going to connect is frustrating.

 

Anyway, this thread can probably die at this point.  There's probably nothing "fixable" on the truck, so I either suck it up or get rid of it.

 

Edited by hawairish
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 ......or get rid of it.

Blasphemy! A BIG NO on that!
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Just to clarify i said what i said from going up over logs to get up a hill. It idles up to the obstacle hits and stops. I smoothly accelerate over the obstacle from the stop with no issue of lurching or seeming like i dont have control. We dont have the gearing or power to just idle over things bigger than half the tire. Dont get rid of ur rig just build it the way you want it

 

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Engine swap! I’m gonna pay extra attention next time I’m in 4LO and see how difficult it is to feather the throttle over obstacles

Edited by PathyDude17
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Engine swap! I’m gonna pay extra attention next time I’m in 4LO and see how difficult it is to feather the throttle over obstacles
Agreed! on all ends

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4 hours ago, PathyDude17 said:

Engine swap! I’m gonna pay extra attention next time I’m in 4LO and see how difficult it is to feather the throttle over obstacles

 

I am too, I know a 4Runner isn't terribly relevant to the issue but it is DBW and now I'm curious! I've been getting in the habit of two-footing it myself honestly, but I still don't trust my left foot with the brakes enough.

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Alright, just watched that vid. First off, great to see you & the Pathy in action. I can see your frustration in that first section. I didn’t think the 2nd looked bad and you absolutely cake walked that descent at the end! Need a new truck - give me a break...

 

 

 

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