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  #85  
Old 01-16-2016, 02:20 AM
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Originally Posted by akinney View Post
Good video.
Thanks.

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Edit: Should have watched the video closer. Power definitely comes on before shift from first to second.
Absolutely. I specifically made several runs to ensure I got a video that simultaneously showed the tach, speedo, gear indicator, and performance effect to elucidate the issue and exclude alternative explanations.

Also, this is subjective, but I swear that video seems milder than the turbo lag that actually happens while driving in traffic. Admittedly, there's far less terror caused by turbo lag in an empty parking lot in the middle of the night (haha).

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Still, I think it's the PCM programming retarding the turbo usage.
That thought crossed my mind. I mean, perhaps FCA went out of their way to cause a deleterious performance effect that isn't technically the same mechanical cause as classic turbo lag but happens to mimic turbo lag exactly. Call it "synthetic turbo lag"? Heh.

Or, you know, maybe it's just turbo lag (haha).

But yeah, doesn't the PCM computer have control over the VGT vanes configuration? Couldn't that be coded poorly and result in a turbo geometry that causes this turbo lag scenario whereas a proper configuration/tune could ameliorate said lag?

Notwithstanding, with a performance effect that behaves as I demonstrated I'm going to continue referring to it as turbo lag.

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  #86  
Old 01-16-2016, 10:00 AM
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Re: Who regrets buy the diesel?

Just my .02c worth.....I think it is the electronic throttle. Had a new turbo diesel Alfa Romeo in Australia and it drove the same. Turbo lag is very different - I also own a highly modified twin turbo Maserati and it's reasonably gentle below 2000rpm ....but then hang the hell on!
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  #87  
Old 01-18-2016, 08:31 AM
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Quote:
Originally Posted by Roadkill View Post
Thanks.

Absolutely. I specifically made several runs to ensure I got a video that simultaneously showed the tach, speedo, gear indicator, and performance effect to elucidate the issue and exclude alternative explanations.

Also, this is subjective, but I swear that video seems milder than the turbo lag that actually happens while driving in traffic. Admittedly, there's far less terror caused by turbo lag in an empty parking lot in the middle of the night (haha).

That thought crossed my mind. I mean, perhaps FCA went out of their way to cause a deleterious performance effect that isn't technically the same mechanical cause as classic turbo lag but happens to mimic turbo lag exactly. Call it "synthetic turbo lag"? Heh.

Or, you know, maybe it's just turbo lag (haha).

But yeah, doesn't the PCM computer have control over the VGT vanes configuration? Couldn't that be coded poorly and result in a turbo geometry that causes this turbo lag scenario whereas a proper configuration/tune could ameliorate said lag?

Notwithstanding, with a performance effect that behaves as I demonstrated I'm going to continue referring to it as turbo lag.
FCA may just be limiting the power in 1st gear to protect the transmission. I know that was the idea behind the torque management programming on the Dodge Ram Cummins Diesels. On the CTD it was both 1st and 2nd gear if I remember correctly.
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  #88  
Old 01-18-2016, 12:06 PM
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Originally Posted by CJ8Rockcrawler View Post
FCA may just be limiting the power in 1st gear to protect the transmission.
Interesting hypothesis, but that seems inconsistent with observed operation on the NA EcoDiesel. The vehicle does exhibit hard acceleration in 1st gear, as seen in my video a few posts back. There is just a lag in power/acceleration up to ~2k rpm, whereupon the Jeep gets spanked while still in 1st. Also, one can turbo launch by spooling up to 2k rpm at a stop with the brake held, then release the brake. Instant power with no lag.
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Old 01-19-2016, 12:24 AM
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Taking a look at Torque app readings on some additional experiments tonight, I'm seeing a turbo boost value of ~15 psi in first gear after the acceleration kicks in during the type of turbo lag scenario from my video. At idle the boost value is a vacuum (no surprise) and while the vehicle is accelerating slowly below the ~2k rpm threshold the boost value ranges from 0 to ~2 psi. I definitely welcome others to run their own lag experiments and report their findings.

Personally, I'm satisfied that the turbo is kicking in and enabling the hard acceleration after the 2k rpm threshold in these scenarios. Whether the turbo lag we experience is due to design limitations or poor PCM tuning/VGT control remains an unanswered question.
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  #90  
Old 01-19-2016, 08:10 AM
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Re: Who regrets buy the diesel?

I'm just curious, the EcoDiesel is a first gen motor, right?
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Old 01-19-2016, 08:32 PM
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Re: Who regrets buy the diesel?

I too have a frustration with the turbo lag. I can deal with the straight line lag but its when I pull into traffic that I run into trouble. Nearly every morning i have to turn left while pulling onto a 2 lane road with heavy traffic. If I floor the accelerator I am halfway into the lane when turbo kicks in and, since I'm sideways, the torque causes the rear to slip which engages the intrusive stability control and basically shuts me down. So I have learned to do the following ritual: Sport mode, traction control off, spool to 2k then release the brake. I've had the rear really kick out on me once but most of the time its nothing a little steering correction can't handle.
I don't love with regrets but the simplicity of linear power of the v6 is a nice feature.
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Old 01-19-2016, 09:04 PM
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Re: Who regrets buy the diesel?

When I have the wheels turned, my GC exhibits what can be perceived as turbo lag. However, as stated, there is no such behavior in a straight line. I believe it's the interaction of the BCM (stability/anti-roll software) retarding the PCM to keep 4 rubber donuts on the ground. However, spool her up and drop the brake... problem solved. The other complaint is the transmissions unwillingness to downside into 1st until you come to a complete stop. This makes those rolling right-hand yields a little scary. However, zero regrets about buying the diesel!


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  #93  
Old 01-25-2016, 07:56 PM
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Re: Who regrets buy the diesel?

Quote:
Originally Posted by Roadkill View Post
I took a video tonight that illustrates the lag. As I mentioned before, the NA EcoDiesel does not hang at a standstill with the pedal floored, and instead immediately begins to roll at low RPM.

After a brief interval (i.e. a subjective eternity if you're in the middle of an intersection with oncoming traffic) of having the pedal floored with slow acceleration the turbo kicks in at ~2k rpm in this case 20 km/h / 12 mph whereupon the Jeep gets a kick in the pants and accelerates briskly.
Thanks for that, it seems consistent with my clip. There is a bit of a blip around 2k, but that looks pretty good. Yes when the turbo kicks in you get a lot more acceleration, but under 2k doesn't look particularly laggy.

I'm seeing something different in my experience with lag, as other have described, I see mine happening on turns from dead stops, but mainly when engine is cold. There is a real delay between revs going up and the trans engaging. I deal with it by stamping the accelerator, and then as the trans engages I lift off.

I'll try to get a video of it one day, and I'll also try to get a video of holding manual shift in 2nd 1500rpm. It pulls hard with zero lag.
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Old 01-25-2016, 07:59 PM
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Re: Who regrets buy the diesel?

Quote:
Originally Posted by ferntree View Post
Just my .02c worth.....I think it is the electronic throttle. Had a new turbo diesel Alfa Romeo in Australia and it drove the same. Turbo lag is very different - I also own a highly modified twin turbo Maserati and it's reasonably gentle below 2000rpm ....but then hang the hell on!
Yep, I came from a VL commodore turbo (Nissan GTR motor) and it had serious turbo lag, especially with the boost wound up a bit. Then the landcruiser diesel, also had turbo lag, being an older standard blower. But this feels like a delay in throttle or trans slipping in 1st or something.....
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Old 01-25-2016, 08:05 PM
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Re: Who regrets buy the diesel?

Quote:
Originally Posted by overlanding View Post
I'm just curious, the EcoDiesel is a first gen motor, right?
Yep, it was developed by VM motori for GM, they were going to put it in a european sold cadillac, before they went bust during the GFC. Maserati use it in the quattroporte and ghibli...
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  #96  
Old 01-25-2016, 09:08 PM
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Re: Who regrets buy the diesel?

Seems to me the general discussion on whether happy or not with diesel is somewhat side tracked to turbo lag but be that is it may, I think anyone who has experienced turbo lag knows what it is: my WIFE had a v6 Cadillac with twin turbos. When you 'punched it' for passing, the engine did nothing for a very long time (1 second?) and it was very noticeable (disconcerting). When I punch my 2015 overland, I notice a slight delay in acceleration but not anything that worries me (ah, is this thing going to accelerate?). I don't know if a lag is inevitable with turbos, but I have never felt like the engine was not responding, which is the most disconcerting driver experience, IMHO.
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