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Continued acceleration after letting off go pedal

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Old 02-05-2007, 08:36 PM
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Continued acceleration after letting off go pedal

I purchased a left over 06 2500 LB 4x4 ctd a few weeks ago and the only gripe that I have is when I am accelerating at average to semi hard acceleration and then let off the pedal the engine continues to accelerate for 2 to 3 more seconds. The problem I have with it is that it has almost cause me to slam into the rear of someone and one other time it caused me to spin around in wet weather as making a turn I started to slightly fishtail and so I let off the accelerator and would have been able to controle the slight fishtail, but the engine continued to speed up in which caused the rear end to spin me around completely 180 degrees. Scared the h out of me.
My question is... Is there something wrong or is this normal? I have not taken it in to the dealer yet as I wanted to see if anyone else has this problem. To me it feels like its dangerous. For example at take off from a light and then the car suddenly stops in front of you I have to fight hard with the brakes to overcome the continued acceleration of the engine in order to stop the truck. Anyone?
Old 02-05-2007, 08:51 PM
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believe that is turbo lag. mine does the same thing. it takes a second for the turbo to spool up and create the power, so when you let off the go pedal, the turbo is still spinning to its fastest rpm, creating more power. that is where a jake brake works nicely.
Old 02-05-2007, 09:13 PM
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Originally Posted by BR1
believe that is turbo lag. mine does the same thing. it takes a second for the turbo to spool up and create the power, so when you let off the go pedal, the turbo is still spinning to its fastest rpm, creating more power. that is where a jake brake works nicely.
THIS IS EXACTLY CORRECT !... TAKES A LITTLE TIME to make your self familiar with the way 'your truck operates'
Old 02-05-2007, 10:04 PM
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Its not turbo lag.Turbo lag is the delay you have when you first stand on the throttle not when letting off.The hesitation you feel after letting of the throttle on the hpcr engine is the pressure in the rail spikes & it takes a second to drain the rail pressure when you let off the throttle.The only trucks you feel this on is the hpcr engine trucks.

Kurt
Old 02-05-2007, 10:07 PM
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I think it's normal, and I agree it's the turbo that is the culprit. I found this out when trying to cross a divided highway. I got on it to beat traffic and had to stand on the brake to stop in the center divider. A little scary the first time so I am more cautious now.
It also took some time to get use to city driving. I found myself pushing too hard on the go pedal because the engine doesn't rev as high as a gasser and it seems the truck is not accelerating as fast as it really is.
Old 02-05-2007, 10:07 PM
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Yep.. Takes slightly longer for it to unload the engine/boost so you DO feel the overrun. After driving the 04 HEMI for 2 years then getting back into the CTD. I basically had to relearn how to drive it. I drive a D-Max worktruck every day but it doesnt do that mainly due to the 19,000lbs. anchoring it firmly into the slow lane.
Old 02-05-2007, 10:34 PM
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My truck does NOT do this. When you let off the throtle, it comes back to idle. I know exactly what you are talking about and have felt it myself on other trucks. It is due to the rail pressures being up and the only trucks I know that do it are the ones running aftermarket pressure boxes. As Streetsmoker about it. His does it bad with all his mods. Does this truck have any aftermarket stuff on it? I know that some one is making a little black box that plugs in line with the rail pressure sensor that does nothing but a little pressure. Is there one of these installed by chance?
Old 02-06-2007, 07:42 AM
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Originally Posted by Viesel
Is there something wrong or is this normal? For example at take off from a light and then the car suddenly stops in front of you I have to fight hard with the brakes to overcome the continued acceleration of the engine in order to stop the truck. Anyone?
I don't think this is normal, you may have a leaking injector. You may notice no more than a second delay between letting off the throttle and the engine decelerating as the motor defuels, but 1-2 seconds and making it hard to stop the truck maybe beyond spec. This feature is not turbo lag.

I see you have a 98 so you should know that there is not much diesel engine braking, not like a gas vehicle.
Old 02-06-2007, 08:53 AM
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I've experienced the same thing if I'm really into the go pedal. Don't know what causes it, but it's always done it and I just got used to it. I just figured it was because diesel engines don't have a throttle butterfly and ignition advance/retard to quickly slow the engine RPM.
Old 02-06-2007, 10:05 AM
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My truck is bone stock, and has always done this. It is only noticeable if you have the thing floored and abruptly pop your foot off. I figured it was just the turbo spinning down and/or rail pressure coming down.
Old 02-06-2007, 11:21 AM
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Yep my stock CTD does it too. Usually only notice it in stop and go traffic, took some time to learn the nuances of it. Try driving the CTD for a while then go try driving a gasser, I'm constantly chirping the tires on my gasser when I switch over on the weekend.
Old 02-06-2007, 11:49 AM
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It should NOT gain RPM's when you let off the throttle. Holding RPM's for a couple seconds is normal, but GAINING RPM's is not normal. thats for sure.
Old 02-06-2007, 08:20 PM
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Mine does this too. Doesn't seem right to me. My buddy's truck with right about the same miles on it does not do it.....
Old 02-06-2007, 09:22 PM
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Originally Posted by ClackClack
I've experienced the same thing if I'm really into the go pedal. Don't know what causes it, but it's always done it and I just got used to it. I just figured it was because diesel engines don't have a throttle butterfly and ignition advance/retard to quickly slow the engine RPM.
Yup!!! Mine did it for the first time on THE DRAGON (DEALS GAP) SCARY.
Boost-Fuel and nothing to stop it. This is NOT a gas engine.
TOMMY
Old 02-06-2007, 10:33 PM
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Our '05 does this too. Frustrating at minimum.

My 516rwhp '98 Dodge doesn't do this, even when going from WOT, to idle with 60PSI boost.

It's the way the ECM is programmed and how the HPCR operates, and it's inherant design.

Merrick


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