Surge on launch

[JWerkheiser]

TPS (APPS) on mine is mounted on the engine. As far as the severity of the problem, it got progressively worse since it started doing it. I have a feeling there will be more complaints as time goes by.





bighammer, you have to time it exactly to make it happen. there's a tiny split second of time when the clutch is let out and the engine is fueling up to recover rpms. This is when I feather the accelerator and it's off to the races. Particularly useful when turning at a 4 way stop. It'll bring the rear end around on these salty midwestern roads. And speaking of salty, that's exactly the kind of words that come out when it happens.

:-{}

 

[bighammer]

There have been a couple occasions when my wife has asked WTF am I doing and I reply "just barely touching the pedal"

 

[JWerkheiser]

Went to dealer today

Reproduced the problem while they had the DRB hooked up. APPS (TPS) was at 2%, engine at 3500RPM when launching. Returning pedal to 0% caused it to defuel to normal. APPS voltage all looked good throughout pedal travel, so it probably isn't the problem. However, there is no other data that looked out of line, so this is definitely going to go up the chain at Chrysler. In 3rd gear the truck went to 3500RPM at low throttle (2%), then wouldn't back down even when the pedal was released. It was out of control for a couple seconds, somewhat unnerving at 45 MPH. No question that it is a safety problem now.

 

[Big_Daddy_T]

Glad you were able to reproduce it. Definitely software. That to me means it is fixable.



There was one guy with a 6. 0 that the rpm surged and he hit his wife. Not hard but it knocked her down. They say misery loves company so I figured Id throw you a bone.

 

[TRaddatz]

Just to let you know. I've got an 03 HO that does the same thing, just not to the extreme of yours. I have driven tractor trailers for 15 years. Based on what you are saying, your letting the motor do the work from take off, or 2nd gear with no accelerator right? What happens is, the computer compensates for the engine "lug", and dumps fuel, thus your surge. Have you had the techs try to duplicate this problem with your load on? Mine does it empty (no load), but like I said, not to the extreme of yours. Just out of curiosity, I'd like to know if you can eliminate the problem by slightly depressing the accellerator on take-off. This is how I found I can eliminate the surge with mine. Basically you're fooling the computer by maintaining about a 1000 rpm's on take-off. Just thought I'd give my 2 cents.

 

[JWerkheiser]

I'm used to the normal temporary surge when you launch with zero throttle. However, if you launch with zero throttle then as the RPMs start to recover, place slight pressure on the accelerator, it will go WOT as long as the accelerator isn't returned to zero. Doesn't matter if the accelerator is at 1% or up to 100%, it still is at WOT, forever if you were brave enough to do it.

 

[JWerkheiser]

Well, the regional rep for DC closed my file yesterday, saying problem wasn't reproduced at dealer. I kindly reminded the customer service rep on the phone that we did reproduce it at the dealer and she re-opened it. The dealer is as frustrated as I am. It's nice to know that Chrysler won't take safety issues seriously. They did volunteer to send a tech advisor out to the dealer to experience the problem. Only problem is, it will be 8 days before he comes out. I work for an insurance company that has close ties to people at NHTSA. Perhaps I will put a bug in their ears.

 

[JWerkheiser]

Well, to all with 6 speeds, Chrysler considers this "normal". A tech advisor came and drove the truck, talked to the engineers. The engineers claim the software is designed that way, that the computer gets confused when you apply throttle when the engine is fueling up. Autos won't do this since they don't experience zero-throttle lugging situations. I am very disappointed. I am worried I am going to get into an accident with it.

 

[Pawpaw]

Sounds like a good time to contact the NHTSA.



A runaway condition is never "normal".

 

[rbattelle]

Oh yeah, it's NHTSA time.

 

[JWerkheiser]

Can anyone else reproduce this with a 6 speed? Here's how to do it. launch in 2nd gear - NO THROTTLE pressure at all. You have to let the clutch out quickly enough to get the RPMs to drop. Watch the tach - when the RPMs start to come up, but before they are back to normal, slightly press on the accelerator. Keep the accelerator depressed just slightly (10% or so), then see how high the RPMs will go. Can anyone get it to go to redline? What I am trying to determine is how "normal" this condition really is, and I need your guys' help. PLEASE!!!! Thanks!

 

[bighammer]

I've gotten mine to do it a few times lately after following how you reproduced it. I got to about 26 or 2700 before letting off just the other day. Next time out, I'll see how far it will go.



I'm curious if the guys with a fueling box still have the same problem. (and if it makes it more touchy )

 

[JWerkheiser]

Mine will go to 3500 rpm, then the electronic governor kicks in. Sometimes it gets there quicker than others. I think it is a matter of timing the pressure on the accelerator.

 

[Greg Boardman-RIP]

I got an idea?????



Drive it like you stole it and it will go to 3500 in every gear. What I don't understand is, If you know how to make it happen. Why do you keep doing it over and over. Adjust your driving styles to fit the situation. I understand that the dealer can't help you but we all know how crappy DC is.



Another Idea????????



Wad it up into all the trucks parked on the corner of this dealers lot and take em for all they got. Make sure to total your rig too. Fall out on the ground, grab your back, and start screaming. Tell them you were bringing it back for a refund when it went out of control and spun up onto their lot... .

 

[rbattelle]

You know, the ECM decides that the engine is running at 650 RPM. Therefore, if you manage to drop the engine below 650, it will assume the engine has quit. This might have something to do with what you're experiencing.

 

[JWerkheiser]

Greg, the point is, that in regular driving, it's pretty easy to run across this scenario. I am not saying I enjoy doing this over and over again, and it isn't like you have control over it when it does happen. You launch out of your stop and you have to get back out of it in a hurry sometimes, because it ramps up so quickly. I'm trying to validate what the Chrysler techs are telling me. I can't believe you're getting on my case with this. It's a serious issue and I'm trying to get it resolved, because I have no doubt someone will get hurt or killed because of it. Don't fault me for it, or I'll do it and go to some other forum that will listen.

 

[Greg Boardman-RIP]

I wasn't trying to get on your case. Not into trying to ruffle feathers on anyone. Sorry if I did. Didn't mean too... . Your post sounded like it was something you can duplicate on command. I was just suggesting to not hit 2% throttle while in this situation. My truck will ramp up to 1700 rpm's if I do the same thing. It is hard to get it to do it too. Letting the clutch out fast to lower rpm's to 650 then barely hitting accelerator pedal is something you have to do. Repeat letting clutch out pretty fast trying to make it stall... ... ?



Greg



P. S. Going somewhere else is not going to help us figure out your problem. We are all trying to help figure it out. I think you might need to trade ECM's with another truck and try that. ECM could be bad...