Surges or Flat spots during acceleration

[PMedina]

As you can see from my signature, I'm used to driving a 1st gen. I need to update my signature for the 2004. 5 6spd 4X4 that I have put about 7K miles on. This new truck does not accelerate very smoothly. If I accelerate moderately from 1000 to approximately 2700 RPMs there are several surges or flat spots along the way. I notice it most in 3rd and 4th gear. I'm wondering if this is normal of if it is something I need to look into.



Thanks,



Paul

 

[rbattelle]

I'm not sure if this will help, but I do notice that torque/power falls off as RPM increases and you have to apply more throttle as the engine accelerates to keep power flowing. I've never driven a 1st gen (or a 2nd gen, for that matter), so maybe they're not like that?



-Ryan

 

[JTeague]

This seems to be normal for the 325/600or610 engines. They more lag than the 305/555 engines and the power is more peaky. I work at a dealer and drive them everyday(I know, flame away. ) They are no where near as smoothe as the earlier models. Might try getting it reflashed if you have not done so already. I've talked to a couple guys who say their truck run much smoother after the flash along with a little better fuel mileage.

 

[p-Bar]

Paul,

I would take it in and start complaining. While you are there take a new one out for a test drive with the manual trans and prove it to em'. You spent to much money to have it running like a piece of crap.



Don

 

[MLee]

This seems to be normal for the 325/600or610 engines. They more lag than the 305/555 engines and the power is more peaky. I work at a dealer and drive them everyday(I know, flame away. ) They are no where near as smoothe as the earlier models. Might try getting it reflashed if you have not done so already. I've talked to a couple guys who say their truck run much smoother after the flash along with a little better fuel mileage.

So what reflash number was done, do you know the number? or just tell them what it is doing, and let them do the fix, and hope they don't use the excuse__they all do it.



marv.

 

[Gary - K7GLD]

UMMmmmm - you guys are MISSING the point of his complaint:



"If I accelerate moderately from 1000 to approximately 2700 RPMs there are several surges or flat spots along the way. "



He's talking about surges and flat spots *as* he accellerates steadily thru the engine's operating RPM, NOT a "peaky" power curve...

 

[jnelson]

A little research will show reflash "TSB" for white smoke/overhead recalibration. I had it done to mine. I did not have white smoke and I dont pay much attention to my overhead mpg - but - the reflash completely downloads your current settings in your trucks brain and uploads any all updates from "S. T. A. R. " and should "repair" any problems in your software. Your problems sound as if they could only be software related.

 

[MLee]

As you can see from my signature, I'm used to driving a 1st gen. I need to update my signature for the 2004. 5 6spd 4X4 that I have put about 7K miles on. This new truck does not accelerate very smoothly. If I accelerate moderately from 1000 to approximately 2700 RPMs there are several surges or flat spots along the way. I notice it most in 3rd and 4th gear. I'm wondering if this is normal of if it is something I need to look into.



Thanks,



Paul

Does it have more flat spots than surges? like the accelerate isn't moving in the direction it should to keep you going forward? and feels like it hesitates? my sons is doing something similar to this, and he is working on a water in fuel idea, it has been doing it since it got cold.

Marv.

 

[Gary - K7GLD]

For what it's worth - not that it helps anything, the 24-valve 2nd generation trucks often do the same thing in colder weather - it SEEMS to be an ECM programming issue, but no one seems to have pinpointed it or corrected it so far...

 

[JTeague]

There were 2 seperate TSBs on the 600 ECM software. The first TSB is 18-007-04 for engine serial #s 57130285 through 57149668 which is roughly between trucks built from 12-10-03 to 2-2-04. This TSB is for white smoke, stumble, misfires, and a flat spot from 1200 to 2500 RPM. The second TSB is 18-037-04 which supercedes TSB 18-007-04 includes engine serial #s 57130285 through and including 57246361 is for poor fuel economy and white smoke in cold conditions. This TSB applies to all 325/600 trucks built until 8-04. You will get the latest software revision when you get your ECM flashed. So depending on when your truck was built there may be a software update to cure your problem.

 

[bombero]

JTeague; Thanks for your input. I am now going to get mine reflashed. Runs great but I would like to get better miliage. (Dont we all). Just to bad you not the one doing the work!!

 

[MLee]

Thanks to all for your in put on my part, Thank goodness for the good o'l P7100 and its manual capabilities.

Marv.

 

[DocDetonancour]

Thanks to all for your in put on my part, Thank goodness for the good o'l P7100 and its manual capabilities.

Marv.

My 04 runs great, with no stumbles. Wouldn't consider going back to the 96. Doc

 

[PMedina]

Thanks for all the input. I believe using the term flat spots in the rate of acceleration is the better way to describe the issue I am talking about. The flat spots feel like the fuel is being reduced for a short period of time, a period that covers 50-150 rpms, and occurs three of four times when accelerating from 1000 to 2700. In other words, as I am steadily applying more throttle to hit 2700 rpms there are several points along the way where the acceleration rate is being dramatically reduced for short periods. You can actually watch the movement of the tachometer slow during the flat spots.



I have not had any TSBs carried out on it yet. The engine number is 57216205 which would make it a candidate for TSB 18-037-04.

 

[Billy Golightly]

My 03 305/555 does that in the upper RPM ranges, I notice it mostly around 2700-2800 when in 5th. Above that it kind of picks back up again. I always figured it was just the torque curve.

 

[Vaughn MacKenzie]

I had the exact same thing on my '03. . . good ol' Rollercoaster Power Delivery characteristic. It was pretty annoying. Push down the pedal X amount and hold it steady in 4th or 5th gear and as the RPM climbs from say 1300 to 2600 RPM the power level rises and falls in waves. It's like the ECM is watching and saying "woops just a bit too quick there, back off the power. . . now that's about right. . . Uh oh we've flattened out too much. . . just a bit more juice. . . ah, there we go . . . whew, he finally shifted"



I figured it's one of the quirks of the HPCR motor and less than perfect D/C software. This 12-valve I have now blows the '03 away, what you dial in is exactly what you get, RIGHT NOW. No surges, delays, no monkey business Oo.



Vaughn

 

[rbattelle]

Vaughn's been around a long time, and he's no fool... it's interesting that he ditched his 3rd-gen for a 12v. Very interesting. As I mentioned in another thread, if I could have a 12v in my truck I probably would. But I'd have to turn it up to at least 305 hp (which it appears Vaughn has done with his... maybe a bit more?).



-Ryan

 

[Billy Golightly]

It is a little weird to me. For a while I wondered if something was wrong, but I had kind of gotten use to it, and if you guys are having the same thing then it must be normal I guess.

 

[Gary - K7GLD]

"if you guys are having the same thing then it must be normal I guess. "



There's a *BIG* difference between what is "common", and what SHOULD be normal and acceptable...



It would be a cold day in %#*@ before *I* would accept ratty performance in a $30,000+ truck! :{

 

[MLee]

On your 3rd gen's Do the flat spots happen while the engine is cold? or after it has warmed up???

My sons acts up after it has warmed up.

Don't these engines have a drive "by wire" type set up? or something similar?

Marv.