High RPM Miss

B

BGarofalo

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Joined
Jun 14, 2006
Messages
248
Im trying to figure out what this problem is with my truck. I have an 03 that has a miss to it at high rpm.
Symptoms:
1. At idle when you put your foot to the floor, at about 3000 and up, it breaks up and pops real bad. Its like the truck is defueling but not how it should be...
2. This is with no electronics on at all, and it dosent change with electronics on either.
3. With the TnT-R it will rev to about 3500 and break up and pop real bad and not go any higher. At times I can get it up further but it still breaks up and pops bad.
4.This is not a new issue it has been ongoing for a while now but is getting worse

I have tried alot of things already in my diagnosis but am running low on ideas...
I have not checked rail pressure readings, im waiting on a gauge to be delivered... While im in limbo does anyone have any ideas??:poke:
 
Sounds like compression loss, if you ask me. I spoke with you the other night, but can not recall what all you have ran on the truck. How does the exhaust sound? I take it the engine is under load at WOT when it does this?
 
Yea that was me... It dosent matter load or no load. The truck runs perfect till you get above 3k. The exhaust will fire out some good size flames while breaking up. Almost like a timing issue...
 
Let me know when you get it figured out, mine does it at 2000rpms, sometimes will go through it and rev on up sometimes it wont.

See if it will do it right after you start it up. As soon as you turn the key on start it and see if it will rev up without it breaking up. I can do that to mine as many times as I want, revs up right after a restart then acts up after that.


Oh ya, forgot to mention I have replaced every possible sensor, pump, fca, ecu, harness, etc that can be replaced and had Don flow the injs all to no avail.
 
BDP I tried what you said an sure enough if I hold my foot to the floor when the truck is started It will rev clean to about 3900 and after a few seconds though it will begin to break up.
You said you have tried a new ECM? That is what I was leaning towards but if it didnt help you im not to sure its going to help me...
I dont think this is problem with a hard part. Im thinking this is an electrical problem.

What its not
Injectors are ruled out,
Electronic boxes are ruled out,
Low Pressure Fuel supply issues are ruled out,
BDP add some of yours if you can

Any more suggestions?? :pop:
 
hahaha, my list of parts changed

ecu
apps
map sensor
intake air temp (maf)
cam
crank
both fca's
cp3 controller
both cp3's plus had them taken apart and checked
cross tubes 3 times


Other things done-
sent injs back to Don- he says they flow perfect
also sent rail and all the lines and he said they were clean
had pumps checked and they are good plus I changed pumps anyway
redone every ground on the engine plus added some
checked for voltage drop at the ecu
checked for fuel return blockage

All of that and it still does it. I have notisced that it will rev through it with a Smarty installed, no smarty and it will not go past 1800rpms. With the Smarty on it will go through it but sometimes it will clear up then miss again up top, sometimes it wont.

I pulled Saturday and fully planned on shutting the truck off once the slack was out of the chain but once it was hooked to the sled it revved fine so I went with it and it ran great, broke front axel shaft though. Then on the way home it ran like total arse and was missing like crazy. Only differance I know of was when I pulled I had about 210 deg water temp and on the way home it was about 150deg. I plan to explore that more but trucks apart replacing the stub shaft that I broke. Here is the video of my 2wd hook with the broke front end, ran good for the hook but temp were very hot. Maby with two trucks doing this we can find a solution, I know I am getting tired of it pulling fuel on the top end, I am running Flux 6's and Smarty revo but still have to run the TST way on up to get the dang thing to fuel. No TST and it doesnt hardly smoke at all and wont pull past 3500 rpms with a load.

Click here to see Video
 
It really sounds like we are having the same problem. Here are two clips I just took. One is reving the truck after it is already running. You will hear it break up real bad. The other is starting the truck with my foot already to the floor. It will rev up and hold then break up.

What year truck is yours??

Mine did it with stock injectors and it didnt change with the new ones I just put in.


I really want to get this thing figured out. I cant believe yours craps out at 2000 rpm. I would have sold the truck by now :bang:bang

http://www.youtube.com/watch?v=3cdexcuVG9k
http://www.youtube.com/watch?v=86t8Q3ooxLI
 
Mines a 05 motor. Its always had a bit of a low end stumble but recently after hanging an injector open it got much worse when the clean injs went back in.

Mine sounds simular to that but about ten times worse when its at its worse. It will pop like a fircracker and miss. I will try and get a vid of it actin up, its really sumthin to see.
 
I put a rail pressure gauge on it today. The pressure comes up how it should and at high rpm when it starts breaking up there is no change in rail pressure... It stays where it is.

To me that eliminates fuel delivery as a culprit.

Do you think it would be worthwhile to data-log one of the injector electrical currents? If there is a change in the voltage behavior (while breaking up) at the injector then that shoud mean it is a programming problem...? ?


Im just thinking outloud...

No other ideas? Bueller..., Bueller..., Bueller...
 
Check the voltage at the bottom wire at the FCA and see what yours does. Mine is right at 4.9-5.2 but spikes every few seconds to full voltage (14+) and others I have probed do not do that.

When mine revs up fine pressure is only 9000 when it acts up pressure is 15-18k. If I start it up and take it to the rev limiter it will sound great but as I hold it there it will start to run bad and rail pressure will start climbing.
 
I believe im on to something. My truck revs up perfect the way its supposed to now. Let me try a few things a to make sure it stays this way and ill let you know what I did.
I havnt gotten a chance to check the voltage on the FCA yet either. I will try it out tonight hopefully.
 
I myself am anxiously awaiting your response..

My truck does just about the same thing but only under load...
 
BGarofalo inks he found his in a bad connection at the cam sensor. I have already tried another harness on mine and it made no differance. The other day I pulled the plugs and one female pin looked kinda funky on the stock harness at the crank but a female pin on both of the TST plugs are missing a piece of the pin that make contact. (Problem has existed with out TST as well) So I tightened them up with a pick and replugged them up, they were tight enough to be hard to plug in but still no better.

But then I was driving it on a rough road and it quit, had crank and cam codes and would not restart. Pulled on the harness and then it fired up. Not sure if its in the TST harness or the stock harness but something is not getting a good connection in there somewhere. Will try some more stuff next week.
 
BGarofalo said:
Im trying to figure out what this problem is with my truck. I have an 03 that has a miss to it at high rpm.
Symptoms:
1. At idle when you put your foot to the floor, at about 3000 and up, it breaks up and pops real bad. Its like the truck is defueling but not how it should be...
2. This is with no electronics on at all, and it dosent change with electronics on either.
3. With the TnT-R it will rev to about 3500 and break up and pop real bad and not go any higher. At times I can get it up further but it still breaks up and pops bad.
4.This is not a new issue it has been ongoing for a while now but is getting worse

I have tried alot of things already in my diagnosis but am running low on ideas...
I have not checked rail pressure readings, im waiting on a gauge to be delivered... While im in limbo does anyone have any ideas??:poke:
Click to expand...

head gasket crossing
 
Garofolo and Beaner- do your trucks miss EVERY time you start them, or intermittent?
 
Its fine when you start it and within a fews seconds it will not be missing at idle but will miss when you try to rev it up.

I dont see how it could be a hg crossing due to the fact that you can shut the truck off at any time and start it right back up and it will run perfect then go bad again.
 
Sorry for the delay. As BDP said i found a bad connection in the harness at the cam sensor. Im not sure why it wasnt throwing a code but it cetainly fixed my problem. The truck will run cleanly right to redline with out missing a beat.

On these common-rail engines isnt it true that the computer will use both cam and crank sensors to locate engine positon upon start up but then only use one or the other while actually running?
If so, that would make sense why when holding full throttle at start up it will rev clean then promptly start to break up...

I think it is too perfect the symptom in my case to be a headgasket issue. It would break up at the same RPM and then change slighty to a differant RPM when the smarty was installed.
In my case it would miss very consistantly after starting the truck.
 
I have watched both sensors on live data and they both read the same when running. I have felt its always been like a bad crank sensor. I have had them get cracked before and act simular to this but with a brand new crank and cam sensor I dont think its the sensor its self. I figured a different harness would rule out the wirring but after it died the other day I think it may still be in there somewhere.
 
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