My truck surges really bad...

[ASTAR]

At WOT with my Comp on, I get a really bad surge. It feels like the truck isn't getting enough fuel. My FP gauge is showing 16-17psi WOT. I replaced the filters on the FASS and it still does it. If I shut the Comp off, it goes away. The pump wire is tapped with a blue chip tap.

I don't have a injection pump code but I do have a check engine light. I think it is just a transmission code. I have to pull the codes and check but does this sound like a bad Comp box? Its not doing the "all lights lit and flashing" thing or anything or could it be a bad connection at the taped wire?

HELP!

 

[HeavyHauler]

Not a bad Comp box, just your typical timing box. You said it goes away when you unplug the Comp - there's your problem. The way the Edge box tries to control timing is causing your shudder (surge). The big injectors don't help anything either - that's contributing to the problem as well. Also, has the weather in your area cooled down any? Specifically, do you notice it more under 50*? It seems to be more common when the air is cooler.



I've developed a bad shudder with my EZ and Mach 5s. It's very noticable at 30psi and above. I'm selling the EZ and getting one of Marco's new Smarty programmers. The dynamic timing that it provides eliminates the shudder.

 

[ASTAR]

It is a little colder but not alot. I don't think the shudder started when it got cold specifically though. I have had this setup for a while and it has been great but all of a sudden here it is. Weird.

 

[HeavyHauler]

I thought mine just sort of "showed up" too. But the more I think about it, I remember the day when I first noticed it, and I believe the weather had turned a little here in TN.



The cooler air doesn't always aggravate it, but most seem to say that it's more common then.



The thread below has a decent discussion about the timing shudder.



https://www.turbodieselregister.com/forums/showthread.php?t=144780



Marco chimes in with some good info.

 

[ASTAR]

First off, thanks for the help but man, it seems like they are having a lot worse issue. Mine is just like a miss. Its like it is running out of fuel or not getting the fuel it needs. It doesn't shake the truck or anything like that, it just doesn't run hard. The acceleration is horrible when it is happening.

 

[HeavyHauler]

Well, you know how some tend to exaggerate, but I guess it's possible that you're experiencing something other than the timing shudder. But if you unplugged the Comp box and it went away, then there's your answer.



My shudder/surge/miss is pretty much embarrasing when I have someone else in the truck. I took a buddy out for a ride the other day after I swapped turbos and I could tell right away he wasn't all that impressed when the truck started to shudder above 30 pounds of boost. My truck doesn't shake either, but you can feel something going on up front. Had I not already traced this to the EZ box, I could see where someone would think they were running out of fuel or not getting enough fuel like you described.



Hopefully you'll get some more opinions. I'm only one person.

 

[ASTAR]

Hey thanks a lot for your input, I really appreciate it. I am thinking about sending the Comp in for a Drag update and hopefully thay address the problem in the flash if it is the box...

 

[Turbo Tim 1]

How is your Comp ground? Does is go to the intake horn or the battery? I had a bad stumble for quite a while that was finally chased to the ground, I ran it directly to the battery and it's been fine ever since. If you have a code P0253 this might be the problem, at least it was for me.



Of course it could be just what Heavy Hauler is saying too.

 

[ASTAR]

Ok, I'll check the codes and also the ground. It does go to the intake horn so hopefully that is the problem.

Thanks!

 

[nps]

Stumble/Shudder/Surge ... all good words to describe my truck. First noticed it on a cold morning just after putting on Jammer 2's. Unplug the EZ and all is good (except the power :-laf ). Sent the EZ to Edge for testing and they say all is good with it. Put the EZ back on, and for 3 days all is good until this morning (OAT reads 50* on the overhead) and the shudder is back.



When it happens boost bangs around between 20 and 35 psi. Real poor acceleration, and a smoke haze.



Next step is to put the CANBus wires onto a relay so I can turn my EZ on and off from inside the cab.

 

[CumminsAholic]

You didn't unplug the comp, you turned it off right? How is it on a lower setting? I had the same problem with my truck with my box turned on, off it was fine. My box has NO timing, so it definately was not a timing issue. I felt like I was running out of fuel too. Wierd part... I was running with a downpipe only, I ordered exhaust and a fass. I put the exhaust on and the miss went away. It still feels like it's running out of fuel, but it doesn't spit and sputter anymore. I think I adjusted my valves a little tight and that caused the problem, putting the exhaust on created enough backpressure to fix it. I still need to put on the fass and readjust the valves.

I know it doesn't help you out any, but I just wanted you to know it isn't necissarily a timing issue.

Mine did it only at over 2700 rpm, the higher the r's the worse it got. At redline it would miss, stip, sputter... . it really sucked. Try lugging your motor so you're at or below 2500 rpm and see if it misses then.

Corey

 

[TNowak]

I had a similar problem with my truck the morning after installing a chip on a recently purchaced 2002 cummins . I thought that it was the chip so I disconnected it and that seemed to fix it. Until the following morning the shuttering got worse and at a lower rpm. Didnt know what to do so I assumed it was the cold weather. Even though I was running an addative I decided to put it into the garage to warm up. After a few hours it ran great and parked it out in the cold. Next morning, took it out and could barely do 30 mph. with extreme shutter and seemed to be lack of fuel. With 80k on it I replaced the lift pump and fuel filter and problem solved, runs great even with the chip on.

 

[CumminsAholic]

FASS installed. Still feels weird on top end, doesn't miss, but doesn't always have 100% power. I was definately lacking fuel before. It smokes more now and it's faster by the somp feeling. Hopefully have a valve adjustment this weekend, I should check the head one last time anyways.

Corey