Pulsing under load
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Post Fiend
Joined: May 2009
Posts: 5,470
Likes: 3
From: Pea Ridge, AR
Pulsing under load
After a small trip I had over the weekend noticed pulsing, high pitched sound. The sound is very similar to the "sneeze" heard under heavy acceleration at shifts. The "service engine soon" light flickers on and off timed with the sounds. I can never get the code to stick on to be checked to find out what is causing it. The "pulse" cannot really be felt in the drivetrain any where. but speed at highway speed (70-75) on steep grade hauling bass boat was slowly falling off. It kicks in about 1/2 to 3/4 the way up the hills and probably drops off 2 or 3 MPH by the summit, of course when I began to notice the issue I do not keep my foot in it for fear of damaging something. I've never had this occur flat land hauling or definetly empty. Just after this weekends trip through the Boston Mountains here in Arkansas, hauling the boat. Any suggestions of things to check or ideas would be greatly appreciated.
Post Fiend
Joined: Mar 2007
Posts: 26,966
Likes: 50
From: Texas
First off, if the SES light comes on for a second, there will be a code stored in the computer, but not all scanners can read the codes in our trucks.
Your noise description sounds like turbo surge. What kind of modifications have you done to your truck? Intake, chip, etc?
Your noise description sounds like turbo surge. What kind of modifications have you done to your truck? Intake, chip, etc?
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Post Fiend
Joined: May 2009
Posts: 5,470
Likes: 3
From: Pea Ridge, AR
Thanks for the reply not many mods just 6637, muffler delete, wastgate disable. I've read so many post with people referring to surge and I never really knew what they were describing, the truck does not actually seem to surge the SES light use to do the same thing with factory box, but I was unable to hear this noise until the 6637 mod. Part of the reason for the mod was my thought about the possibility of the factory box restricting airflow causing some kind of error. BTW every parts store I've spoken to about scanning for stored codes says they can only check if the light is on, should I go to the dealer to have them retrieved?
Post Fiend
Joined: Mar 2007
Posts: 26,966
Likes: 50
From: Texas
There's a video clip on here somewhere that gives an example of surge. I'll try and find it if no one else finds it first. Surge with factory tuning is rare, but still possible. What rpm's were you running when the problem happened? (if you noticed)
We've got a few members in Arkansas. Maybe one of them will see this and offer to scan your truck for free. If not, you don't have to go to the dealer. A good independent diesel shop should be able to scan it for you.
We've got a few members in Arkansas. Maybe one of them will see this and offer to scan your truck for free. If not, you don't have to go to the dealer. A good independent diesel shop should be able to scan it for you.
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Post Fiend
Joined: May 2009
Posts: 5,470
Likes: 3
From: Pea Ridge, AR
Right around 2000 +/- 200 like I said this instance was at interstate speed with cruise control set at 75 and it would scrub off speed to around 72 which I know is not that horrible, but the sound and light made me think something was wrong. It will do it at slower speeds and different gears say for instance a very steep hill from a dea stop once RPM's build all the way through the shift if under acceleration the entire time trying to build speed
Post Fiend
Joined: Mar 2007
Posts: 26,966
Likes: 50
From: Texas
Fleet Owner
Joined: Jun 2004
Posts: 25,090
Likes: 1,112
From: Rio Rico, AZ.
Thanks for the reply not many mods just 6637, muffler delete, wastgate disable. I've read so many post with people referring to surge and I never really knew what they were describing, the truck does not actually seem to surge the SES light use to do the same thing with factory box, but I was unable to hear this noise until the 6637 mod. Part of the reason for the mod was my thought about the possibility of the factory box restricting airflow causing some kind of error. BTW every parts store I've spoken to about scanning for stored codes says they can only check if the light is on, should I go to the dealer to have them retrieved?
Pulling the boat at that speed up hill will easily drive the boost over 24 psi, even on stock tune.
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Post Fiend
Joined: Feb 2007
Posts: 7,191
Likes: 4
From: Blairsville,Ga
That was my thought with the waist gate disabled.I had a new map sensor that would defuel at 18lbs but it would shut it down til about 50 mph or about 30 seconds before it would refire
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Fleet Owner
Joined: Jun 2004
Posts: 25,090
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From: Rio Rico, AZ.
That's interesting.
When my truck defueled it would simply reduce a little power until the boost fell off.
Still ran ok.
Never cut out like that, that sounds like a dangerous bit of programming.
When my truck defueled it would simply reduce a little power until the boost fell off.
Still ran ok.
Never cut out like that, that sounds like a dangerous bit of programming.
Post Fiend
Joined: Feb 2007
Posts: 7,191
Likes: 4
From: Blairsville,Ga
It did act strange the boost gauge would hold the same reading 5 to 10 seconds after the tach and speedo started dropping
since then I put the old map sensor back on,replaced Hypertec with DP,and new turbo with WW and pulling the same hills the waistgate will open at about 22lbs but doesn't defuel
since then I put the old map sensor back on,replaced Hypertec with DP,and new turbo with WW and pulling the same hills the waistgate will open at about 22lbs but doesn't defuel
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Post Fiend
Joined: May 2009
Posts: 5,470
Likes: 3
From: Pea Ridge, AR
I'm glad people are chiming in no chip in my rig and thanks f-350 6 after some searching I was able to find the vid. That is the sound I do not have a boost gauge to see the effects though, I apologize for my ignorance on defueling and do not know what it is my thoughts were possible overboost, but it was actaully worse with the wastegate hooked up. when I think of surge I think of the feeling like running out of gas almost like cutting out, which is not felt at least in the SOTP dyno, if I stay in the throttle it will still gain speed just the sound is so noticable I feel like I'm going to break something, thats why I am looking to you guys I appreciate this site very much and wish I knew of it sooner soo much info even before I signed up.
Cross-Country
Joined: Oct 2013
Posts: 51
Likes: 0
From: Eastern Washington State
This sounds very much like what I'm hearing in my engine. I get the high pitched pulsing sound when going up a long hill while pulling the mule trailer. Does not seem to have any affect on power, speed, or rpm but does sound troubling. 
I don't know where to start with this...
1999, 7.3, no mods, injector rebuild (one replaced) only 500 miles ago but heard this before that,
I don't know where to start with this... 1999, 7.3, no mods, injector rebuild (one replaced) only 500 miles ago but heard this before that,
Fleet Mechanic
Joined: Jul 2010
Posts: 1,753
Likes: 34
From: Los Angeles, Ca.
Probably because they're all ignorant. Have it scanned, the code might be stored, it does happen.
It's a Van Gogh
Joined: Feb 2010
Posts: 7,813
Likes: 1,335
From: Elk Grove, CA
This sounds very much like what I'm hearing in my engine. I get the high pitched pulsing sound when going up a long hill while pulling the mule trailer. Does not seem to have any affect on power, speed, or rpm but does sound troubling. I don't know where to start with this...
1999, 7.3, no mods, injector rebuild (one replaced) only 500 miles ago but heard this before that,
I don't know where to start with this...1999, 7.3, no mods, injector rebuild (one replaced) only 500 miles ago but heard this before that,
Cross-Country
Joined: Oct 2013
Posts: 51
Likes: 0
From: Eastern Washington State