Intermittent Engine Stumble/Hesitation for Split Second During Acceleration

[Krew]

Hi All,

I had thought I posted about this months and months ago but that might have been on a different forum as I can't find the post here. I've searched as well and can't quite find anything that matched my symptoms.

Summary: Sometimes on acceleration, the truck hesitates for a split second and then resumes right along like nothing happened. This issue has been on going for the better part of the year and I have yet to find the problem. I'm not getting any codes and am not able to reproduce reliably... its pretty random. Engine kicks over and idles as expected as well....

In case it isn't in the signature, I have Smarty S06 (latest software) on SW7, Quadzilla Boost Fooler, Fass 95, SB Instake, 5" Cat back, Edge insight ( for gauges), Stock Lift Pump Deleted, fully built 48re.. I think thats about it on the perf side of things... Will update if I can think of anything else

Things I've Tried:
- Fuel Filter/ Water Separator change - filter was clean and in good shape. (Problem went away for a couple of months after this, not sure if coincidence or not)
- APPS replaced with TIMBO
- Fresh Batteries, replaced originals... surprisingly...
- Made sure terminals and grounds were all snug
- Removed tunes back to stock, problem still happens
- FCA changed

Between these changes I've been trying to find a more programmatic way to find the problem without throwing parts at it.

I should also mention that I have the oil analyzed after every oil change and outside of a Iron being a bit high (which I've read is normal in the 325 HO engines, all seems to be in order)


Things I'm Thinking about doing:
- Crank/Cam Position Sensor change
- MAP sensor change
- Look for a short somewhere....
- Pulling Boost Fooler to see if that makes a difference
- LP fuel pressure gauge (to be installed) to check if there is a problem with the FASS, thinking perhaps the filter change making the problem go away for a few months may point to a pressure problem...


Other than the above... do any of you have any ideas? It almost feels like every once in awhile there's a quick lack of fuel. Watching the gauges I've not been able to detect any major changes.. but it happens so fast that it makes it difficult. Hoping to rule out the FASS taking a dump with the pressure gauge.

Like I said above, no codes is making this problem a nightmare to track down... one would think with all the sensors on this thing that SOMETHING would show up...

 

[Krew]

nothing eh? Yeah... this has me stumped too lol

 

[Krew]

last bump before giving up...

 

[cerberusiam]

Boost fooler could be the culprit, there were issues with them. With a Smarty you don't need the fooler. Just off the WG actuator and put a boost elbow on it.

Random stuff is hard to find, LP and Rail pressure gauge might tell you something if you see it happen.

 

[Krew]

Boost fooler could be the culprit, there were issues with them. With a Smarty you don't need the fooler. Just off the WG actuator and put a boost elbow on it.

Random stuff is hard to find, LP and Rail pressure gauge might tell you something if you see it happen.

THANK YOU For responding! I hadn't realized the boost fooler wasn't needed with the Smarty. I'm happy to remove it really as its quite ugly haha. I have rail pressure monitored already, plan on adding a LP gauge as well, just waiting on the sensor to come so I can plumb it in. Can you explain your thoughts on the boost elbow?

 

[cerberusiam]

The boost elbow just limits the boost to around 35-37 psi in my experience. Get a boost fooler and add the correct size nipple for the boost reference hose on the turbo and install it with the bleed hole towards the WG actuator with the screw in elbow bottomed out. The boost elbow with the high drive pressures limit the boost it can make in normal driving. With the WG actuator Off or boost reference hose clamped it will go well over 40 psi with enough fuel and rpm. Not really good for that turbo the way it is designed. Shut the WG controller off with the Smarty and load tune, disconnect the controller, add the boost elbow and you should have no CEL and boost limi8ted to something that is conducive for long life of the turbo. I have over 300k on this very setup running a 420-450 HO 90% of that time and it frequently sees upper 30's for boost.

 

[pgleavitt]

I just experienced the same thing this weekend and it seemed to occur when my fuel was at or below 1/3 of a tank. I’m running a 4g air dog and suspect it may be the in tank pickup. I also noticed my rail pressure would drop and recover very fast and just barely see it on my Edge CTS2 monitor. Also this was under heavy go pedal for passing.

 

[tim0]

Hi All,

I had thought I posted about this months and months ago but that might have been on a different forum as I can't find the post here. I've searched as well and can't quite find anything that matched my symptoms.

Summary: Sometimes on acceleration, the truck hesitates for a split second and then resumes right along like nothing happened. This issue has been on going for the better part of the year and I have yet to find the problem. I'm not getting any codes and am not able to reproduce reliably... its pretty random. Engine kicks over and idles as expected as well....

In case it isn't in the signature, I have Smarty S06 (latest software) on SW7, Quadzilla Boost Fooler, Fass 95, SB Instake, 5" Cat back, Edge insight ( for gauges), Stock Lift Pump Deleted, fully built 48re.. I think thats about it on the perf side of things... Will update if I can think of anything else

Things I've Tried:
- Fuel Filter/ Water Separator change - filter was clean and in good shape. (Problem went away for a couple of months after this, not sure if coincidence or not)
- APPS replaced with TIMBO
- Fresh Batteries, replaced originals... surprisingly...
- Made sure terminals and grounds were all snug
- Removed tunes back to stock, problem still happens
- FCA changed

Between these changes I've been trying to find a more programmatic way to find the problem without throwing parts at it.

I should also mention that I have the oil analyzed after every oil change and outside of a Iron being a bit high (which I've read is normal in the 325 HO engines, all seems to be in order)


Things I'm Thinking about doing:
- Crank/Cam Position Sensor change
- MAP sensor change
- Look for a short somewhere....
- Pulling Boost Fooler to see if that makes a difference
- LP fuel pressure gauge (to be installed) to check if there is a problem with the FASS, thinking perhaps the filter change making the problem go away for a few months may point to a pressure problem...


Other than the above... do any of you have any ideas? It almost feels like every once in awhile there's a quick lack of fuel. Watching the gauges I've not been able to detect any major changes.. but it happens so fast that it makes it difficult. Hoping to rule out the FASS taking a dump with the pressure gauge.

Like I said above, no codes is making this problem a nightmare to track down... one would think with all the sensors on this thing that SOMETHING would show up...

Hi All,

I had thought I posted about this months and months ago but that might have been on a different forum as I can't find the post here. I've searched as well and can't quite find anything that matched my symptoms.

Summary: Sometimes on acceleration, the truck hesitates for a split second and then resumes right along like nothing happened. This issue has been on going for the better part of the year and I have yet to find the problem. I'm not getting any codes and am not able to reproduce reliably... its pretty random. Engine kicks over and idles as expected as well....

In case it isn't in the signature, I have Smarty S06 (latest software) on SW7, Quadzilla Boost Fooler, Fass 95, SB Instake, 5" Cat back, Edge insight ( for gauges), Stock Lift Pump Deleted, fully built 48re.. I think thats about it on the perf side of things... Will update if I can think of anything else

Things I've Tried:
- Fuel Filter/ Water Separator change - filter was clean and in good shape. (Problem went away for a couple of months after this, not sure if coincidence or not)
- APPS replaced with TIMBO
- Fresh Batteries, replaced originals... surprisingly...
- Made sure terminals and grounds were all snug
- Removed tunes back to stock, problem still happens
- FCA changed

Between these changes I've been trying to find a more programmatic way to find the problem without throwing parts at it.

I should also mention that I have the oil analyzed after every oil change and outside of a Iron being a bit high (which I've read is normal in the 325 HO engines, all seems to be in order)


Things I'm Thinking about doing:
- Crank/Cam Position Sensor change
- MAP sensor change
- Look for a short somewhere....
- Pulling Boost Fooler to see if that makes a difference
- LP fuel pressure gauge (to be installed) to check if there is a problem with the FASS, thinking perhaps the filter change making the problem go away for a few months may point to a pressure problem...


Other than the above... do any of you have any ideas? It almost feels like every once in awhile there's a quick lack of fuel. Watching the gauges I've not been able to detect any major changes.. but it happens so fast that it makes it difficult. Hoping to rule out the FASS taking a dump with the pressure gauge.

Like I said above, no codes is making this problem a nightmare to track down... one would think with all the sensors on this thing that SOMETHING would show up...

I’ve had the same problem on my near stock 03 HO, 48re. I recently installed FASS 95. And it happened again after a couple months after installed. After thinking on it I decided to installed G&R sump and replaced both filters. Fuel level seems not to matter when the hesitation occurs. I’ve considered fuel pressure gguage but it would be luck to catch it.
Let us know if you found anything yet,

 

[Krew]

I’ve had the same problem on my near stock 03 HO, 48re. I recently installed FASS 95. And it happened again after a couple months after installed. After thinking on it I decided to installed G&R sump and replaced both filters. Fuel level seems not to matter when the hesitation occurs. I’ve considered fuel pressure gguage but it would be luck to catch it.
Let us know if you found anything yet,

Sadly I have not been able to track this down. I do know that it repros more reliably when using tow/haul mode.

Sorry I couldn't give better news. Let me know if you find out what it is as well.

EDIT: I added a guage to the LP fuel it stays between 16 and 18, right where it should. So its not that.

 

[seafish]

Could also be your Smarty...try returning to stock and see if the hesitation still happens.

 

[Krew]

Could also be your Smarty...try returning to stock and see if the hesitation still happens.

Tried that too, no dice

 

[tim0]

Sadly I have not been able to track this down. I do know that it repros more reliably when using tow/haul mode.

Sorry I couldn't give better news. Let me know if you find out what it is as well.

EDIT: I added a guage to the LP fuel it stays between 16 and 18, right where it should. So its not that.

I did install the G&R sump and put fresh filters on. The Fass 95 is much quieter. I’ve just completed a 4400 mile trip pulling a 6500 lb trailer. There were plenty steep grades on the trip. The engine never missed a beat. If it happens again, I will let you know but it seems that something was going on with the stock pick up.

 

[Krew]

I did install the G&R sump and put fresh filters on. The Fass 95 is much quieter. I’ve just completed a 4400 mile trip pulling a 6500 lb trailer. There were plenty steep grades on the trip. The engine never missed a beat. If it happens again, I will let you know but it seems that something was going on with the stock pick up.

Thats good to know, I plan on putting a sump in as well.

 

[Krew]

Well, fingers crossed, I think I fixed it. Noticed my Fass wasn't kicking on the other day so I replaced the pump and so far it hasn't had this issue. Maybe it was introducing air or something... who knows...