Intermittant Engine stutter at cruise speeds

[cwbyinjeep]

My poor truck has develloped an intermittant stutter while driving down the highway associated with a temporary loss in power. At first I noticed it most when cruising with a load at around 2100rpms on the interstate. Sometimes it would stutter a couple times within a minute and sometimes not at all for 20+ minutes. It started at 82k on a 3k mile round trip pulling around 7500lbs averaging 80mph. I thougt it might be pedal position related, so I started using cruise control and while it seemed not as frequent, it's still present whether I'm loaded or empty. It would also appear my mileage is down 1-2mpg at cruise speeds.



at 82k I did install a Titan large capacity OEM replacement tank, however inspection of the fuel sending unit appeared good both on initial install and subsequently as I had to adjust the indexing of the sending unit to get the fuel gauge happy.



Truck is the one in my sig and has a Smarty Jr with tow mode and a TS Fuel box that I only use for extra juice on command (dial type). Also has a Roktech modded crank sensor. I'm leaning towards fuel lift pump(which I have an oem spare on hand as mine has the out of tank obsolescent style bolted to filter housing) or the FCA. Not getting any real difference in amount or type of smoke.



Filter has been changed twice, been using DieselKlean addititive for a long time. Haven't thrown a CE Light, but have not hooked up the Smarty to see if there are some codes present.



Any help would be greatly appreciated, doesn't appear to be engine or turbo related failure but ECM or fuel supply related (I hope)

 

[HOBrian]

If it is the LP you don't have much time left until you are sitting on the side of the road. It does sound like a LP but mine went from 7psi to 0 psi in twenty minutes and dead on the road in 30 minutes. I would be looking for the fix really fast.

 

[cwbyinjeep]

Ok, so I have gotten a little bit further with this. Finally got a gauge to verify if the lift pump is working. At idle I typically have 8-9psi and driving down the road I'll maintain 7-8psi cruising at 75mph. However I can get the psi down to 3-4psi range on a long pull in gear with my Smarty Jr on Tow setting not towing a thing.



Had a stranger thing happen tonight though, I was playing around on the way home and did a few low rpm to redline runs while cruising down the interstate. Truck started limping but never threw a code. During the limping PSI stayed over 7 psi fuel pressure as it was limping but would not exceed 20 psi of boost no matter what gear and was completely gutless. After about 4 miles it started to act almost normal again. I'm trying to figure out what would be intermittant and cause all of these issues while not throwing out one engine code in the past 20k miles. Have checked all the intercooler hoses and clamps, all boost fittings are in place. With my 03 I have a wastegate and I'm starting to suspect it for my stutter and occassional power loss as when I lost power I was not down on fuel feed PSI.



Sounds like I better upgrade to a FASS setup or something as to maintain a higher feed PSI on long pulls with a load, but I'm not convinced my stock lift pump is the cause of the stuttering and occassional power loss. It's been doing this for almost 7k miles now and not getting much worse, but definitely not fixing itself

 

[cerberusiam]

You got the LP covered so add a rail pressure gauge and see what it does. An FCA on the way will cause similar symptoms as will an injector solenoid getting weak. No codes either which makes it really tough to trouble shoot.

 

[Turbo Kidd]

I am having the same issue... . I just returned from a snowmobile trip today. I was cruising at 70 - 75 MPH and every once in a while my truck would surge & loss power for a second and then be fine. At first I thought it was a head wind, but it started doing it more frequently. No codes, and I also had my Smarty JR. on the tow setting. The truck runs great other than this surge (Temp. loss of power). I do not think it is the lift pump. I had the upgraded in the tank model installed while under warrenty. I also noticed that when my truck is cold and at idle on my driveway that is surges until it warms up. Could they be realted? What should I be looking for?



Thanks,

Karl (TURBO KIDD)

 

[2Rowdy]

Does it act like the engine is cutting off and on real quick. Mine did that and it was the camshaft position sensor.

 

[Turbo Kidd]

Does it act like the engine is cutting off and on real quick. Mine did that and it was the camshaft position sensor.

It may be like that... it is so hard to explain... . One thing I noticed was the RPM stayed solid, but my boost was all over the place during the shutter?

 

[cerberusiam]

It may be like that... it is so hard to explain... . One thing I noticed was the RPM stayed solid, but my boost was all over the place during the shutter?

Its hard to tell for sure but of your boost is bouncing around its probbaly defueling and dropping the exhaust flow.



FCA is the normal culprit for that.

 

[Turbo Kidd]

Its hard to tell for sure but of your boost is bouncing around its probbaly defueling and dropping the exhaust flow.



FCA is the normal culprit for that.

God, I hope that is it and not the injector(s). I just went for a test run with my Smarty JR. on Performance, Tow & Stock... . the issue persists in all settings. I also notice sporatic power loss on hard acceleration. At times it feels like a dog and other times it pulls like a freight train. ? I have also noticed that for the past month or so that my truck surges big time when the truck is cold & at idle... . It does clear up and idle fine when the truck is warm. I am looking for any and all feedback. I appreciate it very muck.



Thanks!

Karl (TURBO KIDD)

 

[Turbo Kidd]

Anyone else have some feedback for me?



Thanks!

 

[F-15I Ra'am]

Maybe it's the Roctech timing sensor? Dont think you should be running it in combination with the Smarty.

 

[Turbo Kidd]

Maybe it's the Roctech timing sensor? Dont think you should be running it in combination with the Smarty.

I do not have a Roctech timing sensor? I'm not being a jerk, I do appreciate any comments or help from anyone... . I just do not have the Roctech.



Thanks!

 

[F-15I Ra'am]

I do not have a Roctech timing sensor? I'm not being a jerk, I do appreciate any comments or help from anyone... . I just do not have the Roctech.



Thanks!

Sorry, got you mixed up with original poster. I would lean to it being the FCA also.

 

[2Rowdy]

God, I hope that is it and not the injector(s). I just went for a test run with my Smarty JR. on Performance, Tow & Stock... . the issue persists in all settings. I also notice sporatic power loss on hard acceleration. At times it feels like a dog and other times it pulls like a freight train. ? I have also noticed that for the past month or so that my truck surges big time when the truck is cold & at idle... . It does clear up and idle fine when the truck is warm. I am looking for any and all feedback. I appreciate it very muck.



Thanks!

Karl (TURBO KIDD)

By the rest of your posts I would rule out camshaft position sensor. Really sounds more like fca. Good luck.

 

[R-Carter]

Mine did the same thing and it was the tone ring dow pin shared

 

[Turbo Kidd]

Mine did the same thing and it was the tone ring dow pin shared

Can you elaborate on this, as I am not familiar with this?

 

[Turbo Kidd]

Well, I changed my FCA today... . My truck is still F*cked up... ... ... ... . Does anyone have any further suugestions?



Thanks!

 

[trafficmstr]

I was having the same problem on my truck. Take a look at your fuel rail pressure sensor and 3 wire plug. problem ended up being the plug was corroded thats why it was an intermitting problem.

 

[R-Carter]

tone ring looks like a skill saw blade,right behind harmonic balancer,crank position sensor looks at it,,replaced and no problem now,also replaced crank sensor,as was receiving code 0336

 

[KCramer]

My 2nd gen showed similar intermittent power loss, but not the limp-in. My solution was a MAP sensor replacement. Checking the sensor output with a Snap-On reader (engine off) indicated a 50psi manifold pressure, preventing the wastegate from closing.



good luck