My truck has just started intermittently surging while driving. Now it's doing it maybe 5 times every 50 miles. It doesn't seem to matter what speed I'm at nor is it just when I accelerate or do anything specific. It's just a slight loss of power and it comes right back in immediately.

It happens so quickly that I can't see a change on my Outlook in the rail pressure if there was one. Thats not to say that there isn't one but there isn't enough time to look at the gauge before it's back to normal.

The truck has a GFS 392 lift pump that has about 80,000 miles on it. Could it be the lift pump cutting in and out? Maybe FCA sticking? Anybody else run into this? Thanks

 

my 06 does something similar but usually only with cruise on.It will do it without the cruise but usually its pushing a headwind or pulling a hill. I always just figured it was the cruise searching for the sweat spot. I now have a surge when i am accelerating until the converter locks up so im begining to think it might be a tranny thing.


06 mega, edge att, magnaflow 5", 295/70-17 toyo mt

 

Sounds like the torque converter slipping excessively. Or an issue with the engine tranny management.

 

I think I can rule out the torque converter and tranny management in my situation I do all of that myself...

The fuel filter has about 5000 miles on it. I've added some injector cleaner to the fuel and I'm going to change the filter to rule that out.

I'm not sure what a sticking FCA feels like but I'm almost leaning torwards that. The only thing that makes me wonder is that I don't see a change in rail pressure but because it happens so fast it's hard to tell. I don't have a fuel pressure gauge to monitor the lift pump.

 

Ya i didn't figure it was a tranny problem for you after i rid your sig a little closer. I'm not sure what a sticking FCA feels like, but i've read that it will also keep fueling if you let off. On mine if you go from a stop to wide open and then let right back out of it doesnt quite fueling for a second or two. I read on here some where that a sticking FCA will do that also. Dont know if yours does that to our not, but maybe we are dealing with that.

06 mega, edge att, 5" magnaflow,

 

I have now replaced both my lift pump and my FCA and I still have the problem. It typically just happens between 50-65 MPH and didn't change at all when I changed these parts.

The first thing I did when this started happening was change the fuel filter, so I can rule that out.

I also had to put a new APPS (throttle position sensor) on the truck less than three months ago.

Anybody else got any suggestions on what this might be? The truck is still drivable it just irritates me that I can't figure it out. I'm almost at the point that I take it to the dealer.

On another note, I have a good FCA that I took off of the truck if someone needs it

 

Have you tried pulling your Bully Dog Power Puck and drive around without it to see if it makes any difference?

 

I'm going to try removing the Outlook Monitor as well as changing the programming back to stock. I don't think this will have an effect because I haven't changed the programming in 100,000 miles. It can't hurt to try.

I'm just confused as to what else it could be. It possibly could be the APPS but with it being so new it's unlikely. When the last one went out it felt different and the truck threw a code, which it's not doing now.

 

Any solution to this, my truck is doing this also.


Thanks

Malcolm

 

I still haven't been able to resolve the issue. It's been back to the dealership twice and the tech says that everything looks good on the scanner. My fuel pressure idles around 18-19 and never drops below 15. He says the rail pressure isn't fluctuating either. I disconnected the wastegate and wired it shut and it didn't change anything but when I reconnected it it stopped for about a week. It makes me think that it's in the turbo but I can't pinpoint it and don't want to spend that much money to find out it's something different. I would think if it was fuel or electronics I would get a code because the actual fuel vs what the ECM called for would be different.

I made another post where I thought it was the pressure relief valve that might have something that could help you - https://www.dieseltruckresource.com/...e+Relief+Valve

So to sum it up, no

 

i had the same problem with my 05 ,took it to the dealer ,they said that the truck had water and dirt in the entire fuel system.they replaced the lift pump,6 injectors,inj lines,complete flush and new filter ,after that the truck is back to normal.you might want to check you injectors,and lines

 

I had a similar problem with the surging, so I put the truck back to stock and the problem lessened, turned out the housing on my turbo was cracked. So when running a tune it just enhanced things since I'm adding pressure and fuel..