Recently while at a stop light or just idling in the yard the engine will surge for a second and then return to idle. it only lasts for a second or two. This has only starrted 500 miles ago, but is a problem when at a light and the truck surges with my foot on the brake. I have a PPE and set on level 4. On our trips snowmobiling we drive 220 miles one way,the PPE has given great power and great fuel mileage. I thought it may be bad fuel and run conditioner in the winter months, temps about zero to -20 in Maine during the winter. The truck has 100 K now and has never given any trouble accept for the usual stuff, fuel filters, wire rub,ice pick fix, etc. Could this be a bad injector, no engine light or codes are present yet

My LB7 did it and put 2 cycle oil in the tank at 1oz per gallon and it smooths it out.Could be a FPR issue

Most likely FPR, mine was changed under warranty. Two cycle as mentioned might free it up...

Fuel pressure regulator (FPR) for sure...mine got so bad that I would have to start putting it in neutral when I would drive to work. When they go bad, they won't often set a code. However, if you look at your fuel pressure through a Tech II the curve will be all over the map instead of a near constant straight line.

yup thats exactly what mine did. new fuel pressure regulator under warranty cured it 100% and ive tried all kinds of additives before taking it to the stealer and nothing helped.

Could be injectors too.

I had one do the same thing, replaced the FPR and that was not it. Had two bad injectors.

Recently while at a stop light or just idling in the yard the engine will surge for a second and then return to idle. it only lasts for a second or two. This has only starrted 500 miles ago, but is a problem when at a light and the truck surges with my foot on the brake. I have a PPE and set on level 4. On our trips snowmobiling we drive 220 miles one way,the PPE has given great power and great fuel mileage. I thought it may be bad fuel and run conditioner in the winter months, temps about zero to -20 in Maine during the winter. The truck has 100 K now and has never given any trouble accept for the usual stuff, fuel filters, wire rub,ice pick fix, etc. Could this be a bad injector, no engine light or codes are present yet

I vote FPR, mine has a slight surge around 1300-1400 rpms, I just put a qt of 2 cycle in it this week, hoping it fixes it. I'm at 98k.

I Have Close To 100k On The Truck, Is It Under Warranty, If Not, How Much Am I Looking At To Buy The Part, Then To Have It Installed.

I Have Close To 100k On The Truck, Is It Under Warranty, If Not, How Much Am I Looking At To Buy The Part, Then To Have It Installed.

When I had mine done I had just over 100K on the clock. That was the first question the dealership asked me because they said it would be covered under the $100 deductable warranty.

Mine had idle surge right before it left me stranded in the middle of the road. Crankshaft sensor went out.

I called the dealer and found out the FPR is covered with a $100 deductable as long as the truck has under 100k, i have 96k now.
It will take the tech ll to tell if it is actually the FPR. It is going in to the dealer on 3-10-09. i cannot get there sooner, will post the outcome.
Thanks SKLEPPY for the dealer tip, you saved me $$$$. Putting 2 stroke oil in for the next few tanks till i get to the dealer.

Dealer will cover the fix with a $100 deductable since i am at 96K miles.
FPR is part of the 100k warranty, hope that is the problem. will post the results, thanks for all the good advise guys.

Where is the fpr located.

On fuel rail.

Drivers side or pass.

Where is the fpr located.

The fuel pressure regulator (FPR) is attached to the cp3 pump. The fuel pressure relief valve (FPRV) is located on the rear end of the drivers side fuel rail.

Mine does this when its getting close to fuel filter changing time. Change the filter and it works fine.

Greg

Changed fuel filter. Didnt help. Put 2 cycle oil and helped for about one day. Could you remove fpr and clean or lub.

I have put in a quart of 2 stroke oil in 1 full tank of fuel until i get to the dealer. It has not surged since the 2 stroke oil has been in the tank, i will see what the rail pressure looks like when it comes up on the computer. I would like to drive it more to see what symptoms pop up, but i am getting close to the 100K warranty and hope to have it covered. Bet they tell me that it is fine and all looks good on the scan, then once i get the truck over 100K they find the problem, at my expense! Truck goes to dealer in 4 days.

Put half tank B-20 bio in tank. Truck smoothed out and runs like new.
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2004 lly Reg. cab 4wd allison, no cat, egr block, pvc re-route, opened up side of air box.

Mine just started doing this right after I changed my fuel filter and a new tank of gas. it smokes bad too. but it only does this while in drive and foot on break. I only have 35k miles..bad gas? fpr? injector(s)?

The ice pick trick on the injector connectors is the first thing I'd try. Mine was doing the same thing as yours tightened up the connectors on the #2 and # injectors and problem vanished.

Alan

how much is a new FPR and how hard is it to change?

I wanted to see if the PR would show up on the scan, turns out injector #2 and # 4 were bad. The dealer fixed the problem and I have a $100 deductable for the fix, thats ok with me. I had ice picked #2 and #7 a year or so back, i will make sure they are still snug after the dealer fix.
The 2 stroke did smooth things out till I got the truck to the dealer.