Engine Surging, Poor Fuel Economy - Diesel Forum

JimmyRice · 11-02-2009, 08:36 AM

I've been having RPM surges for about 3 months now. I don't notice it at highway speeds, only at lower speeds or off throttle like when you're pulling into a parking lot. Also, does not seem to happen with a cold engine, only with the engine at normal operating temp. As it's gotten colder here in Colorado, it seems like if the temp is below 40, there is no problem...but that might just be wishful thinking. The dealer installed a new ICP sensor and wire harness and that didn't fix the problem. I installed a new cam position sensor and that didn't fix the problem. There are no trouble codes shown on my reader and there is no engine light on. Anybody have ideas on a solution? I'm at 100K now and have never had a problem till this.

bgoux · 11-02-2009, 09:29 AM

Welcome to the surgo-matic club
I too have the same symptoms,it has been going on for over a year, been thru the ICP and EGR valve cleaning and replacment cycle, it seems to be a tough fix, never any codes, outside air temp seems to be a factor.
if I pull the AIT2 (air intake temp) sensor and clean it, it seems to stop for a week or so but always returns, it has a cage on the bottom that fills with carbon over time, I have had the oil cooler egr cooler full slam as well.
I read on this forum that the VGT solinoid "CAN" cause this but you have to be comfortable with throwing parts at it. I am not.

AIT sensor is in front of turbo with a 2 wire connector, 13/16 plug socket is perfect fit

My fuel milage seems unaffected tho, wish I could be more help

JimmyRice · 11-03-2009, 03:08 PM

Thanks for the feedback. You're right...I don't want to just keep throwing parts at it. I'm a decent shade tree mechanic and don't mind trying to fix almost any problem, but with no good place to start, I don't want to just keep throwing darts. And that seems to be exactly what the dealership has done as well. My symptoms seem the same as your's except my milage dropped from about 15.8 MPG to 12.2 MPG. I will give the other sensors a good cleaning this weekend and see if that helps.

hooknline · 11-03-2009, 07:10 PM

have you guys checked the specs on the IPR???? that is also a likely cause

JimmyRice · 11-03-2009, 09:22 PM

I have not checked it but I will try that this weekend too....when I'm not hunting elk. Thanks for the input.

**MelloMike** · 11-04-2009, 03:12 PM

This may sound stupid but have you checked your oil level? Levels at the MAX mark while the engine is warm have been known to cause the surging problem. If it is near the MAX drop and quart and see how it performs.

CAMPINGTOM · 11-04-2009, 03:23 PM

Quote:

Originally Posted by MelloMike

This may sound stupid but have you checked your oil level? Levels at the MAX mark while the engine is warm have been known to cause the surging problem. If it is near the MAX drop and quart and see how it performs.

Agreed, I had a surging and stumbling issue that no one could figure out. Someone suggested that I lower the oil level to no more than half way up the hash marks on the stick. No surging since. When I change my oil I only add 13.5 quarts.

JAKE8842 · 11-05-2009, 10:27 AM

i second checking the ipr

4ceFed · 11-05-2009, 11:52 AM

You could possibly have a high pressure oil leak, that will cause a surge and loss of mileage.

JimmyRice · 11-05-2009, 10:22 PM

Thanks for the feedback. I'll drop about 1/2 a quart or so of oil and see if that helps and I'll check the IPR. I'll let you know how I make out.

JimmyRice · 11-10-2009, 01:25 PM

OK fellas, I drained about a 1/2 quart of oil and that had no effect on the surging and stalling problem. This past weekend it got so bad that at every slow down to idle the engine would stall. Always started right back up. I was in the woods hunting and then the check engine light came on. Since I had my programmer with me, I checked the codes...P0611 (FICM Perf [I assume that means FICM performance but I cannot find that specific code in any manual) and P2285 (ICP Senor Cic Low). About 2 months ago, I had the truck in the shop for the P2285 code. That cost me $700 for a new ICP sensor and wire connector. I had no tools and the truck was running terrible so I unplugged the ICP sensor. As soon as I unplugged it, everything smoothed right out. The truck ran for 100 miles without a single surge or stall. Fuel economy went back up to 15 MPG on the overhead computer. When I got home, I plugged in the ICP again, used my tuner to clear the codes, and the truck has run fine since. I know it can't be this simple to fix, but does anyone know what happens if I just leave the ICP unplugged? Something with the ICP or the harness seems to be the real culprit and the truck ran great without it plugged in.

4ceFed · 11-10-2009, 01:52 PM

Where is your ICP sensor, on the valve cover or under the turbo? Also that P0611 code means that your FICM is probably bad, if you have access to a scanner you can monitor FICM M_PWR and it should never drop below 45 volts. I have seen engines that run weird due to low injector voltages.

hooknline · 11-10-2009, 01:58 PM

if disconnecting the ICP fixed the problem, then either the ICP is bad, or your HPOP is going out. Id bet it the HPOP though, just from what you have told us.

JimmyRice · 11-10-2009, 10:50 PM

My ICP sensor is on the valve cover. I don't have a scanner but I can probably borrow one. Hope it's not the HPOP. Right now I have no codes, no check engine light, a smooth running truck, and improved fuel economy. I hate to mess with anything at the moment.

DRJ48 · 11-11-2009, 12:06 AM

Quote:

Originally Posted by JimmyRice

Hope it's not the HPOP. Right now I have no codes, no check engine light, a smooth running truck, and improved fuel economy. I hate to mess with anything at the moment.

I have read thru your symtoms several times and I doubt its the HPOP, ICP or IPR. Those kind of problems don,t come and go, but the FICM code gives a clue and your problem appears to be temp related. I would be looking at the FICM Harness where it runs over the drivers side valve cover for chaffing as well as the rest of the harness for chaffing. This was a known issue on 03 & 04 models that I fixed on my own truck.