99 F350 Super Duty 7.3L Diesel. My truck has over 300K miles, no issues over life. I decided to change out the glow plugs based on being original equipment and the fact I just moved from Oklahoma to Maine.....thought they may want to be in great shape to face the upcoming winter. I also did an oil change and a fresh full tank of diesel. Since I did all 3, basically in the same day, I have had issues starting. Unless the truck is plugged in, the first start of the day is rough. The engine surges from 500 rpm up to around 1200 rpm. I can tap the gas to stop the surge, but the truck lacks power until the truck gets up to temp. If I plug it in, it acts normal. I took apart the fuel bowl and HPOP and did a complete rebuild, replacing all the o-rings, seals, and the IPR (broke the solenoid during removal). I also took off the valve covers and checked all the glow plugs installed and the wires connected, no issues. I started the truck after the rebuild and everything seemed okay on the first start. Today, its acting up again and it's only 60 degrees outside.
I am looking for any advice I can get on this issue. Thinking it could be bad gas? After it sits over night maybe the fuel/water are separating enough to cause issues on the first start of the day.
During the oil change, I used SAE 30 with a 50% mix of Lucas Oil Stabilizer. The mechanic at the local shop says he does it every winter to reduce cold/hard starts. Could this extra thick mixture be causing issues with the HPOP and the injector delivery?
I noticed when I took the return to the turbo there was a bit of oil in the pipe. I know the pipe was clean cause I just cleaned them out 100% only a week ago when I took it apart the first time.

Any ideas or help is greatly appreciated! Thanks.

 

Moved to the 1999 - 2003 7.3L Power Stroke Diesel forum.

 

Most run multi viscosity oil, 10-30,15-40,... and diesel rated (CI). Brands such as Dello, Rotella, Motorcraft are some that come to mind. Also not sure on the Lucas stuff, but thought I heard it causes foaming. Oil additive is not necessary, just clean, proper oil.

If you have straight 30 wt. in there, I think changing it out would be a good start.

And welcome aboard.

 

I wasn't 100% sure on the Lucas additive, but I know of a lot of other people I work with that use the stuff. I will try to just drain and refill with straight oil and see what happens.

 

JMHO but leave the Lucas stuff for your friends & if I was up there in Maine I'd run the Valvoline SYN 5-40 in the winter if not year round

 

The high idle you describe is a normal function to aid in warm up. The EBPV (Exhaust Back Pressure Valve) in the turbo exhaust housing also closes when truck goes into high idle. Not only will the high idle drop to normal when you tap the throttle pedal but it will also drop to normal idle when you tap the brake. When you tap the brake or throttle to get it to normal idle the high idle will kick in again in about a minute. The EBPV will stay closed until the engine warms up and that is why you have a lack of power until it warms up and the EBPV opens.

The fact that it does not go into high idle if plugged in confirms that while sitting over night it gets cold enough to high idle if not plugged in. It may be 60 degrees when you go to start but what is the overnight low. First thing in the morning the air temp might be 60 degrees but the truck is most likely still close to the overnight low.

I second the use of a diesel rated 5-40 synthetic oil for ME winters.

You should also check out your GPR and GP function.

 

So far the evening lows have only been to mid 50's....not nearly cold enough to cause it to act up. I can drive it to work, park it in a garage, come out 10 hours later and it still acts up even when the temp gets to upper 60's or so. It only started the day that I did the 3 things mentioned above. I replaced the GPR after it started acting up thinking maybe the change in resistance of the plugs is causing it to act up some. I replaced the oil today with a 10w-30. I will let it sit overnight and see what happens in the morning.

 

For some reason the PCM thinks it's colder than it really is. A problem with a temp sensor can cause this.

You may have a temp sensor connector that got unplugged or knocked loose.

MAT (Manifold Air Temp) sensor in the front of spider) or IAT (Intake Air Temp sensor) in the lower back side, toward firewall, of the air filter box. Check those connectors.

Also check the connector on the EOT (Engine Oil Temp) sensor. Green connector on the back of the HPOP reservoir.

Edit: Also the coolant temp sensor on the top of the water pump while you're at it.