Cold weather problem/symptom

[Splitrimz]

'94 6.5 TD, Automatic. Crew Dually 2WD. This winter it started a new problem at startup. Here is the sequence. 1. Let glow plugs cycle. 2. Starts after about 5 seconds of crank or less. Once it starts, I have no throttle control and the motor doesn't have the "rattle". As it gets warmed up, and I can't tell it its warmer air, fuel or coolant, the motor sound changes to the diesel rattle, almost like it "woke up" and then I have throttle control.

Once it reaches the above point, which varies in time vs. temperature. The colder it is, the longer it takes to "wake up". I can drive it. Once moving and at about 1500 rpm I get my usual code 37 and the truck runs doggy until it gets warmer. I say usual code 37 because it has been doing that for years.

I have the Engh Tech scanner so I can read all the parameters and they all seem normal during the cold start, but then again, I don't have the experience to zero in on any reading that might help me.

Has anyone had experience with this "waking up" syndrome? It is now above 50 degrees in the morning here in Colorado and the truck starts fine and I have throttle control immediately. I've changed air temp and water temp sensors to no avail. Any suggestions appreciated.

[simon]

Could be the FSD going, I had exactly the same thing acting up with my 95 this winter.

try heating the FSD with a small torch for a bit.

I did that to and my truck fired up as it was suppose to be. no more trouble after i installed a new FSD , remote location this time.

I asume you have no trouble starting during the day after first startup in the morning right?

I did get no code at all

[gmctd]

At cold-start - ECT, IAT, Fuel Temp should be equal at about ambient

Des\Meas Injection timing should be equal at about +12 to +15deg, maybe higher, depending on ambient

Fuel Rate shold be about 12-15mm, maybe higher, depending on ambient.

Then, try a cold-start with the ECT disconnected for more glow, advance and fuel - note any differences in timing and fuel rate.

[JohnC]

Could be a restrictive filter combined with the alleged propensity of ULSD for gelling...

Once the fuel heater kicks in you're good to go...

[Splitrimz]

Thanks for all the tips. I will check them all out. I can answer some specifics.
The FSD is brand new mounted on the plate under the bumper. The Fuel Filter is brand new, I just changed it. Lift pump is OK, I just changed the Oil Pressure Sensor recently and I check the pressure pretty regular.

I'll look at some of the paramaters suggested with my laptop. I just hope I get another cold morning. I'll definately set the laptop "dashboard" to the fuel temp.

One thought, I purchased the JK glow plugs but only changed the easy side. They are mismatched with the right side. ( I got lazy when I saw that the ones coming out were in pretty good shape and measured OK). Is that a potential culprit?

Splitrimz

[gmctd]

Yes, because the PO may have got lazy, also, and 2 or more may be open, particularly the two for #6 and #8.