I am convinced my romps are completely unrelated to the GPR. I run Delo 15w-40 in the warm months and Rotella 5w-40 during the coldest months every year. On Delo 15w-40 my engine will romp at startup below about 30*F. When I switch to rotella 5w-40 for the winter (usually in October or November) the romps are completely cured until the temperature gets down to below 10*F. I have had 2 GPR's fail while I have owned this pickup and they had no effect on whether it romped.

 

That's interesting. This is what typically happens when my engine romps. When it starts it will do it 3-4 times. When the idle smooths out, I put it in reverse, press the accelerator, and back out of where I park. When I let off of the accelerator, it will romp again 2-3 times. I stop, shift into drive, and accelerate down my drive way, when I let off at the end of the driveway (probably 40 yards traveled), it will again romp 2-3 times.

 

I ve heard of this happening going from park (P) to Drive (D). But not the other way around.

Heres another thing to consider, My truck on a completely cold engine will "choke up" as soon as it fires off on a cold start, it will not idle @ 650 like jody has it set at the idle immediately jumps up to about 800. Kind of like an EFI gasser. This is for a minute or so after the engine fires off and does not last at all when you drive it. It will not do it again for the rest of the day. It only does it when the tems are around freezing. Never during the simmer , fall spring time. It has nothing to do with the EBPV. The EBPV never comes on until oil pressure is built and until the truck sits for a while with the E-brake on. I dunno, maybe its a six speed thing. Maybe thats why I do not get the Romps? Sorry for hijacking Tenn.

Tim

 

My idle is a little higher on initial startup too, then it settles down after a minute.
Then a minute later the fast idle kicks in if it's cold enough.

 

Ahhh, so im not the only one. Kwik, do you thing this is why I may not be seeing romps below freezing on a cold motor?

 

I run exactly the same oils as you do...Delo 15-40W in the summer and then I switch to 5-40 Rotella T syn in October or November.

I just finished an experiment and I thought I would post the results. Last night it was 18 degrees here for about 5 hours and it has not warmed up beyond 25 degrees right now (10:40 AM PST) and it is snowing . Truck hasn't been started since Tuesday and it is parked outside..not plugged in.

I went out and disconnected the GPR from my system...cranked the truck...no start for a couple of revolutions of the engine. Stop for a few moments and try again...no start. On the third try it fired off with NO ROMPS...a little white smoke, but NO ROMPING. It idled exactly as Kwik described...a little high at first, then settled down, then went to a high idle.

So, at least on my truck, I conclude that you are correct Clux, the GPR is out of the equation....it is a high pressure oil/IPR problem that causes romps (on my truck). With my rebuilt IPR and running 5-40 syn, I doubt I'd see romping at any temperature.

 

Thanks for that test there Neal. I wanted to check mine with the AE this morning but I am under the weather today. Looks like I don't need to wait for the GPR. What I need to do is get the ICP and IPR info now and then after switching to synthetic. Dang, I am not even halfway through with this oil. Might just put up with it or plug in for a short period.

 

so what wears out, or needs to be replaced to get rid of the romp caused by the oil. mine never did it when it was new.

 

This is interesting because so many people are associating the romps going away to syn oil, I have read no one attributing the romps going away to the fact that the dino oil everyone is using is 15w-40 and the syn is 5w-40. I turned wrenches in MN and it is not exactley warm in one of the coldest places in the nation, i.e. Truckee,CA (Donner Summit area) and I can tell you there is a huge difference in the pour rate of oil between 15w-40 and 5w-40 when it gets cold. I agree the 5w-40 probably helps cure the romps but I would be willing to bet it is because it is 5w-40 vs. 15w-40, not because it syn.

Yes my truck romps when it gets cold, sometimes when it is 25 deg and sometimes when it's 6 deg., but not when it is pluged in on the very cold days. A little accelerator pedal always makes it go away and after reading all this information I attribute this to a spike in oil pressure when the acc. pedal is pushed as RPM increase pushing oil into places it dont like going when it is cold and thick. I run Delo 15w-40, syn is to expensive for 3-5k oil changes.

I might be full of cr-p but that is my take on it.

 

I have heard no one say the romps stopped due to using synthetic oil...it just happens that the 5-40W oil we use is synthetic. If I could find properly rated 5-40 dino, I'd buy it. I agree with you it is the cold flow rate of the 5-40 versus 15-40 that is the factor that stops romping...not the fact that it is synthetic.

 

That's what we are trying to figure out...we do know that oil weight has something to do with stopping the romps (perhaps hiding the underlying problem) and that IPR rebuilding has stopped the romps for one person (from a previous thread noted in a response by me in this thread). This is going to take awhile to cypher. Variables...variables...variables.

 

Thanks, I was wondering if I missed something! Forgive me for my ignorance here, but What is involved in IPR rebuilding?

Edit: Nevermind I just read the other thread on IPR rebuilding!

 

I agree, Neil. Rotella 5w-40 "synthetic" is made by the same process and from the same type of base stock as Delo 15w-40. It's the weight, not the fact that they are synthetic.

 

As other have alluded to, it's more likely related to the fact that the oil is cold & dense. Being that the injectors use the crankcase oil to assist in firing the injectors - cold oil = romp, romp. I know that on mine, once the oil is warm, problem is gone. also, having gone to synthetic I can say in my case the romp is much less when cold.

 

Tenn,

I have Cen-Pe-Co 15-40, Stancor GPR and it hasn't been started since last Sunday. Tonight is supposed to be around 21 degrees for the low. Would you like me to video a cold start in the morning?

Let me know,

Jason