The PCM does not monitor coolant temp at all. Only EOT. You can barely even call the thing in the dash a gauge... Good thought though.

I promise I will program my ScanGauge II so I can FINALLY monitor EOT's - soon! (been waiting for MONTHS to get my Aeroforce Interceptor Scangauge...) I've often wondered how low EOT's get idling - especially in COLD weather. Actually, I know it'll get cold enough to activate EBPV - so thats cool enough EOT to be advancing timing, at least in those FRIGID conditions.

On my system, return coolant from VO loop tee's into return from heater core and goes into top of water pump. Fwiw, I also use a MBZ aux coolant pump on the VO loop to force hot coolant from the block, even at low RPM's when water pump flow is anemic...

Perhaps, but if idle time does produce it - there is NO WAY to say 'tuning' produced the stars. Very few of us have had our trucks from ZERO miles. Hell for that matter, some hobo could've hopped the train and idled that sucker from KY to Los Angeles - or some down-on-his-luck salesman slept in it with the AC on after the old lady finally threw him out... Now, 10yrs and 300k later the star pattern plus certain tunes means something...

I'd really like to know if there is something about idle-time that can make this happen. That would further explain the torn-down race engines I've seen with 'wild' tunes that DID NOT have star pattern - likely they NEVER idled like I do.

 

After my push rod escapade, I have to really wonder about this. The month or so before the rod broke (just one among 15 other straight rods on a stock-tuned truck), I had done a combo of LONG periods of idling in cold weather along with running around in cold weather with a thermostat that wouldn't let my EOT get above 140* until I hit the interstate. I had also run a Superchips for a day to race my Dad so I'm sure I had some advanced timing there as well. I'm wondering if all of this didn't come into play with the broke rod? I also wonder why that clatter has started to come back after I replaced the rod? I may just be hearing things outta paranoia, but I thought for sure it was quieter than that after I replaced the rod.

SUBSCRIBED!!!

 

In case it helps,
I watched my EOT for a while in cold temps and it got up to 165 ish during my 22 mile drive to work, then as soon as I parked and let it idle it cooled way down pretty quickly. I think it was around 120-130 ish if I remember correctly.

The ambient temps were around 40 degrees or so...

 

What is the EOT?

 

EOT= engine oil temp

I wonder if the star pattern is normal. The reason I say that is because most 7.3s are modified in one way or another and most rebuilds are modded engines so it would be easy to say tuning caused it. I have no proof or references just thinking out loud. I wonder if ford advanced timing to meet emmision mandates on stock engines. I know they weren't real strict years ago but they still had them. Have any of you guys rebuilt a few completely stock motors? I wonder how the pattern and tuning is different between ford and international. Just look at how many computer codes and families there are. Its easy to think one may have advanced timing over another.

 

Very interesting. Isn't 130* EOT the beginning of 'normal operating temp'??

40* ambient ain't even COLD - I know the PSD is cold natured, but I did'nt expect EOT to drop that low. We know timing is advanced at low EOT to compensate for more viscous engine oil and the 'delay' it causes to the injectors. I wonder what temp the timing goes to 'normal'?

 

FWIW, I don't even THINK about hammering mine below 150, and 170 before I go all-out. I would love to see what mine look like...

 

x2 i won't even turn the tuner off stock till 160 on the guage.

 

That sounds a bit cold to me... in colder weather than that, I could get mine to around 140 or so just idling. My thermostat was stuck before that so when I replaced it, that was the temperatures I got... might wanna look into that. For me, get 175 or so cruising in about the same temperature... it's cheap enough to replace anyways.

By the way... that star pattern didn't happen to be where the long-lead injector was, was it?

 

The star pattern can be seen on bone stock engines that have never had a tune on them. Even engines that don't have excessive idle time can have a star pattern appear. It's more common than most people think.

SOI is fairly advanced in stock tuning. The reason is emissions. Advanced timing greatly reduces hydrocarbon emissions (although increases NOx emissions). However, hydrocarbon emissions is part of that good ol' visible black smoke (white smoke on a cold engine), and Ford was trying to reduce that as much as possible.

These trucks, in stock form, do not fire all the fuel inside the bowl on the piston. The timing is too advanced. Some trucks are worse than others depending on conditions, oil used, driving style, etc. But in the end, just know that in stock form these trucks run advanced timing, hence the star pattern that appears on bone stock engines.

 

So advancing the timing when cold is really because of emissions, not because cold fuel is "dense" and "slow" due to temperature? Makes no sense really as to why the timing would have to advanced that long... a couple minutes and the block is warm enough to get the fuel above gelling temperature when flowing through the fuel rails. I know you as well as alot of the other tuners out there eliminate the timing advance altogether when you tune a truck... but nothing is really detrimental about that start pattern is what you're saying?

 

I am with pocket on this one. Every 6.0 I have taken apart that DOES NOT have a tune on it still has a star pattern. I have a 6.0 in my garage that has a star pattern and has never seen a tuner. Honestly not sure why ever one is so scared of the star pattern because when cold most trucks advance the timing.

 

Not sure scared is the word... curious is more like it. We just love our 7.3L's and the thought of something serious scares the crap out of us.

Now, why a star pattern? How does advancing the timing make the pattern? Is because the distance between the piston and the head is different when the timing is advanced making the explosion more spread-out across the head of the piston? Is it possible that if a motor has alot of that pattern, it's because it was run many MANY times for short periods of time where the PCM hadn't detected the EOT warm enough to back the timing back off? I.E. lots of five-minute jaunts across the farm?

 

I think the HEUI injectors also have a delay from when the power hits the injector to when the fuel starts being injected.

I believe this is due to the oil flow. The PCM probably calculates this and adjusts the timing.

There was a thread a while ago with a timing graph showing almost 50deg of timing advance, which I believe was to be in effect when the motor was cold.

I think thats how much time it takes when the oil is cold for the injector to actually respond and inject at a normal advance.

Please note that this is all purely my speculation, but I do think that all these variables might explain why someone might get real bad star patterns.

How does the WVO make the engine oil look and feel? thin, normal, thicker?

 

True... never thought of that. I bet there's alot of things that come into play and I'd be willing to bet they're all hidden under the guise physics and thermodynamics when in reality it's emissions.