High Idle mod?

[elibenson]

^^^ That's a little odd. I would have that checked out. I am not sure it is supposed to work that way.

Or maybe I don't have that problem because I don't have a DPF

[Rotorfixer]

Read the PDF from ford fleet on the PTO wiring, it even says it disables all emissions systems, my truck is scheduled into service tomorrow if it doesn't stop, we have given it 6 days...... Although you don't have DPF, I think there are other systems that would be disabled.

[po-po 5.0]

This is very interesting. I wonder if leaving the high idle connection would constitute the world's cheapest dpf delete?

[Rotorfixer]

ummmm .... no.

Not monitoring it has nothing to do with it not plugging up!

[tlb017]

Ok I have a question, dont these trucks already have I high engine setting at a certain temp range? Or is my truck possessed? When the outside temp is below 50F when I go out to warm my truck up in the morning it will idle itself up to around 900-1k, if you put your foot on the brake it will drop back to normal. If you take your foot off with out putting it into gear within 20 sec or less it will idle back up?

Is this the same thing or something totally different???

No have not done anything that I know of to affect this unless the spartan kit does this in its programming??

[Rotorfixer]

You are correct, there is an auto idle up based on the coolant temp. But the high idle mod is udeful for idling when the coolant is already hot (summer/ winter) you should never idle longer than 10 min without high idle ever on these thrucks.

[tlb017]

Originally Posted by Rotorfixer

You are correct, there is an auto idle up based on the coolant temp. But the high idle mod is udeful for idling when the coolant is already hot (summer/ winter) you should never idle longer than 10 min without high idle ever on these thrucks.

Ah ok, thanks for the info, about the only time mine is on idle is for warm up in the mornings and i try to wait 2-3 min before shutting it off. Other than that maybe a run into the store while fueling.

Thanks again

[ol38y]

Originally Posted by Rotorfixer

You are correct, there is an auto idle up based on the coolant temp. But the high idle mod is udeful for idling when the coolant is already hot (summer/ winter) you should never idle longer than 10 min without high idle ever on these thrucks.

I have seen the hi idle mod mentioned before but never understood why it was needed. This thread explains a lot. My question now is, why should you not idle these engines for more then 10 min? There are at least 8 times a year where my truck will idle most of the day. Man, I'm glad I found this place.

[Rotorfixer]

There are several answers to that question, but the most important in my oppinion are :

1) Wet stacking: due to low cylinder temps

Wet stacking is a condition in diesel engines in which all the fuel is not burned and passes on into the exhaust side of the turbocharger and on into the exhaust system. In Diesel generators, it is usually because the diesel is running at only a small percentage of its capacity.

2) glazing: This quote is for diesel generators but explains it well,

Diesel engines can suffer damage as a result of misapplication or misuse - namely internal glazing and carbon buildup. This is a common problem in generator sets caused by failure to follow application and operating guidelines. Ideally, diesel engines should be run at least 60-75% of their maximum rated load. Short periods of low load running are permissible providing the set is brought up to full load, or close to full load on a regular basis.

Internal glazing and carbon buildup is due to prolonged periods of running at low speeds and/or low loads. Such conditions may occur when an engine is left idling as a 'standby' generating unit, ready to run up when needed, (misuse); if the engine powering the set is over-powered (misapplication) for the load applied to it, causing the diesel unit to be under-loaded, or as is very often the case, when sets are started and run off load as a test (misuse).

Running an engine under low loads causes low cylinder pressures and consequent poor piston ring sealing since this relies on the gas pressure to force them against the oil film on the bores to form the seal. Low cylinder pressures causes poor combustion and resultant low combustion pressures and temperatures.

This poor combustion leads to soot formation and unburnt fuel residues which clogs and gums piston rings, which causes a further drop in sealing efficiency and exacerbates the initial low pressure. Glazing occurs when hot combustion gases blow past the now poorly-sealing piston rings, causing the lubricating oil on the cylinder walls to 'flash burn', creating an enamel-like glaze which smooths the bore and removes the effect of the intricate pattern of honing marks machined into the bore surface which are there to hold oil and return it to the crankcase via the scraper ring.

Hard carbon also forms from poor combustion and this is highly abrasive and scrapes the honing marks on the bores leading to bore polishing, which then leads to increased oil consumption (blue smoking) and yet further loss of pressure, since the oil film trapped in the honing marks is intended to maintain the piston seal and pressures.

Unburnt fuel then leaks past the piston rings and contaminates the lubricating oil. Poor combustion causes the injectors to become clogged with soot, causing further deterioration in combustion and black smoking.

The problem is increased further with the formation of acids in the engine oil caused by condensed water and combustion by-products which would normally boil off at higher temperatures. This acidic build-up in the lubricating oil causes slow but ultimately damaging wear to bearing surfaces.

This cycle of degradation means that the engine soon becomes irreversibly damaged and may not start at all and will no longer be able to reach full power when required.

Under-loaded running inevitably causes not only white smoke from unburnt fuel but over time will be joined by blue smoke of burnt lubricating oil leaking past the damaged piston rings, and black smoke caused by damaged injectors. This pollution is unacceptable to the authorities and neighbours.

Once glazing or carbon build up has occurred, it can only be cured by stripping down the engine and re-boring the cylinder bores, machining new honing marks and stripping, cleaning and de-coking combustion chambers, fuel injector nozzles and valves. If detected in the early stages, running an engine at maximum load to raise the internal pressures and temperatures allows the piston rings to scrape glaze off the bores and allows carbon buildup to be burnt off. However, if glazing has progressed to the stage where the piston rings have seized into their grooves, this will not have any effect.

3) blow by/ fuel dilution.

Idling these engines has proven to contibute to oil dilution with fuel. This has always been an issue with diesels but more so now than ever.

[ol38y]

Wow, great explaination, thanks. I guess I'll have to do the mod by this weekend cuz I'll be waiting in line again...