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Modifying ambient air temp sensor to extend glowplug time
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=5&t=80797		 Page 1 of 2
Author:  dsmart705 [ Thu Dec 04, 2014 1:15 pm ]
Post subject:  Modifying ambient air temp sensor to extend glowplug time
My CRD is plagued by terrible starting when it gets cold. Plugging in helps but the reality is that it cant be plugged in wherever I go. The 5 volt glowplug update has been done and all glowplugs seem ok 0.7ohm each. It seems like anything under 32 degrees F or 0 degrees C and it just doesnt want to start. Everything else about the engine is fine and there are no codes other than EGR. The battery is also fine.

So to get to the real question, since the ambient air temp controls the glowplug time on....could it just be bypassed for a resistor that would force it to read "max cold" for maximun glowplug operation. This would just be used in winter.

I bought the jeep with the 5volt plugs already installed so I dont know how the old 7volts used to work but the coldstart on this jeep seems utterly pathetic. My 2004 TDI with over 300K starts even down to -30 degrees celcius without the need to plug it in.
Author:  dirtmover [ Thu Dec 04, 2014 1:40 pm ]
Post subject:  Re: Modifying ambient air temp sensor to extend glowplug tim
I've been running mine for 8 winters, all using 7V ceramics. For the first 2-3 winters it was great and started with no more then a couple of cranks right down to -30C. The reality is that the starting performance has gradually deteriorated over the years and will now sometimes take many seconds to start. I've tried the off/on trick to increase the glow time with minor impact. Although it handles admirably in ice and snow it's not really a very good winter vehicle.

Your starting issues probably have more to do with the vehicle than the GPs. Increasing the burn time may not have much impact.
Author:  gmctd [ Thu Dec 04, 2014 3:10 pm ]
Post subject:  Re: Modifying ambient air temp sensor to extend glowplug tim
Inspect your battery for full electrolyte full charge and battery posts and cables for oxidation\corrosion - the green stuff lowers cranking rpm, as does lead-oxidation, that hard gray coating which is highly resistive - make sure the posts and clamps are shiny clean, coat them with VASELINE petroleum jelly to ensure connectivity and prevent further oxidation
Author:  dirtmover [ Thu Dec 04, 2014 3:17 pm ]
Post subject:  Re: Modifying ambient air temp sensor to extend glowplug tim
gmctd wrote:
make sure the posts and clamps are shiny clean, coat them with VASELINE\KY jelly to ensure connectivity and prevent further oxidation


KY is water based so is great if you want to slip a condom over your post but won't do much to prevent oxidation.
Author:  dh100m [ Thu Dec 04, 2014 4:43 pm ]
Post subject:  Re: Modifying ambient air temp sensor to extend glowplug tim
hi have not posted much here is my solution i changed to 12V glow plugs with mercedes module
and amp / volt meter to gauge current and battery voltage can leave plug on for as long as i like
but the only thing that really matters is battery condition
thanks for listening
Author:  gmctd [ Thu Dec 04, 2014 4:48 pm ]
Post subject:  Re: Modifying ambient air temp sensor to extend glowplug tim
dirtmover wrote:
gmctd wrote:
make sure the posts and clamps are shiny clean, coat them with VASELINE\KY jelly to ensure connectivity and prevent further oxidation


KY is water based so is great if you want to slip a condom over your post but won't do much to prevent oxidation.I just threw that in to see if anyone is paying attention, eh !!
Author:  gmctd [ Thu Dec 04, 2014 4:53 pm ]
Post subject:  Re: Modifying ambient air temp sensor to extend glowplug tim
dh100m wrote:
hi have not posted much here is my solution i changed to 12V glow plugs with mercedes module
and amp / volt meter to gauge current and battery voltage can leave plug on for as long as i like
but the only thing that really matters is battery condition
thanks for listening
One (count'em: 1) post since early 2012 is a lot fewer than "not much", dude - but, thanks for your input - your modification appears very professional and practical
Author:  dh100m [ Thu Dec 04, 2014 5:06 pm ]
Post subject:  Re: Modifying ambient air temp sensor to extend glowplug tim
got confused with another forum i spy on have some more mods would like to post with pix dont
know how ie simpler thermostat mod using existing outlet hose and removal of viscose heater
Author:  dsmart705 [ Thu Dec 04, 2014 5:08 pm ]
Post subject:  Re: Modifying ambient air temp sensor to extend glowplug tim
dh100m wrote:
hi have not posted much here is my solution i changed to 12V glow plugs with mercedes module
and amp / volt meter to gauge current and battery voltage can leave plug on for as long as i like
but the only thing that really matters is battery condition
thanks for listening



More info on how you did that would be great. How "plug and play" was your conversion?
Author:  dirtmover [ Thu Dec 04, 2014 5:14 pm ]
Post subject:  Re: Modifying ambient air temp sensor to extend glowplug tim
dsmart705 wrote:
dh100m wrote:
hi have not posted much here is my solution i changed to 12V glow plugs with mercedes module
and amp / volt meter to gauge current and battery voltage can leave plug on for as long as i like
but the only thing that really matters is battery condition
thanks for listening



More info on how you did that would be great. How "plug and play" was your conversion?


Yeah, can you provide P/N's etc for the plugs & module you're using?

Sounds like you have manual control so do you need to make any other changes to prevent the ECU throwing codes?
Author:  dh100m [ Thu Dec 04, 2014 5:27 pm ]
Post subject:  Re: Modifying ambient air temp sensor to extend glowplug tim
will get my notes and supply part # sourced from uk working to eliminate cel but for now just plug in old gp on bracket for mto test on every 2 yr not much trouble
Author:  thermorex [ Thu Dec 04, 2014 6:51 pm ]
Post subject:  Re: Modifying ambient air temp sensor to extend glowplug tim
ID just get weeks intake heater and call it a day, no more hassle and it's a better idea overall, you feed the engine hot air on the top of hot temperature from glow plugs for combustion. Maybe some better glow plugs for cold weather like those in Alaska or Minnesota-nuts won't be a bad idea also... I'm just curious how hot those 12v plugs can get...
Author:  gmctd [ Thu Dec 04, 2014 8:40 pm ]
Post subject:  Re: Modifying ambient air temp sensor to extend glowplug tim
All glow plugs must reach ~1200F to ignite Diesel fuel - the glow will look like the bottom row of the font color chart just to the right of the reply window - brite yellow to near white - the gp's for the GM 6.5L TD will glow like that for 24hours with no deterioration, as long as the battery is on a charger with greater output than the gp drain - the gp tips is made of nichrome material, like the heater wire in your bread toaster, or electric range and oven - once lit off, cylinder temps reach upward of 1750*F - the aluminum piston survives the heat because the flame-front never touches the crown surface, which is rapidly receding below the hot quickly-expanding nitrogen gas that's left-over from earth's atmosphere, which is ~17% oxygen, rest is nitrogen and some other stuff - luckily for us motor-heads

That's right folks - all you got is a hot-air engine - Chicago Pneumatic and Ingersoll Rand: ya got nothin' on us...............
Author:  WWDiesel [ Thu Dec 04, 2014 10:10 pm ]
Post subject:  Re: Modifying ambient air temp sensor to extend glowplug tim
gmctd wrote:
That's right folks - all you got is a hot-air engine - Chicago Pneumatic and Ingersoll Rand: ya got nothin' on us...............

Yep you right, a diesel engine has got a lot more in common with an piston type air compressor than a gas engine. :wink:
We just add a little go juice (diesel fuel) to make it have the giddy up and go go go.... :ROTFL:

I still think that heating the air entering the combustion chamber to promote combustion on a very cold morning is still a better solution than trying to heat the fuel vapor in the combustion chamber using glow plugs. Glow plugs are problematic and are a really bad solution to a simple problem.... :roll:
Author:  ArmyChief [ Thu Dec 04, 2014 10:24 pm ]
Post subject:  Re: Modifying ambient air temp sensor to extend glowplug tim
Weeks/Sasquatch intake heater is not available to the masses yet. You northerners will just have to wait an see if it gets produced :)
Author:  mecne [ Thu Dec 04, 2014 10:41 pm ]
Post subject:  Re: Modifying ambient air temp sensor to extend glowplug tim
ArmyChief wrote:
Weeks/Sasquatch intake heater is not available to the masses yet. You northerners will just have to wait an see if it gets produced :)


I just tabb'd back from looking on Sasquatch Motors site and was just about to ask this ..

Any more details ? Do tell? @Weeks101

:BINGO:
Author:  thermorex [ Thu Dec 04, 2014 10:47 pm ]
Post subject:  Re: Modifying ambient air temp sensor to extend glowplug tim
ArmyChief wrote:
Weeks/Sasquatch intake heater is not available to the masses yet. You northerners will just have to wait an see if it gets produced :)


I am lucky to be one of the testers, and so far I love it, it's a very promising concept! Faster starts and smoother idling. I'm positive it's a good product like everything else he makes. I think he'll have it mass produced, this without talking to him specifically about it, but why would somebody test a product and ask for feedback without intention of mass-producing it? If money is not an issue, even a southerner should have it, for those cases when going north for Christmas vacation :D.
Author:  ArmyChief [ Thu Dec 04, 2014 11:33 pm ]
Post subject:  Re: Modifying ambient air temp sensor to extend glowplug tim
Well money is ALWAYS an issue to some. Look at Jeff's awesome, well engineered thermostat housing option. It's $450, many are and will just put an inline thermostat. Even though someone can prove it won't function as well...not to mention cosmetics.

As a fellow developer of software and hardware, I've been stung with sinking money and time (which is also money) into a product I believed many would want. Just to find out it did not sell well.

Based off the limited production of our vehicles, how many are still around...then how many are in climates that need GP's with how much will a good product cost..lastly expected profit to make....now we are closer to if it will be mass produced.

This is completely based off my thoughts. I have no knowledge of Seth's thinking.
Author:  dsmart705 [ Thu Dec 04, 2014 11:35 pm ]
Post subject:  Re: Modifying ambient air temp sensor to extend glowplug tim
Great responses guys, there are certainly afew ways to deal with this problem. Im guessing from the lack of response to my specific question about using a resistor to mimic the "max cold" glowplug time hasn't been done so im going to do some testing and see if it helps. Jumping the connector with the appropriate resistor is likely to cost less than $1 which is alittle cheaper than any other method mentioned. I realize its not a permanent fix when the temp gets really low but I dont have much interest in buying an intake heater and all the other stuff that goes along with it if it can be avoided.

5/7 volt glowplugs work in other engines....what is so special about the VM that makes it so cantankerous when the temperature gets low?
Author:  ArmyChief [ Thu Dec 04, 2014 11:49 pm ]
Post subject:  Re: Modifying ambient air temp sensor to extend glowplug tim
dsmart705 wrote:
Great responses guys, there are certainly afew ways to deal with this problem. Im guessing from the lack of response to my specific question about using a resistor to mimic the "max cold" glowplug time hasn't been done so im going to do some testing and see if it helps. Jumping the connector with the appropriate resistor is likely to cost less than $1 which is alittle cheaper than any other method mentioned. I realize its not a permanent fix when the temp gets really low but I dont have much interest in buying an intake heater and all the other stuff that goes along with it if it can be avoided.

5/7 volt glowplugs work in other engines....what is so special about the VM that makes it so cantankerous when the temperature gets low?


I am so sorry for missing your original question. I will have to review the service info and operations manual (when I comes in) to see if a VM/DC even published their GP operation and strategy to give you an educated response.

If I am allowed to guess based off of other vehicle platforms and knowledge, I would say it won't do much or even worse, could cause GP damage. What other PCM function relies on that input. If the PCM uses PWM to achieve desired heat...the PCM mapping might be weak...where even if it thought it was -30 degrees outside...it just won't or can't drive a high enough duty cycle and for long enough to make a difference. The software may also understand that this vehicle only had a single 700 CCA battery and not dual batteries like many diesel vehicles...so maximum current is limited.

Just thoughts for now..but keep us posted
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