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Discussion Starter #1
Remembering glow plugs are 6v appliances running in a 12v system, here is how the PCM determines glow time based on ECT (degrees C) and measured battery voltage (under full load) at the glow plug relay

Max glow time should be 21.8 seconds if your batteries are junk, and you live at the North Pole.

Happy calculating! maybe this will get a sticky :coffee:

glow_time.JPG
 
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The oe glow plugs were 6 volt. The new Bosch or AC are 12 volt self regulated. With the old 7gs they would swell and burn out and possibly melt off if they were run manually too long. The Bosch and AC G60s take longer to heat up and will not overheat.
 

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The oe glow plugs were 6 volt. The new Bosch or AC are 12 volt self regulated. With the old 7gs they would swell and burn out and possibly melt off if they were run manually too long. The Bosch and AC G60s take longer to heat up and will not overheat.
So does that mean the factory program/chip should be re-flashed to generate longer glow cycles (based on temps, etc) for Duratherms or AC G60's?

Reason I ask is I notice rougher starts in cold weather with Duratherms unless I use my handy-dandy ECT cut out switch. With the ECT "off" truck starts fine.
 

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I just pulled a swelled 8G out of an engine. Makes me not think much of the 8G's and AC delco in general. Same engine also had 2 dead (but not swelled) Autolite ASP1107.
 

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Discussion Starter #6
Theoretically, extended glow won't help anything with a duraterm since it self regulates. You should actually be cutting the glow time short to get more heat...

Check this out from Bosch directly:
 

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In my situation, my truck had 9Gs in it and in really cold weather like 20F or below it i maybe had a glow cycle of 7-8 seconds and it started kinda hard. Now with Duraterms, in the same temp, it will go at least 10-11 seconds and it obviously starts like a dream. I'm just wondering what made the computer change glow time with the new plugs? I also put new connectors on and cleaned the relay lugs.
 

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On the original chart I don't get why the voltage goes so low. You get below around 9 volts and the computer based stuff tends to get a little unpredictable.

The Duratherm chart is interesting that peaks twice as fast as the 'standard' plug. Also interesting that they don't show any more of the 'standard' curve.

I would also like to see a chart showing how quickly they cool when they shut off.
 

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FORD used 6 volt plugs, GM used 11 volt plugs. Early glow plugs were a non regulating type where they kept heating at the same rate whereas the 60G's are a self regulating type where the carbon pile inside them regualtes once it gets to a certain temperature. The plus side is they can stay on alot longer to allow for more cylinder heating, down side is the regulaitng type requires more heating time to get hot VS the early non regulating plugs. As to the question about how duraterms could have extended the glow time, if they draw more amperage they would pull the battery down more during the glow cycle, and as you can see from the glow time chart the chart is based off of ECT and battery voltage. So lower voltage from more amp draw would give longer glow time. I know I ran 60G's in my 6.5, and even down here in Florida it started like crap in winter time unless I manually kept them on for another 5-8 seconds. Nothing like whiting out your yard in 40 degree temps starting the BURB up(don't have them problems anymore).

As to the chart, is this from an OBD1 or OBD2? Looks like an OBD1 which should be noted is not long enough for 60G's.
 

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Theoretically, extended glow won't help anything with a duraterm since it self regulates. You should actually be cutting the glow time short to get more heat...

Check this out from Bosch directly:
Negative. Extending the glow plug time will allow the heat to be absorbed by the precup better. The longer the glow time, the more heat saturation you will get into the pre chamber, and the more heat in there the better the fuel will ignite. I have my neighbors bobcat outside for moving some stuff around, and the glow time that thing needs is RIDICULOUS. It needs 20 seconds of glow time to start in 60 degree temps. Down close to freezing it needs 60 seconds. And even with that amount it still smokes on startup.
 

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Discussion Starter #11
FORD used 6 volt plugs, GM used 11 volt plugs. Early glow plugs were a non regulating type where they kept heating at the same rate whereas the 60G's are a self regulating type where the carbon pile inside them regualtes once it gets to a certain temperature. The plus side is they can stay on alot longer to allow for more cylinder heating, down side is the regulaitng type requires more heating time to get hot VS the early non regulating plugs. As to the question about how duraterms could have extended the glow time, if they draw more amperage they would pull the battery down more during the glow cycle, and as you can see from the glow time chart the chart is based off of ECT and battery voltage. So lower voltage from more amp draw would give longer glow time. I know I ran 60G's in my 6.5, and even down here in Florida it started like crap in winter time unless I manually kept them on for another 5-8 seconds. Nothing like whiting out your yard in 40 degree temps starting the BURB up(don't have them problems anymore).

As to the chart, is this from an OBD1 or OBD2? Looks like an OBD1 which should be noted is not long enough for 60G's.
This is the OBD-I PROM calibration, I forgot to mention that in the first post.

Also, when did plugs switch to 12v? Based on the 2002 ASE manual, all ECU's were programmed to deal with 6v plugs (that's the only reason I mentioned this in case it has a factor in the cold startup issues that show up on the forum every winter)

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Any data for glow times on the 93 without an engine computer? How is the post-start glow regulated?
 

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Good thread. I tested some Duraterms, old and new and found 12 secs they were fully red and the longer you kept them on, the more the heat moved up the GP. I held them for 25 secs and NO swelling.

I tested a 6 volt Ford Duraterm and that swelled badly after 13-14 secs.

Any data for glow times on the 93 without an engine computer? How is the post-start glow regulated?
They have a controller on the back of the drivers head that's self contained.
 

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But what is that controller doing? It is getting a temperature signal and changing the length of the wait to start light, at least.
 

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Mitchel shows GP's as 6 volts.

But what is that controller doing? It is getting a temperature signal and changing the length of the wait to start light, at least.
Its doing it based on temp, its all internal. The HD setup has an inhibutor.
 

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Discussion Starter #16
Good thread. I tested some Duraterms, old and new and found 12 secs they were fully red and the longer you kept them on, the more the heat moved up the GP. I held them for 25 secs and NO swelling.

I tested a 6 volt Ford Duraterm and that swelled badly after 13-14 secs.

They have a controller on the back of the drivers head that's self contained.

I'm wondering what they do at 9 volts since that's about what they get when they are all on with a full load. I have a jump pack that I could discharge some but only have the wellman plugs on the bench that I pulled out previously.
 

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Negative. Extending the glow plug time will allow the heat to be absorbed by the precup better. The longer the glow time, the more heat saturation you will get into the pre chamber, and the more heat in there the better the fuel will ignite.
This makes sense to me. And it correlates to what I experience with cold weather starts with the ECT "on" and with the ECT "off" using Duratherm GPs.
 

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On the later 6.2 and pre computer 6.5 controllers do they use the glow plugs themselves as a temp sensor to judge engine temp? Presumably they also have an internal ambient sensor?

I see that some people list a mod disconnecting the wire that goes between the glows and controller and replacing it with a switch that goes to ground. My assumption is that grounding that terminal makes the controller think its cold. Cold glows would have a lower resistance than warm ones so a direct ground would seem to simulate a dead cold engine and presumably give you the longest possible glow cycle.
 

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Discussion Starter #19 (Edited)
On the later 6.2 and pre computer 6.5 controllers do they use the glow plugs themselves as a temp sensor to judge engine temp? Presumably they also have an internal ambient sensor?

I see that some people list a mod disconnecting the wire that goes between the glows and controller and replacing it with a switch that goes to ground. My assumption is that grounding that terminal makes the controller think its cold. Cold glows would have a lower resistance than warm ones so a direct ground would seem to simulate a dead cold engine and presumably give you the longest possible glow cycle.
This is interesting as well as it also traces back to a controller that has it's head stuck in 1993 (at the latest) and is firing model year 2014 glow plugs. The only difference is a manual override is the ONLY way to fix those...unless there was an updated controller that worked for everyone....
 

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