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Old 12-08-2014, 08:48 PM   #1 (permalink)
quadstar87
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Here's how long your glow plugs should be running

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

glow_time.JPG

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Old 12-08-2014, 10:50 PM   #2 (permalink)
Freddyack
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Added to Glow Plug FAQ

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Old 12-08-2014, 10:54 PM   #3 (permalink)
bk95td
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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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Old 12-08-2014, 10:58 PM   #4 (permalink)
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Quote:
Originally Posted by bk95td View Post
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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Old 12-08-2014, 11:03 PM   #5 (permalink)
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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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Old 12-09-2014, 12:07 AM   #6 (permalink)
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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:
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Old 12-09-2014, 09:03 AM   #7 (permalink)
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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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Old 12-09-2014, 09:09 AM   #8 (permalink)
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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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Old 12-09-2014, 10:07 AM   #9 (permalink)
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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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Old 12-09-2014, 10:10 AM   #10 (permalink)
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Quote:
Originally Posted by quadstar87 View Post
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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