Glow plug cycle time.

[turbo elk]

So, for ever my plugs have cycle has been 10 sec. even when it's cold out. And now here latly it's gone to 15-16.5 sec. by the stop watch...is something wrong or is this an acceptable time?... it's onle been in the upper 30*s.
this is on the 91 F 250 withan automatic glow plug controller. Thanks for any help.

 

[mblaney]

Mine run somewhere in that range; this morning it was -15 F and they ran for closer to 15 seconds. The tattle tale for me is the cycle time after the main burn. If even one glow plug is burned out then your main heat time will be shorter and the cycle time will be erratic.

IMO, if everything is good then you will see: on - 10 to 15 seconds - off - 2 seconds - on - 1 second - off - ... repeat

Burned GP: on - 5 to 10 seconds - off - 0.5 seconds - on - 0.5 second... repeat... except that the short cycle time will be all over the place.

You can observe this after the engine starts, your headlights will flicker, battery voltage will flicker. If it looks deliberate then you are good. If it looks like you voltage gauge is possessed then there is a problem.

This is an easy job; pull each GP connector off, ohm the GP to make sure it is still good (<1 ohm). Clean the inside of the GP connector. You could have a bad connection. I use fine emery paper and polish the inside. Tighten the connector with pliers if necessary.

Note, my GP connectors no longer have the white insulation (most disintegrate after this many years). I found my harness connectors to be dirty and tarnished but they cleaned up easily.

 

[turbo elk]

yeah it goes through the post cycle time like normal. It just hasn't taken over 10-12 sec.for the WTA. light of time out even below low30's just seems kinda long now... I was just wondering if something was going bad... gp's are zd 9's. Thanks.

 

[OLDBULL8]

http://www.youtube.com/edit?o=U&video_id=tfTUka27UVo

http://www.youtube.com/watch?v=ez2R7kfC5vA

This might do it. Having a hell of a time with this new computer.

One video shows current draw, starts out at 196 amps, the other shows voltage drop during cycle, starts at 12.3, reduces to 8.5 during cycle.

 

[franklin2]

Note, my GP connectors no longer have the white insulation (most disintegrate after this many years). I found my harness connectors to be dirty and tarnished but they cleaned up easily.

I have found out not having the white plastic on the glowplug connectors is a major problem. There is not as much tension on the connectors with this gone, and corrosion seems to set in quicker. You may find your polishing routine may turn into a ritual you have to repeat once in awhile. I never went to all that trouble, but found I had to unplug and then plug back in the each glowplug connectors every two weeks or my controller would not work correctly. I went to the manual button system, and it starts fine, but it still misses a cylinder or two now and again, and I attribute that to one or two glowplugs not getting as hot as the others because of connection problems.

 

[turbo elk]

so what is the consensus... does 16 seconds seem excessive with the temperature in the mid 30*'s?

 

[rhkcommander]

so what is the consensus... does 16 seconds seem excessive with the temperature in the mid 30*'s?

Depends on the glow plugs, some can handle that time better than others . Bosch won't last long, Beru's should last a lot longer comparatively.

http://www.youtube.com/edit?o=U&video_id=tfTUka27UVo

This might do it. Having a hell of a time with this new computer.

One video shows current draw, starts out at 196 amps, the other shows voltage drop during cycle, starts at 12.3, reduces to 8.5 during cycle.

Nice video, hard to see until cranking quality to 480p. I jsut wanted to note for others that the voltage drop is due to the battery - not the controller. A common misconception is that the controller adjusts voltage, it does not. The batteries are draining and the voltage drops under the load, afterwards it bounces back.

I have found out not having the white plastic on the glowplug connectors is a major problem. There is not as much tension on the connectors with this gone, and corrosion seems to set in quicker. You may find your polishing routine may turn into a ritual you have to repeat once in awhile. I never went to all that trouble, but found I had to unplug and then plug back in the each glowplug connectors every two weeks or my controller would not work correctly. I went to the manual button system, and it starts fine, but it still misses a cylinder or two now and again, and I attribute that to one or two glowplugs not getting as hot as the others because of connection problems.

Could always slap a zip-tie on the end and crimp it down snug then connect it for a tight fit. Bullet connectors can sometimes be found in a size that fits well too

 

[bbjordan]

That is normal.

 

[turbo elk]

Thanks Jordan and commander..I was just wondering if something was starting to go bad.

 

[rhkcommander]

Anytime. Also, you might want to use some electronics cleaner spray on the two main power cables for the glow plugs, there are 2 and they are yellow on one side of the engine harness and brown on the other (if i remember correctly, been a while sorry) and really thick compared to the rest. The connector is usually hard to get apart, you can coat it in the electronics cleaner as long as it says dries clean non conductive to get it apart easier. Corrosion on wiring increases resistance!

 

[turbo elk]

The two 10g wires from the fender mounted solenoid to the glow plug controller?.. I've already replaced those with stereo amp cables, due them starting to melt the connector... and the solenoid to battery cable.

 

[rhkcommander]

yeah them, they melt usually from the corrosion - right at the big gray connector