Hi all,

I just bought a CRD and as of the other day I got a check engine light for the number 1 glow plug. I tested the resistance and it is definitely bad @ 275 ohms while the others are at about 1.5 ohms.

While looking around the motor, the timing belt cover still had a 7v ceramic glow plug warning and from the looks of it the number 1 glow plug had a white collar. I decided to dive deeper and pulled the plug out, sure enough the plugs were 7v Bosch plugs. No big deal right, I thought ok I'll just order the 7v Etchno plugs and call it a day... but wait there's more!

I decided to test the voltage to the plug and while in accessory mode the plug connector was only 4.35 volts (accessory mode, engine not running since I had the alternator off). Which leads me to think the last owner had gotten the GDE tune but got the 5v by mistake.

Besides the plugs not getting as hot as they should, are what kind of negative effects would be seen by pumping 5v to the 7v plugs? Im still learning diesel, but besides startup help do poorer performing glow plugs effect power after warmup, or effect fuel efficiency?

I know there are 2 plug options depending on what tune you already have either 5v or 7v. From what I've seen on this forum so far the 7v plugs do seem to help those who live in really cold climates, but is there any other benefit? I plan on getting the GDE hot tune, I'm currently on the low torque eco, but the TC has now been upgraded. Since I'm getting a tune update and there is an option to 5v or 7v and I'm buying new plugs should I stay 5v or is there any benefit to going by to 7v since there is no cost difference and I'd be doing all the work at the same time?

-Daryl

The only downside of using the 7v GP's on a system configured for 5v GP's would cause some very poor GP performance and poor cold starting issues! It would not hurt the GP's at all!
Installing 5v GP's on a system configured for 5v would probably be the best option.
If your system is still configured for OEM 7v GP's? Some on here have installed the 5v GP's on the 7v system and have reported good results so far!

You may want to check with GDE and see if they can tell you what GP program you have and provide you with some guidance since you are running one of their tunes?



Remember, the voltage to the GP's is not constant, the ECM PULSES the voltage as needed based on temperature!

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Yeah, you'll want to check if you have the hardware for the 5v "upgrade"

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Good to know! I did not come across anything yet that stated the voltage is pulsed based off of temp. thanks.

Mountainman, besides the plugs themselves, what other hardware would be apparent to see if you have the 5v conversion? I thought the plug voltage change, besides the plugs themselves was ECU programming only.