Using 5V glow plugs in the 7V System

65Corvair · **Posted:** Sun Dec 04, 2016 11:38 am

I am looking to improve the cold weather starting since the 7V steel glow plugs are marginal at best. Has anyone done the drop in 5V replacement with the 7V system? (Running the 5V glow plugs at 7 volts.) If no one has I would be willing to try it and report back how it goes. Worse come to worse I install the 7V glow plugs back in as the 5V burn up.

Ceearedeedriver · **Joined:** Fri May 06, 2016 8:44 pm **Posts:** 177

Watch this space, I've got a dozen on the way from Germany. I'll decide whether to use them with my 7V system or get the GDE 5V update depending on how long they last.

The other concern is that 5V plugs in a 7V system probably means that the GP module is having to dissipate more power which may result in premature failure but I don't mind risking a 10yo module.

geordi · **Posted:** Sun Dec 04, 2016 2:25 pm

The glow plug module isn't dissipating anything. All input power is sent directly to the plugs.

It isn't anything more than a normal relay that is being cycled very fast (so kinda buzzing) to switch the 11+ volts on and off very fast to "simulate" 5v or 7v at the resistive heating element in the plug. The amount of time it is "off" is longer for the 5v program, but it is the same input voltage and the computer is commanding the pulse-width-modulation to simulate the voltage.

So the relay module should be just fine.

Sent from my iPad using Tapatalk HD

Ceearedeedriver · **Joined:** Fri May 06, 2016 8:44 pm **Posts:** 177

I like the simplified description but there's no buzzing relays in there :lol:

The module has actually got quite a sophisticated controller that creates 4 individual channels slightly out of phase with each other so that they are not all switched at the same time. This strategy minimises electrical switching noise. The switches they use are MOSFETs so there's a small voltage drop which means there is indeed power dissipation in the controller. But this is not wasted, by measuring this voltage drop across the transistors they are able to determine the current flowing through each circuit and in turn determine the health of each glow plug. This provides the diagnostic monitoring that is sent back to the ECU as a serial data stream.

The closest analogy would be a light dimmer. They dissipate power too which is why they get warm as they start to approach their maximum rating.

FYI the upgraded controller uses beefier switching transistors to account for the higher current. Applying wider pulses to a 5V plug will result in a higher output power but also require the controller to dissipate power.

flash7210 · **Posted:** Sun Dec 04, 2016 4:57 pm

Quote:

FYI the upgraded controller uses beefier switching transistors to account for the higher current. Applying wider pulses to a 5V plug will result in a higher output power but also require the controller to dissipate power.

Is it really upgraded?
The Bosch parts numbers are exactly the same.

Ceearedeedriver · **Joined:** Fri May 06, 2016 8:44 pm **Posts:** 177

Yeah, the same but still upgraded from what was put in at the factory. Most, if not all, were manufactured with 56044671AA. The upgraded version 56044671AC was introduced mid 2006 and works with either 5V or 7V plugs. So, unless you've replaced the GPM at some point you probably have the AA version.

mass-hole · **Posted:** Mon Dec 05, 2016 7:41 pm

I've had 5V plugs on mine since I bought it with 42k miles 3.5 years ago. I got a GDE tune, which they later told me was meant for 7V, around 3 years ago and have only replaced two plugs by 96k miles. One was half way through last winter and one was a few weeks ago. Ill have to check on the GPM part number but I assume its probably upgraded since my jeep had the 5V plugs installed already.

Starts decently in the cold but I also believe that my battery may be the original optima that was installed in 2005, so I have troubles if its below 32 and I leave it out without the Battery Tender hooked up. I am waiting for the new battery tray from Weeks before I replace it and then I will really know how the plugs do.

Ceearedeedriver · **Joined:** Fri May 06, 2016 8:44 pm **Posts:** 177

That's interesting mass-hole. I don't have a problem with a couple of failures in 3 years.

What was your logic behind not getting GDE to fix the tune?

mass-hole · **Posted:** Tue Dec 06, 2016 12:31 pm

Ceearedeedriver wrote:

That's interesting mass-hole. I don't have a problem with a couple of failures in 3 years.

What was your logic behind not getting GDE to fix the tune?

I don't have the flash tool. I originally sent my ecu in to get flashed. I also didn't find out it was a 7v tune until last winter when I had the first plug fail so I figured it was not a big deal and just haven't bothered to send the ecu back in.

Mountainman · **Posted:** Tue Dec 06, 2016 12:58 pm

mass-hole wrote:

Ceearedeedriver wrote:

That's interesting mass-hole. I don't have a problem with a couple of failures in 3 years.

What was your logic behind not getting GDE to fix the tune?

I don't have the flash tool. I originally sent my ecu in to get flashed. I also didn't find out it was a 7v tune until last winter when I had the first plug fail so I figured it was not a big deal and just haven't bothered to send the ecu back in.

How cold of starts have you had?

mass-hole · **Posted:** Tue Dec 06, 2016 1:31 pm

I mean last year we had some very cold weather here in Utah. Usually the Jeep is in the garage overnight which rarely gets below freezing because it's fully insulated. There was water on the floor that dripped off the cars and it only froze for a few days where it was sub zero for a week or two. My wife usually drives it to work so I'm sure a couple times it sat 8-9 hrs outside on days that never broke 0F. Usually you just cycle the key a few times and it starts up. Only time I have problems is if it sits in the cold for a few days and the battery craps out but then it just doesn't crank at all. This happened a few times when I parked at the airport for work trips last winter.

Mountainman · **Posted:** Tue Dec 06, 2016 2:11 pm

Right on, I think it's definitely worth a shot.

jws84_02 · **Posted:** Tue Dec 06, 2016 7:03 pm

This will be my second winter running 5 volts plugs on 7 volt tuning. I swap them back out in the spring. So far so good.

Mountainman · **Posted:** Tue Dec 06, 2016 9:39 pm

jws84_02 wrote:

This will be my second winter running 5 volts plugs on 7 volt tuning. I swap them back out in the spring. So far so good.

You had any super cold starts that way?

jws84_02 · **Posted:** Tue Dec 06, 2016 9:52 pm

Mountainman wrote:

jws84_02 wrote:

This will be my second winter running 5 volts plugs on 7 volt tuning. I swap them back out in the spring. So far so good.

You had any super cold starts that way?

Not really yet this year. But we normally will see below zero here for periods of time. I usually always plug in but just in case I am in a rare situation and can't it does seem to help a bit getting the 5 volts hotter

skjeep · **Posted:** Thu Dec 08, 2016 7:12 am

Hi all.
i have a similar problem with cold weather starts.

I had 7v ceramic glow plugs. Two of them gone, so i replaced all of them with 7Volt metallic Etecnos. We all know that these are not so fast as the ceramic ones, so winter starts are not as good as before. It starts every time, but first 15seconds does not run on all cylinders and i get a lot of smoke.

I know i could just drop the 5volts there and use 7volt programming but i do not like that idea

What about selectively tune /reprogram the ECU (via MPPS) to increase the glow plug time and duty cycle?

The original programming is so written, that when the outside temp is between 5°C and -10°C it glows only for 3 seconds with a duty cycle from 35 to 55%. This is not enough for the etecnos to get hot. So if i could change the pre-glow phase to 80-100% duty cycle i think it would help.

What do you think about that idea?

I have allready PMd to Yeti :twisted:

as he is the guy who knows that stuff

mass-hole · **Posted:** Thu Dec 08, 2016 3:11 pm

skjeep wrote:

Hi all.
i have a similar problem with cold weather starts.

I had 7v ceramic glow plugs. Two of them gone, so i replaced all of them with 7Volt metallic Etecnos. We all know that these are not so fast as the ceramic ones, so winter starts are not as good as before. It starts every time, but first 15seconds does not run on all cylinders and i get a lot of smoke.

I know i could just drop the 5volts there and use 7volt programming but i do not like that idea

What about selectively tune /reprogram the ECU (via MPPS) to increase the glow plug time and duty cycle?

The original programming is so written, that when the outside temp is between 5°C and -10°C it glows only for 3 seconds with a duty cycle from 35 to 55%. This is not enough for the etecnos to get hot. So if i could change the pre-glow phase to 80-100% duty cycle i think it would help.

What do you think about that idea?

I have allready PMd to Yeti :twisted:

as he is the guy who knows that stuff

I think there is a way to reprogram the ecu for the proper voltage but I don't think we really know how it's done yet.

It wasn't until recently that I understood how the ecu handled PWM so I may take another look through our tunes and see if I can find it. The ecu doesn't look at 0-100% duty cycle, it uses 0-8192 where 8192=100%, this is how the control for the VNT works. With this in mind it may be easier to find the voltage PWM.

speedtriple1 · **Joined:** Tue Jan 01, 2013 1:39 pm **Posts:** 2

I did this on my wifes CRD for 3 years. We live in Michigan and get really cold winters but she does plug in every nite. That being said the 5V plugs on the 7V system will not last the winter if its really cold. I have had to replace all the glow plugs by spring every year as they fail quickly in the cold. This summer i did head studs and put in the 7V steels and they really stink for starting in the winter. I think after this winter i will be installing the Intake Elbow heating element from Sasquatch as it seems like the real solution to the problem but it is expensive.

Sir Sam · **Posted:** Mon Dec 12, 2016 12:35 pm

I'm running 5V glow plugs in my 05 and 06. The 06 they were installed this summer and the 05 they were installed last summer. They have not specifically had a 5V reflash done but according the Yeti I have the software for the 5V control already. I'm not sure this is really the case, or what the differences are, but the 05 hasn't seen a dealer since 2006 before the 5V plugs were an item.

I didn't get many chances to test my glow plugs last year but this year I'm watching it between the two.

I have noticed that both CRDs seem to have issues at about 15 degree overnight low. If I can hold on the starter I can eventually build enough heat that it stays running.

Above 15 degrees and just a little warm up time on the GPs seems to do it.

With the ceramics it seemed like even down to 15 degree I didn't hardly need to let the plugs warm up, I could just crank and go.

Even at 30 degree overnights I need to let them warmup, this was unheard with the ceramics.

Ya the metallics are not as good at starting, but at least they shouldn't damage engines.

I have not played with plugging in the block heaters yet, I have rarely used them in the past. I am going to get a timer setup and see how many hours before I need to turn on the block heater to make a difference in starts. My goal is to develop a table - or just experience, to see what it will take to get the thing started during the winter. I run a group 65 battery which has a few more CCA amps and capacity. However if that battery is dead no amount of jump starting will get this thing going - I have two batteries here that I can swap out in case one is dead I can drop in a charged shelf spare to get me started.

mass-hole · **Posted:** Mon Dec 12, 2016 12:39 pm

Sir Sam wrote:

I'm running 5V glow plugs in my 05 and 06. The 06 they were installed this summer and the 05 they were installed last summer. They have not specifically had a 5V reflash done but according the Yeti I have the software for the 5V control already. I'm not sure this is really the case, or what the differences are, but the 05 hasn't seen a dealer since 2006 before the 5V plugs were an item.

I didn't get many chances to test my glow plugs last year but this year I'm watching it between the two.

I have noticed that both CRDs seem to have issues at about 15 degree overnight low. If I can hold on the starter I can eventually build enough heat that it stays running.

Above 15 degrees and just a little warm up time on the GPs seems to do it.

With the ceramics it seemed like even down to 15 degree I didn't hardly need to let the plugs warm up, I could just crank and go.

Even at 30 degree overnights I need to let them warmup, this was unheard with the ceramics.

Ya the metallics are not as good at starting, but at least they shouldn't damage engines.

I have not played with plugging in the block heaters yet, I have rarely used them in the past. I am going to get a timer setup and see how many hours before I need to turn on the block heater to make a difference in starts. My goal is to develop a table - or just experience, to see what it will take to get the thing started during the winter. I run a group 65 battery which has a few more CCA amps and capacity. However if that battery is dead no amount of jump starting will get this thing going - I have two batteries here that I can swap out in case one is dead I can drop in a charged shelf spare to get me started.

I found 2 hrs is usually enough to get you hot enough for a clean start. 4 hrs and the temp needle will be starting to move. I just ordered a digital programmable plug from amazon for this reason. Even though the jeep sits in the garage at night I think I am gunna plug it in from now on and just have the timer start it an hour or two before my wife usually leaves for work.

Using 5V glow plugs in the 7V System

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