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Author Topic: Glow plug voltage.  (Read 3519 times)

November 26, 2014, 03:41:03 pm

offalot

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Glow plug voltage.
« on: November 26, 2014, 03:41:03 pm »
I am putting a mTDI into my MK1 caddy.  I heard the glow plugs in a TDI run on a lower voltage than the old IDI engines. 9v vs. 12v and could fail prematurely if repeatedly overpowered. Is this true? If so how can this be remedied? I was running the "pimped" setup on my 1.6.   
If I can run my old setup, anyone know a good connector that metes up to the TDI glow plugs without having to spend around $100 on the TDI harness?    Thanks.



Reply #1November 26, 2014, 04:09:41 pm

vanbcguy

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Re: Glow plug voltage.
« Reply #1 on: November 26, 2014, 04:09:41 pm »
Not true at all, at least not until you are getting up to the much newer TDIs.  I'm assuming you are using a 1Z, ALH or AHU - they all feed 12V to the glowplugs.  Use Bosch Duraterms - they have an internal regulator that will stop them from overheating and burning out.

The BEST way to do the glow plugs is to find yourself a 10-32 tap and thread the ends of the glowplugs.  Make sure you hold on to the metal ring ABOVE the 10mm 'nut' part of the plug when you do this as you can twist the center out of the plugs otherwise.  Then you can just use a ring terminal and a 10-32 nut on the top, you'll NEVER have issues with them that way.  Use some heat shrink to make it all look really nice:




Also get yourself a nice 4-fuse holder, something like this:

Bryn

1994 Jetta - AHU M-TDI - Jezebel Jetta
2004 Jetta Wagon - 1.8T - Blitzen

Reply #2November 26, 2014, 04:21:29 pm

offalot

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Re: Glow plug voltage.
« Reply #2 on: November 26, 2014, 04:21:29 pm »
Awesome reply man! I will do exactly that. So basically I'll be making them the same style as the old IDI plugs. Only thing with that is I'll have to do it any time I replace the plugs, but that doesn't seem like too big of a deal.
 I already did the fuse block. That and an automotive selanoid (relay)  And yes, it's an ALH.

Reply #3November 26, 2014, 08:54:29 pm

libbydiesel

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Re: Glow plug voltage.
« Reply #3 on: November 26, 2014, 08:54:29 pm »
That's a fine way to go, but on each of my mTDI conversions I've just used the stock tdi glow plug bar to the stock MK2 fast relay.  The glow plugs are much less necessary than on an IDI, won't trip the engine light on an mTDI and are much easier to test/replace than on the IDI engines so I haven't felt the need for the individual fuses or to get fancy with the connectors. 
Use, abuse or ignorance of any information is at your own risk, confirmation or refutation is your own responsibility, no further 'proof' will be given, take it or leave it, YMMV,terms subject to change without notice, avoid contact with eyes or skin, contents known to cause cancer in California

Reply #4November 27, 2014, 11:58:09 am

vanbcguy

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Re: Glow plug voltage.
« Reply #4 on: November 27, 2014, 11:58:09 am »
In my case I didn't have a stock TDI glow plug harness, sounds like the OP is in the same boat. 

For what it's worth, the stock 1Z/AHU/ALH glow plug harnesses are trouble.  Seems lots of folks on the e-TDI side of the fence are replacing them every so many years due to corrosion issues.  Seems they trap stuff around the GPs and corrode inside the plastic harness.
Bryn

1994 Jetta - AHU M-TDI - Jezebel Jetta
2004 Jetta Wagon - 1.8T - Blitzen

Reply #5November 27, 2014, 12:27:55 pm

libbydiesel

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Re: Glow plug voltage.
« Reply #5 on: November 27, 2014, 12:27:55 pm »
My understanding is that the TDI glow plug harness is problematic for eTDI owners not because the glow plugs stop functioning but because with a small change in resistance you get the check engine light, flashing glow plug light, etc...  With an mTDI, there are no codes to trip so the real consideration is reliable starting.  The TDI harness is plenty good enough for that.  There are also push-on connectors that fit the glow plug ends that will work plenty well-enough for reliable starting and won't require modifying each glow plug.  I fully agree that your setup makes a better electrical connection I just haven't felt that it was necessary.   
Use, abuse or ignorance of any information is at your own risk, confirmation or refutation is your own responsibility, no further 'proof' will be given, take it or leave it, YMMV,terms subject to change without notice, avoid contact with eyes or skin, contents known to cause cancer in California

Reply #6November 27, 2014, 08:05:44 pm

offalot

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Re: Glow plug voltage.
« Reply #6 on: November 27, 2014, 08:05:44 pm »
I already have the ring terminal setup in there, so I guess it's 6 of one half dozen of the other. I would not be against the newer harness, but if they are about the same it might be just as easy and definitely cheaper to screw on the terminals. I'll keep my eyes open at the yards in the meantime fo a harness if I decide to go that way.

Reply #7November 28, 2014, 11:30:17 am

rbremiller

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Re: Glow plug voltage.
« Reply #7 on: November 28, 2014, 11:30:17 am »
I'm using a new stock TDI plug harness and a MKII GP relay. I split the output from the relay to a 2 place fuse holder. There's a  25 amp fuse for each lead off the harness. It works great down to -15 f. The original VW TDI's have an afterglow period for up to a few minutes after starting which the older relays don't have. This feature is most desirable in the coldest regions for faster warmup, lower smoke & emissions. My relay is 28 years old; it's been in almost continuous service through 4 different cars.
'91 180k Audi 80Q mTDI DD AHU, K14, LT pump,
http://www.motorgeek.com/viewtopic.php?t=45645
'99 Jetta TDI 204k '02 engine, RC3+E, 11mm IP, .216, Racepipe, 2.5''SS exhaust, PD Lift pump,  Boostvalve, PanzerPlate, boost gauge, MAF delete.
'89 Audi 80Q ...waiting
'85 BMW R80

Reply #8November 28, 2014, 01:41:09 pm

vanbcguy

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Re: Glow plug voltage.
« Reply #8 on: November 28, 2014, 01:41:09 pm »
I have the original AAZ glowplug controller on mine - it has the famous "start up glowplugs after driver's door is closed" feature you see mentioned but rarely found in the wild, along with about a 2-4 minute afterglow too.
Bryn

1994 Jetta - AHU M-TDI - Jezebel Jetta
2004 Jetta Wagon - 1.8T - Blitzen

Reply #9November 28, 2014, 07:07:55 pm

rbremiller

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Re: Glow plug voltage.
« Reply #9 on: November 28, 2014, 07:07:55 pm »
I have the original AAZ glowplug controller on mine - it has the famous "start up glowplugs after driver's door is closed" feature you see mentioned but rarely found in the wild, along with about a 2-4 minute afterglow too.
I've heard rumors of their existence :) What does it look like? Is it similar to the MKII, the early TDI or something else? I never found much info on them.
'91 180k Audi 80Q mTDI DD AHU, K14, LT pump,
http://www.motorgeek.com/viewtopic.php?t=45645
'99 Jetta TDI 204k '02 engine, RC3+E, 11mm IP, .216, Racepipe, 2.5''SS exhaust, PD Lift pump,  Boostvalve, PanzerPlate, boost gauge, MAF delete.
'89 Audi 80Q ...waiting
'85 BMW R80

Reply #10November 29, 2014, 04:49:29 am

vanbcguy

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Re: Glow plug voltage.
« Reply #10 on: November 29, 2014, 04:49:29 am »
I have the original AAZ glowplug controller on mine - it has the famous "start up glowplugs after driver's door is closed" feature you see mentioned but rarely found in the wild, along with about a 2-4 minute afterglow too.
I've heard rumors of their existence :) What does it look like? Is it similar to the MKII, the early TDI or something else? I never found much info on them.

To be honest I've never located the actual controller.  Rumor has it that it's located below the radio in the dash, or that it is a relay-shaped device in the fusebox.  There's a very cheap and simple glowplug relay, but all the control logic is located in the actual controller which is separate from the relay in the Mk3.  Upside is the glowplug relay is super cheap, downside is if the controller ever failed it's basically unobtainable.  Mine all works perfectly so I've never messed with it.
Bryn

1994 Jetta - AHU M-TDI - Jezebel Jetta
2004 Jetta Wagon - 1.8T - Blitzen

 

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