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Time of Relay Off for GPs
by
ORCoaster
on 14 Jun, 2011 20:31
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Here's a weird development. I slapped some gauges on the Rabbit a couple of weekends ago but was waiting on the Amp gauge until last weekend. Now that they are all in the glow plugs seem to stay on for like twice the time they used to. I have the slow glows so in the past they were on for just a bit short of 30 seconds. Now it is over a minute.
How do I know they finally kick off? Visual on the amp gauge and audio on the relay that I pimped in for the plugs. Very loud clack when that goes down.
I am taking my VDO temperature gauge reading off the same sensor that leads to the instrument cluster L to H sweep gauge. Would running these two off the same sensor make any difference to the
GP sensor on the other side of the water flange? I can not think that would be the problem. When I am sitting there waiting the Volt reading is right at 12 volts and dips ever so slightly when I throw the starter in the mix.
I also picked up a delay on when the plugs turn off after the engine is running. Some mild afterglow going on there.
Any ideas? Welcome to them all.
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#1
by
8v-of-fury
on 15 Jun, 2011 22:01
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weird. stock gp system? other than your extra pimping to monitor stuff?
Your gp relay seems to be crackalackin'. does it not control what all is going on? Thought they had a 30 second cut-off incase something happened..
If those are old stock slow glows, leaving them on for a minute has probably shortened their life... If they are still working at all :O
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#2
by
ORCoaster
on 16 Jun, 2011 07:08
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System is stock except that the wire that used to go to the glows now triggers the added starter relay. I followed vinces guide and ran the power to a distribution block where all individual plugs then get their own 10 amp fuse and wire down to the plug itself.
I pulled the stock vw relay out and plugged it back in to the main fuse box just incase I was running some sort of resistance on the connections there and did not see or hear any changes. I think I will just have to pull the VDO gauge off line and see what, if any difference it makes.
Yes, stock old glows but replaced all four when doing the rewire mod. So only about 3 mths old. I never leave them on for the full time the relay wants. I hit the key at about 25 secs for the start and then the relay kicks off shortly there after. My guess is when the alternator kicks in. But I should check for that as well now that I have the amp gauge working it should show me draw and charge.
Keep thinking and I will post back if anything comes of the remove the gauge thing.
Evening the second day. Being out in the sunshine I yanked the gauge sensor wire off the water flange on the side of the head. With the engine hot, fan was cycling, I shut it off and hit the ignition one click. On comes the gp relay and the light on the dash. Hooked up the wire and it stayed on for over 30 seconds. I shut it down after that. No need to burn them up.
If I just crank the car over without letting the relay cycle off there is a short like 5 second delay until the relay finally shuts down. I couldn't see if the ignition light was on or off as the sun was on the dash.
Weird eh?
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#3
by
Rabbit79
on 18 Jun, 2011 11:17
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I wonder if the temp sensor for the GP relay has some fault that is keeping the GP relay energized longer than it should be. I believe both the GP and gauge sensors are the same so an easy way to check would be to swap the wire over to the sensor for the gauge.
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#4
by
Vincent Waldon
on 18 Jun, 2011 19:38
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I am taking my VDO temperature gauge reading off the same sensor that leads to the instrument cluster L to H sweep gauge. Would running these two off the same sensor make any difference to the
GP sensor on the other side of the water flange?
In general you can't run two gauges from the same sensor... they are low-impedance devices and will likely interfere with each other unfortunately. Maybe you'll get lucky however.
Having said that, it certainly sounds like your glowplug temp sensor thinks it's artificially cold out... are you pretty sure your new gauge is sharing the temp gauge sensor and not the glow plug sensor?
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#5
by
ORCoaster
on 18 Jun, 2011 19:55
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Yes they share the same sensor. When I pull the wire from the sensor I get zip on the dash gauge as well as the VDO. I was planning to do a tap off the flange with an eighth inch tee and decided I could splice into the original gauge wire and save myself that problem. Well, maybe not. They will stay on a long time prior to the start if I let them. But I just watch the clock and at 15 seconds hit the starter. It fires right up and within about 5 seconds I hear the relay click off.
OH by the way, thanks for the write up on how to take that heavy load off the VW wires. It really works slick and I don't have to worry about plugs not working and which one is it. Test wire to each and fuses protecting individual glows. All for about 25 bucks. Those distribution blocks are not cheap for some reason.
I guess I will go to the split system with separate sensors for each gauge. It isn't bad the way it is.
I thought the glow plug sensor was an on or off thing. If warmer than x degrees then no relay kick in. Is that not true?
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#6
by
Rabbit79
on 19 Jun, 2011 09:30
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I thought the glow plug sensor was an on or off thing. If warmer than x degrees then no relay kick in. Is that not true?
The way I understand it that sensor varies the amount of time your GP relay stays energized. The lower the temparature of your coolant the longer it will stay on. I had the wire break off my sensor once and my GPs were staying on for a really long time(and I have the short glow system in mine), so I don't know for sure if the relay has a maximum time limit where it shuts itself off. I was just letting them glow for what I guessed to be the right amount of time and then starting it, but once I popped the hood and saw the wire hanging there I knew right away what was causing that problem. It is true that once the coolant is above a certain temp it won't energize the relay at all, so you're correct in that regard.
When I put an aftermarket gauge in mine I was like you in that I wanted to keep the factory gauge in the dash working in addition to the aftermarket gauge. There was a temp switch in the flange on the front of the head (the one your upper radiator hose hooks to) that wasn't hooked to anything so I pulled that out and put my sensor for the aftermarket gauge in that spot. What you were saying about putting a tee fitting in the factory spot for the sensor would work as well I'm sure, although if I remember right those are M10 x 1 threads so it might be kind of hard to find something ready made. Might have to have a machine shop thread something for you if you want to go that route.
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#7
by
ORCoaster
on 19 Jun, 2011 12:21
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Nicely said. Going to poke around for a second plug hole and see what I can find. I have the sensor from the VDO gauge and it has those weird pitch threads on it. So that would not be a problem unless the plug I find is something different. I doubt that as most of the sensors I have seen are this size.
Thanks,
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#8
by
Rabbit79
on 19 Jun, 2011 20:47
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The thread on the sending unit for my aftermarket gauge (it's a VDO also) is 1/8 NPT, which looks very similar to M10 x 1, so you might want to double check on that.
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#9
by
R.O.R-2.0
on 20 Jun, 2011 11:07
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The thread on the sending unit for my aftermarket gauge (it's a VDO also) is 1/8 NPT, which looks very similar to M10 x 1, so you might want to double check on that.
the thread pitch is the same, but the metric is a straight thread, and the SAE is a tapered thread..
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#10
by
ORCoaster
on 20 Jun, 2011 21:51
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Yeah, I hunted all around for a metric thread and I think the tee I purchased was just a regular one that was thrown into a metric only box. I taped everything up with Teflon tape and didn't experience any leaks so far on the oil gauges.
I pulled the VDO gauge for now to see how it affects the dash gauge. I know that in doing so I now have standard operation on the GP relay. At about the 20 one thousand count things are clicking off. Like the dash light. Then the big arse relay under the hood goes clunk and I know that means the cooking is over and hit the key. No or very little smoke on start up.
I might just run with the dash sweep for a bit then switch it over to the VDO just to see if all is well individually. Who knows I might move the VDO to monitor the oil temp for awhile. I have a cooler installed but want to hook up a better cooler than what VW had going. That is just a take off from the hot side of the radiator and yes I know that would help on cold mornings but not so much on hot afternoons pooled on I 5 waiting for some bonehead to merge across 4 lanes of traffic before he misses his exit.