Secondary Glow Circuit - Sounds like Morse Code!

[ianmair]

I'm not sure if my secondary glow circuit is working correctly.

When starting from cold my primary glow circuit works as it should and the engine starts, but it quickly becomes rough and then struggles to run smoothly for about 5 minutes. After this it's as sweet as anything (see here for why  8-)) I've tried jumping a cable from my battery to my glow plugs AFTER the engine has started and the lumpy start disappears within seconds leaving a very nice sounding engine! I cannot hear the secondary glow relay clicking on and off (as it has done on previous l300's) straight after starting, but it does kick in 20 minutes later when i'm driving along happily. It then decides to click on and off in rapid and random succession.

I've read a few similar stories and wondered if anyone has found the cure of 'The Dance of Glow Solenoid #2'?!

I have read Mystery Machine's diagnostic guides here and here and worked through the diagnostics. The only finding from this was that the dropping resistor read about 300mOhms rather than the 150mOhms on Bruce's guide.

Does anyone with a spare moment fancy whipping the cover off behind the driver's seat and measuring the resistance on their super-quick glow dropping resistor (shown on the RIGHT, below)

The best way is to disconnect it by disconnecting the green plug from the end of the resistor wires and putting a multimeter across the two pins.

Would be grateful if anyone gets the chance. Cheers

[mararmeisto]

What's the temperature gauge on the dash reading? Dollars to donuts it's not correct, which means you temperature sensor is not correct, which is why you've got a captive castenet clacker trapped under your driver seat. Replacement sensor is possible with NA version but I changed two of those before I just bought the Mitsubishi version (correct value range).

Search for a thread by me with "temperature sensor" in the title. It'll explain everything much better than this post.

[ianmair]

Hi mararmeisto,
Appologies i seem to have overlooked the "new post" email for this question. had assumed nobody had replied. I've attached an update from mdocuk below.
I am planning to change my sensors next week, so fingers crossed. Also my AC rad fan is permanently on with the ignition. looks like it's been hard wired to the injector pump solenoid for always-on. Can you or anyone confirm that the wire for the fan connects to the second temperature sensor (with the single spade connector)? If so i think i can re-connect, but i'm keen to change the sensor as i guess it's probably failed - hence the override! Anyway the fan isn't going to help with a quick heat up of the engine, so fixing seems a good idea too!

Bit of an update...
I revved my engine up a bit the other morning when i went to start it, to about 1500-2000rpm from cold and low and behold the 2ndary glow circuit came on. The reason i did this was that the night before i noticed that the speed of my interior blower and brightness of head/interier lights improved *significantly* when i revved the engine whilst stationary at a junction. (I know it's bound to a bit, but this seems quite a difference)

It got me thinking that if i had either an alternator problem or my batteries weren't holding a decent voltage then the resistance values of the glow plugs or the temperature sensors may differ enough to fool the ecu into thinking that secondary glow is not required.

I put my meter across the batteries whilst the engine wasn't running and saw 12.5v, then started the engine and tested again. I get the same reading, but i was expecting more like 14. I've also had my ECU out and given it a thorough test/clean/re-solder

So i've not really got any further, but thought this would bump the topic and might give someone an idea as to where i should go from here. I have the push switch standing by to wire up an override, but i don't think i'm ready to give up on my ECU just yet! any thoughts? cheers

[ianmair]

Another Update...

Not managed to get into town and pick up another temp sensor yet. Got a bit of a cashflow problem currently so prob couldn't afford one if i did find the price!

I have wired up a push switch to the secondary glow solenoid. This should replicate what goes on if my secondary system was working as it should - and whether getting a new temp sensor would fix the prob!
So having heated the plugs as normal on the ignition switch, i started the engine, then used the push switch to simulate the "click on, pause, click off" i'm used to hearing in my other 300's.

I had expected the problem to disappear, but it seemed there was no difference - lumpy engine within seconds of starting, lots of white smoke suggesting unburnt diesel. GAH! i really thought i'd found the issue.
So it's back to the drawing board on ideas. I'm now going to focus on the fact that i have replaced one plug, and the other 3 are 1992 mitsi 6.2v originals (although i've tested and they all work). The new plug i fitted is an obscure brand 6.2v that was matched to my Reg. number by a supplier. I'll check resistance and see if there's a difference between it and the originals. I expect to find that its resistance is higher, explaining why it takes another second or two to glow as bright as the others.

[TardisDeli]

HI, Something in yr post about AC fan always on at start up, and causing dimming. Do u know there is a little square switch on the dashboard by the AC control, that u push in for ON, then push in again for OFF, on some people do get dimming on start up from that.

My glow plugs click on and off repeatedly only when I havent warmed up the engine a minute before driving off. Or if it is near freezing weather and the fuel is a bit thick, or if I have debris in the fuel. Maybe you need to let yr fuel get real low so you have less to pump out, then undo the bolt dead centre bottom of the fuel tank and drain it into a large clear container (ie the oild cube that's restaurants use to put new oil in the deep fryer) and filter it through a food strainer then thru a coffee filter and let settle a couple days for water and debris to settle out, before returning it to yr tank. Also, Have you drained the water separator in the fuel system (turn the large white plastic key at its base, and also replace the tiny 3/8 inch ish black O ring at the base of that white plug -- easy fix, instant fix).

I have a vague recollection that the main problem with the circuit board is that a resistor dies, and as it is dying it does the madly clicking. Apparently you remove the board, and take it to an old time TV repair man or amateur radio anorak who looks at it and says Yep that thar resistor is getting a bit toasty coloured, I'll just solder on a new one for you. Search post of Marsgal42.

Mararmeisto on here is a great expert on the electronics side, so trust his replies.

Cheers, Christine.

[trialsmaster2]

Hi Ianmair,
Did you ever get this secondary glow plug issue resolved in your Delica? The reason I ask, is that ours sounds exactly like yours...first two clicks are like normal, but it starts up lumpy. When I give it a bit of gas to keep the revs up, that's when I hear the morse code from the glow plug controller for the first little bit. I wouldn't think old glow plugs would cause the glow plug controller to do the morse code thing, right?

Once the Delica has been driven for a bit, it purrs nicely.

If the Delica's block heater is plugged in, it does start up like a champ.

The outside temperature gauge reads within 1 degree usually of the read-a-board temperatures that I pass by in the van, so I don't think it's a faulty temp sensor, in my case...

Thanks,
Aaron