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The mkiv Supra Owners Club

The Diesel Tuning thread.......


Lucifer

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OK I have my trusty steed, A Rover 420 SDi 1996.

 

Ill start by saying I know nothing of diesel tuning.....

 

Recently its been a bitch to start when icy Cold, so I treated her to new glow plugs and a high CA Battery. It got alot better.

 

But when it is REally cold, ie. below zero, it takes ages to start, a few glow plug warmups, but it still takes 20 seconds of cranking to get it to start.

 

When I get it started, turn it off, its fine. Starts first time everytime. Its just when its cold. And no the diesel isnt draining down as the primer is rock rolid in the morning.

 

Have I missed something? Is there a diesel Heater somewhere I can replace or something?

 

Cheers guys.

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My dads had diesels and after glow plugs.

 

Maybe a new starter motor.

 

Then if thats not worked, put another battery in series on the lead to the starter so that it get 24V when starting. I know my dad did this to his diesel as a last resort. It helps turn it over much faster and worked for him. You then just have to take the 2nd battery off every now and then to give it a charge.

 

Or is that a bit extreme ?

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I have a Ford Escort diesel, now when starting that, it has a symbol come up on the dash which is a type of heater on the injectors you, you should let this light go out before attempting to start, if your alredy doing this sorry if I sounded patronising, you can put a small amount of petrol in which will stop your diesel from freezing about £4 worth on a full tank of diesel. Hope this helps.

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OK thanks guys, but:

 

1. The starter is fine, turnes over very quickly and strong.

2. As said, I usually let the Glow plugs go 3 times before trying to start.

 

As for the petrol idea, I might add a bit of meth to it, but I dont think its a freezing problem, as when it does eventually start, get a diesel cloud ot the back for a second or too..

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Very strange, the symptoms you've got are exactly the same as I had and 2 of my glowplugs had gone off.

 

You've really got to test them in situ connected to their electricity supply.

 

On my van I could remove the injectors and look into the cylinders to see the ends of the glowplugs, when you put the ignition you can see them glowing red after a few seconds.

 

If you can't do that you would have to remove the glowplugs and leave them all connected to their wiring and again try the ignition to see if they're working.

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If you've replaced the heater plugs, the next thing you've got to check is the power supply to them.

 

Its usually on some sort of timer device these days, but just a basic check to see if you're actually getting power to al the heaters would be a start.

 

If you're getting power down there, you then need to check to see if the heaters stay on for long enough. This is controlled by a timer unit in conjunction with a temperature sensor. My first instinct would be this sensor, if everything else is working.

 

Stick a voltmeter from the heater connection across to earth, make sure you can see 12v

 

You could try disconnecting the power to the heaters (to make sure you don't blow up any circuitry) and then connect them directly across the battery for 20-30 seconds and then immediately try to start the car (it helps to have an assistant :) )

This will check the timer circuit.

 

If not, there's always Easy Start :D

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Its really odd, cos once its started its perfect all day.

 

Once you've got it started the engine will heat up and retain some of this heat during the day.

 

It needs this heat to get the diesel to burn and to start the engine, on some diesels the compression of the fuel/air mixture isn't enough to get it to explode. You need the help of the glowplugs when starting from cold after it's been standing all night.

 

I'm using my van all day, on a cold morning I sometimes have to wait 20 seconds or so for the glowplug light to go out before I can start it.

 

But during the day I don't wait at all because the heat is already there and you don't need the glowplugs.

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Right. put 12v to them for 20 secs direct from battery. Still the same. Im convinced there is a diesel heater element somewhere ive missed.

 

 

i dont think they have a diesel heater as such. the fuel/air mixture is enriched on cold start via the coolant temp sensor on modern engines.

and the only other factors that are likely to cause starting problems are as follows

1 glow plugs

2 fuel leak

3 weak battery/starter or earth (not allowing the engine to crank fast enough )

4 low compression pressure

5 injection pump

 

i sure you can tick most of them off by now.

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