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Discussion Starter #1
Hi,

I have had a Madman EMS2 fitted with an EGT probe 50mm below the turbo for a year or so now. It a great unit and has an alarm and saves maximum reading levels.

In that time i've had 4 massive but momentary EGT spikes of approx but very close to 1034 Degrees C. the last one being last night. (1034 was yesterday)

Typical scenario:
  • Nothing in tow
  • Acccelerating normally away from a stop (such as traffic lights)
  • EGTs in the space of 1 second goes over my 500 Degree C alarm level setting of the alarm.
  • Back the foot of the throttle and glance at the gauge.
  • EGT is likely over 600 but already falling. And likely would still be falling even when maintaining throttle input.
  • EGT normalise within a few seconds. The whole episode, start to finish all over in 3-4 seconds.
  • When i check the max reading. Typically between 1030-1040
I constantly run 1:200 two stroke but will easily have put multiple dual tanks worth through between these events. (I've raved before about how good i think the 2 stroke is)
I did add 20 litres of Shell diesel the evening before the latest episode and added the 2T as normal plus Chemtech diesel power at the normal rate, 1 to 1000. I normally do this to both full tanks every 3 to 4 months for maintenance. I will be on the look out next time as well. (this time i had a jerry can of fuel that i wanted to use up).

So i'm not desperately worried (should i be) as the spike is so fleeting. But as ever i'm interested in whats happening in my GU. I would imagine those with a dial type gauge or a gauge with alarm or no recording function would easily miss these spikes as they are over in the blink of an eye.

I have an idea that it might be something like soot getting burnt of the tip of the probe, and that might also be chemtech related but thats only a hunch.

Your thoughts,

Grogey
 

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Sounds like the diesel is still burning in the Exhaust

It does sound like the diesel plus 2 stroke is still burning in the Exhaust pipe past the turbo. Leave the two stroke out of the equation next time and see what happens. I would be thinking also about draining the tanks to 10% capacity and then filling them with diesel only.

Temperature is only caused by one thing in the patrol, burning fuel and air. Also your inlet air temp would also be up as the turbo would be a lot hotter also.

I also run Chemtech but not every tank I fill up.
 

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Totally agree with Tee, sounds more like connection and guage problem. Or you have molten piston and exhaust valves passing your probe
 

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Im with brad, EGT gauges are pretty reliable, i would say you arent getting a proper burn in the head and she is still on fire as it goes thru the turbo. probably to do with your 2stroke oil not mixing enough with the diesel. try running it without 2stroke oil, see if it still happens.
 

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Discussion Starter #6
In the last 45 mins my wife has taken the car as normal to drop of our son at day car. Its happened 5 times again in the first 1km. The EGT reading rocked for a split second then returned to normal. The first time happened when my wife touched the throttle for the first time to reverse out of the driveway.

She was getting massive momentary (1 second) spikes and alarms showing temps well over 650. 650 is as far as the bar on the screen goes and the temp would return to normal (say 140 when she had just started or 2-350 when driving away from home.

I told her to call into the nearest petrol station (1km away) and fill up the main tank. She put 62 litres of caltex diesel in. Last spike occured as she was arriving. Since then she has driven 12km to work with no recurrence. EGT are normal for a round town driving (in the 300).

Could the Chemtech be causing some sort of soot burn off. I thought maybe i'd screwed up and added it at 1 to 100. but on refllection that would have been 200ml and the dispenser doesn't hold that much in one go, so i'm sure it was 20ml in the 20 litres.

Dilution definitively seems to have had an effect.

Grogey

 

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Discussion Starter #7
Im with brad, EGT gauges are pretty reliable, i would say you arent getting a proper burn in the head and she is still on fire as it goes thru the turbo. probably to do with your 2stroke oil not mixing enough with the diesel. try running it without 2stroke oil, see if it still happens.
Yes diluting the main tank with fresh diesel has definitely had an effect. As the temps virtually instantly drop to normal it might be a drop of poorly mixed 2 stroke coming through the lines.

I've been running the 2 stroke for over a year now at 1:200 and this has happened a few times. the biggest difference this time was i chucked a jerry can full into a near empty tank. I added the the two stroke and ?chemtech to the jerryca first and then pourer it in. I would have thought that the pouring in would have given it a good mix around.

Grogey
 

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Discussion Starter #8
It does sound like the diesel plus 2 stroke is still burning in the Exhaust pipe past the turbo. Leave the two stroke out of the equation next time and see what happens. I would be thinking also about draining the tanks to 10% capacity and then filling them with diesel only.

Temperature is only caused by one thing in the patrol, burning fuel and air. Also your inlet air temp would also be up as the turbo would be a lot hotter also.

I also run Chemtech but not every tank I fill up.
As it only lasts for a second i hope the damage is neglible. At the first alarm this morning it went back to 140. Is it basicially a lick of flame due to an incomplete burn shooting through the turbo into the dump pipe?

Grogey
 

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subscribed.

There is more to this than just guesses 2T is is causing soot burn off. There should not be that much soot that close to the head.

Confirm you have a ZD30? Is it running standard fuel and boost?
 

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Discussion Starter #10
subscribed.

There is more to this than just guesses 2T is is causing soot burn off. There should not be that much soot that close to the head.

Confirm you have a ZD30? Is it running standard fuel and boost?
3.0 D auto in my signature. yep a ZD30.

I'm leaning toward poorly mixed 2T burning through into the dump pipe. It stoped as soon as the fuel was diluted with straight diesel.

Grogey
 

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Discussion Starter #12

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I would think it's some kind of electrical issue.

To get that kinda of increase in a split second I would have thought be beyond what's physically possible.

Need to ask yourself how that much energy can be generated that quickly?

How can fuel or two stroke burn that hot outside of a combustion chamber? I think a few laws of thermo dynamics have been broken.

It really seems like an instrument/probe problem IMHO.

Cheers

Justin
 

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castroltrol 2t mineral oil (for motorcycles)

I am running the same oil and have been for 6 months with no issue. I would be more inclined to say its an electrical issue as the spike itself is seems too quick. A spike of 900C for just one second, it's unlikely your probe would pick up a short flame or burst in amongst all that exhaust gas and read it accurately that quickly and also cool that quickly too. I would check the probe wiring for a short circuit as vibration or the rocking of the engine when the accelerator is pressed and de-pressed seems to be a strong symptom. Even a dry solder joint in the gauge itself could be the culprit also.
 

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I would think it's some kind of electrical issue.

To get that kinda of increase in a split second I would have thought be beyond what's physically possible.

Need to ask yourself how that much energy can be generated that quickly?

How can fuel or two stroke burn that hot outside of a combustion chamber? I think a few laws of thermo dynamics have been broken.

It really seems like an instrument/probe problem IMHO.

Cheers

Justin

x2 mate.
 

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Discussion Starter #17
I am running the same oil and have been for 6 months with no issue. I would be more inclined to say its an electrical issue as the spike itself is seems too quick. A spike of 900C for just one second, it's unlikely your probe would pick up a short flame or burst in amongst all that exhaust gas and read it accurately that quickly and also cool that quickly too. I would check the probe wiring for a short circuit as vibration or the rocking of the engine when the accelerator is pressed and de-pressed seems to be a strong symptom. Even a dry solder joint in the gauge itself could be the culprit also.

I'm not arguing and would prefer it to be a gauge issue, here are some facts

  • I am consisent in runing with 2T in the fuel to the point that my wife can tell the odd time i didn;t have 2T when i filled up.
  • I am careful to stay in and about the 1:200.
  • it alarmed 5 times in 1km on the way to the petrol station. Each time was during a throttle input.
  • Then after 62 litres of straight diesel the spikes stopped. Tested over a 12km run including hills
  • The fuel lamp had came on when i put in the jerry can of fuel in when mixed at 1:200. The previous refueling had 2T as well
  • I can remember 2 occasions when after filling the tanks and adding the 2T (i put the 2t in and fill on top to make sure it was agitated) it spike once and once only when pulling away from the lights when leaving the petrol station.
  • on some occasions i didn;t have my 2t at the station and just topped it in at home later. I can't recall this rather poor mixing technique causing any issues on those occasions
  • I have recently fitted a DB180 s dual battery system. The auxiliary battery was under no load.
  • Gauge is earthed directly to the -ve on the starter battery and has a positive feed from the accessory circuit in the dash.
Maybe theit is a few seconds of temperature ramp up before the gauge registers, but it all does happen sharply after a throttle input. You don't get to see 1034 on the gauge as i don;t think it has time to flash it up before it changes. But it is consistently recorded in the max value menu.

Could the fact there was only 30L in the tank be a contributing factor?

I will check for electrical issues.

Grogey
 

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I'm not arguing and would prefer it to be a gauge issue, here are some facts

  • I am consisent in runing with 2T in the fuel to the point that my wife can tell the odd time i didn;t have 2T when i filled up.
  • I am careful to stay in and about the 1:200.
  • it alarmed 5 times in 1km on the way to the petrol station. Each time was during a throttle input.
  • Then after 62 litres of straight diesel the spikes stopped. Tested over a 12km run including hills
  • The fuel lamp had came on when i put in the jerry can of fuel in when mixed at 1:200. The previous refueling had 2T as well
  • I can remember 2 occasions when after filling the tanks and adding the 2T (i put the 2t in and fill on top to make sure it was agitated) it spike once and once only when pulling away from the lights when leaving the petrol station.
  • on some occasions i didn;t have my 2t at the station and just topped it in at home later. I can't recall this rather poor mixing technique causing any issues on those occasions
  • I have recently fitted a DB180 s dual battery system. The auxiliary battery was under no load.
  • Gauge is earthed directly to the -ve on the starter battery and has a positive feed from the accessory circuit in the dash.
Maybe theit is a few seconds of temperature ramp up before the gauge registers, but it all does happen sharply after a throttle input. You don't get to see 1034 on the gauge as i don;t think it has time to flash it up before it changes. But it is consistently recorded in the max value menu.

Could the fact there was only 30L in the tank be a contributing factor?

I will check for electrical issues.

Grogey
Any idea of boost when the spike occours???
 

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Discussion Starter #19
I would think it's some kind of electrical issue.

To get that kinda of increase in a split second I would have thought be beyond what's physically possible.

Need to ask yourself how that much energy can be generated that quickly?

How can fuel or two stroke burn that hot outside of a combustion chamber? I think a few laws of thermo dynamics have been broken.

It really seems like an instrument/probe problem IMHO.

Cheers

Justin
I don;t know the thermo dynamics but a flame will be at a predetermined temperature, i'll classify it as hot. If that flame licks down into the dump pipe it should fill the dump pipe with the superheated incandescant gas that it actually is. I'd imagine the tip of the probe could react pretty quickly to contact with it.

I have no idea when fuel 2t or chemtech would still be burning outside the pistons.

Grogey
 
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