Exhaust gas temp question

Just finished off putting an egt gauge and boost gauge in my disco 2 and the egt temps seem ridiculous for an unmapped car. It's idling at around 550 degrees and the slightest prod of throttle maxes the gauge out at 980 degrees. It's a brand spanking new aem gauge and I've tried two different probes with the same result.
It has a stainless exhaust with decat, alive intercooler, egr delete, allisport manifold and alive hybrid turbo fitted (very recently so, was fitting the gauges before I sorted getting it mapped) only running 19-20psi of boost so by no means pushing anything.
Just wondering if anyone else has had any experiences of wild egt readings and if anything in particular could be causing it.
Cheers,
Nick

IMO you should try with another gauge cos at those values there should be a lot of black smoke, it's almost impossible to get 550 degrees on idle...or are you speaking in Fahrehheit?

BTW...at those values i have the feeling that it's reading in Fahrenheit cos then it would be close to normal though a bit high = > 287 at idle and 526 under throttle which should be under load... so are we speaking about C or F degrees?

Gauge says its in Celsius and it's an analogue gauge, just almost maxes right out as soon as you rev it when stationary and constantly runs off the scale under normal driving conditions. There's nothing between the probe and gauge to calibrate or anything it's just two wires in a loom that send a signal to the gauge back. I've had one gauge that didn't work (just flashed a red light and maxed out as soon as it got voltage) so got a new one and this is the result. No black smoke at all which is what's confusing me, and it's not a cheap ass gauge either. I spose that's the only option, find and try a different gauge all together

Nope, gauge number 3 probe number 3 still the same reading so must be running really really hot for some reason

that's scary...unplug the MAF and see what happens... 550C at idle is something near the twilight zone... tha max i've got at idle was close to 300 but it was really cold outside... if the MAF thing doesnt help remove the glow plug relay(R6) for test as well... beside that turbo tuning do you by any chance have a boost box fitted?

Yeah I tried unplugging the maf which made no difference. Yeah it's has an alive boost box fitted to it, put on the same time as the turbo about 4 months ago (it's been parked up for the past 3 months as both the keys got nicked in a burglary). It towed a car from Cornwall back up to leeds in its current spec in early June before I had the egt gauge fitted and didn't seem to have any issue. It's just a bit scary that it's getting THAT hot. After a good blast earlier today I opened the bonnet and the manifold was blue!

Unplug that frigging boost box and see then, at least at idle cos under throttle it might go to overboost... the MAP sensor is the most important in the addaptive strategy's fuelling calculations and that boost box is mixing up all it's readings... IMO a boost box for a Td5's management is the worst thing ever especially if it's at fault, itseems that those who are selling them dont care or dont know how the management works

Okie dokie I shall bypass that and see what difference it makes to it first thing in the morning. Going to put a fresh tank of fuel in it tonight see if anything changes. It's got another run to Cornwall due in the next few weeks and I'd rather not melt it!

Look up at what temperature cast starts to emit visible light.

Ill give you a clue - its less than 980c.

Unless your manifold is actually visibly glowing, there's an error in your measurements.

ps. i found this for you -

https://en.wikipedia.org/wiki/Red_heat

Unfortunately it seems that all the management is mixed up on your's due to that turbo tuning cos for such job a dedicated fuel map is necessary with increased overboost limit, wide range MAP sensor and eliminated wastegate modulator default cos i presume that this is not used anymore with the hybrid turbo and the fuel map must be suited to this new setup... IMO better not trust 100% those who are making money from these products.

What kind of condition is your air intake and filter in

Boost is now wound back down to 1bar, no boost box connected up, has a new air filter in a recently de-leaved air box, fresh tank of fuel and still just the same.
I can't really say whether the manifold is glowing as it's kinda hard to get under the bonnet while I'm driving but after pulling up I can feel the heat as I open the bonnet and the manifold is a purple-blue colour. The actual exhaust gas coming out of the tailpipe is noticeably hot too.
Could it possibly be a knackered map sensor causing an issue?

You should hook it to a tester and see live data,find somebody near you with nanocom to save a data log and post it here cos the AAP(airbox) sensor can mix thing up too... if you can't try to replace the MAP sensor cos the boost box might have disturbed it, it's possible... the lower the boost is the higher EGT you'll get, also removing the boost box shouldn't have droped the boost at all it just tricks the ECU to override the overboost limit

If the cast manifold is blueing then maybe the sensor is correct...

...in which case I think I'd have too much fear to drive it for anything other than testing. How long has it lasted like this?

I can't really see how an air issue would cause the temp to rise like that. Less air means poor combustion and hence smoke. If the exhaust is clean...

julianf said:

If the cast manifold is blueing then maybe the sensor is correct...

Click to expand...

Which sensor is correct?

I meant the temperature one... The one that's claiming crazy numbers!

I wound the wastegate back down to set as much as I can back to stock levels. So it's got no boost box, standard boost levels, I've cleaned off the map sensor as it was pretty gunked up. Double checked the air box and air filter. Boost gauge takes its reading from just in front of the inlet manifold so boost is getting there. Only upgrades it now has really are increasing exhaust flow and increasing charge cooling and it's still running hot. It's a little cooler today so idling on the drive it's pushing around 450 not the 500+ it was before.
I'm not sure how long it's been running these temps as I've only put the sensor on it in the past day or two and it's done about 80 miles so far. It was sat for 3 months prior to that and had the turbo fitted about a month before that. Between fitting the turbo and it standing it towed a loaded car trailer up from Cornwall for well over 7 hours non-stop and didn't suffer.
And yes the exhaust is completely clean apart from the odd little hazy puff setting off up a steep hill

Sensor probe is plumbed in here and the tip is pretty much smack in the middle of the gas flow. Connectors are soldered and heat shrunk then from there to the gauge it's just two wires in an insulated sleeve