LoFi

CEL came on at the weekend although car ran fine I drove off boost. Dealer called today to say fault code was exhaust gas temp high. The car is a MY01 with the following engine mods

TD05
APS top mount
STi pink injectors
Uprated fuel pump and regulator
Panel filter
TEK3 remap
Full decat

Now I have had the exhaust temp sensor fail before (in fact b4 the above mods) but this time the sensor is ok just gave a high reading. Is this just and unusual one off or could it be a mapping issue? The car has been at the above spec over a year running a modest map to 300/300. I will get the specifics from the dealer when I collect (engine speed, temp etc) but does anyone have any initial advice?

Pies LoFi

hades

Two things. Firstly, a "high" reading may be an indication of a failed EGT sensor - they can fail to give a "too high" reading, rather than no reading at all. Even if it isn't, slightly high EGTs aren't as much of a worry with a decat up-pipe. You could leave the sensor in place, and put a 2.2kOhm resistor across the plug, that would give you an "all OK reading" whatever the temperature. There's a very high probability that if the EGT is the only indicated problem, it's a dodgy sensor / no problem, so you'd be fine with just the 2.2kOhm resistor.

The disclaimer with this is that if EGT's are genuinely very high suddenly, that would indicate a more serious problem. A CEL on exhaust gas temperature won't tell you how hot it is,or whether that reading is genuine. The only way to be 100% certain is to actually measure EGT's using appropriate new sender unit and appropriate guage or other monitoring kit.

LoFi

Thanks Hades,

On the phone the dealer said the fault occured at around 2600rpm at 70mph, whihc isn't even on boost, which may support the faulty sender theory. They tell me now the fault is cleared it is ok. If the sender was faulty would it not continue to report a fault even though the sender has not failed?

You seem to suggest that I'd be better off fitting the resistor and then using a new sender and gauge to show actual tempretures?

Pies LoFi

WRX_Rich

iTrader: (5)

do a search for 2.2k resistor

my cel is still on

LoFi

Rich

Read your thread. Is the concensus that there is no need worry about EGT readings and it is ok to ditch it? Wont something explode in a nasty way? Is the EGT sensor only there to protect against up pipe cat failure or is there more to it?

Pies

WRX_Rich

iTrader: (5)

there is no egt sensor on a sti and most the regulars highly modded wrx's on here have replaced the sensor with a resistor - a bodge i know, I looked at the defi egt gauge but went with the flow after a chat with BRD

hades

General concensus, is that monitoring EGT is un-necessary. Ir isn't implemented in STi's, and many people don't use one. However, several of the seriously tuned cars do monitor EGT in amongst other things.

I'll try and be more clear about my original post. If it was my car, I'd just check everything else was healthy, if it was I wouldn't worry, and justwait and see if the CEL comes back. If it does, I'd put the 2.2k resistor in, and keep an eye on everything else. I'd consider that a fairly informed decision that I'll live with the very small risk there is genuinely high EGT due to a problem. However, it's a different matter telling someone else to do something without making them aware of that small risk.

Final disclaimer - be aware that I'm not one of the real "exsperts" (to quote a recent post), just a keen amateur with a way to monitor some things

Midlife......

iTrader: (2)

Lofi

I'd get in touch with your mapper just to check they have altered the EGT high temp error code settings ......... they normally set the EGT high temp error code so high the ECU never sees the fault !! so any fault is with the EGT sensor!!

I run around with the CEL light on my bugeye (EGT sensor circuit malfunction) illuminated as I havn't got round to fitting the CEL fix !!

Midlife.....

harvey

iTrader: (48)

Exactly. Take specific advice from your mapper. If there is an EGT over temp then it could be the prelude to an expensive engine failure. On the other hand, hopefully, it could be a sensor fault or there may be another explanation.

LoFi

Good advice guys. Picked the car up today and the technician said the only real cause of a real high temp would be DET (no, no knocklink activity) or serious overboosting. So I checked boost levels on the way home and was worried to see the needle under WOT in 5th wander between 1.4 and 1.5kg/sq cm. I have an odd DEFI gauge.

This equates to 19.9psi to 21.3psi or 1.37bar to 1.47 bar. Sounds a bit high to me? Dont DEFI gauges read a bit high or should I be worried. I'm sure it was never this high and may have crept up?

Currently running on the reduced boost map, no more than 0.6kg.sq cm. Still seems quick.

Pies LoFi

jb2000

if you can do a ecu reset this may cure your overboost as my01 every so often got a bit over excited ecu reset always put it back to normal again