I've got an EGT gauge, I noticed today I'm reading very high EGT temps In a high gear with WOT this morning on the way to work I noticed the gauge getting above 900 C, I immediately backed off and it started to drop although even on less throttle cruising in a high gear the temp was up around 700 C I've had a bit of a look on TTnet this morning and found post that say EGT shouldn't go over 850 C I realise the high temp is an indication of possible detonation (although I couldn't hear it) But what is the cause ? A lean condition, high ignition timing or a combination of both ? I've not really noticed this before but I'm not sure if I've really been looking for it... Is it possible a boost/vac leak could cause this ? I've got no air flow meter on my car I've actually got an HKS VPC so even if there is a boost leak it's actually measuring MAP so should compensate !? Although boost does seem to be a bit lower at the moment, I used to be able to boost to around 1 bar but it seems to be about 0.8 at the moment. Any help suggestions much appreciated Thanks, Matt.
i think my egt occasionally ventures into the low 900 range... though i can't remember.. from my reading, i though less than ~950 deg is safe... another possiblity is that the gauge needs calibration.
Minor boost leaks will not affect Manifold Absolute Pressure (MAP). Boost leaks will affect the total air entering the combustion chamber which will affect AFR, idle, etc.
Worked out what was going on... Was having a look for the problem and found one of my det. sensor wires had broken. This is a bit long so bare with me... ! The broken wire would send the ECU into safety map mode. As my car has an HKS VPC which replaces the air flow meter with a MAP sensor there is also a custom chip in my ECU. The tables in this chip look nothing like the normal tables as it has to take the VPC into account (it must have been a full custom tune by the previous owner in Japan). When I first got the car and started looking at the maps in the ECU I saw that the safety maps were the same as the normal maps so I thought that wasn't too good ! I burnt a new chip with the safety maps changed to standard safety maps - This is where I think I went wrong Because my custom maps take the VPC into account I think that the standard safety maps actually run my car very lean, hence the high EGT temps ! I fixed the broken wire on the det. sensor and all is well, EGT temps are back to normal levels 450-550 at Idle, around 600 when crusing and a max of about 850 at WOT I also know when I broke the wire, I've been replacing all those little water hoses at the back of the engine so must have been when I was doing that... Bloody hoses ! I don't think that anyone else would have this kind of problem ! but good to know what was going on instead of being a mystery to pour huge amounts of time/money into ! Now to change that safety map back.... Cheers, Matt.
Generally standard turbos about 850 max but also depends where the EGT probe is situated. If between the head and turbo it will be a different reading obviously to after the turbo. I just got my aircraft grade 6 sensor kit from the states and will mount 1 sensor in each runner of the heads on the manifold this way it will tell which cylinders are leaning etc also have dual wideband 02 sensor kits which I am testing currently and may do a GB on them if all goes well. Its a very fool proof way of detecting a lean condition as well. Good work
