EGT too high. Exhaust Gas Temperature gauge, gage maximum [merged]

[RuBiCaNT5X]

Forgive the rookie question, but what exactly is the EGT telling you besides the temp of your exhaust? What does higher/lower temps tell you about the status of performance from a tuning point of view. Thanks fellas..

 

[tgounev]

I have a 95 AWD with typical mods (see my profile). I was getting ready to get bigger injectors and DSMLink, but I decided to put an EGT gauge first. I got the gauge from Glow Shift and installed it in the 1st runner 6-7’’ from the head (as recommended by many).

I started testing the car. During hard acceleration the EGT climbs quickly. In 2nd gear the EGT is above 1500F, in 3rd it goes over 1600F, and in 4th it gets to 1700F at which point I let off afraid of melting something. I am running 17 psi boost on stock injectors and a Walbro 255 fuel pump. It’s summer, so the outside temperature is high ~95F. Cruising EGTs are also high. At 2000rpm ~1400F, at 3000rpm ~1550F, at 4000rpm ~1650, and at 5000rpm ~1700F. This is with no boost, cruising on a flat road at about 65 mi/h and changing the gears from 5th to 4th to 3rd so I can get higher rpms. At idle the EGTs are around 1000F after a cool down (let of the gas in gear), but can be as high as 1200F if I just put the car in neutral after a run.

The funny thing is that before I got the EGT gauge, I was pretty happy with my car running at 17 psi. The A/F gauge was showing rich (9 out of 10 bars) at WOT, so I didn’t wary much and kept abusing the car all the time. I even ran at 18-19 psi for a while because my boost gauge wasn’t right. So if what people say about EGTs is correct, I should have melted something by now. Either my new EGT gauge reads too high or the EGT info circulating around is not completely accurate.

Here is my take on it. The EGT readings get higher with increasing rpm because the cylinder fires more often so even if the EGT stays constant, the readings from the probe will increase. Also as the manifold gets hotter during a run, the body of the probe will get hotter too due to contact with the manifold, so the readings may go up even if the EGT stays the same. I would have to wait and see how the car behaves on a colder day, but I was wondering if anyone has a similar experience with EGTs and how reliable the readings are?

 

[10's or bust]

The Exh probe readings are as acurate as U can get period Which is why all shops and dynos us them to tune your car when making changes to fuel and ignition maps I would recommend U first change out the injectors for at least some 550cc injectors which the Big16g will damn near max out...the stockers are fine with the 16g with low boost but will definately lean out and cause high exh. temps at high boost aslo have U rewired the fuel pump yet..if not then it is highly recommened you do so to help out with leaning out in high boost situations..

 

[Locke]

The Exh probe readings are as acurate as U can get period Which is why all shops and dynos us them to tune your car when making changes to fuel and ignition maps

Dyno shops use a wideband-on-a-stick, not an EGT probe.

 

[CanadianTSi]

I'd turn the boost down until you get a wideband

 

[tgounev]

OK, I haven't rewired the fuel pump, and I understand the problem at high boost levels, even though my A/F gauge is showing rich at WOT. I will be getting 680cc injectors very soon. But I don't understand the high readings at zero boost when barely pushing the gas especially at high rpm. At cruising speeds the A/F mixture is stoichiometric (at least my A/F gauge shows that) so the combustion is pretty efficient and the temperature should be pretty high. But how high is too high?

 

[Eclipse98_RS]

My GS-T runs around 1400 degrees at like 75 mph. Id get that checked out.

 

[awdrst]

In this day and age where wideband setups can be had for almost nothing its foolish to not have one. EGT was a ok way to tune when widebands cost over 1000 dollars. As far as your problem goes your egts can climb if you are having timing pulled way back or running really really rich. The flame with burn as your exhaust valve opens and it will pass by the egt probe. Also I'd suggest dumping that air fuel gauge as it doesn't really do anything since it reads off of the narrowband 02.

 

[tgounev]

Yes, I should have gotten the wideband. I guess we learn from our mistakes and spend a lot of money along the way.

Regarding what you said about the "really rich" condition, could this produce flames in the manifold? I would think that if you are rich, all the oxygen is gone so no combustion. But may be the combustion is incomplete in the cylinders and continues in the manifold? And if that's the case, is the EGT reading indicative of the actual temperature in the cylinders and could this condition hurt the engine?

 

[awdrst]

There could be a flame that hits the probe. As far as it hurting the engine you can wash down the cyl. walls which will be very bad for the motor. I would suggest getting a wideband since you can get them now in the 200 dollar range. It has been the best tuning tool I ever invested in.

 

[tgounev]

Where on the exhaust do you tap the wideband probe?

 

[talonawd1995]

I need to lower my EGT. When the car is running in 5th at 75mph the EGT is at 1400 degrees
Can I lower the EGTs by tuning the car or do I need to buy bigger injectors or what?

Car has
Stock Injectors, 16g Turbo, AFPR, SAFCII, FMIC, BOV, NGK plugs/wires, Boost Controller, 255 fp, 3' turboback ex, K&N Intake

 

[HustlerTalon]

My EGTs are about 700*C which is roughly about 1300*F when I am crusing at 75mph...just make sure you don't go over 900*C~1650*F

 

[Dragon TalonTsi]

I can vouge for that too. At about 55-65 cruising speed, its usually at 500-650 C. 950 C is about max for a stock cast 4G63, but a Forged 4G63, its EGT's are usually lower, and can also handle higher temps as well. About 1100 C is max, and if you have your piston's coated, even higher. A buddy of mine had his coated from FFWD on his 2.3 Stroker, and his EGT's are extremely low, and we have the same EGT setup. Different manifold and turbo though. And with a tubular, it builds and expels heat really fast, but a cast, it retains more heat longer, by far...

Wait, specify 1400 Degrees? If that is F (I am assuming it is) then that sounds a little high. As I stated above, its all dependent on the supporting mods as well.

 

[talonawd1995]

yes it is 1400 degrees F
At night if I stop and open the hood after driving over 50mph for a few minutes the manifold will be glowing red hot
which is why i want to lower my egts

 

[Mazlee]

Hello!

same problem like others.

AFR shows rich but at 18 psi WOT the EGT goes up to 1600F when I stop pushing it forward... no knock... EGT probe is in the exh manifold end. near the turbo.

what happens? few days earlier it goesn't went over 1500F


YouTube - little high EGT