EFS.O

Ok gyus,i was returning from a 200 miles trip last night and here is my story:I was "cruising" at 100 miles/h and my egt temps where between 700-730 C.The road was empty,so i decided to raise the speed up to 110 miles/h or better, to 4300-4400 rpm.Suddently the egt's went in no time,from 700 C to 800 C !!!.I think wtf,i let of the throttle and Bam! the ex.temp climbs to 900 C in 0.001 sec,and back to 700 C.Now,i now that mazda did deliberately the "surge" stage so the secondary turbo comes smoothly,but that think is crazy.900 C doesn't sound good to me,and if that behavior is normal,means that i cannot "cruise" for a prolonged period at 4400 rpm right?OR is it something wrong with the turbo control solenoid?Any ideas are welcomed.....

jeff48

Is you EGT sensor placed pre-turbo (in the manifold) or post turbo (in the downpipe). 900C is a high peak reading to be sure, but not unheard of. 900 C is just not a good temp on a regular basis and indicates a fairly lean condition.
What modifications do you carry?

EFS.O

The sensor is placed parallel to the O2 sensor.As for the high peak,what troubles me is that the temp went to 900C in zero time after cruising for a few sec,at exactly 4400 rpm in fifth.I went to 5000 rpm and the temp went back to 750C.In other words,it either gets lean at 4400,or because at this point the crv closes thus causing the secondary turbo to surge,the temps go skyrocket.What i want to know is if my thinking about the crv is right or there is something wrong with the seq turbo system....

My only mods are efini-y pipe and downpipe,and i have a profec for the spikes.Also note that my water temps where 180F.

Fish

This is not good. The spike when let off the throttle could be excess fuel (flames), but the rest is down to mapping.

Fish

EFS.O

Yep,i know that its not good,and the excess fuel idea sounds right,but i am still not sure...Anyone else care to answer?

Godzilla-T78

Its fine man, thats just decel cut, its unburnt fuel burning up after turbo.. no hard done.. My cars on vacuum *lean* pull 1600and up.

EFS.O

Man,Lets hope that you're right...I should never have installed that EGT gauge lol...

Kento

You cannot use an EGT gauge alone to determine the overall state of fueling for your engine. Crusing at partial throttle/steady state for even the slightest amount of time will always lean out your a/f mixture, which can bring up exhaust gas temps, depending on how hard you were driving before. Also, as previously stated, the rotary is notoriously inefficient with regards to burning the a/f mixture in the combustion chamber, and there is often some trailing combustion going on in the exhaust ports, which sends the temps soaring as well.

Unless the temps skyrocket and/or remain at an unusually high temp, I wouldn't pay too much attention to the EGT gauge.