High EGT Question

[Jerryl]

Did a search but could not find much.

Have a lot of concern about my EGT.
EGT's are around 1850's (maxed) and it is scaring me!
WB 10.5, 22 deg timing, 3600 rpm

Even just cruising, with just a little bit of throttle, it will climb to low 1600's!

Probe is Casperselectronics unit, installed 1" below NB, all the way in.
Any ideas?

 

[tb3]

what are your o2's showing?

in my experiance, sudden high egt is usually a injector (or 2) cutting out.

 

[T- Type Tim]

those are almost exactly the same numbers i saw on mine with the probe at the o2 sensor. My o2mv looked normal and the car ran great, tried adjusting the tune but the EGTs would stay 1700 - 1800s, can't compare these # s to an 87 setup.

 

[steve hughes]

Running a very rich afr and low timing will drive egt's up. 10.5 is way fat.

 

[Jerryl]

what are your o2's showing?
in my experiance, sudden high egt is usually a injector (or 2) cutting out.

Possible, but, all plugs look the exact same under my magifying glass.
(Just pulled and changed them thought maybe a "misfire")

those are almost exactly the same numbers i saw on mine with the probe at the o2 sensor. My o2mv looked normal and the car ran great, tried adjusting the tune but the EGTs would stay 1700 - 1800s, can't compare these # s to an 87 setup.

Interesting.
Do you recall what cam you were running?
I am thinking "overlap" may have a lot to do with it as it allows fuel in the exhaust and burn in there, raising the EGT's. Dunno.

Running a very rich afr and low timing will drive egt's up. 10.5 is way fat.

Very true.
Don't know if 10.5:1 is fat with alky.
I was running right at 10.8 with alky and richened it up to see if there would be a difference.


Keep the ideas comming.

 

[cool 84]

I agree with the above. #1 is low timing. Coupled with a very rich AFR it may be igniting unburned fuel in the exhaust.

Does the turbo spool abnormally well?

 

[T- Type Tim]

I was running a decent size cam its in the sig.. I also thought t was way rich igniting unburnt fuel,, i leaned it out quite a bit and did not see more than 30 degree drop in temps

 

[Dwayne]

Running a very rich afr and low timing will drive egt's up. 10.5 is way fat.

+1...........with your set-up, you're on the verge of making alot of HP.....

...........................as a wise man once told me.....you've got alot of tuning ahead of you..........good luck :biggrin:

 

[turbo6x2]

Seems a bit rich with the alcohol. My car only runs about 1600 degrees with the probe in the down pipe for reading on a quarter mile run. I usually only see about 800 on the street on very hot days. Otherwise around 600-700 and goes up if I get into the boost. I don't think I've ever seen egr readings that high on my set up. Interesting.

 

[tb3]

could this have anything to do with the tt chip you had made for you that keeps the afr constant?

 

[Jerryl]

I was running a decent size cam its in the sig.. I also thought t was way rich igniting unburnt fuel,, i leaned it out quite a bit and did not see more than 30 degree drop in temps

Tim,
Thanks for the reply.

I agree with the above. #1 is low timing. Coupled with a very rich AFR it may be igniting unburned fuel in the exhaust.

Does the turbo spool abnormally well?

Don't think 25deg timing is "low" on 93 and alky.
Spool is ok.

+1...........with your set-up, you're on the verge of making alot of HP.....

...........................as a wise man once told me.....you've got alot of tuning ahead of you..........good luck :biggrin:

Dwayne,
Care to share who that wise man is?

Seems a bit rich with the alcohol. My car only runs about 1600 degrees with the probe in the down pipe for reading on a quarter mile run. I usually only see about 800 on the street on very hot days. Otherwise around 600-700 and goes up if I get into the boost. I don't think I've ever seen egr readings that high on my set up. Interesting.

The probe is mounted right before the NB sensor, in the header.
This is where I thought you needed it, as close to the exhaust port as possible.

Regarding AFR;
My uderstanding is that most run in the 10.7-11.0 AFR range with alky (780-790 mV), so I am not sure it is rich ........... But I have been wrong before. :frown:
This car actually likes 10.8-10.9 with alky.

could this have anything to do with the tt chip you had made for you that keeps the afr constant?

Everything must be questioned at this point.
The chip has AFR target adjustments for Mid and WOT.
Mid range is running leaner and higher timing, so I am not sure.
From experience, it will be one of the last things I will look at since the PL is indicating timing and AFR.




I talked to few people and I have some "theories" :tongue: on this high EGT. :tongue:
1 - Caspers no longer sells the probe (ungrounded)
2 - The EGT amplifier from FT should be OK.
3 - The WB sensor is new.
4 - The ignition timing was verified.
5 - The plugs are new (Old ones looked OK)

EGT indicates 1571F @ 800 rpm, 13.5 AFR, 16.5 Deg timing

 

[Jerryl]

EGT indicates 1571F @ 800 rpm, 13.5 AFR, 16.5 Deg timing

Should be "26.5 Deg timing"

 

[Chuck Leeper]

What does the meter read w/ the probe in open air?
Are you using the mini probe "K"? Have you tried to back it out of the pipe, so only 1" is exposed to exh gas flow?
Is the probe straight, or did you bend it to clear something?
My Percy's read steady at 1590-1640, WFO at 25#...
BTW, I have a NIB Percys w/ a dual probe, backlit set up, for sale.
Still in the plastic wrapper.
Included is:
2 k probes, clamp on, w/ 10' leads. NIB.
2 soft wire probes w/ plugs.
1 screw in probe, w/braided wiring[10']. Used 1 chassis dyno session.
1 extra clamp mount.
Directions.
Total cost @ Summit $496.00
All for $300.00 shipped lower 48.

 

[Jerryl]

What does the meter read w/ the probe in open air?
Are you using the mini probe "K"? Have you tried to back it out of the pipe, so only 1" is exposed to exh gas flow?
Is the probe straight, or did you bend it to clear something?
My Percy's read steady at 1590-1640, WFO at 25#...

Chuck,
Thanks for the reply.

The probe has a 90 deg bend from the factory and I did not bend it in any way.
It is the 1/8" Dia probe which Caspers "used to" sell.
Probe is about "all the way in" without touching the opposite side.

I will conduct more testing late today on ambient readings.

 

[Jerryl]

Here are some numbers;
IAT 125F
Coolant 128F
EGT 137F

(hmmmmmmmmm )

 

[Chuck Leeper]

Huh???

Here are some numbers;
IAT 125F
Coolant 128F
EGT 137F

(hmmmmmmmmm )

SUMPTIN WONG!!
looks like all the readings are nuts...
Bad grounds?
Power source?
Are these all off the Powerlogger?

 

[Jerryl]

SUMPTIN WONG!!
looks like all the readings are nuts...
Bad grounds?
Power source?
Are these all off the Powerlogger?

Yes, the car is slightly warm.
Should have mentioned this. :frown:

On a cold engine, I know the IAT and Coolant temps are at ambient.
I was more/less looking for a big discrepancy.
Readings are with PL.

 

[Jerryl]

Another snapshot for viewing .......... idle speed and under boost
Notice how the EHT maxes out around 6 PSI
Any other ideas?

 

[Chuck Leeper]

Is this a hot air car??I didn't see a signature on the posts..
Have you checked exh back psi? Got a cat on it?
Looks like the EGT is way ahead of the boost rise. That would give me a suspicion that maybe the egt reading is bogus.??
What's the egt meter reading, engine dead cold?? IE: just turn key on, and look at the PL...
What do the other PL readings show at this same time?
What's the 40* + spike in the timing? The egt takes a fast rise, once that 40* hits.
The O2 volts look to be changing frequency at that point, also.
Timing jumps to 40*, the O2 volts tank, and stay there for some period, and the EGT shoots up, all at the same point in the log, yet the boost is still below 0/0.

 

[Jerryl]

Is this a hot air car??I didn't see a signature on the posts..
Have you checked exh back psi? Got a cat on it?
Looks like the EGT is way ahead of the boost rise. That would give me a suspicion that maybe the egt reading is bogus.??
What's the egt meter reading, engine dead cold?? IE: just turn key on, and look at the PL...
What do the other PL readings show at this same time?
What's the 40* + spike in the timing? The egt takes a fast rise, once that 40* hits.
The O2 volts look to be changing frequency at that point, also.
Timing jumps to 40*, the O2 volts tank, and stay there for some period, and the EGT shoots up, all at the same point in the log, yet the boost is still below 0/0.

Chuck,
AWSOME feedback. THANKS!
Yes, this is a HA with PAC to keep things !


- Engine dead cold, EGT was reading Ambient+10 (It was around 97F here yesterday) Based on the enormous range, I am not expecting extreme accuracy at the lower end of the scale.
- The other sensors read ok, meaning around 97+-3.
- Car has a 3" single, gutted cat. (Matter of fact, next project on my list was logging BP/boost)
- I am thinking the reading is bogus as well, but not sure yet until I verify "what is broke" in the DAS. :frown:
- 40 Deg timing - Don't know. I thought the EGT's would (should) drop with the high timing?? Sure, it goes lean, which should increase EGT, but that should help spool the turbo ......... (Yes?? )
- Regarding O2 readings - I will post a snapshot of the WB at the same frames sometime today.