EGTs still too HOT (1 Viewer)

This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.

Joined
Nov 10, 2018
Threads
44
Messages
574
Location
Conifer, Co
My EGTs still seem hotter than they should be. Let me tell a tale...
I have a 1993 KZJ78 with 249K kilometers on the clock. Purchased this vehicle from an importer last December.
Things done:
3” dump pipe and exhaust.
EGR delete and intake manifold clean
Spill control valve turned back about 1/3 turn from when I acquired it.
Timing set to factory specs.
Aftermarket aluminum radiator came with vehicle.
Tridon 170 degree t-stat
New coolant
New fan clutch, but still need to set temp and change out fluid in it.

Current situation:
Water temps measured at top hose rarely exceed 200F and if they do, it is not by much.
EGTs however, can climb to 1300F (measured post turbo) in a heartbeat if I am not vigilant and watching my gauges. This only happens when going up a hill.
No black smoke except I were to really step on it.
33” tires without a lot of weight like bumpers, equipment, etc.

This vehicle (even though it has a 3L engine and is working at 6k to 9k feet above sea level) has to be capable of keeping temps down better than this. What am I missing? I know it ideally needs an Intercooler and that is in my long term plans, But shouldn’t I be able to keep temps down better than this? Fuel pump? Timing? Cracked head that just isn’t showing up yet because my bubble test is being done without load on the engine?
??????
 
High EGT's are the product of a rich AFR (too much fuel for the given amount of air).

Do you have a boost gauge? How much boost is the turbo putting out?

Was the cap pulled off your spill valve before you adjusted it? That would indicate someone before you messed around with it and your fuel could still be above the factory setting.

If it were me I'd buy a manual boost controller and set the turbo to around 14psi. If EGT's are still high, then turn OUT the spill valve to reduce fuel until they are safe.
 
Thanks so much for your input!
Cap was on and rusty - no indication that it had ever been messed with.
I do have a boost gauge - turbo seems to be operating properly and tops out at 12 psi.
I think I have read you referencing a boost controller before and that was next on my list. (As a side note, any purchasing tips?)
Do these kind of temps seem reasonable to you and does it seem reasonable that I could get them under control with a boost controller?
Cracked head seems unlikely with water temps staying low, right?
 
Temps are definitely too high. Especially post turbo. You are probably seeing 1500F pre turbo, not comfortable territory to be in.
I am in a similar situation on my truck, though that has a lot to do with how I have it tuned. I can hold it and still hit 1400F pre turbo on a good hill. I don't, but I can.
Any boost controller will do, however a nicer one will give a finer adjustment. I am running an NSX Motorsports controller currently and have been really happy with it. I started with a cheaper one, but it didn't work as smoothly across the curve.
As Nick said, get you boost up to 14psi and then dial the fuel back slightly if it's still creeping up on you. Boost first, then fuel if needed. Several things are working together here, so it's finding a perfect combination to make it all work like you need. If you start hitting your fuel cut, you will need to dial the boost back slightly until you stay off of it.
Yes, cracked head is unlikely just on that description. EGT's can lead to a cracked head. But, the relationship between water temp and EGT is sort of loose. High EGT won't lead to high water temp in the short term and vice versa. Obviously the longer either of them are allowed to rise, they can start increasing their effect on each other.
 
Thanks guys. I guess I have my next steps in line - keep my fingers crossed.
Is this the type of controller you are running
1565389098076.png
 
Yep, that's the one. It's worked really well.
Mine is actually bottomed out, but to get to 14psi you will have a lot of adjustment.
Getting up in the 19-20 range required cranking it down.
 
Pretty tight quarters around the turbo on a KZJ78! Can anybody confirm that I tap into the vacuum line in the circled part of my pic (hard to see much from the pic, but pretty sure I have it)?
Thanks!
741CAA45-8618-45D5-A51E-1E4EBAC3EC30.jpeg
F9B48927-F9A8-4005-B66F-A1DBC108B4F0.jpeg
 
Not it.
I can't quite see the wastegate on yours in those pictures. I believe it's underneath on the KZJ78. It will be a round metal thing with a short tube coming off of it.
This picture will give you an idea what you are looking for. You need to tie into the wastegate boost line. It moves a diaphragm that is attached to the the rod and opens a vent on the turbo that allows excess pressure by. That is what you are trying to adjust.
That's an overly simplistic version of what is going on, but should lead you in the right direction.

71QC8i3q9kL._SL1200_.jpg
 
I have been looking at similar pics and from that pic and explanation that is what I thought I was already looking at? The hose comes off at a 90 degree angle just like the pic you attached. Maybe the pictures that I attached just aren’t showing it well enough.
Thank you!
 
REALLY tough to get back there for a picture, but here is what I think is it (for reference, you can see the same numbers from this shot as the numbers within the red circle on my previous second picture)
48E4171A-862C-45F0-82F6-8329E13FD854.jpeg
48E4171A-862C-45F0-82F6-8329E13FD854.jpeg
 
Yep, you found it. Looks fun to get to on your engine. My LJ is right up on top. Much easier to deal with.
I actually thought you were talking about the tubing closer in on the picture you circled. I couldn't even see that thing. But, after you said that about the numbers I realized it actually was in your picture. Just under a mountain of stuff to get in your way.
 
its actually not to bad(compared to replacing the oil return!), im 6"2 and got my hands down there with the intake pipe removed and some long nose pliers
to run 17-20 psi without adjusting anything I used a 1/4" "Y" fitting inbetween the black line so it bleeds off and only allows the wastegate to open at a later point, you can actually hear a little air noise blow out of this, no adjusting, 5 min install,extremely basic, you could go with 3/16" y and this gave about 13-15 psi, or like what happend to my wife , this fitting fell right off when I had not secured anything and got to see 25psi
 
25 psi - 😳
You are right - wasn’t that bad. Got my line installed and everything put back together. Tomorrow I will splice in my boost controller if it arrives.
Adjust it to max at 14 psi, right?
 
So I got my boost controller dialed in to peak at 14 and WOW - EGTs finally came down! I am still goi g to mess with my SCV a little, but for the first time, I feel like I have a handle on the EGT problem.
Super happy about that!
But.....
Saw higher engine temps than I have ever seen today. EGTs went down, but saw a 219 engine temp (I was too distracted looking at EGT gauge and boost, and missed it). Maybe I was just pushing it harder than usual finding my limits? In any event, this seems more fixable to me - will replace fan clutch fluid and set it to engage earlier and see where I get.
Making progress - thanks all!
 
You probably got a little to frisky enjoying the extra boost!!!
Definitely tackle that fan clutch next. It will make a difference.
I can't recall, have you already done the high flow t-stat? That made my engine temps much more manageable. Mine used to creep up over 200F like that if I wasn't paying attention.
 
Yes, I have a high flow t-stat.
I think the SCV can be backed off just a little bit more, set fan clutch opening temp and change the fluid out and I might actually have heating issues under control!
...
.
That still won’t stop me from adding an Intercooler later!
 

Users who are viewing this thread

Back
Top Bottom