Low EGT at manifolds - 99 7.3l Powerstroke
#1
12-18-2018, 11:12 AM
Low EGT at manifolds - 99 7.3l Powerstroke
Ive been trying to track down the cause of little power under 2100 rpms and I decided to check the EGTs at the manifold. Parts of the manifold read around 100 degrees, other drivers side reads 140-160 and the rear part of drivers side reads 206 degrees. These temps are at idle warmed up, Ohio 20 degree weather.
To me it looks like something’s going on with fuel maybe? Injector o rings? I also have a good amount of blue smoke at cold start but it goes away when warmed up and never comes back no matter the load.
Im still learning about diesels, any thoughts?
To me it looks like something’s going on with fuel maybe? Injector o rings? I also have a good amount of blue smoke at cold start but it goes away when warmed up and never comes back no matter the load.
Im still learning about diesels, any thoughts?
#2
12-18-2018, 11:25 AM
Fleet Owner
What are the miles on your truck and what are the miles that you suspect are on the injectors?
How long have you had the truck?
Do you know the history of the injectors?
Does the truck idle and run fine best that you can tell?
Have you ever been under the valve covers for a visual inspection or to do some work like replace glow plugs?
What year is your truck?
How long have you had the truck?
Do you know the history of the injectors?
Does the truck idle and run fine best that you can tell?
Have you ever been under the valve covers for a visual inspection or to do some work like replace glow plugs?
What year is your truck?
#3
12-18-2018, 11:30 AM
What are the miles on your truck and what are the miles that you suspect are on the injectors?
How long have you had the truck?
Do you know the history of the injectors?
Does the truck idle and run fine best that you can tell?
Have you ever been under the valve covers for a visual inspection or to do some work like replace glow plugs?
What year is your truck?
How long have you had the truck?
Do you know the history of the injectors?
Does the truck idle and run fine best that you can tell?
Have you ever been under the valve covers for a visual inspection or to do some work like replace glow plugs?
What year is your truck?
Thanks for the quick reply.
Its a 1999 that I bought about a month ago now with 257,000 miles on the engine. I’m unsure of the mileage on the injectors.
I haven’t replaced anything yet I’ve just been testing and so far everything has check out, until now. Fuel pressure is good, holds at 63-65psi under a load.
It fires right up first time not plugged in when it’s 0-10 degrees outside and runs good and smooth just seems to lack power at under 2100 rpms to the point where I’ll hold it out at 2000 rpms at 20 to 30mph and it take a good while to increase speed. It’s hard to describe but man it’s EXTREMELY sluggish unless I get on it and this is with NO towing no trailer.
#4
12-18-2018, 11:48 AM
Tuned
Do you have a scanner and the ability to run any tests? Running a buzz test and a cylinder contribution test could be a good start...
Also if its bone stock, and auto, stall on the stock converters is rather high, and an aging converter could have an even higher stall speed...could also explain the lack of power...
Also if its bone stock, and auto, stall on the stock converters is rather high, and an aging converter could have an even higher stall speed...could also explain the lack of power...
#7
12-18-2018, 01:33 PM
Lead Driver
All good things to look at.
Is it running rough too or just down on power by SOTP dyno?
Has your oil consumption gone up? Color of the fuel filter? Fuel economy gone up? (signs of injector o-rings)
Is your SES light on?
"Down on power" will bring lots of questions as there are a lots of things it could be based on your definition.
Is it running rough too or just down on power by SOTP dyno?
Has your oil consumption gone up? Color of the fuel filter? Fuel economy gone up? (signs of injector o-rings)
Is your SES light on?
"Down on power" will bring lots of questions as there are a lots of things it could be based on your definition.
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#8
12-18-2018, 02:07 PM
Tuned
#10
12-18-2018, 02:27 PM
Ive been trying to track down the cause of little power under 2100 rpms and I decided to check the EGTs at the manifold. Parts of the manifold read around 100 degrees, other drivers side reads 140-160 and the rear part of drivers side reads 206 degrees. These temps are at idle warmed up, Ohio 20 degree weather.
To me it looks like something’s going on with fuel maybe? Injector o rings? I also have a good amount of blue smoke at cold start but it goes away when warmed up and never comes back no matter the load.
Im still learning about diesels, any thoughts?
To me it looks like something’s going on with fuel maybe? Injector o rings? I also have a good amount of blue smoke at cold start but it goes away when warmed up and never comes back no matter the load.
Im still learning about diesels, any thoughts?
#11
12-19-2018, 05:25 AM
A thermal gun is not a good way to test the EGTs. I have been led down a merry path on multiple occasion with the gun. Get the truck up to full temp after a drive, and check the symmetry of the temps from left to right. Short answer - the rear of the manifold has more heat soak. The heat builds from front to rear - the front part of the manifold has one cylinder feeding it, where the rear has 4 cylinders feeding it.
I have dual EGT gauges, and I can compare left-to-right on-the-fly.
The turbo really kicks in at 2000 RPM, so maybe you should look at air. The bushing on your turbo might be a thing.
I have dual EGT gauges, and I can compare left-to-right on-the-fly.
The turbo really kicks in at 2000 RPM, so maybe you should look at air. The bushing on your turbo might be a thing.
#12
12-19-2018, 07:12 AM
Hotshot
A lot of good tips above but the one thing that I see missing is...is the truck stock? Is it slower than it was when you got it? Without some goosing these trucks are slow and you might just be expecting more than you should from it without modifying some things. And I'll reiterate that the turbo's help really shows up at and above 2000 RPM's.
#13
12-19-2018, 07:39 AM
Lead Driver
Were it mine.....buzz test to listen for poppet wear, and then a compression test.
If the injector o-rings are bad, you won't get oil in to the cylinders directly, but you will get oil in to the fuel side, which will cause a blueish cast to your exhaust. If indeed the o-rings are bad, a symptom is oil consumption.
If the injector o-rings are bad, you won't get oil in to the cylinders directly, but you will get oil in to the fuel side, which will cause a blueish cast to your exhaust. If indeed the o-rings are bad, a symptom is oil consumption.
#14
12-19-2018, 07:49 AM
Wow a ton of replies, thanks guys. I’ll try to respond to everybody’s responses.
yes I might be expecting too much out of this truck but right now, the reason I believe it has to be low on power is because our old escalade that has the same mileage with a 6.2 vortec tows way better than my f350..
no loss in power since I got it.
it has some kind of intake system installed, 4” straight back exhaust, a sct tuner and some chip (I turned it up and there wasn’t a noticeable difference), otherwise completely stock besides the lift and wheels.
im going to do what you are all suggesting and buzz test it, I’ll be ordering a scan tool.
as far as boost, I can’t tell what it’s making but I know it’s got a decent whistle at 2500 and I can feel it punch. 2500-3000 and there’s definitely power but lower rpms I can’t tell if the turbo is doing anything, it’s silent.
Im going look at the turbo wheel in a few minutes.
one other thing I forgot to mention, it sounds like air is gurgling at the fuel pump, it has new fuel lines but I’m getting ready to drop the tank and check filters, pick up screen, and on top of the tank for leaks but I’m more concerned with the blueish smoke and bad smell.
yes I might be expecting too much out of this truck but right now, the reason I believe it has to be low on power is because our old escalade that has the same mileage with a 6.2 vortec tows way better than my f350..
no loss in power since I got it.
it has some kind of intake system installed, 4” straight back exhaust, a sct tuner and some chip (I turned it up and there wasn’t a noticeable difference), otherwise completely stock besides the lift and wheels.
im going to do what you are all suggesting and buzz test it, I’ll be ordering a scan tool.
as far as boost, I can’t tell what it’s making but I know it’s got a decent whistle at 2500 and I can feel it punch. 2500-3000 and there’s definitely power but lower rpms I can’t tell if the turbo is doing anything, it’s silent.
Im going look at the turbo wheel in a few minutes.
one other thing I forgot to mention, it sounds like air is gurgling at the fuel pump, it has new fuel lines but I’m getting ready to drop the tank and check filters, pick up screen, and on top of the tank for leaks but I’m more concerned with the blueish smoke and bad smell.
#15
12-19-2018, 08:28 AM
Lead Driver
What do you mean by "tows way better"? Gassers and diesels are two different animals.
The 7.3L is no hot rod but it will flat out haul the load. In stock form you won't be keeping up on the freeway if there's any headwind or incline but you will get there every time.
IMO rather than comparing it to other vehicles, make sure the truck is at 100% then see how it does. I would recommend an EGT gage and maybe fuel pressure since the truck does not have a sensor to monitor either one of those. For relatively cheap you can get a bluetooth OBDII adapter and monitor just about everything the truck sees too. These will give you access to a ton of truck data and a lot of what people here will ask for to help you narrow down any issues.
It doesn't take too much to give the truck some oomph (intake and tuner since you have an exhaust) to liven up a truck that's pushing 20 years old. But they are old. These trucks were the top of the heap back in their day but are the back of the pack now as far as performance.
Not knowing how the SCT is set up would concern me. Have you tried removing it completely and see how the truck runs? Have you re-installed it and have the same symptoms? Something to consider is that there a number of custom tuners out there that do a better job of coaxing better performance out of our trucks than the bigger name brands.
Just my .02
The 7.3L is no hot rod but it will flat out haul the load. In stock form you won't be keeping up on the freeway if there's any headwind or incline but you will get there every time.
IMO rather than comparing it to other vehicles, make sure the truck is at 100% then see how it does. I would recommend an EGT gage and maybe fuel pressure since the truck does not have a sensor to monitor either one of those. For relatively cheap you can get a bluetooth OBDII adapter and monitor just about everything the truck sees too. These will give you access to a ton of truck data and a lot of what people here will ask for to help you narrow down any issues.
It doesn't take too much to give the truck some oomph (intake and tuner since you have an exhaust) to liven up a truck that's pushing 20 years old. But they are old. These trucks were the top of the heap back in their day but are the back of the pack now as far as performance.
Not knowing how the SCT is set up would concern me. Have you tried removing it completely and see how the truck runs? Have you re-installed it and have the same symptoms? Something to consider is that there a number of custom tuners out there that do a better job of coaxing better performance out of our trucks than the bigger name brands.
Just my .02