Well, Here We Go Again!!.. 6.7L Ford

[BGlidewell]

at least ford is in control of their own destiny now. I'm pretty sure they can fix this mess.

 

[rscurtis]

I took a look at The Diesel Stop which I haven't visited in months to see what is going on. I am not a member and visit the site very infrequently as the site is very slow. There have been some problems with injector harness chafing, failure of hold down clamps, and death wobble. Ford supposedly has a caster kit for that one. Perhaps "Ford tough" isn't all it's made out to be.

 

[AH64ID]

A turbo doesn't cool the fuel and losing boost won't burn valves. If the turbo fails boost and power drop off dramatically and black smoke is emitted.

A turbo adds more air, which keeps the fire cool... x fuel at y boost will be hotter than x fuel at 2y boost (assuming everything is in the proper efficiency range)

It depends on the level of failure.

While I haven't ever had a turbo fail my OEM IC did fail, and would have the same symptoms as a failed turbo. My boost would drop off a few psi, and the EGT's would start to skyrocket. The truck ran fine, a little less power but mainly the only reason I knew something was wrong was the gauges. If I didn't have gauges I would have either melted a piston or dropped a valve, there was zero black smoke.

So if you have a turbo that doesn't move the air it should it would be VERY easy to run way too hot!

Anyone know if the ECM on the 6. 7 Furd monitors EGTs?

 

[HBarlow]

A turbo doesn't cool the fuel and losing boost won't burn valves. If the turbo fails boost and power drop off dramatically and black smoke is emitted.
__________________
Harvey Barlow

2008 Ram 3500 SLT QC & Chassis w/ CM bed
2007 HitchHiker Discover America 32 LKTG
2010 Goldwing XM/Nav


So, you are saying that if you reduce air intake the EGTs won't climb??? I am, of course, taken aback by this gross misunderstanding. With a given amount of fuel, EGT is controlled by air. More air = lower EGT. Period. So why is my theory being shot down so quickly??
If one of these big trucks is cruising down the road during regen, and the turbo is only moving half the air that the programming is allowing for, EGT could skyrocket to the point of burning valves.
One of our farm tractors was working in our field, and I noticed heavy black smoke shoot out the stack suddenly. The driver caught it and stopped, idled it down. We couldn't duplicate it right away. We checked the air cleaner and it was fine. Tractor started working hard again, and same thing. . black smoke. Upon further investigation, there was a bird nest in the intake chamber!! At high flow, it would get sucked up into the intake pipe,reducing airflow, and skyrocketing EGTs. When idled down, the nest would fall out of the way where we couldn't see it.
Surely you misread my post...

I said your theory of boost cooling the fuel was wrong because it is. Turbo boost surely does not cool fuel. Boost increases combustion, power output, and egt.

In the very simple terms of my understanding, reducing boost results in unburned fuel and greater smoke emission. Why is the fuel unburned? Weaker combustion occurs without boost.

Years ago the MAP sensor on my '01 HO/six speed Ram went bad. Turbo boost was reduced, EGT was lower (couldn't produce full boost or normal peak egt, power was down. I could feel the power was down pulling a trailer but the lower boost and lower egt told me a sensor was probably bad. I didn't know at the time what the cause was.

Edit: After posting, I was thinking about the issue. I know that performance enthusiasts often write that at some level of increased fueling a larger turbo is required in order to keep egts within tolerable limits. I recognize that at some power level more boost is required to cool combustion and keep egt under control. What I have not seen and am not sure about is whether no boost with constant fueling will increase EGT.

Maybe EGT does rise in the absence of boost?

 

[Wingate]

at least ford is in control of their own destiny now. I'm pretty sure they can fix this mess.

this is true!...

 

[MChrist]

Harvey, your MAP sensor problem may have called for a lower fuel demand. That would have equaled lower power and lower EGT. What I was trying to say was that IF the Ford programming (being new and all) doesn't compensate for reduced air flow, the lack of air going into a motor getting a lot of fuel could lead to high EGT, and possible damage.

AH64ID, the post you are responding to was Harvey's quote that I incorrectly copied. If you look at the earlier posts, you will see what I said in full.

And yes, I do understand that boost doesn't cool fuel. What I meant was that boost/airflow cools high EGT caused by too much fuel. I thought I was being clear, it seems I wasn't. My apologies.

 

[AH64ID]

Whoops. . sorry.

 

[AH64ID]

I said your theory of boost cooling the fuel was wrong because it is. Turbo boost surely does not cool fuel. Boost increases combustion, power output, and egt.

Boost does none of what you are stating, that is fuel... Boost allows for more fuel, more fuel means more combustion, power, and depending on the fuel:air ratio higher EGTs. Boost doesn't make power, fuel does.

In the very simple terms of my understanding, reducing boost results in unburned fuel and greater smoke emission. Why is the fuel unburned? Weaker combustion occurs without boost.

Only when the boost is greatly reduced does it effect combustion. At first it simply increases the combustion temp. Like my example with a failing intercooler, which provided less boost and lower air flow, but was still above the min psi for full fuel (approx 23 psi on my 05), no smoke, no unburned fuel, but VERY high EGT's. My EGT's would have gone much higher than the 1350* I let out at. The seal on the IC was the problem and at high boost it would fail, so I would be pulling a grade at 30 psi and 1100*, the boost would start to fall off and EGT's would start to rise. I wouldn't slow, but couldn't accelerate, EGT's just kept climbing and climbing but there was no other indication. At about 26 psi the EGT's would be at 1350* and I would slow down. Te seal would then work again until I hit 30ish psi.

Years ago the MAP sensor on my '01 HO/six speed Ram went bad. Turbo boost was reduced, EGT was lower (couldn't produce full boost or normal peak egt, power was down. I could feel the power was down pulling a trailer but the lower boost and lower egt told me a sensor was probably bad. I didn't know at the time what the cause was.

That is because the ECM uses the MAP to determine the fuel rate. If its not seeing boost then it won't fuel. But there is a point where if the boost is at or above then the ECM will allow full fueling. The HPCR's in 04. 5-07 use about 22-24 psi for that number, even thou peak boost is about 32.

This is a good example of why if a failing turbo is the culprit on the 6. 7 that it is only partially failed, as a full failed turbo would produce CEL's, lack of fueling, excessive smoke (if it gets past the DPF). But a partially failed turbo would probably be able to send the EGT's thru the roof, but show no other signs of failure.

Edit: After posting, I was thinking about the issue. I know that performance enthusiasts often write that at some level of increased fueling a larger turbo is required in order to keep egts within tolerable limits. I recognize that at some power level more boost is required to cool combustion and keep egt under control. What I have not seen and am not sure about is whether no boost with constant fueling will increase EGT.

Maybe EGT does rise in the absence of boost?

That power level is not far above stock, but there is more to it that just a boost number. I have a different turbo than stock on my truck that actually produces lower EGT's with less peak boost, and more hp to the ground than I ran with the stock turbo, this has to do with exhaust flow increase and efficiency of the compressor wheel. . But generally speaking more fuel requires more air, and since the restrictions are unchanged the greater flow means more boost must occur.

 

[Wingate]

Anyone know if the ECM on the 6. 7 Furd monitors EGTs?

I am almost certain that it does... From what I understand, it is part of the regen system to monitor pre turbo exhaust temperature. Not sure about post...

 

[HBarlow]

Boost does none of what you are stating, that is fuel... Boost allows for more fuel, more fuel means more combustion, power, and depending on the fuel:air ratio higher EGTs. Boost doesn't make power, fuel does.



Only when the boost is greatly reduced does it effect combustion. At first it simply increases the combustion temp. Like my example with a failing intercooler, which provided less boost and lower air flow, but was still above the min psi for full fuel (approx 23 psi on my 05), no smoke, no unburned fuel, but VERY high EGT's. My EGT's would have gone much higher than the 1350* I let out at. The seal on the IC was the problem and at high boost it would fail, so I would be pulling a grade at 30 psi and 1100*, the boost would start to fall off and EGT's would start to rise. I wouldn't slow, but couldn't accelerate, EGT's just kept climbing and climbing but there was no other indication. At about 26 psi the EGT's would be at 1350* and I would slow down. Te seal would then work again until I hit 30ish psi.



That is because the ECM uses the MAP to determine the fuel rate. If its not seeing boost then it won't fuel. But there is a point where if the boost is at or above then the ECM will allow full fueling. The HPCR's in 04. 5-07 use about 22-24 psi for that number, even thou peak boost is about 32.

This is a good example of why if a failing turbo is the culprit on the 6. 7 that it is only partially failed, as a full failed turbo would produce CEL's, lack of fueling, excessive smoke (if it gets past the DPF). But a partially failed turbo would probably be able to send the EGT's thru the roof, but show no other signs of failure.



That power level is not far above stock, but there is more to it that just a boost number. I have a different turbo than stock on my truck that actually produces lower EGT's with less peak boost, and more hp to the ground than I ran with the stock turbo, this has to do with exhaust flow increase and efficiency of the compressor wheel. . But generally speaking more fuel requires more air, and since the restrictions are unchanged the greater flow means more boost must occur.

From what you have written here it appears that you are one of the performance enthusiasts who has some experience with modifications to a turbocharged diesel engine so I'll assume you know more than I do about tinkering with them and how modifications act and interract with each other.

But when you try to tell me that additional boost in the presence of additional fueling does not increase power you're getting carried away and running off the track.

Old non turbo diesel engines didn't produce a lot of power for their displacement. It is because of turbo boost that modern turbodiesels make big hp and torque numbers. Failure of a turbo will absolutely reduce power output. It is the combination of more fuel and more oxygen that makes more power.

 

[HBarlow]

Harvey, your MAP sensor problem may have called for a lower fuel demand. That would have equaled lower power and lower EGT. What I was trying to say was that IF the Ford programming (being new and all) doesn't compensate for reduced air flow, the lack of air going into a motor getting a lot of fuel could lead to high EGT, and possible damage.

AH64ID, the post you are responding to was Harvey's quote that I incorrectly copied. If you look at the earlier posts, you will see what I said in full.

And yes, I do understand that boost doesn't cool fuel. What I meant was that boost/airflow cools high EGT caused by too much fuel. I thought I was being clear, it seems I wasn't. My apologies.

That may be correct. The MAP sensor probably provided an input to the VP-44 and influenced fueling. But the engine was unable to produce normal full boost on my boost gauge. What controlled turbo boost that reduced boost to correspond with reduced fueling?

 

[Wingate]

im fairly certain that with these trucks, if you lose boost, it will immediately de-fuel. . actually it goes into an active REDUCED SPEED condition... at that point, the truck will barely move when shifted into gear.

With such tight emissions controls, I would think the ECU is egt, coolant temp, emissions stack status, IMAT, IMAP, engine speed, engine load..... and from that, it is making a decision about the FRC (fuel ratio control) fuel limit (aka rated smoke limit). We have NEVER seen one puff of smoke out of these trucks, nor have we smelled the pleasant aroma of diesel fuel being burned... the exhaust has a harsh chemical smell. .

The trucks won't even smoke when you drop valves and wreck a turbo... !!!!

 

[MChrist]

Wingate, I would assume this as well, (that the motor would de-fuel with lower boost). But something must be causing these problems. In my opinion, it is most likely an imbalance of fuel to air, causing high enough EGT to melt the internals, causing your catastrophic failures.

Hey, didn't you say that one of your trucks went in for a bad turbo, or that it needed to go back for a new turbo after the motor got replaced?!
If that's right, it may be more than just mere coincidence... . (scratching my chin again)

 

[AH64ID]

But when you try to tell me that additional boost in the presence of additional fueling does not increase power you're getting carried away and running off the track.

I am not saying it doesn't increase power in the presence of fuel, I am stating that if the fueling is the same and you increase boost you don't increase power, you just run cooler EGT's.

Old non turbo diesel engines didn't produce a lot of power for their displacement. It is because of turbo boost that modern turbodiesels make big hp and torque numbers. Failure of a turbo will absolutely reduce power output. It is the combination of more fuel and more oxygen that makes more power.

Correct, they just couldn't get enough air in them to burn more fuel without cray EGT's. Boost simply allows for more fuel.



I agree a complete turbo failure would reduce output and have all kinds of other symptoms, but if you had turbo's that were either not moving enough air or blocking the air flow due to a partial failure it would be very possible to not have any electronic, smoke, or power symptoms but still do damage.

 

[Wingate]

Wingate, I would assume this as well, (that the motor would de-fuel with lower boost). But something must be causing these problems. In my opinion, it is most likely an imbalance of fuel to air, causing high enough EGT to melt the internals, causing your catastrophic failures.



Hey, didn't you say that one of your trucks went in for a bad turbo, or that it needed to go back for a new turbo after the motor got replaced?!

If that's right, it may be more than just mere coincidence... . (scratching my chin again)

It was one that got a new long block and re-used the turbo... . it made it less than a day before the turbo gave it up... .

I am merely speculating... but it would not surprise me if it were an imbalance in the intake tract... our little Cummins have the same issue with the end cylinders running higher exhaust temps... . some of this is attributed to the intake system in the cylinder head causing higher intake air temps... especially at cylinder #6. .

 

[Mikey-KE7LBB]

Bump to the top just to see if another Furd Pooperduty bit the dust again and the beginnings of a third thread on the subject :-laf



Any updates to report???



Surprised that the replacements have lasted almost a month so far :-laf:-laf