Power Problem with FM260

[JRhetts]

Charlie

I do not have a pyrometer. From yours and others comments I can see it could be useful, and I am thinking about it. Tho right now I am mostly focused on the waste gate actuator, trying to to see ifI can arrange more even delivery of a bit more of the available compressor-side output.

I am not sure [I am still a neophyte!] what the feedback is between intake manifold pressure and the fuel injection computer. I DO know that both a factory turbo boost sensor and my analog dashboard gauge are plumbed in at the intake manifold.

Because my exhaust is routed out the side just behind the passenger door, I can see it in one of my mirrors. I have never observed any black smoke [nor any white] under any circumstances to date. [Of course, doesn't mean its not there, just that I've never seen it.]

I will seriously consider adding a pyrometer after I get to the end of this waste gate thread.

John

 

[kerry]

EGT will show a higher temp when there is a lean fuel situation, more fuel = lower temps as the fuel will help keep things cool.

I'm almost certain this is not the case. One time, the air filter on my CAT 3208 got plugged and it started spewing black smoke. The EGT's skyrocketed. For a general discussion of the issue there's a thread over on the 6.5 diesel forum:

http://www.dieselplace.com/forum/63...-engine/536617-how-make-black-smoke-more.html

Here's another quote from a Cummins forum:

"You also should have seen a fairly big increase in EGT's when your truck started smokeing. Was the locking nut tight on your fuel screw when you adjusted it after your trip?"

 

[westyss]

I'm almost certain this is not the case. One time, the air filter on my CAT 3208 got plugged and it started spewing black smoke. The EGT's skyrocketed. For a general discussion of the issue there's a thread over on the 6.5 diesel forum:

http://www.dieselplace.com/forum/63...-engine/536617-how-make-black-smoke-more.html

Here's another quote from a Cummins forum:

"You also should have seen a fairly big increase in EGT's when your truck started smokeing. Was the locking nut tight on your fuel screw when you adjusted it after your trip?"

Kerry, you might be totally right in respects to diesels but in gas engines when we lean mixtures EGT will rise, there may be other reasons that the cummins are smoking, also that quote doesnt say much as far as what the problem was, smoke from what? If the air intake was reduced was the fuel being delivered all the same or is there some metering from the ecu if equipped, I would say smoke can come from too much fuel or wrong mixture and improper burn, Anyway, all I wrote was EGT will rise when leaned, fall when enrichened,that is the only thing I know for fact as I do that every day.

 

[charlieaarons]

Not sure I'm following this. My experience with diesels is that the more unburned fuel (ie-more black smoke), the higher the EGT's.

Yes, like I said, with more air, the black smoke should go away and EGTs drop. I think my syntax was confusing.
Westsyss, what you say is true for gas engines which always run richer than stoichiometric but false for diesels which are supposed to be leaner than stoichiometric.

Charlie

 

[Amesz00]

EGT will show a higher temp when there is a lean fuel situation, more fuel = lower temps as the fuel will help keep things cool.

westyss, you are correct, except that diesel are almost opposite from a gasser. on a diesel a richer AFR will result in higher EGT. this is due partly to the way throttling is controlled on each type, ie a gasser air/fuel is pre-mixed and airflow is throttled to control how fast/how much power. on a diesel fuel is injected directly and self-combusts. air is not throttled at all, except by engine speed. diesels always run much, much leaner than stoich (about 15:1 for diesel), ie 18:1 would still be a bit smokey but give awesome power, most factory tuned heavy trucks run in the range of 28-35:1. this is both for emissions (leaner burn means more complete burn means less "bad stuff") and cooling the combustion.
another factor is that petrol wont burn properly unless it is more or less @ stoich. diesel will burn on a much wider AFR range, so you cant kinda 'drown' it in fuel to cool it if you get what i mean.

John, is your engine commonrail? and does it have an exhaust filter (or DPD, DPF, all the same thing)??
if it does this could be a reason you dont see black smoke, as the DPD would filter it before it goes out the end.
another possible explanation if fuel input is indeed richer, is that it may still not be rich enough to make it 'smokey'. your engine likely runs 30-odd:1 AFR, if it was 24 or 25:1 now it still wouldnt be smokey.
also i notice you are trying to slow the pressure input from compressor to wastegate actuator? i think thats what you said.. anyways, how about one of these. designs for that purpose
http://www.turbosmart.com.au/product/boost-tee

 

[JRhetts]

Regarding Oil analysis - that began this whole thread

I got my oil analysis back. Isn't this what started all this?

Iron, Lead and Magnesium all higher than 'universal averages'

Blackstone: "metals were high in this sample for just 882 mi on the oil; iron and lead together probably show some bearing wear; viscosity was fine and no contamination so we don't see any reason for the wear."

Rx: "change this oil and use 600 miles to monitor."

so, to me it would appear that there is nothing big as an explanation or a canary in the mine.

Now, back to your regularly scheduled programming......

 

[charlieaarons]

Mg is always from detergent additives in the oil, along with Ca. How many miles does the engine have, and what kind of oil is being used? Certain synthetics like Redline have esters in them which can cause "washout" of previously accumulated metals. If the engine still "young" (<20000 mi) higher metal levels are usually from breakin.
What were the Fe and Pb levels?

Charlie

 

[JRhetts]

Mg is always from detergent additives in the oil, along with Ca. How many miles does the engine have, and what kind of oil is being used? Certain synthetics like Redline have esters in them which can cause "washout" of previously accumulated metals. If the engine still "young" (<20000 mi) higher metal levels are usually from breakin.
What were the Fe and Pb levels?

Charlie

engine miles: 38,000
oil used: Shell Rotella T 15W/40
Fe: 25
Pb: 26
Mg: 828

Any thoughts?

 

[JRhetts]

John,

1. is your engine commonrail?

2. and does it have an exhaust filter (or DPD, DPF, all the same thing)??

3. if it does this could be a reason you dont see black smoke, as the DPD would filter it before it goes out the end.

4. your engine likely runs 30-odd:1 AFR, if it was 24 or 25:1 now it still wouldnt be smokey.
also i notice you are trying to slow the pressure input from compressor to wastegate actuator? i think thats what you said.. anyways, how about one of these. designs for that purpose
http://www.turbosmart.com.au/product/boost-tee

1. yes it is commonrail

2. No, it is 2007 engine and does not have anything more than an exhaust muffler- that is why I went with it. simple - I thought.


I read the info on the site in your link, but I cannot figure out what it does. Lots of claims, but do you know what it actually does?

sorry to be do dense

John

 

[gait]

something niggling in the back of my brain .....

my understanding of the wastegate is when the boost pressure exceeds the pressure required to overcome the spring the gate will open and dump air from outlet of turbo reducing the pressure which allows the spring to close a bit. Much like a SCUBA demand valve.

Looks like it operates off pressure (not flow). Restricting the pipe to the spring operating side may slow the response but it won't change the pressure at which it occurs. It won't get the pressure up to the spec of 22psi.

A different test may be to temporarily put a washer behind the spring, increasing the pressure at which it actuates. Hopefully easily accessible.

May even find there are different springs available? Or simply replace the spring with a new one.

Disclaimer ..... I don't know a lot about turbos! There are other designs.

Nice bit of "deductive reasoning" so far John. Brilliant thread.

 

[FusoFG]

I don't know about the FM engine, but my 2004 FG has a valve on the rear of the intake manifold that opens to bleed off excessive boost pressure in addition to the waste gate. If it opens too soon that might cause a problem.

When my 93 FG showed a 3 mpg drop in mileage, Mitsubishi replaced the turbo / waste gate and that fixed the problem. I didn't have a boost gauge at the time so I don't know if it would have indicated a low boost pressure.

 

[Flys Lo]

1. yes it is commonrail

2. No, it is 2007 engine and does not have anything more than an exhaust muffler- that is why I went with it. simple - I thought.

4. I cannot yet determine the AFR. Yes, at this point my thought is to slow the pressure input to the waste gate actuator so that it does not respond quite so quickly. I don't have any aspirations of limiting the overall boost to above the factory spec of 22 psi, but so far it seems that the mechanical waste gate actuator is actuating too soon, dumping boost that would other wise be used safely by the rest of the engine.
I read the info on the site in your link, but I cannot figure out what it does. Lots of claims, but do you know what it actually does?

sorry to be do dense

John

I genuinely think it is going to be difficult to diagnose without an EGT gauge (preferably pre-turbo), I would strongly recommend you fit one - its how almost all engine calibrators on diesels tune the AFR.

As mentioned previously, diesels are simple. Its either an air or a fuel issue, based on the lack of black smoke I am going to guess the latter, but without an EGT gauge and trying to diagnose it over the internet is like trying to hit a clay target at 2000 yards with a .22 pistol.

something niggling in the back of my brain .....

my understanding of the wastegate is when the boost pressure exceeds the pressure required to overcome the spring the gate will open and dump air from outlet of turbo reducing the pressure which allows the spring to close a bit. Much like a SCUBA demand valve.

Looks like it operates off pressure (not flow). Restricting the pipe to the spring operating side may slow the response but it won't change the pressure at which it occurs. It won't get the pressure up to the spec of 22psi.

A different test may be to temporarily put a washer behind the spring, increasing the pressure at which it actuates. Hopefully easily accessible.

May even find there are different springs available? Or simply replace the spring with a new one.

Disclaimer ..... I don't know a lot about turbos! There are other designs.

Nice bit of "deductive reasoning" so far John. Brilliant thread.

Flow/pressure are linearly related unless you are dealing with a VGT turbine.

Unless you can determine the cause of the issue, I wouldn't play around with the wastegate - I am not familiar with the enignes on the FM, but lifting boost pressures too much may cause blown head gaskets/thrown rods and a bunch of other not-so-fun stuff.

 

[kerry]

He's not talking about increasing OE boost pressures. He's trying to get his boost to the OE level. The cause of the problem appears to be a malfunctioning wastegate.

 

[Flys Lo]

ah - I missed that in post 42. My bad, please disregard my post above.

I would check for boost leaks first, and would also (as he has done) suspect the sensor given its electronically actuated.

 

[JRhetts]

I don't know about the FM engine, but my 2004 FG has a valve on the rear of the intake manifold that opens to bleed off excessive boost pressure in addition to the waste gate. If it opens too soon that might cause a problem.

When my 93 FG showed a 3 mpg drop in mileage, Mitsubishi replaced the turbo / waste gate and that fixed the problem. I didn't have a boost gauge at the time so I don't know if it would have indicated a low boost pressure.

After reading this I went to the truck and to the shop manual. I can't find evidence of a valve on the intake manifold. That doesn't mean definitively that there isn't one, but so far I can't find one.

I'll keep looking, but consider my next post.

John