Exhaust gas pressure limits?

[Badger]

Anybody know an average pressure / safe pressure for the exhaust? Mine reading 137 inHg / 67psi . Dealing with high EGT only above 1600rpm. Send like maybe to much back pressure on hot side?

[Rawze]

what kind of truck?.
What kind of engine?.
some history?.
is it de-mandated (deleted)?
what is the boost pressures getting to?
what is the egt's getting to?

I.E.> some details.

[Badger]

(06-16-2022 )Rawze Wrote:  what kind of truck?.
What kind of engine?.
some history?.
is it de-mandated (deleted)?
what is the boost pressures getting to?
what is the egt's getting to?

I.E.> some details.

CM 870, stock 565 tune file but De-mandated , egt’s are way higher at higher rpm’s ( would get 1400° Fast if I let it, ecm says it gets up to 1676° But it’s calibrated not actual temp)
Barometric pressure outside is 30.2, but my sensor is reading 29.1 at 3.77 V
For some reason the boost has been lower than normal so I put shims in the actuator and it runs a steady 40 psi now. I put a unmolested actuator back on to confirm and it runs way hotter

[Badger]

I basically cruise down the flat interstate @ half throttle and still run a constant 8-900°

[tree98]

Part of your problem is you have a bad program in the ECM. Pull a copy out and send it over to Rawze for review.
Im not sure exactly what you mean but you shouldn't be "shimming" your turbo actuator. If everything is working properly you don't need to do something like that.

[Rawze]

My guess is that you have the typical garbage-can bad de-mandate programming.

If it has de-mandate programming in it then start by taking take the truck to a stealers$it and have the correct, original ecm programming put back into it (saving and restoring all the truck/dash settings). As a CM870, it will not shut down with factory programming if the thing is de-mandated. It will have a CEL light on and a boost derate, but it will run while you straighten out its other mechanical issues.

After that, fix any issues with it before trying to even think about putting another (properly made, instead of the typical garbage) de-mandate program back in it.

ALSO >>>> 40 PSI+ BOOST IS TOO HIGH FOR THAT ENGINE AND WILL KILL IT!!!. It should not be more than about 37,38psi absolute max, even at 600+ HP.

As well, Post turbo, you should not be seeing more than about 1050-F or so EGT's. Having 1400+egt's, something is very wrong.. and you screwing around and turning up the boost to fake it out is doing nothing but covering up a problem that is killing the lifespan of that engine!.

Also, fix the sensors that you say are reading wrong.

Also ensure that the exhaust is not clogging up (old plugged up muffler, etc.), and that the intake is not restricted in any way due to someone installing an after-garbage CAC unit, or some other reason.

Also wedge the cams and ensure they match the CPL of the engine to ensure they have not slipped: ref: http://rawze.com/forums/showthread.php?t...6#pid29926

Also... do an overhead valve adjustment followed by an injector leak test ...
ref: http://rawze.com/forums/showthread.php?t...8#pid67948

[Badger]

Ive had 3 different tunes, over a 3-4 year span, one being from most reputable guy ive ever came across. and they all act the same, and wasted my money.

WITHOUT my actuator modification,(which are just shims inside that keep the vg fins from closing all the way) , it just seems to get the same amount of fuel, but a lot less air. if i mash the throttler it spools up to 36-38, but then peters back down to 30, which leads to high egt. thats why i shimmed it to keep the boost around 38-40, been like that for probably 3 years now.

ambient pressure sensor is brand new, and reads the same as the stock one from 1.4 mil miles ago..., that why i dont know why its reading so low.

i was considering pulling my muffler off to inspect it even though i think its a straight-thru type. will check that.

has aftermarket intake with no bulky egr cone inside, CAC is not that old and the sensor that reads manifold pressure is right before the head, so if the CAC was the issue, the sensor and engine would not be getting the 40psi. Would be 40 psi pre CAC and less afterwards, if it was plugged or restricting.

Ive had this engine apart numerous times over the past 4 years so im 100% sure the cams or overhead is not the issue. ive made some drastic changes but the overall outcome is always the same, low boost - high egt

all new injectors., no improvement over the old factory.

egt probe is BEFORE turbo, i dont let it go over 1200 degrees pulling hills, only quick instances like getting on the highway shifting through the gears,

Does NOT make sense that i can lug a hill at 1250rpm , and it runs way cooler than if i take it up to 1800rpm.

1250rpm = 1100 degrees
1800rpm = 1300 to 1400+ degrees ( ecm calibrated temp was 1676)

im very close to throwing the vgt in the trash and visiting my menonite buddys dyno/tune shop but, figured id see what the rawze man has to say about all this, id love to put another driver in this truck but i cannot because i cant rely on him to babysit the PYRO like i do.

[Rawze]

That is a whole lot to unpack there.. but I will try. It looks like to me your problems are really obvious but you did not pay much attention to it. Instead, it seems clear that you are trying to justify putting on some after-gabrage turbo crap on it .. which is absolutely the wrong thing to do!.

Your post there reveals EXACTLY WHAT IS WRONG WITH YOUR ENGINE!!!. IT IS A BAD DELETE.. and --- YES,.. YOU CAN WASTE MONEYS OVER AND OVER AND OVER AT 100 PLACERS AND SPEND ENDLESS AMOUNTS OF MONEYS GOING FROM SHOP TO SHOP AND 'REPUTABLE' PEOPLE ALL YOU WANT TO, BUT YOUR OWN DESCRIPTIONS ARE clearly describing THE EXACT PROBLEMS WITH YOUR ENGINE!!!

YOU HAVE A BAD DE-MANDATE!!... PERIOD!.


ALMOST ALL BAD DE-MANDATE PROGRAMS OUT THERE FOR A CM870 HAVE THE SAME PROBLEM OF THE BOOST CAPPING OUT, THEN FALLING BACK!!... THIS IS BECAUSE ALL OF THOSE BAD DEMANDATE PROGRAMS THAT PEOPLE USE OUT THERE DO NOT SHUT OFF A VERY WELL KNOWN TURBO DERATE THAT YOUR ENGINE IS CLEARLY SUFFERING FROM!!!. <<-- THAT IS THE PART THAT YOU ARE NOT UNDERSTANDING!!!

- And you shimming the turbo to try to fix it IS THE WRONG THING TO DO! because the rest of the program is most likely garbage too, especially if they could not even figure out how to deal with a very well known, and obvious problem that the CM870's in particular are known to have.

These engines have been around for a lot of years... and it is a well known issue .. and NO, no one gives a damn about fixing it because ALL THEY WANT IS YOUR $$$$ MONEYS for trash programs that they got off the interwebs from those garbage truck-tuning sites.


Do you want to know what the exact signs of most all Bad delete programs for a a CM870 are?...

BOOST THAT SPIKES UP TO NORMAL LEVELS, AND THEN FALLS BACK TO ABOUT 30-32 PSI EVERY TIME YOU GET IN A HARD PULL!.. LEADING TO EXCESSIVE EGT'S -- WE HAVE SEEN IT ON HERE AT LEAST 500 TIMES IN THE PAST!... THAT ENGINE HAS BEEN AROUND FOR A LONG TIME!>.. IT IS WELL KNOWN BY NOW!... AND THAT IS WHAT YOU SEEM TO NOT WANT TO UNDERSTAND!.

Here it is on a RANDOM SEARCH ... , talked about back in 2016... your situation is not unique at all!.
http://rawze.com/forums/showthread.php?t...39#pid8139

So that fact that you have had 3 or 4 people 're-tune' it does not mean SQUAT!.. and yeah.. YOU WASTED YOUR MONEYS!.. BECAUSE YOU CAN TAKE IT TO 100 MORE PLACES AND GET THE SAME VARIATION OF GARBAGE-CAN TUNING DONE TO IT OVER AND OVER WITH IT!.

YOUR FIGHTING A WELL KNOWN BOOST DERATE PROBLEM IN THE ENGINE!!!.. -=PLAIN AND SIMPLE=-.. DUE TO BAD ECM PROGRAMMING!>

The reason for this is that THE DERATE ITSELF IS NOT EVEN IN THE FLASH FILE AT ALL!!>. IT IS IN THE ECM's RAM MEMORY ITSELF!.. AND THESE GODDAMN MORONS OUT THERE WHO DO DE-MANDATE PROGRAMMING ARE NOT SMART ENOUGH TO SHUT IT OFF PROPERLY!.

YOU ARE FIGHTING A GODDAMN BOOST DERATE IN THE ENGINE ECM!!! .. PLAIN AND SIMPLE! Your own words describe it very, very well...

(06-20-2022 )Badger Wrote:  if i mash the throttler it spools up to 36-38, but then peters back down to 30, which leads to high egt.

THAT IS BAD PROGRAMMING, HANDS DOWN!... BECAUSE PROPERLY MADE PROGRAMMING WILL NOT DROP THE TURBO BACK LIKE THAT!... which also leads my and everyone on here with CM870's to know that the rest of the program in your ecm is likely nothing but engine killing garbage too!... AND GARBAGE IN = GARBAGE OUT!

AND BY THE WAY.. NO ONE HERE IS TELLING YOU THESE THINGS BECAUSE THEY ARE TRYING TO TAKE MORE MONEYS FROM YOU!!!... THE ENTIRETY OF WHAT NEEDS TO BE CHANGED to make a cm870 run properly in the ecm is public information! / freely shared ...
ref: http://rawze.com/forums/showthread.php?t...0#pid53580

THERE IS ALSO A SCREEN FILE FOR 'CT' THAT YOU CAN USE TO SEE WHAT THAT ECM IS DOING!!! .. IT WILL REVEAL WHAT IS GOING ON AND WHY THE TURBO MIGHT BE DROPPING BACK LIKE THAT!!! .. HERE IT IS!.
ref: http://rawze.com/forums/showthread.php?t...3#pid58693

stop goddamn guessing!!!.. stop WASTING MONEYS.. AND SHIMMING TURBO'S LIKE A FOOL AND OTHER GARBAGE!...

STOP CHASING GHOSTS AND WORK THRU THE ISSUE PROPERLY!!!. -- YOUR CHASING YOUR DAMN TAIL BECAUSE NO ONE YOU HAVE BEEN WORKING WITH SO FAR IT SEEMS HAS ANY CLUE HOW TO PROPERLY TROUBLESHOOT (OR PROGRAM) THE ENGINE!

==========

NOW THIS LEADS TO A LOT OF OTHER THING S YOU SAID...

(06-20-2022 )Badger Wrote:  all new injectors., no improvement over the old factory.

We know now that your chasing ghost derates and bad programming .. so ...

WHY did you replace all the injectors>?. DID ANYONE BOTHER TO do a proper leak-down test on them before just accusing them of being bad?.. or was someone just wasting goddamn moneys, throwing parts at a problem that is mostly a ghost!?. - It sounds to me like someone does not know a whole lot about the CM870 engines if they are throwing expensive parts at it like that without verifying if they had actually failing injectors or not. I DON'T KNOW ABOUT YOU.. BUT I DO NOT LIKE WASTING MONEYS AND GUESSING AT THINGS!. Injexctors will not cause excessively high EGT's unless they were bleeding pretty damn badly.. and they would have failed an in injector leak test (mentioned in my previous post) RIGHT AWAY!...

ALSO... you need to verify that the new injectors ARE NOT ALSO LEAKY!!.. so this is why I said to do the test again!.


The afater-garbage CAC....

IT IS NOT BOOST PRESSURE DROP THAT MAKES THEM RESTRICTIVE ... BUT THE FACT THAT THE VG TURBO HAS TO WORK HARDER TO OVERCOME ITS RESTRICTIONS!... MANY BRANDS OF AFTER-MARKET CAC UNITS ARE NOTORIOUS FOR THIS!... ESPECIALLY THOSE DURA-LITE GARBAGE UNITS!... THEY ARE THE WORST OF THE WORST!... AND WILL CONTRIBUTE GREATLY TOWARDS TRAPPED HEAT, EXCESSIVE EGT'S, SOME BRANDS CONTRIBUTE TO EXCESSIVE INTAKE TEMPS, AND THESE THINGS WILL CAUSE FUEL MILEAGE LOSSES!. IT IS WELL KNOWN!!.. SO depending on what brand.. IT EVERY WELL MAY BE A BIG FACTOR in your issues.

I, and others on here have been trying to help you.. but you seem to be really stubborn. i don't know if it is because you simply do not understand.. or if it is because some morons out there have brainwashed you.. but those things you are doing .. you need to get those bad ideas and bad arguments out of your head.. they get you nowhere and they solve nothing. Re-read my posts a few times.. try to understand what I and others are saying.. IT IS THOSE THINGS YOU NEED TO LOOK AT AND DO!.. AND NOT TAKE FOR GRANTED AS FODDER FOR A DISAGREEMENT!.

=====================

(06-20-2022 )Badger Wrote:  Ive had this engine apart numerous times over the past 4 years so im 100% sure the cams or overhead is not the issue. ive made some drastic changes but the overall outcome is always the same, low boost - high egt

This is a pretty vague statement. Maybe some elaboration?.

====================

(06-20-2022 )Badger Wrote:  egt probe is BEFORE turbo, i dont let it go over 1200 degrees pulling hills, only quick instances like getting on the highway shifting through the gears,

Does NOT make sense that i can lug a hill at 1250rpm , and it runs way cooler than if i take it up to 1800rpm.

1250rpm = 1100 degrees
1800rpm = 1300 to 1400+ degrees ( ecm calibrated temp was 1676)

First of all, when you lug the engine at 1250 rpm at high throttle positions, which in itself causes a lot of accelerated wear, and is NOT good for that engine long term, .. the engine is unable to make its full horsepower output. it is essentially the same as a higher rpm where you do not press the pedal as far ... making only that same lower HP output to the flywheel. -- This is why the EGT's are lower., it is NOT the RPM making the egt lower.. but the fact that the engine is unable to make full output power.

Also, if the pyro is pre-turbo then the max EGT's you should see on that engine should be in the ballpark of about 1190F - 1230F. Above 1320F+ is too high. We already know you have bad demandate programming that is boost derating it.. so that is the first thing that needs to be fixed!.

You also do not know what engine operating mode the engine is running in. For all you know, it could think it is at high altitude.. or it could think that the egr gas is still going into the intake (most bad deletes have this issue too).. you have no clue!... so that is also WHY proper programming and subsequent proper testing needs to be done TO ENSURE IT IS NOT SOMETHING IN THE ECM CAUSING THE COMBUSTION PROCESS TO BE INCORRECT, LEADING DIRECTLY TO HIGHER THAN NORMAL EGT'S!.

STOP FIGHTING THAT GHOST TO BEGIN WITH!... and ARGUING AT AWAY does not make the problems disappear. - GETTING THE ENGINE INTO A KNOWN RELIABLE STATE DOES.

- And if your goals are to put a driver in it who does not care about EGT's etc. .. .. THEN set the engine and truck up for just that!.

* Copy the program out of the ecm and send it to me for a proper review.

* DO an injector leak test on it... make sure it passes with flying colors.

* Pull the metering and timing actuators off of it and inspect them for excessive wear and 'step-wear' on the plunger shanks.. especially the timing actuators. if they are going bad, they can cause improper injection timing and contribute to higher than normal EGT's.
ref: http://rawze.com/forums/showthread.php?t...619#pid619

* GET RID OF THAT GODDAMN AFTER-GARBAGE CAC UNIT AND PUT THE OEM ONE BACK ON!... ESPECIALLY IF IT IS A DURALITE BRAND!. Many after-garbage CAC units have less passageways and cause a lot of heat/restriction related problems for the engine. - OR at the very least!.. count the number of passageways that are in the one you have .. and compare it to the OEM one. ... and also inspect it internally with a mirror to ensure the welds are not restrictive. When one is restrictive.. it does not cause a "boost" drop .. but makes the turbo work harder to overcome the flow problems.. creating higher exhaust pressures, trapping heat in the turbo / exhaust directly and causing engine efficiency losses.

* Wedge the damn cams!. Make sure they match the CPL of the engine according to this reference: http://rawze.com/forums/showthread.php?t...6#pid29926
There are different wedge settings for different CPL engines on the CM870's and they are very important .. if they are wrong then the injection process will suffer problems!. Don't take it for granted!... DO IT!. I already mentioned it in my earlier post for good reason.

* You did not mention the oil temps. The oil temps are just as important as the exhaust temps.. especially when troubleshooting any kind of combustion issues. What do the oil tempts get up to in a hard pull?.

* You need to find out what the injection timing, engine operating mode, and other various important things that are going on inside that ecm are .. before blindly guessing at it and throwing more stuff at it like a blind man... and NO.. an aftergarbage turbo IS NOT GOING TO SOLVE ANY OF THOSE PROBLEMS! but only make things much, much worse.

Do you think that if I owned that engine it would have those problems?!> --- NO IT WOULDN'T ! - SO IF I CAN MAKE IT WORK PROPERLY ... SO CAN SOMEONE ELSE!

[Badger]

im not in denial over the issues and just making excuses for what i THINK is going on, its just in my brain to question things, whether someone tells me A or B i look at both sides, instead of believing the first person who tells me something. nothing against you or your knowledge, but if im wrong i try to comprehend WHY, not just say "oh, ok!" like a democrat.
ANYWAYS
the reason i rebuilt it last time was because i had a fire ring burn out of hole 2, broken ring on hole 5 or 6, and the injector cups leaking in the head, and the injectors had 1.3 million miles on them so i just did them while i was in there.

-- note that this time around it was small hp 8520cpl , and i swapped pistons and turbo to 8518 and wedged the cams to 4/6. so im not getting greedy with HP, i just want a reliable 565 hp, should be easey peasey since they came factory with that much and more. ( even before cpl and tune changes this general " egt / boost issue" has always been there, not from the cpl change alone)

i would GLADLY let somebody look at this file and figure it out, i have insite and teamviewer but if 99% of tuners in the world cant do it right, how was i supposed to know who CAN do it right?! i will look at the attachments and links you included .

yes someone could very well have my ecm thinking my elevation is something different than the 1400ft it should be. but hell i dont know how to see that lol.

water never gets real warm, oil temps never get over 230, factory CAC cracked years ago so i cant compare it to this one. but ill see if i can find a brand or part number on it.

im not being stubborn, just like to know the logic behind things , expecially if im wrong.

will the file you want a copy of, be in "Advanced ECM data" on the left side of insite?

im thankful for the help, dont think im here just arguing, im trying to comprehend this ECM stuff