2006 CM870 high EGTs

[JBaird]

I have a 2006 CM870 in a Kenworth. I’m on the 4th head, and 2nd bottom end in 425,000 miles. This engine has been worked on by 4 different shops, including Rush Peterbilt the last time. Every tuning result and rebuild still ends with high EGTs. I have 2500 miles on the current inframe with new liners, rods, pistons, oil pump, rebuilt oil cooler, rod and main bearings, and head. We did not change the turbo (still stock VGT rebuilt 150,000 miles ago) we reused both cams (injection cam has approx (175,000) miles, and reused rocker arm assemblies. The truck was remandated by Rush Peterbilt on the last head replacement. They couldn’t get rid of a shutter in the 1200 to 1400 rpm range. If you fall into that rpm range under a load the EGTs would skyrocket. With the current build the truck is not mandated. The truck with an empty trailer will run between 850 and 1000 degrees. The EGT actually seems to run cooler while loaded unless you are on a long pull, then I have to be soft on the petal to keep the temps under a 1000 degrees. I think sometimes the truck may be boosting at idle, the exhaust temps at idle won’t come under 500 degs. The truck is tuned at a 530 that is what it came stock at from the factory. The exhaust only has a small resonator. This truck does about 75 miles a day off pavement, and also somewhere around 350 red lights a day and is mostly over gross with a permit. The shop that worked on the truck are good folks and has bent over backwards trying to help me solve this, and I think they are at a loss and I know they have lost money on this rebuild. So I’m reaching out to this group with my hat in my hands to try and figure this out. Thanks

[Nilao]

You're going to have to get the software and hardware to pull the program and then running rough is the only guy here that does the 870 due to special consideration that have to be taken during reflash and editing of live ram.

[Rawze]

Fourth head and 2'nd bottom end in 425k miles?? = someone does not know how to build the engine properly at all!@.. and taking it to the stealers$it is the WORST place to have an engine rebuilt, hands down. Those clowns are beyond absolutely clueless!.

Here is your story in a nut shell...
ref: http://rawze.com/forums/showthread.php?t...5#pid41315

And here is what SHOULD have happened.. THE FIRST TIME!!!... and that stealer$shi#t is not about to do things this way .. even if you had paid them extra...
ref: http://rawze.com/forums/showthread.php?t...6#pid70606


And BY THE WAY>>>> an ISX should be cresting at about 1050-F on the exhaust temps, post turbo, in a hard pull if you get on it hard/long enough. Oil temps should crest at about 230-235F~ish as well. At 240+F, the oil temps are getting too hot.

You also DID NOT MENTION what your boost was doing in a hard pull. It should be holding steady at about 37-38 psi (not deleted).. and about 36 psi or so if it IS properly deleted. If it jumps up there for a short bit, and then drops back down to only about 32psi or so,.. then the engine is an active boost derate. CM870's are notorious for this if something is wrong with the programming, or it detects the EGR system has issues, etc.

As far as local driving goes.. I hope you have the rear ends spec'd as such,.. especially if your hauling a bit over 80k.lbs. The rears should be about 4.11's on the high side.. and about 4.68 on the low end of the spectrum. -== If that thing has a set of 3.55's or god forbid taller (3.42's, 2.79's etc) in it.. then IT IS GEARED WRONG FOR THE APPLICATION AND TORTURING THE ENGINE!!!

Also THAT isx's sweet spot for maximum engine load and its hardest pulling as at 1650-1700RPM for longest lifespan, ... and not down at 1400 and below!. Keep that in mind while driving it!.

As far as a harmonic in it at 1400-1500 range.. this is well known. Any time the injection timing is too high, or something else causes the final CA for the firing angle to be too close to BTDC.. this occurs in the ISX's. .. A slipped cam,.. the wrong timing wedge was used during the rebuild for the valve or injector cam... bad programming,.. bad deletes.. bad fuel-air-mix.. you name it.. it gets amplified greatly. Even an after-garbage intake manifold can make them do this... as they have no baffles in them like the factory one does to, prevent intake cavitation on the back 2 cylinders.

Lastly.. but not least.. IF THAT MUFFLER is more than about 8 yars old.. ASSUME IT IS GETTING CLOGGED UP!!! AND REPLACE IT at first signs of higher than normal EGT's or slight power losses.


and WHEN WAS THE LAST TIME an EGR tune-up was done?... When s the last time someone replace the Delta-P sensor and its feed-lines?. The Intake pressure sensor?.. intake temp sensor?.. The exhaust pressure sensor and verified the circuit for it is not clogged up ion the thermostat housing (they are notorious for this and no one ever catches it).

WHEN IS THE LAST TIME??.. that someone pressurized the intake/cac, etc.. and checked if for leaks??..

AND/OR DOES IT HAVE AN AFTER-GARBAGE CAC UNIT IN IT LIKE THOSE STUPID DURALI$ITE BRAND OR SOME OTHER SEVERELY RESTRICTIVE NON-OEM charge air cooler TRASH???.

-- WHEN IS THE LAST TIME an injector leakage test was done to it???.. according to this video>>>??!!
ref: http://rawze.com/forums/showthread.php?t...8#pid67948

WHEN was the last time someone checked the timing and metering solenoids?...
ref: http://rawze.com/forums/showthread.php?t...619#pid619

I.E.> ...
YOU KEEP TAKING IT TO THE GAGGLE OF COMPLETE MORONS AND DON'T GRAB A DAMN WRENCH.. AND YOU WILL ONLY KEEP REPEATING YOUR COSTLY MISTAKES!!!> Throwing your problems at every stealers%it in town is the kiss of death for your equipment.. and your trucking business.

[JBaird]

I need to work on so some of the things you mentioned
I’ll reply to as many as I can.
The EGTs won’t stop going up if I don’t soft petal when I hit a 1000 degs I usually grab a gear to get the RPMs up, but will still have to be gentle on the petal to not turn the warning lights on.
I do not have an oil temp gauge on the dash. I need to add one.
The muffler is not clogged, it is just a hollowed out resonator. Coming off the turbo though it is 4” pipe that runs for about 4’ until it converts to 5”. I’m going to change that to 5” right off the turbo.
I’ve never thought of the gearing as being a problem, the truck does have 3.55s with a 13 speed. It turns 1500 at 75 in 13th, or around 1750 at 70 in 12th.
A new egr was installed about 70,000 mile ago, and i followed your recommendations for the tune up. Both timing actuators have been replaced in the last month. Fuel actuators have 425,000 on them.
Turbo initially will his around 34 pound of boost, then immediately falls off to 30 lbs and stay there.
Intake pressure sensor and intake temp sensor has been cleaned but not replaced. Exhaust pressure sensor is new.
Charge air cooler is new with this rebuild, approximately 2500 mile, I’m not not for sure of the brand, it was bought though Kenworth. Charge air cooler and boots were all pressure tested, I don’t think the intake was. The truck has the factory intake, although is does have an aftermarket exhaust manifold. The delta p shouldn’t be in play now.

I haven’t done an injector an injector bleed down test. I just watched you video, and will order what’s needed. I also need to check the thermostat housing.
Thanks for your help
Jeff

[Rawze]

(07-16-2023 )JBaird Wrote:  ...Turbo initially will his around 34 pound of boost, then immediately falls off to 30 lbs and stay there.
...

It is most likely in a boost derate condition.
here is more info on this...
ref: http://rawze.com/forums/showthread.php?t...2#pid72522

another related post...
http://rawze.com/forums/showthread.php?t...4#pid64964

[Aleeex]

There’s a chance your vgt is not active. Have someone watch the vgt arm and start the truck . The arm Should move.

I’ve had an 870 that was similar. the box that controls air to the vgt actuator failed.

[JBaird]

(07-17-2023 )Aleeex Wrote:  There’s a chance your vgt is not active. Have someone watch the vgt arm and start the truck . The arm Should move.

I’ve had an 870 that was similar. the box that controls air to the vgt actuator failed.

We ran the turbo and actuator through a test on insight. Both passed.

[Aleeex]

Look at it visually to confirm.

[JBaird]

Since my last comments, I’ve pulled the resonator off and the truck it is running straight exhaust. Put new IMAP sensor, exhaust pressure sensor, and new intake temp sensor. Did an injector leakage test, it passed. Replaced both oil coolers and put a 215 deg oil thermostat in it. The result is the same, I still have EGTs that are not acceptable. I’m at a loss where to throw more money at. Last ditch effort I’ve got Dyno time scheduled Tuesday morning in Dallas. Hopefully the Dyno will show if it is tuning or something mechanical that has been overlooked. I’ve never had a truck put on a Dyno, so I don’t know what to expect. The good news is that I’ve found another truck, so if the Dyno doesn’t work out Tuesday, Wednesday I’ll purchase the other truck. I’d like to thank you guys that took the time to make suggestions.