ISX15 overheating after vgr turbo installed

[Yady]

Hi my truck was demandated when I purchased it. It also had a K29 turbo in it. Engine brakes weren't working so I decided to install a vgr turbo. It fixed the engine brakes problem. Since I installed the vgr turbo though its been heating up and it takes longer to lower the temp even when I turn the fan on which before would lower the temp right away. Its giving me a check engine light. When I check insite the code is for Exhaust Gas Pressure I. Any thoughts on what could be going on? Thanks in advance.

[tree98]

When you say "VGR" do you mean VGT the proper turbo that the engine came with from the factory?

If it had an aftermarket fixed vane turbo on it when you bought it there's no doubt you have a bad tune and that's likely what's causing your problems. Copy the program out and send it to Rawze for review.

How high is your boost getting? Over boosting can cause severe damage, what engine is this CM870,871,2250,2350,2450?

https://rawze.com/forums/showthread.php?...&pid=72945

[Rawze]

(NON-VGT delete programming) ...
When some complete moron of a shop removes the VGT, which in itself is bad/harmful, they also typically remove functionality for other stuff, like important sensors, that the engine needs to run itself properly. That kind of crap shortens engine life significantly as a result.

BAD delete programming is plague in the trucking industry, and non-VGT mods are a fine example of the worst of it.

The typical scenario is ... Bad/crappy delete programming gets done where the engine gets perpetually stuck in DPF rapid warm-up mode due to missing/hollowed out cans and incomplete programming mods. - It gets stuck in the wrong engine operating mode(s), permanently, it trying to choke the exhaust all the time via the VG turbo, over-spooling it, combined with causing all kinds of internal engine friction to heat up the missing exhaust components. The turbo ends up over-spooling/over-heating and failing due this, simply due to horrible, poke-and-prod, delete programming attempts.

... . And because the morons who programmed it like total crap, they then blame the turbo, engine, etc. on the issues, and then resort to solving it by removing the VGT (which is also very bad for engine long term). - This relieves some of the heat issues, but now the engine is still running with excessive friction, still stuck in DPF warm-up mode, eating its own guts out over time underneath all of it.

The exhaust pressure sensor is also most often bypassed/disabled too (which is needed for proper cylinder balancing and miss-fire detection), because it complains about improper boost, etc. too, so they unhook it, and/or shut it up to hide the issues they they themselves caused. This along with other important engine sensors that have nothing to do with a de-mandate .. simply out of sheer stupidity.

Removing the VGT It is one of the worst things you can do to these newer style engines that require them. It is nothing but back-woods, red-neck trash, done to a $40,000+ commercial engine, and it results in trading DPF problems with severe engine failures that cost far more in the end.


Undoing that trash involves putting back the VGT, and making the more important sensors like exhaust pressure sensor, etc.. work again properly. It will also involve repairing/removing the garbage-delete programming that causes all the underlying issues to begin with.

The de-mandate can actually be done right... 100% right ... but it involves keeping the important hardware and sensors that the engine needs to operate itself correctly. This includes the VGT turbo. - And then a program written that is not full of half-baked, blocked faults, incomplete crap, and places the engine in its proper operating mode(s) that prevents it from trying to warm up a DPF/SCR that is no longer there.

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Also, what is the engine ser# (the esn number)?.

and did you out a VGT turbo on it?.... and if so, did you put the exact part# model that belongs to that ser# engine?.

Did you re-install the front exhaust manifold piece that has the connector for the exhaust pressure sensor?... and crossover pipe, etc. so that sensor can operate correctly?. - It makes someone wonder what other hardware changes were done incorrectly.

What was done under the truck?. Are all cans gutted .. including SCR?. Some places do not even properly gut the SCR or other cans. - And some places straight pipe the exhaust, but then screw up royally by unplugging the main harness under there,.. messing up the J1939 network. - The result is a turbo that acts up, fails, etc. because can-buss #2 is now unstable and missing its terminating resistors, etc.

- The list of trash/crap/redneck mods that is done to these engines is a long one. Its amazing how utterly stupid most of the repair shops that are out there with regards to this type of stuffs really are. - All of which the engine ultimately gets blamed for when it blows a head gasket, or kills 3 turbos in a row, puts a piston thru the block, and/or other major issues happen in the end.

Like Trtee98 said... copy program from ecm and send it to me for a review of what someone did in there.

.

[Yady]

Thank you. Yes I meant VGT turbo. I'll get the program and send it to Rawze along with the ESN and the VGT turbo part number. All cans are removed. I'm thinking that they must have unplugged the harness under there. I'll take some pictures and send them along with the program to have you take a look and let me know what you think happened. Thanks for your help.

[tree98]

(08-28-2025 )Yady Wrote:  I'm thinking that they must have unplugged the harness under there.

You might be missing a terminating resistor too if someone was messing around with the wiring under there.

[Rawze]

I looked at several pictures you sent me. That engine has been butchered into oblivion from what I can see.

EGR crossover piping missing, ... a red flag during any inspections at a DOT station or by a state trooper.

EGR cooler is missing, and it does not appear to have a crossover pipe for the coolant. If this is the case, cylinders 5 and 6 are going to run hot, and eventually have a serious failure.

You sent me a lot of pictures of the underside of the cans.. but none that show if they are all hollowed out properly. For all anyone knows, they might not have been done correctly at all.

The intake picture you sent me shows that you have an intake throttle valve. Has the butterfly been removed from it?..,, its anyones guess if you don't inspect it internally. Also does the crank case filter have a maintenence free filter in it, or has been gutted?.