Healthy enough for tuning?

[bighorn466e]

I am putting together an International 4300 for use as an RV hauler and have been working to kill off all of the gremlins and collect some baseline data before turning things up. I've been able to work everything out but one issue and am hoping for a bit of help in determining if I'm chasing a phantom.

The 4300 was originally a VACIS mobile xray system used at the port. This means that it spent the majority of its life moving back and forth at <5mph powering a 5kw underhood generator. On my initial test drive the vehicle felt like it hit a bit of a power cliff after driving for 10ish mins. I negotiated with the seller to drop the vehicle off at a local international dealer and they diagnosed it as having low boost (19psi) and a bad turbo. Seemed like an easy fix so I purchased the vehicle and pulled the turbo only to realize that not only the turbo but the entire engine seemed to be a fairly recent Navistar "Renewed" unit. After confirming with a turbo shop that there was nothing wrong with the unit I bolted everything back up and changed the fluids/filters with no change.

I purchased a grandview rp1210 cable and did quite a bit of datalogging with the Navistar software before realizing that the brass bodied Intake air sensor had no underhood airflow on the outside of the sensor with the generator in front of it and was recording IAT's well over 150*. I unscrewed the sensor, draped it into the airbox so the entire sensor was in the airstream being measured and that issue was "solved" and the truck seemed to be running great.

I pulled the xray body, installed a flatbed and and used the truck to haul the camper (36' 5th wheel ~12k lbs) to a race in early January and then in mid march. On the way to the race in January temps were in the 60's and below and I didn't notice any problems. A few weeks ago however while loaded with the camper I once again had an issue where when the truck was "hot" the turbo sounded different while spinning up and the truck was struggling to do 60mph when it previously would pull >65mph.

When "hot and misbehaving" the truck has ICP within half a percent of requested, coolant temps at ~196, oil temp ~217, IAT ~105 with ICP's around 3200 and pulsewidths around 2400. If there was defueling occurring I'd assume that the ICP, Pulsewidth, or Boost values would be different between the cooler runs where the butt dyno suggests things are healthier and the hotter runs where something "feels" off but I can't find data to back that up. The only "smoking gun" of sorts I have is that in the attached datalog where things didn't seem right you can see the boost pressure drop from 20ish psi to 16ish psi right at 54mph. Given the consistency of the other parameters I'm not quite sure how to interpret this.

My outstanding question at this point is what I can or even should do to verify everything is healthy before turning things up. I have a sneaking suspicion that the servicemax software doesn't have the granularity to go much further.

[Powerstroke Cowboy]

Howdy,

What kind of noise does the turbo make? What you describe sounds like turbo "surge" to me. Loss of boost, power and the turbo makes a strange noise.

If you tune it, most times it will get worse. Have you tried down shifting and getting the rpms up and in turn drive the turbine harder?

[bighorn466e]

Is it possible that my truck is pulling boost in order to keep my engine oil temps down?

After doing 24 pulls collecting just under 8000 datapoints with the truck unloaded I think I may have found a bit of a trend across quite a few datapoints.

I repeatedly recorded runs accelerating from 60ish to 70ish mph. I then built a table of the median recorded boost pressure for all of the points with over 5 samples and an engine load over 95%. The smooth gradient that resulted looks shockingly like a limiter to me but it is at a temperature much lower than expected.

Looking at a graph of engine oil vs coolant temp it seems like there is a thermostat of sorts properly regulating the oil to ~225* because as coolant temps rise oil temps remain constant which is not the behavior I would expect with a blocked or otherwise malfunctioning oil cooler. I also don't particularly want to try to add an aux oil cooler at these temps and risk keeping the oil too cool to boil off any moisture.

Given that (to me) the issue seems to be an unknown limiter is there any risk in using orion to go to a "known" programming that wouldn't have any strange limiters and then monitor EOT closely? If this is an unknown limiter I'd expect this lower power behavior around 2100 rpms to stop and temps to stay the same.

As requested here is a video when hot showing how the truck was accelerating faster at higher rpm, the differences in the turbo sound I am hearing are not as noticeable in the video:
https://photos.app.goo.gl/vpL6TuoBYTNVtywy8

[bighorn466e]

I just finished another series of road tests with the IAT sensor in its original place, an oil cooler that was disassembled and verified to be clean and a new viscous fan clutch adjusted two notches counterclockwise from the factory setting shown in the attached picture.

No major changes were observed, when the engine is cold at full load I see ~18psi at 2100 rpm and then as things heat up I drop down to 15ish psi. The strange part to me that makes me feel that this has to be an issue with the computer side of things is that hot or cold I am back to the spec 20lbs of boost by 2400 rpm.

Next steps for me are installing a pyrometer and fuel pressure sensor. My thought is that if I can observe lower egt's corresponding with lower boost at the same fuel pressure than I'd feel fairly confident saying something is causing fuel to be pulled as the engine warms up.

Other Notes:
The old fan clutch certainly wasn't helping things. The new clutch is a bit quieter at idle and coolant temps don't exceed 190. Before installing the new clutch I adjusted the bimetallic spring 2 notches counterclockwise to keep underhood and coolant temps a bit lower while working everything out. The maximum IAT recorded was 137 compared to a max of 105 with the sensor draped in the airbox.

While disassembling the oil cooler I did note that the oil cooler temperature valve had a 220 and 240 stamped in it. Thinking these were the open/close temps of the oil cooler I tested the valve in boiling water and then in the oven. The valve didn't open at 212 submerged, started opening around 220 dry (13mm) and was fully open (26mm) by 240 dry. While this didn't wind up being helpful for me it may be good to keep in mind that there is likely negligible cooling happening in the oil cooler until 220 EOT.

Truck has had oil, oil filter, fuel separator, and fuel filter replaced as part of the troubleshooting process.

The engine was replaced with a navistar renewed unit while it was still a customs and border patrol vehicle. I'm fairly confident the engine has <3k miles on it because the oil thermostat was stamped 3/17, carfax has towing and service records on 1/19 at 16k odo and the truck was sold 11/20 with 18k on the odo. The turbo and longblock seem to be new while the computer seems to be original. One of the considerations I have had is whether there could be a mismatch between the newer engine and the original ecu.

[bighorn466e]

I realized that I never gave an update here!

I wound up getting 6th gear enabled and purchasing an Orion shortly after my last post.

I took the truck and Orion out to do some unloaded pulls and compare behavior, other than getting the brakes a bit warmer than I wanted everything went far better than expected. After running through some power from acceleration calcs I found that the factory 230 rating matched up with the Orion 190 with the difference that the problem described earlier was gone. I then moved to the 250 tune and my overly simplified calcs showed a 26% power increase with EGT's staying below 1250. Life seemed good.

Next time I towed with the camper and checked the datalog I noticed that my EOT was creeping quite high and I was getting the feeling of a bit of power loss. After the trip I pulled the thermostat element out of the oil cooler, did a change with t6 and got a clean bill of health on the old oil from blackstone.

The next trip was quite long (FL->DE) and there were significant ambient temp changes. I noticed that on the cooler days I was getting about a MPG better and didn't feel like I was losing any power on the top of long grades. This was a bit of an eureka moment as I was losing ~12% mpg and 12% of 250 is 30hp which happens to be about the power consumed by my mechanical fan according to some engineering spec sheets. EOT tracks almost perfectly with coolant temp and I'm not noticing any significant difference in warm up times although I've only had the truck down to 50ish degrees since pulling the thermostat.

Next planned step is to get drive, boost, outlet temp, intake temp, and egt datalogs to Bill from the factory turbo setup. I have a feeling that we are going to discover that we are quite far out of the ideal efficiency island of the factory turbo once we have the data in hand. If that's the case my WAG is that I'll wind up upgrading to an s364.5sxe turbo with a 0.91 housing. That may change once I have the numbers to better estimate what would be a good fit for the engine.

[pwerwagn]

The next trip was quite long (FL->DE) and there were significant ambient temp changes. I noticed that on the cooler days I was getting about a MPG better and didn't feel like I was losing any power on the top of long grades. This was a bit of an eureka moment as I was losing ~12% mpg and 12% of 250 is 30hp which happens to be about the power consumed by my mechanical fan according to some engineering spec sheets.

I noticed a similar phenomenon with my VT365. It felt way stronger when cold, and even tho the fan sounded like it was pulling as much when cold as hot it wasnt. I replaced it with a horton EC450 elec fan clutch, and in ambient temps below ~72 or so, it never comes on. My IAT runs a little hotter due to less flow thru the CAC, but it doesnt seem so affect anything other than peak egt when I'm above ~2600rpm WOT.

The power increase with the fan on vs off is huge. On long hills I have left it on, and turned it off after speed stabilized and it will typically gain 5-7mph. I know kitmasters has a fan that is like ~20% on at all times, and then 100% on when called for. I think that would be the real ticket. OR perhaps a big electric pusher fan, and then bring in the mechanical when necessary.

What year is your truck? I have been heavily considering swapping out my VT365/A2500 for a ~03-05 ish DT466/A3000. I assume loaded with the 5th wheel you are in the ~22klb range? How does it pull tuned at that weight?

--Jeff