2012 258 sluggish . . .

[LostDeere59]

I have a 2012 258 in rollback service with a lack of power . . maybe.

The truck runs fine, no Check Engine light, rough run, or other obvious symptom. However compared to another, virtually identical truck, and to our other Hinos in general, this truck feels down on power. It accelerates with less vigor, feels sluggish when pulling hills, and these symptoms are magnified when the truck is loaded. Strangely however, the symptom doesn't get worse when the truck is used to tow 2 cars.

Several shops have looked at this truck, although I doubt in any detail - pretty much everyone says the same thing "If there's no Check Engine light, its fine"

The truck has about 425k on it, and has had the usual barrage of repairs - DPFs, injectors, various sensors in the DPR and SCR systems, etc. I believe it had an injection pump at one point. Most recently all of the pressure side intake hoses and clamps were replaced. None of these repairs has improved the power of the truck, although they did address the acute issue that led to their replacement.

Fuel filters are replaced with Hino filters pretty much every 10k along with a standard PM.

Anyone have any suggestions on what/where to look that I can share with a local shop? Or encountered something similar to this and found a root cause?

Thanks, Gregg

 

[greasytshirt]

Try cleaning or replacing the mass airflow sensor. Check the CAC for cracks and leaks. Do a valve adjustment. These are some of the things I'd check for a low power complaint with no CEL.

 

[LostDeere59]

Thank you sir, I will discuss these with our repair facility. I believe they tested the charge air cooler as part of the diagnostics that led to replacement of the charge air hoses and clamps, but I will confirm this with them. I doubt this truck has ever had a valve adjustment, and I find your suggestion of the MAF sensor interesting having dealt with them as a tech in the past.

Gregg

 

[LostDeere59]

If I might ask a follow-up question . . .

The MAF sensor on this truck is a Denso 22204-E0010, also identified as 197400-5301.

We have a Toyota dealership, so obviously I can obtain this sensor (it is a good Toyota number, for some of the Hi-Lux diesels I believe) substantially less expensively through our parts department than ordering one from our local Hino store.

However I have read in a variety of places online that the Hino, Toyota, and Volvo versions of this sensor are all slightly different in calibration, and in fact even within the Toyota applications there are calibration differences.

While this sounds silly - they all have the same part number - I have been a tech long enough, and seen enough of this kind of silliness from various manufacturers, to think there may be something to this idea.

As one tech to another what do you think? Should I get the senor from Hino and just be done with it? Or is this an old wives tale originally badmouthing aftermarket multi-application replacement sensors?

Gregg

 

[greasytshirt]

I honestly couldn't tell you if calibrations have changed.
I've found the MAF to be the culprit many times with a low power complaint with no CEL. Debris gets baked onto the sensor elements. You can very gingerly pick the debris off with a toothpick or something, and then hose it down with MAF cleaner. CRC QD contact cleaner in the red can works well too, especially if blasted directly at the sensor elements at point blank range.

 

[Mattmidford1]

Hi I'm working on 2017 195. It had urea wicking all over the harness and a bad pump. I replaced the pump and cut out all the connectors and soldered in push to connect fittings. Owner did not want to spend the $ for the 3 harnesses needed plus we could not get 2 of them because of back order. The DEF system is now okay and the reduced power is gone but now the tach stopped working. I have a communication code for VSC or VCS. I don't remember the code but I do have it logged at my shop. I checked all connections, grounds and fuses and Tach worked before I performed work. Again I double checked everything and cut and soldered one wire at a time seeing how some wire colors are different on either end of connectors i cut out.
Any help would be greatly appreciated.

 

[greasytshirt]

I'd like the code.

 

[LostDeere59]

So I replaced the MAF sensor, along with it's housing. When I went to replace the sensor I found one of the mounting screws boss on the housing had cracked and fallen apart, the insert pulled out, and the sensor was cocked in the housing bore. Since the housing was available (with sensor) I figured that was a simpler and more dependable repair than trying to fix the old one.

Road testing after the replacement was disappointing - I ran the truck for 15 miles or so to give the adaptations a chance to reset after the component replacement, and I think there may have been a minor improvement, but not the solution I was hoping for.

One thing I noticed is that after the cold start I could hear plenty of turbo noise on throttle release, but once warmed up this went away. I don't know if that's normal, but it seems odd.

This is currently a "spare" truck, and since our two primary trucks are due for services in the next few weeks it will get used, and I'll see if the performance improves as the adaptations find their new normal.

I plan to look into having the valve adjustment done as you suggested once we get through the services on the primary trucks, and I can let the shop have the truck for a few days.

My biggest struggle with this whole issue is that I can't get anyone to take my concern seriously - everyone is short handed and has plenty of more clear-cut and profitable work to get done.

Gregg