JO8E injector, Pcodes in UD

[safetruck]

2005 UD 2300 JO8E, 335K miles
I owned for 100K miles without a local shop to scan or hardly want to touch it (hindsight)

1st current issue is Limp mode w/no symptoms: Average 5 times a week for last 8 weeks or so...the engine light comes on with de-rate/limp mode occurring. Most common times this happens is at (re)startup with slightly warm engine in middle of our delivery day. Lately has also been occurring at 65-70mph after 30+ miles on xpressway as well. Switching key off and back on usually corrects this 1st try sometimes 2nd try. Again NOBODY local can scan/sync this truck. Finally, an out of town shop and former dealer could scan and they diagnosed and assessed issues over a few hours (more below).

2nd current issue: 2 weeks before getting it diagnosed the cab was flipped up which "accidentally" caused a large/heavy amount of goods to smash onto the top, right dash at the fusebox and what looks like ECM enough to bend and crack the dash. After this happened I instantly started getting uneven idle, rpms dropping and surging, sometimes seems as if it will stall. This symptom is intermittent and had never before occurred. This is in idle and is worse in gear.


All codes pulled were Inactive codes even though when I pulled into the shop it was in limp mode at that moment. I had never been able to clear codes so...

PO193
PO0088

P0102
PO113

V0073

Injector #4 running +3.75mm
________________________________
I was advised to start by replacing:
#4 injector
Intake Air Flow Sensor
Rail Pressure Sensor

Should I assume that the UD injector 1665OZ503A (denso?) and Hino injector is the same part? Retail is more $$ than expected.

Any further thoughts or contradicting advice?

 

[greasytshirt]

The parts are almost identical. You can put Hino parts on it. Hino injector codes cannot be entered into a UD ecu, but it doesn't really matter.

The rail pressure sensor never goes bad. The connector can get loose and cause a bad connection. The connector is available separately.

I'd ignore the injector.

U0073 is likely the cause of occasional limp mode. Lost CAN communication with the VNT controller. On Hinos, this often means you need a new turbo, if CAN communication, power and ground to the VNT controller are all ok.

Im out of time right now, I'll revisit this later.

 

[greasytshirt]

P0088 is high rail pressure. Often the suction control valve (fuel pressure regulator) is the root cause.

P0193 is common rail pressure sensor high input. I'd still be looking at the connector as likely faulty. I mean, it could be the sensor, but in six years I think I've replaced one or two.
P0102 is the airflow sensor, P0113 is the intake air temp sensor. The temp sensor is inside the airflow sensor. It would be extremely unlikely that both of these sensors would die at the same time, so it's safe to say that the sensor does not have power or ground. Perhaps that got interrupted when the ecu took a hit. This circuit may also be fused, so check them all. I don't have any UD wiring diagrams to look at.

 

[safetruck]

Been waiting to give a solid update, so here's the current report: Ground issues and beyond (I should've known!). Thanks to MR! greasytshirt for promptly correcting our steps to diagnose/resolve this. That is not saying that I still follow or understand proper diagnoses steps so bare with me...

Upon testing, I was getting questionable ground readings at VNT controller, MAF and ECM housing and my meter/leads were somewhat suspect or at least not guaranteed. With a hose off to access the VNT controller connector I also curiously opened and inspected the actual VNT controller including the internal motor. Controller looked fine, put everything back together, nickel anti-seize on linkage.

Since truck was only occasionally acting up we drove the following day planning to work on it further over the next evening, but she went into limp mode at every interval of deliveries. So I thought we were getting warm since this worsened right after I had opened up the VNT controller and a few sensor connectors. Next day we did some inspections and meter tests and decided to immediately clean/replace/improve grounds (battery-chassis, chassis-engine, chassis to cab). Then the truck ran phenomenal like I had not seen before. More power and speed with less RPMS and the air/fuel ratio seemed top notch. I was actually laughing over the improvement. But...

3 days later while back into service she started her same de-rate fits again and some extra drama. I was like a desperate dad trying to coax my child into behaving. Headlight blows, running lights shut off (short or open circuit). Bought a nice meter to go through these circuits again and found some issues.

Ground paths between chassis and VNT, MAF and ECM housing jumping in resistance when key is on, park lights on, or full lights on. Ohms go higher with every load from around .8 to 13-50 Ohms. The resistance increase was slightly less on the ECM, but same at the sensors. I pulled fuses to isolate this disturbance and found Starter Relay fuse, dash light fuse, and ignition relay all eliminate the ground disturbance. I brainstormed possibilities with this wiring for days and days seeking out the culprit, but kept hitting stand-stills after staring at wiring harnesses and circuits both on a chart and hands on.

She is now at the automotive electrical specialist in town. Wish her well.

 

[safetruck]

Update with question:

In review, months ago we had repetitive limp-mode issues. Various inactive codes, unable to scan while light was on. Greasy recommended checking all grounds before getting into replacing parts/turbo. I had found that all sensor grounds showed major resistance with lights on/key on (sensor grounds/negative battery read: .7 ohms when off, 22 ohms with lights on, 50 ohms with key and lights on). I spent countless hours tracking and brainstorming ground disturbance, unplugging dash light connectors and finally took this to a few different shops for help. The electrical mechanics would not consider the bad ground readings nor did they understand or listen to my theory of the ground problems possibly causing this malfunction. I tested another UD same generation and found the ground readings were all clean under the same tests supporting the abnormality of my truck's electrical.

Now she is at the 4th shop referred by UD headquarters, a true UD shop 4 hours away. They cleared codes twice and came up with VNT code twice and advise to replace turbo. However they have ignored the ground issues which I believe may be causing the ECU to malfunction by misreading the sensors and prompting this limp-mode. Any thoughts?!?!

As mentioned, lights and key cause ground disturbance. Problem worsened early on after disconnecting and taking the VNT controller apart, the dash light fuse is one of the circuits affecting this ground disturbance. Im not too excited to throw a turbo on with these grounds jacked up as I logic tells me Im rolling the dice and need to resolve the grounds...

Thanks in advance!!

 

[greasytshirt]

You can add an auxiliary ground directly at the vnt wiring.

 

[Hino123]

I guess I'm not sure why your Checking resistance on a live circuit. Its impressive that you have dived in and attempted to make a wiring repair yourself but... I think you may be over thinking it a little. If the ground will hold a load, its a good ground. I would install a headlamp in the power and ground at the VNT and at the ECM, turn the key on (this will most likely set codes) and verify the headlamp lights and is bright, if its not bright you have either low voltage or a faulty ground. As greasy stated just run a dedicated ground to the VNT, or the ECM. I have been working on Hino's for over ten years and spent 2 at a UD dealer. Everything you are describing points to a faulty turbocharger controller. In my experience when the MAF and Intake air temp codes set together someone has usually unplugged them and had the key on. Do you have the freeze frame data to go along with the codes? Look and see if they set at the exact same time. Also the ECM should be under the pass seat, not in the dash, the diagnostic connector is on the low rh side of the dash, im pretty sure it has a white tag with black letters that says diag. In the future you can just short it and get blink codes to come up in the cluster. Im not sure why you get desirable range "ground disturbances" from a sister truck. Maybe you could swap ECM's from this test truck to yours and see if you have the same issue.

 

[safetruck]

Thanks Hino123 for your time I never seen your reply...

Misunderstanding. The ground’s were not a live circuit. The harnesses were disconnected with the engine off and key both off/on. The various sensor grounds are very erratic and way out of acceptable range. No doubt some electrical interference. Just for the heck of it I put a new turbo on to no avail even though the UD dealer swore that was the only problem and I really wasnt surprised.

This is all very occasional attempts to diagnose because I have a “new-to-me” 2006 Hino 268 with 115k miles. Stepping up in the world!!

I dont have regular down time to stop and chase this UD issue until the summer comes. Nobody within 4 hours wanted to look at it and the one that would at it did not look beyond the turbo even though I showed them them the funky ground issue they could not comprehend.

Yes, I should have ran dedicated ground to ECM and tried to swap. More to come when i can.