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Runaway RPM

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redline808

New Recruit
Owner/Operator
Okay, I have a problem with my 2015 Hino 258 rollback tow truck. Issue started yesterday. When I start up the truck after about a minute of idle the engine RPM instantly goes to 3000, no way of stopping it, I just need to turn the key off. It only does this when in neutral. Another example is I'm driving, I'll come to a stop and almost right after I shift into neutral the RPM runs away. It does not matter if the parking brake is on or off. Note; a few days before the issue started, I had the DEF system deleted. I scanned the truck and I get a P1133 Malfunction of operational accelerator sensor (high)

Anyone ever have this problem? any advise. There is no dealer in my area.

Thanks!
 
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danthewolf00

Veteran Expediter
redline808 said:
Okay, I have a problem with my 2015 Hino 258 rollback tow truck. Issue started yesterday. When I start up the truck after about a minute of idle the engine RPM instantly goes to 3000, no way of stopping it, I just need to turn the key off. It only does this when in neutral. Another example is I'm driving, I'll come to a stop and almost right after I shift into neutral the RPM runs away. It does not matter if the parking brake is on or off. Note; a few days before the issue started, I had the DEF system deleted. I scanned the truck and I get a P1133 Malfunction of operational accelerator sensor (high)

Anyone ever have this problem? any advise. There is no dealer in my area.

Thanks!
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Might be the delete.
 
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redline808

New Recruit
Owner/Operator
It almost sounds like its trying to do a regen. lot of rushing air sound coming out of the exhaust then the RPM goes nuts
 
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redline808

New Recruit
Owner/Operator
When I say the DEF system deleted. The emissions computer and the engine computer were sent out and all the emissions related stuff was deleted from the computers, DEF SCR EGR and so forth.
 
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danthewolf00

Veteran Expediter
redline808 said:
When I say the DEF system deleted. The emissions computer and the engine computer were sent out and all the emissions related stuff was deleted from the computers, DEF SCR EGR and so forth.
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Yet the racing engine didn't start till after it was deleted....something was missed.
 
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danthewolf00

Veteran Expediter
And fyi if you get pulled over and get inspected you will be ticketed for deleting it even possible placed out of service.
 
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redline808

New Recruit
Owner/Operator
danthewolf00 said:
Yet the racing engine didn't start till after it was deleted....something was missed.
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I'm wondering if that is the case. I also noticed that the throttle position sensor 2 is out of spec? should read voltage 0.7-1.0 and it reads 1.7 if I recall.
 
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coalminer

Veteran Expediter
Retired Expediter
Once it is deleted you are going to have a hard time finding someone to work on it. There are 2 Hino mechanics on here and when they see your post they will respond and give you a couple of things to check but if you were to take it to one of their shops, I bet they would not be allowed to work on it.

I know this is going to offend people but if you delete emissions from an on road vehicle, that vehicle needs to be confiscated and scrapped, period.
 
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Hino123

Hino123

Expert Expediter
Researching
Sounds like it’s time for a test ecu. If they didn’t program the VCS as well that could be the problem. Seen this exact issue once on a propane truck that rolled over. It laid in the ditch for a few hours on its side. Truck ran great but the rpm would creep up after a minute of idling. No codes just ramp up. I removed the VCS and found corrosion on it. Replaced it and the problem went away. I have a used one with 100k on it. Came out of a Penske wreck. If you need one let me know.
 
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redline808

New Recruit
Owner/Operator
coalminer said:
Once it is deleted you are going to have a hard time finding someone to work on it. There are 2 Hino mechanics on here and when they see your post they will respond and give you a couple of things to check but if you were to take it to one of their shops, I bet they would not be allowed to work on it.
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That's why I purchased the HINO DX2 software.
 
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redline808

New Recruit
Owner/Operator
Hino123 said:
Sounds like it’s time for a test ecu. If they didn’t program the VCS as well that could be the problem. Seen this exact issue once on a propane truck that rolled over. It laid in the ditch for a few hours on its side. Truck ran great but the rpm would creep up after a minute of idling. No codes just ramp up. I removed the VCS and found corrosion on it. Replaced it and the problem went away. I have a used one with 100k on it. Came out of a Penske wreck. If you need one let me know.
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Thanks for the offer, I really appreciate it! Turned out being a emissions sensor feeding back bad information.
 
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Hino123

Hino123

Expert Expediter
Researching
Do you know what sensor exactly? Just being curious. Thanks. Glad you got it straightened out.
 
greasytshirt

greasytshirt

Moderator
Staff member
Mechanic
There's also a connector in the junction box that has all the accelerator wires going through it. I've seen that cause unintended acceleration.
 
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redline808

New Recruit
Owner/Operator
I unplugged all the emission sensors and turns out a sensor was not the issue, because the rpm ran away again a few days later. Upon further inspection of the harness under the dash I took note of moisture in the box that all the harness connectors are housed and the main cam lock harness plug was wet, I now believe that water was creating the problem. So far, its been dry and no issues since.
 
greasytshirt

greasytshirt

Moderator
Staff member
Mechanic
Pull up the floor mat on the passesenger floor and see if the insulation is wet. If it is, the windshield seal is leaking. I often find them leaking from the upper right corner.
 
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redline808

New Recruit
Owner/Operator
greasytshirt said:
Pull up the floor mat on the passesenger floor and see if the insulation is wet. If it is, the windshield seal is leaking. I often find them leaking from the upper right corner.
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What causes the leak? bad body seam at the windshield bad glue? my truck does have a leak here, what do I tell the glass shop to do?

Thanks!
 
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