Big Truck I work on Hino trucks. I'll answer any questions I know the answers to.

[greasytshirt]

Hello Greasytshirt,


Thanks in advance for your time and hope all your problems are entertaining enough to keep you from getting bored.

Ha, it's never boring. I have a story from today. A lease truck rolls up, it's a big ol' moving van. Same setup as yours, '09, DPF only, no SCR system. The complaint is low power and a check engine light. It has an inactive P2002 code, and it's out of warranty. The DPF indicator is at ten bars. Whatever you do, don't let it hit ten bars. Not long after that, it reaches a point where the truck can't clean the soot via regen, it'll have to be cooked out or the whole thing replaced.

So yeah, P2002, no other codes. On cold start, there was lots of clatter. I know that sound. Either the injectors are going south, or it has an original, unmodified Intake Throttle Valve on it. I hooked the computer up, ran a SCV test, and watched the injection quantity jump all over the place. Pulled the black tube off of the intercooler, and there it is, an original, unmodified ITV. I took it off and performed the needed modification. There was oil in the intercooler outlet, so I checked the oil level. Massively overfilled. I drained about six quarts. The air filter was filthy, replaced it. Checked the hoses at the DPF differential pressure sensor, and one was clogged. It tok a while to get all the junk out of it.

Any one of these things could have caused a P2002, if bad enough.

Since this thing is out of warranty, I'm not going to condemn the DPF without trying to regen it first. I initiated a forced regen and watched the DPF temps. Everything was looking ok at first, but the outlet temp was soon far behind the inlet temp, indicating that it's not heating evenly. Usually they're only about 100-200 degrees apart, give or take, then the inlet and outlet match each other for several minutes, then it's done. In this case, there's a 500 degree difference between the inlet and outlet. A few minutes later, the outlet temp starts to rise. And boy, she's coming up fast. Alarm bells went off in my head when it hit 1100. 1300 degrees came less than five seconds later. At this point, I clicked 'End Inspection' and I'm going for the key when the exhaust brake opened, and with a loud "BOOM!" it shot a fireball out of the tailpipe. Never seen that before.

I'll have to look at the system protection data and see how many times it's hit an overheat condition. Dozens, I'll bet. The exhaust brake was set way too high when it arrived, so I adjusted it down before even attempting it. Then I'll drop the DPF and see if it's melted down. This one is a candidate for going in the DPF oven, since soot has not permeated the filter (which was a huge surprise).

 

[greasytshirt]

My wife informs me that ceramic catalyst substrates can start melting as low as 1100 degrees, so try to keep it below that. Its normal for them to butt right up against that threshold, so don't be concerned if it gets close.

She's a mechanical engineer with extensive fuel additive and catalyst testing, so I respect her insight.

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[allways]

Hi Greasy,

Sounds like another fun day for you. Your wife sound like a great asset. Some day I may have a question for her since I am also fighting with a 15L Cat that was retrofitted with a Cleaire Horizon unit that from what I understand should have never been put on in the first place. This has been a 2 year battle now with the state of CA to solve this problem - but that another really long story for another day. For now problem remains this Hino.

Got the truck back and this is what I have found so far.

1. Back pressure during a manual test has not gone over 10 kPa or 1.45 psi

2. Spikes to 23 kPa for a slit second during WOT event and then settles at around 15 kPa under steady acceleration.

3. If throttle is depressed to floor from a stop truck will barely move and then start to buck multiple times - intake pressure drops significantly during this event

4. If I slowly accelerate same symptoms.

5. If I stab throttle twice or more during initial takeoff truck runs great and no bucking at all. This does not work every time but approximately 80%. Other times power & buck still present.

6. Throttle plate has no holes so it needs the mod. Is there a TSB to reference this from? I would not expect this to cause this symptom.

7. Air flow through inter-cooler seems fine with hose off.

8. Pushed a tie strap through both tubes of the exhaust pressure sensor and seems ok when watching pressure.

9. EGR valve opens and closes similar to bucking symptom. This is only noticeable when you pull off the air inlet tube at throttle body and rev engine to 2k. Does not do it on either of the other trucks that run fine.

10. No codes have set during any of the road testing.

Will fill in a few more blanks as the day goes.
Working side by side with a 2010 with 175k on clock and runs great also a 2009 with 335k on clock almost exactly the same as problem child.

Thanks Ron

 

[greasytshirt]

Hi Greasy,




1. Back pressure during a manual test has not gone over 10 kPa or 1.45 psi

2. Spikes to 23 kPa for a slit second during WOT event and then settles at around 15 kPa under steady acceleration.

3. If throttle is depressed to floor from a stop truck will barely move and then start to buck multiple times - intake pressure drops significantly during this event

4. If I slowly accelerate same symptoms.

5. If I stab throttle twice or more during initial takeoff truck runs great and no bucking at all. This does not work every time but approximately 80%. Other times power & buck still present.

6. Throttle plate has no holes so it needs the mod. Is there a TSB to reference this from? I would not expect this to cause this symptom.

7. Air flow through inter-cooler seems fine with hose off.

8. Pushed a tie strap through both tubes of the exhaust pressure sensor and seems ok when watching pressure.

9. EGR valve opens and closes similar to bucking symptom. This is only noticeable when you pull off the air inlet tube at throttle body and rev engine to 2k. Does not do it on either of the other trucks that run fine.

10. No codes have set during any of the road testing.

Will fill in a few more blanks as the day goes.
Working side by side with a 2010 with 175k on clock and runs great also a 2009 with 335k on clock almost exactly the same as problem child.

Thanks Ron

Numbers 1 and 2: Sounds normal.
3-6: Since there are no codes for low or high rail pressure (P0087, P0088) I'm assuming the scv valve and injection pump are fine. The scv sticks sometimes, but it's almost always accompanied by either one or two of the codes above. A P0087 is common if there's a fuel restriction too.

That leaves the ITV (the throttle plate thingy) or the transmission (?!).

We can probably rule the transmission out too. What happens with the transmission is if there's a problem with the taillights, and power backfeeds into the brake light switch circuit, the TCU sees that as the brakes being applied, and it tells the ecu to limit fuel flow. Basically, it doesn't want to allow powerbraking. Since stabbing the throttle fixes the problem, it's not this. This was more common an issue in 05-06 trucks with the way the tail light circuits were wired (the brake light circuit had an additional ground wire, and the lights were not supposed to be grounded to the chassis).

Yes, an unmodified ITV will definitely cause weird problems. If there's any wear, or if there's a lot of egr junk built up around it, it will suck the blade shut and the rotary actuator doesn't have enough strength to unseat it. You're gonna need to drill three holes in it, in the lower half. Here's a link to a pic, it's all in metric.

http://i.imgur.com/geMyTGP.png

 

[greasytshirt]

This should be done to every 08-10 truck (DPF-only, not ones that take urea) that has a six cylinder engine. Don't do this to a 4 cylinder engine of any year.

Also, in case it's not obvious, take the thing off before it's drilled. The engine doesn't need to suck in metal shavings.

 

[allways]

OK will do it tonight and let you know. And yes will remove & bench the throttle body - will allow for a better inspection also. As usual great info. Throttle body is pretty clean also - FYI. Do you think this could be a result of weak magnet over time. I would agree that it sure could be sucking the plate closed but not due to contamination. Sounds like a new throttle body could also solve this problem. Three holes are sure a lot cheaper thou. Thanks again for the fast reply. Will owe you one after this.

CIAO

 

[greasytshirt]

OK will do it tonight and let you know. And yes will remove & bench the throttle body - will allow for a better inspection also. As usual great info. Throttle body is pretty clean also - FYI. Do you think this could be a result of weak magnet over time. I would agree that it sure could be sucking the plate closed but not due to contamination. Sounds like a new throttle body could also solve this problem. Three holes are sure a lot cheaper thou. Thanks again for the fast reply. Will owe you one after this.

CIAO

They can wear a surprising amount, so if it has movement in any direction that wasn't originally intended, it ought to be replaced. A new valve will not have the holes, but the holes should be added before it's installed.

 

[greasytshirt]

Oh yeah, that truck that shot the fireball out the back did not melt the DPF, but the injectors are bad. Goodwill warranty is paying for a set of injectors and a DPF (since the injectors were an earlier design, didn't hold up as well, and they caused the DPF to fail).

 

[allways]

First of all let me thank you for a job well done.

You were absolutely right about the performance effects that the holes in the throttle body plate can resolve. Removed TB and found throttle plate had come loose from shaft could move a little. Tightened 2 screws down and drilled 3 holes slightly smaller that 3 mm as test. Drove much better and completely stopped bucking - still a little flat out of the hole at times. Went back and opened them up some more and felt a little better. Driveability symptoms are almost completely gone. Left with an intermittent sluggish feeling from a WOT event - intermittently. Back out of throttle and almost instantly improves. Will cut truck loose tomorrow and have driver monitor. Will see how DPF loads up and monitor frequency of needed regens. Would guess that a new throttle body may help this problem and that it may be related to loss of EMF strength. Will monitor a few of our other trucks as we modify throttle plates and see if I can find any significant variations that could be underlying cause of flat spots on acceleration.

This repair saved me well over $3000 and has only confirmed my suspicion of the inexperience at this local dealer. This same Hino dealer said I needed a fuel pump on one of our trucks that would not start and at over 300K was out of warranty. After I contacted the local regional for assistance it was taken care at no charge. Was told that it is very rare for a pump to fail. I paid $1000 for some diag time and a few other things. After the pump was installed the truck still would not start and was told that it now needed injectors but those were covered under warranty. Called the regional back told him of the new news and asked if the initial diagnostic could be covered since this looked like misdiagnosis on the original pump and was eventually told no and left it at that.

Well I will keep you posted and can't thank you enough again. You are an inspiration to our profession and hope you get paid well for your efforts. Thanks again and take care.

CIAO

 

[greasytshirt]

First of all let me thank you for a job well done.

Allways is buying the next round!

 

[greasytshirt]

Left with an intermittent sluggish feeling from a WOT event - intermittently. Back out of throttle and almost instantly improves. Will cut truck loose tomorrow and have driver monitor. Will see how DPF loads up and monitor frequency of needed regens. Would guess that a new throttle body may help this problem and that it may be related to loss of EMF strength. Will monitor a few of our other trucks as we modify throttle plates and see if I can find any significant variations that could be underlying cause of flat spots on acceleration.

Your next step is to hook up DX, go to data monitor, and select a few things.

Target Common rail pressure
Common rail pressure
Final value of pump current target
Scv driving current value

Hit start, then go for a test drive, and try to recreate the hesitation.
After driving it around for 5 minutes or so, stop and mash the gas to the floor for five seconds. Let off, let it recover for five seconds, then hit it again. Do this five times. You are looking for a large, momentary difference between Final value of pump current target and SCV driving current value. (think of these as Target SCV Current, Actual SCV current). Stop and Save the file to your desktop. I may ask you to email it to me. What we're looking for is if the SCV is sticking. SCV is suction control valve, aka fuel pressure regulator. This is a fairly common problem.

Oh, one other thing. Get an aerosol can of Loctite Nickel Antiseize. It's hella expensive, but it works awesome. In particular, You'll want to periodically give the turbocharger vane linkage a shot of this stuff on the pivots. Where road salt is used extensively, the pivots rust and it can kill the VNT controller.

Actually, there is a long-standing recall out for this. If it's never been done, you local dealer should do it. They'll hook up DX, command the VNT through it's whole range of movement, and if it sticks or is more than 5% off, you get a new turbo for free. If it's ok, you get Nickel antiseize sprayed all over the turbo linkage.

Nothing beats this antiseize for putting together exhaust manifold parts, either. It's simply the best stuff available.

 

[allways]

Hi Greasy,

OK did as you suggested and ran those pids and have data saved as a text file and an excel sheet so I could look and compare data better. I see many instances of data that is above threshold of 160 mA variation. Would be happy to send it to you for your opinion. Engine still seems to have low power event unless throttle is moved, sometimes only slightly, and she gets up and goes just fine. Have not had much more time today to play with other trucks - will try again tomorrow. Will be in office for awhile if you have time to look at data. FYI file size is larger than forum allows. Will need plan B if you want to view data.

Thanks, Allways

 

[greasytshirt]

I sent you a pm, but send it to me tonight if you get this in time. I may be able to find graphing macros.

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[greasytshirt]

Hi Greasy,

OK did as you suggested and ran those pids and have data saved as a text file and an excel sheet so I could look and compare data better. I see many instances of data that is above threshold of 160 mA variation. Would be happy to send it to you for your opinion. Engine still seems to have low power event unless throttle is moved, sometimes only slightly, and she gets up and goes just fine. Have not had much more time today to play with other trucks - will try again tomorrow. Will be in office for awhile if you have time to look at data. FYI file size is larger than forum allows. Will need plan B if you want to view data.

Thanks, Allways

Since you have Hino Diagnostic explorer already, you can do this if you have Microsoft Excel 2010 (at least). If you open the .txt file with excel, then highlight the lines you want to compare, go over to the insert tab, select line graph, then the first graph option.
Pic too large to attach, so go to this link: http://i.imgur.com/IpwlpN2.png

See how final value often has problems matching target? Scv valve is sticking.

It's a pain to get to, best tool I've found is a six inch, 5mm (I think) ball-end allen socket. They sell the Gearwrench brand set at Advance Auto Parts for $35, and i haven't broken one yet. Lifetime warranty.

Sometimes target and actual never quite match each other, but it's more of an annoyance than an actual problem.

Before you grate all the skin off of you knuckles going after the SCV, try this: Modify the ITV on one of your other trucks, and put it on the problem truck. If the problem completely goes away, replace the whole throttle body. Remember to modify the new one before installing it.

Let me know what happens.

 

[allways]

Hino Update,

Well Greasy we swapped TB and all have holes and both trucks run great. Both have 335k. Problem truck went over the hills and through the woods and never missed a beat.

Both seem to regen about 1-2 times during a 8-10 hr shift. To much? Obviously this could vary significantly based on load, terrain, driver, etc.

Do you agree that the SCV is sticking based on my recording? Dont have Excel 2010 but considering upgrade for company - funds are tight right now. Have to finish installing 3 retrofits on our HD tow rigs. There goes another $60K

There does seem to be more lag if in Econ vs Power trans mode and this could be normal. Still comparing to tell if we are good to go.

Trucks so far have made everyone happy and have not heard a single complaint.

Will keep tweaking and learning.

Thanks again - Allways

"Keep On Truckin"

 

[greasytshirt]

Hino Update,

Well Greasy we swapped TB and all have holes and both trucks run great. Both have 335k. Problem truck went over the hills and through the woods and never missed a beat.

Both seem to regen about 1-2 times during a 8-10 hr shift. To much? Obviously this could vary significantly based on load, terrain, driver, etc.

Do you agree that the SCV is sticking based on my recording? Dont have Excel 2010 but considering upgrade for company - funds are tight right now. Have to finish installing 3 retrofits on our HD tow rigs. There goes another $60K

There does seem to be more lag if in Econ vs Power trans mode and this could be normal. Still comparing to tell if we are good to go.

Trucks so far have made everyone happy and have not heard a single complaint.

Will keep tweaking and learning.

Thanks again - Allways

"Keep On Truckin"

I wouldn't worry too much about buying Excel, it's a handy visual tool but not essential. If you go through the hassle of looking through the .txt files, you can compare dips and spikes. An earlier version may work fine, you'll have to test it.

Yes, the scv appears to be sticking, but not too badly. It may give you a moment of low power, similar to what you described earlier. If it's not significantly limiting performance, then you can dismiss it for now.

An automatic regen every hundred miles is within the realm of normal. Are your drivers noticing the auto regens, or is it asking for a manual regen? If it's crying for a manual regen every hundred miles, that is definitely not normal.

Econ vs power mode: Power mode delays transmission upshifts, so the engine is forced to run near peak power vs peak torque. In Econ, the trans definitely shifts earlier, and some folks don't care for, I don't know, the driving experience. Unless you run very heavy or in hilly terrain, you may consider pulling the switch out, unplugging it, then sticking the switch back in the hole. Permanent econ mode. It does use less fuel in econ.

 

[greasytshirt]

Oh, if they're driven with the exhaust brake on all the time, it will interrupt auto regens if it activates during one. Turn it on when you need it, off when you don't.

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[alldayair]

Thanks for all of your help.

I have a 2007 hino 268A. She had a head gasket replaced aproximately 23000 miles ago due to a broken head bolt walling out the head gasket. The truck got hit by a drunk driver and was knocked down on it passengers side. The truck was down for 4 months getting frame work and a new box. We did an oil change and put her back on the road. We drove her 1700 miles and the truck was running great. All of a sudden I started getting gray smoke out of the breather tube, and upon looking I found smoke coming out of the dipstick and oil fill. The truck then started running a little rough. I am getting oil out of the breather tube. I am about to put her in the shop but am trying to find out what I should expect. Any suggestions are greatly appreciated. Thanks.

 

[greasytshirt]

Thanks for all of your help.

I have a 2007 hino 268A. She had a head gasket replaced aproximately 23000 miles ago due to a broken head bolt walling out the head gasket. The truck got hit by a drunk driver and was knocked down on it passengers side. The truck was down for 4 months getting frame work and a new box. We did an oil change and put her back on the road. We drove her 1700 miles and the truck was running great. All of a sudden I started getting gray smoke out of the breather tube, and upon looking I found smoke coming out of the dipstick and oil fill. The truck then started running a little rough. I am getting oil out of the breather tube. I am about to put her in the shop but am trying to find out what I should expect. Any suggestions are greatly appreciated. Thanks.

How many miles total?

So blowby has increased quite a bit, and it's running rough. Hmm. Did the truck have an overheat event? If I were working on it, id hook up the computer, see if it got hot, see what the injectors are doing, see what happens when I disable individual injectors (to check cylinder balance), then yank em all out and do a compression test. And check valve lash at same time. Were the valves adjusted when the head gasket was replaced? They should have been, of course, but some mechanics are lazy.

So all of this is pure speculation, but the blowby plus rough running sounds like you scuffed a piston.

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[greasytshirt]

Oh, another thing: has it been 'making oil'? Is the oil real thin, and does it smell like fuel?

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