Hello, I have a Deere 2008 710J Serial T0710JX160266 w/ 7700 Hours. Engine is a 6068HT 067. I purchased it with a engine idle miss and am seeking advise on what may be causing this. Symptoms: -No active codes -audible engine miss at idle -miss can be heard/felt while slowly bringing rpms up -No issues at full throttle tractor has plenty of power I had deere come out today and plug into the unit (No active/stored codes). They performed multiple cutout tests and checked rail pressures. Tech told me #1 has the issue and likely a bad injector but to inspect the harness first. After removing all the shields the injector harness looks ok no visible signs of rubbing. Replaced the #1 injector with a Deere injector and no change in the miss, may have gotten worse. Deere is supposed to come back and "calibrate" the injector but i dont think this would cause the continued miss? Going to pull the valve cover in the morning to inspect for overhead damage/proper valve lash adjustment but any input is appreciated. The service records i received with the unit do not make mention anywhere about adjusting valve lash which makes me think it may have an overhead out of adjustment or a failure of some sort.
Thanks for posting the serial number. If there are no active/stored codes then it is a mechanical issue (injector, flow damper, injector line, valve adjustment, valves, compression, fuel delivery, etc). A valve adjustment would be a good place to start. I would expect the fuel system to have good pressure since you have plenty of power at full rpm. But I'm a stickler for always checking the lift pump pressure on any engine issue. Was the lift pump pressure checked? Also was the system checked for air (clear tube on the return line)? Did the dealer ever perform an injector fuel return line flow test? You can hit the exhaust manifold with a heat gun while missing to see if in fact #1 is running colder than the rest. Did the dealer perform an injector clean? Those tier 3 engines with HPCR fuel systems were particularly sensitive to deposits causing sticking (although I find the cleaning only works about 10% of the time). When the Dealer comes back out to calibrate and if it still misses after calibration have them perform an injector cutout test, misfire test and a relative (electronic) compression test. Also ask if they can perform a recording of the actual and desired rail pressure and graph it and ask them to print the graph and send you the results as well as the tests mentioned (if the tech is computer savvy he can email you the results while there). Then post them. With 7700 hrs there is a good chance that you may need the other 5 injectors replaced. But let's eliminate the simple stuff first.
check return line and fittiing off the INj. pump to fuel tank to see if flowing good
Can someone post up the valve lash adjustment procedure? I found a couple procedures on the web but don’t want to pull this valve cover again. I can roll the engine over without the baring tool but am unsure about locking it at TDC and 360 from TDC. Can I stick something else in the bellhousing timing hold to pin timing?
this is the easiest procedure to remember, you might work harder, and turn the engine more than doing it by the book, but you won't have to think about it that hard. 4 and 6 cylinder inline engines have pairs of cylinders, the inner pair, the outer pair, and on a 6 cyl #2 and #5 are on the same throw. Each of the cylinders in these three pairs is on the same throw, TDC at the same time as it's pair, so when one is at TDC with both valves open (or one opening and one closing at the same time), then it's pair is TDC on the fire stroke and that's the one you check the clearance on. If you have that info and the firing order it should be easy to do it in two turns of the engine. You don't have to lock anything to check the valve lash, the TDC and 360 from TDC is what I'm describing as the valves being open on your cylinder (360 from TDC, and it's pair at TDC).
Thank you but what is proper clearance?
Removed the return line at the injection pump and ran a clear hose into a bucket test ran machine, no air in the line and clear flow into the bucket still has a miss.
Update -adjusted valves (14/18) none of them far out -reassembled and test ran no changes. -cut oil filter and changed oil for kicks no metal in the filter. -changed fuel filters no improvement in miss -removed return line at injection pump and ran a clear tube into a bucket no aeration or improvement in misfire. -while I had the injector harness off I ohmed it out couldn’t find ant breaks
Lift pump pressure is 8-9 psi key on and at idle while missfire occurs. Checked at final fuel filter.
Anyone have suggestions on where to go from here? Call Deere out to Calibrate the 1 new injector? Remove all injectors and take to local shop for testing? Cutout tests have been inconclusive in showing any cylinders are dead, its almost more of a timing miss at this point not 1 cylinder. What is the best way to troubleshoot this HPCR system?
Unfortunately only with a laptop and diagnostic software (doesn't necessarily have to be a Deere program). Need the ability to read codes, perform cutout/misfire/compression tests, see readings and graph results. Fuel quality good? Don't waste your time chasing anything electrical if there are no codes. That system is sophisticated enough that any electrical issue with the injection system will throw codes. Usually excessive leakage from injectors will throw intermittent low pressure fuel codes, but not always. You could isolate the fuel return line from the injectors and run the return line from the injectors to a beaker or some other measuring device and measure flow at idle for one minute. Based on the emission level of that engine and the hours on it I'm betting you have sticking injectors. Each injector has a calibration code that has to be programmed into the ECU for proper running. I have never had those injectors to an injection shop so I don't know if they will issue new calibration numbers. My experience has been that it is best to install new injectors. So maybe have an injection shop test them. If they are bad then get new (regardless of new/rebuilt, a calibration will be necessary). On rare occasions I have also seen the flow restrictors cause a misfire, but they have usually been intermittent misfire complaints.
not often do we hear that diesel engine is missing (skipping), would you please explain what it sounds like, lots diesels sound different when idling espc. in cold weather,,, my 555a has a rapping sound when idling, had a tractor dealer pick it up and take to they shop, checked out ok just a normal sound for that engine, its still has a rapping sound 22 years later JUST SHARING INFORMATION good luck
I don't know what his engine sounds like, but a miss is pretty common when starting a cold diesel with a lot of years and hours. They fire and take off but not hitting on all cylinders until they get a little speed and maybe warmth built up. Sometimes takes a minute to for the last one to fire right, that's what I'm thinking of as a miss. It's not the clack and clatter, it's the relative smoothness of most of them vs the pop of the bad one.
Did not know that about HPCR engines! As to what a miss sounds like. I would describe it as promoting idle roughness. I had a miss and found that the valve seat was cracked on a Chevy diesel once. Had both heads reworked and was back in business.
Update: Pulled all 6 injectors and dropped off for testing.
What is seen quite a bit with HPCR engines is what is described as either a miss, though slight, but enough to know that the engine is not quite right (and also quite common at idle and not fast idle) or the other complaint we get is described as a flutter. If you were to stand where the exhaust points and listen you would actually here a flutter sound (hard to describe in text but it would be obvious if you heard it).
Injector testing Update: #1 tested good (brand new this is the one I replaced) #2-5 tested wore out, high return bypass I’ll post Bosch machine test results when I get them #6 they couldn’t test, nozzle showed signs of pitting from water in the combustion chamber thoughts?
Injector tests 1-3
Injector tests 4-6
The leak test I mentioned in post #11 should have had the same results (excessive return flow), except you wouldn't know which injector/injectors were the culprit. Thanks for posting the results ! Good reading. #6 showing signs of water internally or externally? Quality of the fuel good? Any water, no matter how slight, plays he** on those injectors. If it is external pitting from the cylinder, are you using coolant at all?
I have to wonder if this is your miss and what's the compression in that cylinder.
Update: With all 6 injectors removed i put shop air (120 psi) in each combustion chamber @TDC compression stroke through the injector hole with a rubber nozzle. All tested ok except #2 bled out the exhaust side. Pulled the head and found a couple things... #6 head gasket is blown between the combustion chamber and water passage, this explains the pitting on nozzle #6. I did not have the machine long enough to know if it was using water as i bought it with the miss and tore into it right away. #2 exhaust valve is flat wore out and carbon buildup on the seat is not allowing it to seal, this should be our miss. Between these 2 i think we have an explanation for everything. Going to shop around for a reman head and gasket kit monday.
That head is probably still good. It would be much cheaper I suspect to have that head inspected, decked if need be and reworked by a shop that specializes in doing it than to outright buy a reman.