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740b regen headache

jon holt

Member
Joined
Feb 1, 2023
Messages
19
Location
kansas
I have a 740b that has regen issues. It will fail a regen and set a code for loss of ignition and ard nozzle heater voltage above normal. Customer replaced the spark plug, ard head and nozzle heater. Ard nozzle heater code was cleared, but will still fail a manual regen and set a failure to ignite code. I put the nozzle heater/dpf inlet heater on. I have also tried a engine ecm, air control valve and fuel check valve. Fuel pressure during manual regen is 270 psi., there is spark at the spark plug with an inline tester while in regen and the nozzle heater is 4 amps. The flame tip temp always cools down during regen, it will never warm up. I have 11 psi boost at high idle no load. I am running out of ideas and wondering if anyone has had this problem.
 

ahart

Senior Member
Joined
Nov 7, 2020
Messages
808
Location
Indiana
Definitely need a lot more info but based on what you’ve posted I’m guessing you’ve for a failed to ignite event when attempting a manual regen. Need to confirm you are actually getting a hot spark by doing an override of the primary transformer in ET. I have seen weak transformers cause an issue. Another thing we need to look for is the presence of raw fuel in the ARD combustion chamber after attempting a couple regen cycles. There are two ARD fuel solenoids, a pilot and a main. The 270 psi confirms you are getting fuel to them but doesn’t confirm getting it past them.
 

jon holt

Member
Joined
Feb 1, 2023
Messages
19
Location
kansas
The serial prefix is t4r. I have swapped the ignition transformer and coil wire with another 740 that was working properly with same results. The code numbers are e1025-2, e992-3, e995-3. It has also set an e991 and I have pulled the dpf for cleaning. I am getting the code while trying to do a manual regen. It is getting raw fuel in the combustion chamber after a failed manual regen. I have noticed that fuel is getting behind the swirl plate and it is also wet at the elbow for the air inlet. Not sure if this is normal or if there is an issue with the air control side. I hadn't thought about the fuel system too much because it was wet every time I pulled the ard head off after a failed regen but there could be an issue with that but judging by the flame temp sensor it doesn't look like there is any light off of the fuel.
 

jon holt

Member
Joined
Feb 1, 2023
Messages
19
Location
kansas
Yes I have. All tests passed. Originally the nozzle heater was bad and the customer had replaced the spark plug and ard head. I have put the harness to the nozzle heater on as well. It has ignition with a spark tester. It passes the ard air test. Fuel pressure to the CEM is 270 psi.
 

ahart

Senior Member
Joined
Nov 7, 2020
Messages
808
Location
Indiana
If you still have a e1025 you need to start over because if it passes everything then it wouldn’t have a failed to ignite event. I’m going to guess you have a spark issue. Post some pictures of the ARD head swirl plate and anything else you see that could be relevant. You do have access to SIS and ET correct?
 

jon holt

Member
Joined
Feb 1, 2023
Messages
19
Location
kansas
I do have access to sis and et. I am going to the machine today to put the dpf filter on and do further troubleshooting. I am bringing a new ignition transformer with me and I am also going to look at the fuel circuit as I haven't looked closely at the fuel except to check the pressure coming to the cem.
 

ahart

Senior Member
Joined
Nov 7, 2020
Messages
808
Location
Indiana
One thing I may suggest is running a datalog in ET while trying to run a manual regen. It may help you see what’s going on with the fuel side. Also make sure you override the primary transformer with the ARD head pulled back so you can visually see the spark quality.
 

jon holt

Member
Joined
Feb 1, 2023
Messages
19
Location
kansas
I got to the machine and installed a cleaned dpf filter that customer had extra as their one out of this machine was cracked. Got the filter in and reset the ash interval and reset the codes. Could not reset the first level high soot level code. Before I could even get the engine warmed up, the soot level high -3 set and it went into temporary lockout. Looked and soot level was at 116% Reset ash level again and soot level stayed at 116% Had to look at another machine that the customer wanted me to look at instead of the 740 but am going to order a differential pressure sensor and the steel tube from the doc as it was stripped out and not tightening up. Will check the spark tomorrow first thing to see how good the spark is.
 

ahart

Senior Member
Joined
Nov 7, 2020
Messages
808
Location
Indiana
You’ll have to run a manual regen before it will go to zero. That’s the only way once it codes for high soot level.
 

jon holt

Member
Joined
Feb 1, 2023
Messages
19
Location
kansas
Pulled off the ard head and went to override the ignition transformer and watched the spark. It is jumping across the gap but i am not sure if it is strong enough. I am also seeing some spark from up in the porcelain to the housing. I will upload the video when i can get my computer to accept it
 

ahart

Senior Member
Joined
Nov 7, 2020
Messages
808
Location
Indiana
I’ve got a thread on here that talks about weak spark on a 627k. On that one, the swirl plate had high resistance and wouldn’t spark well. Ended up wiping out the primary transformer also. I have only seen that the one time. Use an ohm meter and check resistance from the ground probe on the swirl plate to the ARD head body.
 

ahart

Senior Member
Joined
Nov 7, 2020
Messages
808
Location
Indiana
There’s definitely an ignition issue there. I’ve never seen one spark down inside like that, must be an easier path than the probe at the end. Do that ohm check on the swirl plate.
 

jon holt

Member
Joined
Feb 1, 2023
Messages
19
Location
kansas
I was wondering if the spark jumping down around the porcelain was not normal. One other thing I was thinking is that I had the ard head just laying there and it was sitting on some hoses. Would the white wire ground the ard head? I am not sure where that white wire goes to at the moment. When I get back up there I will check the resistance
 

ahart

Senior Member
Joined
Nov 7, 2020
Messages
808
Location
Indiana
I believe it goes back to one of the mounting bolts on the primary if I remember correctly so, yes it should ground the ARD head. When I was doing the 627K I could put a screwdriver to frame ground and use it as the ground probe for the spark plug and I got good spark but with the swirl plate I had about what you’ve got, cool yellow spark.
 
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