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Weird warm start issue
- Thread starter vrt93
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21k in an unloaded stock truck is normal, you won't see more than that unless you max the engine load and that is near impossible in an empty stock truck. The CP-3 has more than enough flow with stock injectors to cover up issues so max pressure is never a good indicator. A contribution and rpm drop at kill test will tell you more than any SOP or gauge reading, if you really want to dig it will point to what to cap off first and retest.
Reman injectors are notorious for lack of balance and poor consistency across the pressure range, that just creates problems that sometimes seem worse than they really are. Even production run stock injectors are not all that consistent.
Reman injectors are notorious for lack of balance and poor consistency across the pressure range, that just creates problems that sometimes seem worse than they really are. Even production run stock injectors are not all that consistent.
Ozymandias
TDR MEMBER
That means shut down every cylinder one at a time and see how much the rpm drops at each. Can be done with a decent software.
Return flow test is usually last step to validate the problem. It is harder to do and more involved but does not require a scanner to look at the contribution percentages and rpm drop. The good scanners have the ability to kill each injector separately, along with the contribution percentage it will tell you if the injector is working correctly. Typically you would do that on ones reading way high or low to see what the potential problem is.
Return flow test is harder as you have to have special fittings, you would do a baseline of all injectors together, then cap each one. The problem with that is you need a scanner that will do the test parameters correctly to get a valid reading also. The test requires 1100 rpms and 20k psi for 30 seconds to read the return. You can get close with the idle up feature and unplugging the FCA but that requires knowing how much higher the flow is form the standard test procedures.
If you don't have a scanner the AutoEnginuity product will do a lot for under $500, it has all the basic Cummins CR tests in it already.
Ok, I finally had a chance to perform an injector return flow test, anddddd.......
Nothing.
Ran it 3 times, twice in a row, and then I drove it around to get it back up to temp and ran it again. Volume returned with all 6 injectors hooked up was 80-100mL per min which is well below what my cummins manual says is a problem area (>180mL).
I'm ruling out injectors for now since every test I've performed tells me that they're not the culprit. I might try blocking off the injectors one by one and trying that, but I'm not expecting any significant findings. I might be thinking my cp3 is the culprit now
Nothing.
Ran it 3 times, twice in a row, and then I drove it around to get it back up to temp and ran it again. Volume returned with all 6 injectors hooked up was 80-100mL per min which is well below what my cummins manual says is a problem area (>180mL).
I'm ruling out injectors for now since every test I've performed tells me that they're not the culprit. I might try blocking off the injectors one by one and trying that, but I'm not expecting any significant findings. I might be thinking my cp3 is the culprit now
You didn't do the test correctly if that was all you got for volume in 1 minute. 160ml per 30 seconds is absolute minimum, a set of remans more likely in the 200-220 ml per 30 second range.
Umm, what were the instructions?
Basically this:
INJECTOR RETURN FLOW TEST
1. Operate the engine until the engine is at operating temperature.
2. Remove the banjo connector from the fuel drain tube at the rear of the fuel filter housing.
3. Install fuel system test fitting 9012 in place of the banjo connector.
4. Remove the vehicle fuel return line from the engine fuel drain tube. Route this hose into a container to catch bled fuel.
5. Install a piece of fuel line onto the test fitting and into a fuel container or into the fuel tank.
6. Install one end of a test hose onto the fuel drain tube. Place the other end of the test hose into a graduated cylinder.
7. Start the engine and let it idle for one minute.8. Measure the amount of fuel in the graduated cylinder.
9. If the flow is less than 180-ml/minute, the test has successfully passed.
10. If the flow is greater than 180 ml/minute, shut off the engine and remove all of the fuel injector supply lines. Re torque all of the high-pressure connector nuts. Install all of the fuel injector supply lines.
11. Start the engine and idle for one minute. Measure the amount of fuel in the graduated cylinder.
12. If the flow is less than 180ml/minute, the condition has been fixed.
13. If the flow is greater than 180 ml/minute after step 12, shut off the engine and remove the #1 fuel injector supply line. Re torque the high-pressure connector nut. Cap the #1 fuel port using tool 9011 on the fuel rail and the #1 high pressure connector.
14. Start the engine. Measure the amount of fuel in the graduated cylinder.
15. If the amount of fuel is less than 180 ml/minute, shut off the engine and remove the #1 high pressure connector and the #1 fuel injector. Inspect for damage, repair/replace as necessary.
16. If the amount of fuel is not less than 180-ml/minute, repeat steps 14-16 for cylinders 2-6.
17. Install all high-pressure connectors, fuel injectors, and fuel injector supply lines. Repeat steps 1-8 to confirm repair.
SPECIFICATION:Less than 180 ml/minute total fuel return flow
INJECTOR RETURN FLOW TEST
1. Operate the engine until the engine is at operating temperature.
2. Remove the banjo connector from the fuel drain tube at the rear of the fuel filter housing.
3. Install fuel system test fitting 9012 in place of the banjo connector.
4. Remove the vehicle fuel return line from the engine fuel drain tube. Route this hose into a container to catch bled fuel.
5. Install a piece of fuel line onto the test fitting and into a fuel container or into the fuel tank.
6. Install one end of a test hose onto the fuel drain tube. Place the other end of the test hose into a graduated cylinder.
7. Start the engine and let it idle for one minute.8. Measure the amount of fuel in the graduated cylinder.
9. If the flow is less than 180-ml/minute, the test has successfully passed.
10. If the flow is greater than 180 ml/minute, shut off the engine and remove all of the fuel injector supply lines. Re torque all of the high-pressure connector nuts. Install all of the fuel injector supply lines.
11. Start the engine and idle for one minute. Measure the amount of fuel in the graduated cylinder.
12. If the flow is less than 180ml/minute, the condition has been fixed.
13. If the flow is greater than 180 ml/minute after step 12, shut off the engine and remove the #1 fuel injector supply line. Re torque the high-pressure connector nut. Cap the #1 fuel port using tool 9011 on the fuel rail and the #1 high pressure connector.
14. Start the engine. Measure the amount of fuel in the graduated cylinder.
15. If the amount of fuel is less than 180 ml/minute, shut off the engine and remove the #1 high pressure connector and the #1 fuel injector. Inspect for damage, repair/replace as necessary.
16. If the amount of fuel is not less than 180-ml/minute, repeat steps 14-16 for cylinders 2-6.
17. Install all high-pressure connectors, fuel injectors, and fuel injector supply lines. Repeat steps 1-8 to confirm repair.
SPECIFICATION:Less than 180 ml/minute total fuel return flow
That is mish mash of both test procedures. If you are running it at an idle with idle pressures the return is 10-12 cc's per injector in 1 minute being normal.
That test has been superseded because it doesn't capture valid performance of the injector. The updated test is 30 seconds at 1200 rpms and 20k psi, that should net 180 cc's for all injectors to be good. Up to 220 cc's is still an acceptable range but anything over that they are candidates for replacement. You need software to do it correctly though.
You could test for 30 second return at 1000 rpms and the FCA unplugged and that will put you in the ball park. Not exact but it is a better snapshot at pressure of injector return.
That test has been superseded because it doesn't capture valid performance of the injector. The updated test is 30 seconds at 1200 rpms and 20k psi, that should net 180 cc's for all injectors to be good. Up to 220 cc's is still an acceptable range but anything over that they are candidates for replacement. You need software to do it correctly though.
You could test for 30 second return at 1000 rpms and the FCA unplugged and that will put you in the ball park. Not exact but it is a better snapshot at pressure of injector return.
Sorry for digging this back up, but I've had more down time with the quarantine.
You are correct! I did it wrong the first time. Redid the test and these were my results:
30 sec, FCA unplugged, 23k psi Rail Pressure, engine temps ~170-180 degF,
1. 800 rpm idle, 240mL returned
2. Attempt to hold 1200rpm (varried between 1000 and 1400), 340mL returned.
Needless to say I'll probably be buying injectors soon.
You are correct! I did it wrong the first time. Redid the test and these were my results:
30 sec, FCA unplugged, 23k psi Rail Pressure, engine temps ~170-180 degF,
1. 800 rpm idle, 240mL returned
2. Attempt to hold 1200rpm (varried between 1000 and 1400), 340mL returned.
Needless to say I'll probably be buying injectors soon.
UPDATE!
Ok, so I pulled my injectors and all 6 look more or less like the pictures (injector 1). I'm assuming that's a result of oil getting into the combustion chamber and clogging the injectors causing excessive return, but I don't have any blow-by. I'm also running an aux fuel filter/water separator that I change every other oil change so I don't think its a fuel contamination issue either. 3/6 injectors had one hold down bolt that was a little more than finger tight so that would explain it for those injectors, but I'm stumped on the other 3.
Honestly with this, my A/C now not working, both main seals leaking and a clutch on the way out, I'm almost at my breaking point with this truck.
Ok, so I pulled my injectors and all 6 look more or less like the pictures (injector 1). I'm assuming that's a result of oil getting into the combustion chamber and clogging the injectors causing excessive return, but I don't have any blow-by. I'm also running an aux fuel filter/water separator that I change every other oil change so I don't think its a fuel contamination issue either. 3/6 injectors had one hold down bolt that was a little more than finger tight so that would explain it for those injectors, but I'm stumped on the other 3.
Honestly with this, my A/C now not working, both main seals leaking and a clutch on the way out, I'm almost at my breaking point with this truck.
Pretty normal for a set of injectors that are not working correctly. I have seen a LOT worse with carbon build up. Remember, diesel fuel IS oil, what you are seeing is just the uncombusted diesel mixing with the soot. There can be many reasons from bad spray angles from bad ports or incorrectly setup injectors or just a bad reman job all around. Those do not look that carboned up so they may be usable yet. I would reinstall all the injectors and tubes TQ'ed correctly, make yourself a high detergent, extra lube additive package and use it religiously. 96 oz of Power Service with aquart of MMO and dump 15-20 ozs every 1/2 tank will do wonders cleaning up the nozzles, injector, and fuel system.
Next best thing you can do is hook on to 6-10k load and driver it hard for several hundred miles at a time. The only way to clean out the crud in the cylinder is burn it out and that takes extended cylinder temps. A pyro in the exhaust manifold is needed with constant temps over in the 1000-1100 degrees range for hundreds of miles.
There is NO substitute for working the engine hard and getting the cylinders temps up. Modern diesel are programmed to run stoich rich for emissions purposes, if you do not work them hard for extended periods that will cause carbon and soot build up in the cylinders.
Best investment is something like a Smarty or even custom programming to rid the engine of the 3rd event and stoich rich programming. Get the timing advanced, retool the fuel curves for optimization, and drive it hard.
You are not going to get oil to plug the nozzles, fuel is injected from 5k to 20k psi so it isn't plugging nozzles. What happens is low quality nozzles and incorrect injector setup causes errant injection events that do not promote adequate combustion. Emissions tuning create a scenario for 2 strikes by its nature, it only takes 1 more to cause problems.
Next best thing you can do is hook on to 6-10k load and driver it hard for several hundred miles at a time. The only way to clean out the crud in the cylinder is burn it out and that takes extended cylinder temps. A pyro in the exhaust manifold is needed with constant temps over in the 1000-1100 degrees range for hundreds of miles.
There is NO substitute for working the engine hard and getting the cylinders temps up. Modern diesel are programmed to run stoich rich for emissions purposes, if you do not work them hard for extended periods that will cause carbon and soot build up in the cylinders.
Best investment is something like a Smarty or even custom programming to rid the engine of the 3rd event and stoich rich programming. Get the timing advanced, retool the fuel curves for optimization, and drive it hard.
You are not going to get oil to plug the nozzles, fuel is injected from 5k to 20k psi so it isn't plugging nozzles. What happens is low quality nozzles and incorrect injector setup causes errant injection events that do not promote adequate combustion. Emissions tuning create a scenario for 2 strikes by its nature, it only takes 1 more to cause problems.
Thanks for the info Cerberusiam! I'm still learning so this kind of stuff helps. I think ill try and get everything clean and re-installed and make/run some fuel additive. Maybe I was freaking out over nothing lol. I've been eying tuning for a while so maybe ill be pulling the trigger on that sooner rather than later
Since you have them out why don't you have them flow tested. It isn't that expensive, and they can install new nozzles if required for about $140 each.
Just be careful who does the work. Not very many shops have genuine Bosch flow/test bench. When I was still working we sent hundreds of injectors to Pro-Formance Fuel Injection in Pennsylvania for testing/cleaning/repair. We sent them overnight, they tested the same day and sent them back over night. I'm sure Marty gave us a good price because we were doing so many, but they still seem reasonable for what they do.
Just be careful who does the work. Not very many shops have genuine Bosch flow/test bench. When I was still working we sent hundreds of injectors to Pro-Formance Fuel Injection in Pennsylvania for testing/cleaning/repair. We sent them overnight, they tested the same day and sent them back over night. I'm sure Marty gave us a good price because we were doing so many, but they still seem reasonable for what they do.
Update:
Had the injectors tested. Nothing abnormal and everything was within spec save for 2 injectors falling a little high (like a couple mL over the limit) on the high rpm flow test, but the shop that tested them said that wasn't really a big enough issue to warrant replace/rebuild. I described my issue to the guy who ran the shop. He mentioned the transfer pump on the back of the cp3 possibly being the culprit.
Long story short, I reinstalled the injectors and checked valve lash while I was at it. Lo and behold, the problem is still there. Truck runs fine, but wont start if it gets up to temp and sits for more than 10 minutes. It almost left me stranded in the Home Depot parking lot. The only other thing I can think of is trying to find a way to test for the transfer pump going bad or maybe removing my CP3 and having the shop test it.
This problem has been going on for almost 6 months now and I'm at the end of my rope with this truck. Compound this with a now leaking rear main seal and ac that stopped working right before summer and I'm about ready to send this truck down the road.
Had the injectors tested. Nothing abnormal and everything was within spec save for 2 injectors falling a little high (like a couple mL over the limit) on the high rpm flow test, but the shop that tested them said that wasn't really a big enough issue to warrant replace/rebuild. I described my issue to the guy who ran the shop. He mentioned the transfer pump on the back of the cp3 possibly being the culprit.
Long story short, I reinstalled the injectors and checked valve lash while I was at it. Lo and behold, the problem is still there. Truck runs fine, but wont start if it gets up to temp and sits for more than 10 minutes. It almost left me stranded in the Home Depot parking lot. The only other thing I can think of is trying to find a way to test for the transfer pump going bad or maybe removing my CP3 and having the shop test it.
This problem has been going on for almost 6 months now and I'm at the end of my rope with this truck. Compound this with a now leaking rear main seal and ac that stopped working right before summer and I'm about ready to send this truck down the road.
Ok, so I think I did that and I think I have air in my fuel. I connected the miller 9012 fitting to the return port (? not sure what you call it. Its the one going from the CP3 to the side of the fuel filter/PRV) of the CP3 and ran it into a jar and noticed a steady stream of bubbles at idle.
Assuming I did the test correctly (who knows, I didn't find much on the internet and the Cummins manual I have is a little more geared to industrial applications so It was a little hard to decipher what was what) and I have air in fuel, now what? I'm finding less on diagnosing the source of the air.
Assuming I did the test correctly (who knows, I didn't find much on the internet and the Cummins manual I have is a little more geared to industrial applications so It was a little hard to decipher what was what) and I have air in fuel, now what? I'm finding less on diagnosing the source of the air.
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