Engine/Transmission (1998.5 - 2002) HELP! Truck runs worse with bigger injectors

[zman]

I have been having problems with a very noticibly rough running engine lately. I am currently running bigger injectors (DD2s), but I don't think I had the problem when I first installed them. I recently had the dealer do a cylinder shut down test and it showed the #2 injector was bad. Since I thought the problem was injector related, I returned my first set for a second set but after installing them today I still have the same problem. While I was waiting on the second set, I put my stock injectors in and things ran much smoother, but still not perfect.



I'm starting to think that the bigger injector is exaggerating a problem that isn't as noticible with the stock injectors. I'm gonna take the truck in to have another cylinder shut down test done to see if by chance it shows the same injector as being bad. If so, I'm guessing it's the injector pump. Does anyone have any ideas? Any and all help is appreciated - this is getting VERY frustrating!!!



Thanks in advance!



Steve

 

[csutton7]

did this happen as soon as you installed the DD2's or later on???... ... . chris

 

[zman]

Chris -



If I was having problems right after the initial install of the 2's, I don't think it is as noticable as it is now. The idle is noticably rough, but the roughness is more evident around 1000-1200 rpm. Assuming the same injector shows up bad during the next cylinder shut down test, I suppose I might have a bad injector tube, but that doesn't explain why it runs smoother with the stock injectors.



Any ideas???



Steve

 

[csutton7]

1)bad injector--but I think this is not it

2)did you get the copper washer(on the bottom of the injector) out with the original injectors--you probably did

3) damaged injector tube or something is lodged in it

4)is the injector tube properly seated

5)is the injector hold down bolt tight

6)crack the injector line and see if you're getting fuel to it

7) kinked injector line from the VP44

8) valves out of adjustment



this is what I'd look into first... good luck. . chris

 

[zman]

Thanks Chris! I redid the tubes and hold downs but still have the same problem. Your list is a good place to start. I'm gonna stop at Cummins on the way home tonight and pick up a couple of tubes...



Steve

 

[MD500E]

I installed DD2's about this january. From the moment it started it had a rough idle. It shakes the drinks in the cupholders a litle. I thought it was normal and shruged it off. When i had my transmission upgrades by mass diesel he mentioned that the rough idle was not normal. If it is a bad injector, will it hurt anything?

PS: I also replaced the conector tubes at the same time.

98. 5 auto.

 

[Ethdee]

Originally posted by zman

I'm gonna stop at Cummins on the way home tonight and pick up a couple of tubes...



Steve

Steve, I'd appreciate it if you'd let me know what an injector tube costs from Cummins.



Best of luck with the troubleshooting!



Jim

 

[Neal Cassady]

$$

Don't have the receipt handy but I think they were around $18. 00 a piece. Probably cheaper at most other Cummins shops, the prices at our local places are usually a little high.



Dave

 

[zman]

Dave's number was right on. Cost at Mid-States Cummins is $17. 64 each.



Steve

 

[andrewkoperdak]

Large injectors

Zman,



I just put a set of STAGE 3 injectors (100 hp) in my truck and did not have any idle or rough running issues. Seeing as I just did this job I have all the parts fresh in my head.

Everyone that responded to your thread had good suggestions; I would however like to add one more:

There is the intermidiate fuel injector to fuel line piece that runs in the head itself. It is grey abut 3. 5" long with one o-ring. This piece has a filter of sorts built into it. The triangle filter is meant to break up any debris that made it past the fuel filter . Once past the filter the debris should be small enough to pass through the injector, in theory. If it, the intermidiate, is partially clogged it would cause all the problems you listed both with new and old injectors. It would simulate a faulty injector. All you need is an air supply and blow them out. You could have very easily gotten foreign material in there during you intial install of DD2s.



Best of luck,

Andy

 

[csutton7]

Andy--that's an excellent pc of info you just shared--I had forgotten about the filter in the injector tube... . chris

 

[Stefan Kondolay]

I would check the tubes they have given me problems before.

 

[zman]

thanks!

I plan to pull the tubes tonight and blow them out, but I have a couple of questions. I have 31k miles on the truck. Do I need to replace all of the o-rings when I do this? Is it possible to accidentally blow the screen out of the tube by using too much air pressure or is the screen integral to the tube? Thanks again.



Steve

 

[csutton7]

no on the orings, unless they look damaged---anything is possible with to much air pressure--but since those things are getting pounded by 4000psi of fuel I doubt you could blow the screens out--but be careful--chris

 

[BV]

Injectors

I thought you should always replace the copper crush washers each time you R&Red an injector?

 

[Vaughn MacKenzie]

zman, if you pull the injector tubes try blasting them with carb cleaner in reverse flow direction. I did this once and dislodged a fair amount of crud. Also, try switching tube and injector position to rule out tubes or injectors next time you do the cylinder shutdown test.



Like mentioned I would be sure and adjust the valves to make sure they correct.



Only 30K miles on a '98??



Vaughn

 

[Bob Wagner]

Originally posted by Vaughn MacKenzie





Only 30K miles on a '98??



Vaughn

Vaughn, Its a 2k1

 

[zman]

nothing.......

Well, I tried about everything listed above tonight, including replacing the #2 tube (the #2 injector was originally diagnosed as bad but the entire set has since been replaced and still no improvement), but NOTHING helped. The tubes had absolutely nothing caught in the screens. I'm still experiencing the exact same roughness. I think I have ruled out everything on the engine side of the injection pump except valves. I guess I'll get another cylinder shut down test to see if #2 is still the culprit.



Another thought: I had to have the lift pump replaced about 10k miles ago due to VERY LOW pressure. I figured out the problem the day I installed my fuel pressure gauge. I have no idea how long I was running with low pressure (actually showed a vacuum at WOT). Could this have caused my injection pump to begin failing. I really think my symptoms are getting worse over time, but it's hard for me to remember what the roughness sounded like the first time I noticed it. At first it seemed like I had to really listen to hear it, now it seems quite obvious.



I still think it is strange that the larger injectors make the problem much more noticable than the stock injectors. Any more thoughts?? I really appreciate the input so far!! Thanks.



Steve

 

[lberch]

try reading this

This was my white whale, hope it helps ya.



LB



https://www.turbodieselregister.com/forums/showthread.php?postid=365309#post365309

 

[zman]

taking it to Dave's Diesel...

Well, I've decided that whatever is wrong, it's something that I can't fix, so I'm taking it in to Dave's Diesel in Muncie. Based on our phone conversation, they suspect the injection pump. I'll report back when they get the problem figured out.



Steve