Engine/Transmission (1998.5 - 2002) Can injectors go bad??

[Clmsnow]

I have DDII's that have been on my truck for about 90K miles. I have noticed that ever since I got the injectors that my mileage dropped to about 16mpg on the freeway and 15 in town. Lately I notice more smoke and even a gray colored smoke. I am not pulling any codes and I have never adjusted my valves. I know I need to adjust the valves but wondered if the injectors could go bad. If so, what is the biggest injector I could replace it with and still be safe with my set-up(Comp, HTBG-12)? I was considering Mach 2's or maybe like a Mach 2. 4. I was hoping the newer style injector would be a little cleaner, and possibly run the same EGT's as my current set-up but with more power. I occasionally tow, but never much over 5000lbs. Any suggestions???

 

[Regcabguy]

DD2's

I have DDII's that have been on my truck for about 90K miles. I have noticed that ever since I got the injectors that my mileage dropped to about 16mpg on the freeway and 15 in town. Lately I notice more smoke and even a gray colored smoke. I am not pulling any codes and I have never adjusted my valves. I know I need to adjust the valves but wondered if the injectors could go bad. If so, what is the biggest injector I could replace it with and still be safe with my set-up(Comp, HTBG-12)? I was considering Mach 2's or maybe like a Mach 2. 4. I was hoping the newer style injector would be a little cleaner, and possibly run the same EGT's as my current set-up but with more power. I occasionally tow, but never much over 5000lbs. Any suggestions???

Speaking from experience,my DD2's did exhibit the same symptoms as yours did. I sent them into Diesel Dynamics and two were faulty. They replaced the two and upgraded(shimmed the spring),sonically cleaned,and tested all six. They were returned in sealed bags in one week. I had bought mach 1. 6's and an currently running them but cannot enough good things about DD's customer service and support. I sold them to a member at a great price. DD supplies a lifetime guarantee to the original purchaser.

 

[Clmsnow]

How do the 1. 6's compare to the DDII's?

 

[PKozlowski]

I wish I could drop to 16mpg! I never get over 12 empty and 9 towing and I don't beat it.

 

[2-ND TIME]

injectors going bad

Yes they do wear out and have them pop tested, they ??? should testout at about 4500 psi. I told the dollarshop to test mine and they didn't think that it was nessecary because the EGT was within 5 degrees of each other. I had them done elsewhere and the worst poped at ( peed out of two nozzles) at 2600 psi and the best half atomized at 4100 psi. My mileage went form 16. 6 back to 22. 6 mpg. Did alot of the same road so could tell easily. Back and forth to the different dollarshops and work. ( could a fford it for awhile.

 

[Greenleaf]

I have to replace injectors on the 24 valve engines often. I have yet to require replacement of the 12 valve injectors outside of performance purposes. The fleet consists of 25 school buses w/ a mix of 12 and 24 valve power.

 

[PC12Driver]

Hey, shouldn't you be working on your sled this time of year and not your truck?



I like Bob's idea; buy another set of F1s (since you've wanted them for what, a year-and-a-half now?), get the DDs refurbed and sell them off. That way the truck isn't down while the sticks are getting fixed and you end up with what you wanted anyway.



The 2s would be safe with your setup. If you're gonna swap 'em out you may as well get a little more power, too.



What setting do you normally run your Comp on?

 

[Clmsnow]

LOL... . yeah, I am waiting for snow alright!!! The sled is all ready to rip and figured I would do a few last minute things to the truck before winter hits. I normally run my Comp on 3x3. I think the Mach 2's sound like a nice idea, unless of course I could go larger; say 2. 4's or 3's????

 

[PC12Driver]

With the larger injectors you could run the Comp on a lower setting for normal driving (probably easier on the VP44) and save the higher levels for play time. You won't be able to hold your foot to the floor for as long with the box on kill, but you will get stronger acceleration up to the point that you temp-out. And under normal driving/towing, I'd bet that you won't even notice a temp difference (since you've got a great midrange rpm turbo).



You're seeing what now, about 1350*?

 

[Clmsnow]

1350 max... only for a second or so. Usually on kill, up a hill I hit 1300. So, 2's or 2. 4's or 3's? Will my fuel mileage be better? What abut adjusting the valves, I have never had it done since owning the truck.

 

[PC12Driver]

If you're only flashing up to 1350* I'd say you've got a bit of room to add a little more fuel if you want. Just speculating, but I don't think you'd see much more egts from the 2s, and the 3s would probably still be quite controllable. Keep the box turned down for towing and you'll be okay with any of those injectors.



Think about the steepest hill you pull when you're taking your sled to the mountains. With all other factors being equal, it doesn't matter if you have stock injectors or Mach 5s in your engine - your truck still uses about the same amount of fuel to pull your 5k lbs trailer up the grade at 65 mph. When you're using the "extra" fuel from the larger injectors you'll see higher temps. Running partial throttle up the hill, your temps should be about the same. Goose the throttle and they'll come up more quickly with the bigger sticks, but they should stabilize at about the same peak. So I wouldn't worry about temps while towing, as long as you keep the box on the low numbers. And as far as street racing, the occasional flash over 1350* is no big deal.



As far as mileage, if your old injectors are indeed getting worn, then I'd think you'd see an increase in mileage from a new, tight, balanced set. Maybe not enough of an increase to justify the $ for new injectors, but factor in the bonus hp and that should do it!



The smoke at idle thing may not go away, since thats a trait of larger sticks. That also starts to happen after you get a few miles on your engine.



And don't be afraid to adjust the valves. The procedure isn't that hard at all. And most folks (including myself) have noticed a smoother running engine after doing so.



I'm a little disappointed; you didn't even mention Mach 4s in your list of injector choices. What happened? :-laf

 

[Clmsnow]

Oh no, 4's are too big for my little HTBG. I guess if I went to a HTB2 I would get 4's in a heart beat, but I thinki I'll keep this turbo as it seems to be working well for me. I understand the thing about towing and temps, that is not a concern at all. I guess I will do 2 or 3's... . or something in between.