Hey, look, another injector question thread!

First, the info that would be in my sig if I could have a sig: '96 F250 CCSB XL 4X4 ZF-5, 160K miles. SMF, 6637, 3" DP, lost cat, custom 10K mod, EGT gauge

I picked this truck up completely bone-stock in February from the original owner, and I've been steadily fixing and improving it about every weekend while I drive it all over the place for work during the week. I've put about 10K miles on it in the last few months, and I've developed a pretty solid miss on one cylinder. It's been getting progressively worse, and doesn't seem to depend on engine temp. It's most noticeable at low RPM / high load, but stays consistent all the way through the RPM range. Lately I can feel a little stick shake at idle, too, when it used to be smoother. Here's the checklist of relevant recent work, etc:

-New valve cover gaskets, UVCH, and glow plugs 7K miles ago (did not affect the miss)
-New fuel pump, overhauled fuel bowl and FPR
-Delo 5W-40, 2500 miles old, FL1995

I don't suspect fuel pressure or high pressure oil issues, because there are no other symptoms at all- full throttle with my 10K mod activated will puff a little black smoke and then pull really strong up to the RPM limit- this truck will go from 70 to 100 in just a few seconds on the freeway, I can't imagine the injectors are starving for oil or fuel.

I do have the IPR o-ring kit and it's on my to-do list, but that wouldn't cause a single cylinder miss, would it?

Would I be missing something obvious if I assumed I had a worn injector? And if it is an injector, what would your opinions be about replacing just one at this mileage? 160K seems a little low for all 8 to be worn out, but I'm familiar with Dzl Jim's philosophy about replacing onesy-twosy, and he's probably right.

I can't really figure out how much a new set of injectors will cost until I figure out if I have split-shots or not- Truck is a California emissions truck built 5/96... If I have split-shots, I either have to replace them with the same or get a chip/pcm reflash to run single shots, right? Does anyone know a reliable way of determining the injector code for a truck without removing the valve cover? I just don't have as much time as I'd like for working on my truck, and so I'd prefer to only remove the valve cover one time- when I swap injectors.

Thanks in advance for your advice, this forum is pretty darn valuable and I appreciate it.

 

Have you tried driving it with the 10k mod removed? Can't hurt to try. I'm guessing you have split shots in there. If you want you could unplug one of the four wiring plugs at a time and narrow it down to one of two cylinders without pulling the vc's off if its a bad enough miss.

IPR orings won't cause a single cylinder miss.

160k isn't that high for mileage on them but without knowing the previous maintenence , like scheduled oil changes, who knows for sure what kind of shape they are in.

 

Yeah, I should have clarified that. My 10k setup is actually a switch and a potentiometer that goes from infinity down to 5.6k. After playing with it for a few days, I realized the best way to use it is to leave it set on 5.6k and switched off for all normal driving. If I need to pass somebody on a two-lane or show up a Cummins at a light I flip the switch on and floor it. I'm actually thinking of a way to wire it up so it only activates when the accelerator is floored, but that's .

 

Split shots would have the pulse dampener on the fuel pump.

What's the code on your PCM?

 

It did have the pulse dampener, before I threw that leaky POS in the trash. Did they ONLY put pulse dampeners on split-shot trucks? If so, that would pretty much be my answer, right?

I'll pull the PCM and get the code as soon as I can just to verify, but in the meantime I guess I'll assume split shots.

What are the forum's thoughts on replacing AB codes with reman/overhauled AB's vs stage 1's or AC's? I'm really not sold on needing a chip, I don't tow anything heavy and I don't compete or race. Could I just have the PCM reflashed to support AC code injectors and call it good? And one last one, how important would you consider new nozzles and new plungers? Worth the money as preventive medicine or can I assume a reman/overhaul with "reconditioned" nozzles will be OK?

 

There should be a tag on the driver door with strategy and part number of your PCM. You can read the designation on the PCM from the driver side fender.

 

Ahh, thank you, got it. Looks like the code is AUG6.

 

I'll throw my $.02 at these questions... I think it is worth the money for the new parts... I don't see why you would want to pay big bucks for reusing old parts... It doesn't cost that much more and you will know the condition they are in. If you are happy with the performance of your truck and not looking to spend $30k and have 600hp, then rebuilding your AB's is perfectly fine. They are not that much less than an AC or stage 1 injector. A typical stage 1 is 160cc with stock nozzles. Your Ab's are roughly 120-130cc with a stock nozzle... A chip would be a huge improvement over the 10k mod and will put a grin on your face when driving your truck. If you do decide to go with stage 1 single shots, you will have to either have a custom tuned chip or reflash your PCM for the singles...

Lastly, yes, your cali truck had a dampener for a reason...

 

That's a Cal code for splits.

 

You could also do AD codes 140cc

 

Might want to add a better HPOP then... The extra fuel will certainly work that 15* HPOP...

 

if you suspect a miss and you think it could be an injector, A buzz test couldnt hurt your troubleshooting process.

 

I don't have the scanner to do a buzz test or a contribution test, but I guess I'll have to pay to get that done. I double-checked all the valve cover harnesses and swapped the camshaft position sensor tonight for justincase, no luck. The miss has definitely gotten worse over the last few days, so it's probably not just a bad connection. What about checking the poppet screws, how often do those end up being the culprit? 4.5mm Nintendo bit, right?

 

Pull the valve cover and unplug each injector one at a time to see which one make the least amount of difference in the way the engine runs