AB's flow more fuel than AA injectors 120cc if I remember correct but they are split shots so you will need tuning for them to run properly in the truck.

 

Ok so for instance on a truck like mine (bone stock no chip no adds) would the split shot (AB code) injectors function in the same manner as the AA code injectors or would they just not function at all??

 

Good Question! what kind of tuning are you talking about???? Like just a chip or something?

 

Yea you will need custom tuning on the chip

 

Umm... If I'm not mistaken, you're running AA's and AB's mixed???

Very bad idea...

 

What would be bad about running them mixed on a stock truck? Just trying to learn here. I know if the question came to my mind someone, somewhere had to have been as uneducated as myself and tried it or done it?? Thanks for the response in advance.




Rob

 

You can replace the entire set of AA's with AB's and run them with tuning because they are split shots. But i would not mix AA's and AB's together. You will then have a mix of split shots and single shots and it will run like crap.

 

Yeap. The injection will be all wrong. If will run really really crappy

 

Yes they will run but the injection timing is off and they will run like hammered dammit.

If you run any AB injectors in an OBS truck they are going to run rough. Unless the truck was originally a Cali truck. Those came in 1997 with split shot injectors.

 

My truck is a '97 but not sure how to tell if it is a Cali truck or not?

 

Sounds like you don't know how a split shot injector works compared to a single shot. The difference between the split shot and single shot are the single shot just inject one charge of fuel per cycle, whereas the split shot releases a pre light load before the main charge. Taken right off wikipedia

 

Yeah read about the split shots and I understand they release a smaller shot then they release the second shot of fuel required.

Split-shot injectors were originally installed on 1996 and 97 model/year trucks with California emissions, and are used in engines from 98.5 on. These injectors prolong the injection time to decrease emissions without reducing power. Fuel is delivered to the injector past a check valve in the same manner as in the standard injectors. As the intensifier piston is forced down the fuel is pressurized and the check ball is lifted off its seat and fuel injection begins. Cut into the piston is a land which receives fuel through bleed holes as it is pressurized. As the piston travels down the land aligns with a port in the injector. When this happens, pressure drops below the piston and the check ball reseats and injection is suspended. As the piston travels further, the port in the injector is covered and fuel injection recommences.

I am just trying to learn a little more about what is under my hood and what will and will not work with it. What the differences are between the injectors that are basically from the same engine platform just different years. I'm a Small Block Chevrolet man and a small block Chevy is pretty interchagable don't matter if it's a 1968 350cui or a 1983 350cui engine. Sure there are differances but you can swap parts pretty freely with them.

Now what I'm wondering is on the AB Injectors is the Pre shot a seperate signal from the IDM then a second signal from the IDM to inject the main fuel shot, OR does the IDM send only one signal to the injector and the pre shot & main fuel shot is just the normal basic function of the injector? I mean after reading all that I have read it seems once the injector is set into motion it is just a process the injector takes to fire one pre shot then the main shot of fuel??

Like I said I'm just trying to stir some conversation to learn a little about the different types of injectors and WHY they are different and which is best............ Thanks for all the input so far guys.


Rob

 

Then yours is a single shot truck

 

My truck also has an IDM out of '01-'02 truck in it. Will that make any difference??

 

I'm not sure what all went into your decision to buy new injectors but just FYI there are certain CPSs that will caused failed CCTs. I'd sure hate to see you spend all that money because of a false CCT failure.

 

Well my friend has scanned my truck several times with his IDS (I believe it is??) scan tool. And we have run several Cylinder Contribution and Buzz tests on it. That is why we are under the impression that the injectors are bad. Am I missing something or is there something else that will lead one to believe injectors are bad when they really aren't??? This is my first diesel but not the first diesel my friend has worked on.

By the way what is a CCT and CPS?? As I said I'm new to the diesel world and dont know all of the terminology yet.


Thanks,
Rob

 

My first 97 had 2 splits in it, ran fine smoked to beat helll with an edge evo !
That truck was a freak it ran like a bat outa hell !!

 

Have you checked the under valve cover harnesses? The connections tend to go bad and you can have burnt pins, wiring that can cause similar symptoms. Just a thought. Good luck.

Rusty

 

Rusty we been in both sides already and nothing looks burnt or bad? They actually look very clean and the wires are not stiff and brittle feeling either?? The plugs where they hook to the injectors was full of oil but from what I hear and what my friend says that is pretty much par for the course.

 

If you have an Ohm meter, double check to make sure all of the circuits are good. Cheap way to check them out.

Good luck.

Rusty

 

Sorry guys but there is some slight misinformation in this thread. Not all the IDM's are the same but they are interchangeable. The SD IDM is higher voltage and if modded takes a different resistor than the OBS IDM.

On to the topic of Injectors- I see alot of folks state that the OBS needs tuning to run splits. It does not. Splits will run just fine on OBS tuning. You cannot however run singles in a Super duty without tuning for it... The SD will run like crap with singles, but the OBS runs just fine with splits.

 

96 f250 7.3 powerstroke has ad type injectors installed working good for years. mechanic says vin number calls for aa injectors, he wants me to tell him the injector to use and how many to replace. i need help to make sure the truck run correctly. injectors #2 & 4 are bad. should i change from type ad to aa. how many injectors should i change and what other problem may happen if i change or put back ad type?