Two weeks ago I put a new 1.00 a/r exhaust housing on and while I had the turbo out I decided to run some new 3/8" fuel lines to the back of the heads for a future regulated return system. I had it so the pass side was fed in the same way as factory, the driver side I dont know why I did it but I had the head being fed from both the front and rear. This was just a temp setup till I got parts together for the regulated return. Once it was all back together it fired up fine with no problems, but I noticed that once the engine got to operating temp it seemed as the #8 injector started knocking at idle. I figgured since the head was being fed from both ends air was being trapped, so a week ago I did the regulated return, ran all new 3/8" feed and return lines to the engine did away with the factory lift pump and have a FASS system. I have a 1/2" new pickup tube in the take feeding the FASS system regulating about 65psi through the heads, feeding the front and return on the rear (both heads). I also made my own high presure crosso-over line for the hp oil. I finally got it back running the other day only to find that it is still knocking at idle. Thought it may be air in the oil, but I have drove it around for 2 days and still the same. There is know loss of power or any other problems other then the damn thing knocking, I thought the regulated return would make things quiter not make things louder or knock?? I never have and a problem with injector knock before untill now, Im thinking I may just get a reman AD injectore off ebay ($99) and swap it in to see what it does. other then the knock I did notice much more lower end power and better throttle response. I did not use a kit for the return, I got the aeromotive regulater and bent/made all my own lines. Sorry for the long post, if anyone has any thoughts ideas let me know. thanks
-Kurt

 

Don't have anything for you but here's a bump.

 

Could it be something simple like the injector needs to be torqued? Just coincidence that it started knocking after the mods? All your mods should be making it quieter/smoother. I would pretend you hadn't done the mods and approach it that way.

 

You may be right on changing out the #8 injector. In the stock configuration, the #8 injector is different, longer if I remember. I replaced my #8 injector when I did my reg fuel return mod. It's been awhile so the details are a bit fuzzy. Don't know if I needed to change it, but since it was a different injector used to compensate for the poor fuel system design, I thought it may be a good idea to change it when I did the regulated return. Good luck!

 

The LL injector was thrown in as Ford's "bandaid" for starvation issues on the #8 cylinder. When you compare the LL to the other 7 AD injectors, the LL has a larger pilot shot. This larger pre-fire shot on #8 is designed to help balance the engine out and to fix some cylinder contribution issues that can arise from a dead-head fuel system. On top of that, the #6 cylinder fires right before the #8, so in stock configuration, the #8 cylinder is always starved out.

When you fix the deadhead issue, the #8 cylinder can now contribute and deliver more fuel without starvation. As a result, that pilot shot fires just a tad bit more fuel, and the pre-detonation knock at idle is louder. It becomes louder than the other 7 cylinders, and that's typical after a regulated return install.

 

Curtis will it hurt anything to leave the LL in there or should it be changed after the reg return is done

 

It shouldn't hurt anything. Quite a few people run around with regulated returns and keep the LL in there.

A while back I saw a thread where someone took their truck to a mechanic who accidently threw in LL injectors on all 8 cylinders. The truck ran fine. It was odd to say the least.

 

Crap. I just got a reman #8 LL on my work bench to toss in the hole. And a CCK on its UPS way.. Sounds like they Clash. Should i send it back and get a Standard Injector?

 

Good news I never even thought of it. Been running the reg return for about 2 years now and never even thought about changing out the LL

 

Tom you get a idle knock? I had one. This is why i was going to replace the ll and get a cck.. Needed glow plugs which is why i thought why not on the injector replace.. Sorry for the Hijack.

 

I have a little idle knock but its not that bad at all. Just didn't want to leave it in there if it was going to cause damage down the road

 

I have a knock on #5 or # 7 cylinder at all speeds. I installed a cck and all AD injectors and it did not change anything. When we pulled the old injectors, the AE was in hole #4. Never heard a noise from #8. Maybe I have a reverse-rotation engine!

 

Sounds like someone was doing some trouble shooting at one point.

 

Mine started doing the exact same thing after putting in the CCK (like the RR, only much cheaper). Drives me CRAZY! I was looking around and getting a regular injector for it, but I didn't want to spend the dough on a new one since I'll be putting in hybrids soon anyway. So I just live with the knock.

It's funny that someone got an engine full of LLs -- I think it was Kris that was saying that they would make a little more power since they shoot in a little more fuel (something like 10 or 15cc more). Makes sense.

 

Not sure what way to turn now. I have a rebuild LL and a CCK. Should i send it back to get a standard injector now? My knock is the reason i am going through all this. Just want to do the best thing i can.