Im on a trip 1400 miles from home and notice a slight knocking at idle coming from my 1999 2WD Auto 7.3 Super Duty.... It seems to come and go. Once seemed like it was coming from the right side of the engine then the next time the left. I had the Cam Posistion Sensor replaced on Friday before I left and a Speed control Module as part of a recall... Could it be related?

 

how low is the fuel in the tank? mine will make that if it is to low.

 

The first time I noticed it had between quarter and half now it has over half?

 

if air gets in the lines i can take it a wail to get out, and some times mine dose it even when full, but much more when low. maybe others will chime in.

 

What about altitude? I am a sea level guy and have been runing above 7700 feet and now at 6400 feet?

 

Mine developed a pretty loud idle knock a little over 2 years ago that would come and go. Found out I had a bad injector and replaced it. Much quieter now.

That may or may not be your issue. You said the idle knock started after the CPS swap. The new recall CPS's do have some issues, and maybe finding an original black one could fix it.

It's kind of a crap shoot though. There's been a few other members who have had that same idle knock for one reason or another. I only found my issue by removing the valve covers and starting the engine, and watching the bad injector **** oil all over the place.

 

I have noticed a knock near the driver side wheel well and if you go under the truck near the back of the engine you can hear it a little clearer. The truck seems to run fine. Its not smoking or anything as a sign that there might be an injector problem.

 

How many miles?

I'm with Pocket, could be worn injectors.

 

Do you have a tuner? Because I had what seem to be a knock at idle and told Jody about it and he said that it was to much ICP pressure and something to do with oil temp so I sent back my chip to him now everything is much more quite,I'm not say that's your problem but might want to check it out if your chiped.

 

I stopped by the dealer today and of course it was not making the noise. There thought it was the summer blend of diesel fuel? Since I am out of my home state I cant say. It has not made the noise since yesterday so it's time bomb waiting to go off or it fixed itself. I am going with it fixed itself!

Thanks for the input...

 

If its a late 1999 with AD code injectors then check number 8 and see if it has the AE code fuel injector "longlead". This should help correct your issue. This can also come and go as per navistar AFC letter. hope it help

 

If it is an early 99 it may be the torque converter, especially if you can hear it better from under the truck. E99s are known for noisy TCs. I know mine is.

 

have you done any tank mods? could be your starting to pull air from the quick connects. I suspect the same thing on mine but I'm waiting on funds to purchase some equipment then time to drop the tank and get rid of the quick connects.

 

The problems started in Moab and continued to Gallup New Mexico where it stopped. I spoke to the Ford Dealer in Grants NM and they are the ones that said it was the fuel. It has not doen it since and I have been to Fort Worth TX and about 2 or 3 tanks of fuel. I will check on the injectors.

Thanks...

 

Mine started all of sudden also. Just one day out of the blue.. Mine was a LL. Did the tank mod/CCk. Got a cheap reman injector. International CPS. #8 still continues to knock intermittently. Lately i swear it it getting louder.. Going to drop in a new injector in that hole shortly when time permits. Or i just might try swapping it with the #4 injector and see if the knock goes to #4. If knock continues on #8. Must be something else. And i don't know what to do then.

Dads 2000. Non LL doesn't make this annoying knock. His runs good and quiet. Did the tank mods but was quiet before i did that. Same international CPS.

I made this contraption to prove it was #8. Works good. Turns off each injector by flipping a switch.

Or you could pull the #10 (for the #8 inj) wire out of the 42pin connector. Or loosen it so you can can pull it out to disconnect it while the truck is running. Be careful here. High voltage. I did the pull wife thing on my buddies truck in the parking lot. He had a knock and he needed to know which injector is was. I found it in about 15 minutes pulling wires. It was number 2.. he replaced it and all has been good.

Have you done the fuel tank mods? Could be sucking in air at the tanks disconnects.
An inline Glass filter between the tank and the Pump would show you if air is getting in i would think. I have one and i don't get/see one air bubble going through.


Also attached a .pdf for the 42pin connector.