I am moving to Alaska and leaving on the 24th next week.

I have a 2003 7.3, auto trans, 117k miles. Truck has a DP tuner but had these issues before I installed the tuner.

The truck has a LOUD crackle/TAP TAP TAP sound when the engine is warm, becomes more pronounced the harder the engine is worked. Only heard at idle.

I also have, what I believe to be an unrelated issue, is a miss/shimmy at idle. The RPMs don't change but you can hear and feel a vibration/shimmy every few seconds. It's extremely annoying.

So far I have:

Done the hutch mod and added a riffraff fuel rail cross over. No change to anything.

Changed the CPS with three different styles (grey, dark blue, bog warner old black style equivalent). No change to anything.

Unplugged ICP sensor, the miss at idle seems to go away. Replaced ICP sensor. Miss at idle returns when new sensor is plugged in.

Replaced idler pulley. No change.

Checked the flex plate. Bolts are tight, not cracked.

Checked torque on injectors under driver side valve cover (where the loud TAP TAP TAP sound appears to be coming from). No change.

Ran a buzz test. All injectors sound find. Ran a contribution test, no codes.

Frustrated as hell, I took the thing to a mechanic. Very reputable shop in the area and the owner drives a 7.3.

They thought it was the problem was the #8 injector. So I had them replace it ($245 bucks just for the part). Still no change.

The mechanic says anything else would just be a shot in the dark and suggests I just live with it until it gets worse, or something fails. Well I really don't want to do that.

My fuel pressure at idle is 65-66lbs.

Does anyone have any ideas on what could be causing the TAP TAP/crackle noise or the miss at idle?

I have a 2500 mile drive coming up at the end of next week and would REALLY like to get this resolved. I can probably live with the crackle but the miss at idle drives me crazy.

Thus far I am probably 7 to 800 bucks in having the shop diagnosis and replace the injector only to fail to have them resolve anything.

HELLLPP please!

 

I presume you have run a fully warm engine with the serpentine belt removed and there is no change either?

 

I had that also. I changed the #8 and it was a little better. Someone on here said to listen to each injector with the valve covers off, with auto probe on the ears and they found out what injector it was. Replaced that one and problem solved. Mine went away. I believe mine started after I, yes me, put in the fuel filter with out the o-ring around the center of the filter. At least that's when I first started hearing it. It didn't start right away, but 5K later it did. If its just the injector at idle like you said and won't really hurt anything if its not heard at cursing speeds. That's the way mine was. Good luck, it drove me nuts.

Chet

 

I have not... I will ask the mechanic if they have tried this. Still haven't gotten my truck back yet and they've had it all week. If they haven't I will try it when I pick it up, hopefully tomorrow.

 

Whats the main reason for this? What does this tell you?

 

It will tell you if there are any components linked with the belt giving him the problems.
I had a Jeep J2000 one time and I had the oil pan off three times and all rod and main caps off looking for the "knock". Turned out after pulling the belt, the knock went away. Bad alternator.

 

This is a bad #7 injector... and #3 was right behind it.


This is a loose injector hold-down bolt with a damaged cup. I tried my quiet tune while isolating the noise.

 

I pulled the belt off and ran the engine today... no changes...

 

AAARGH.... my truck sounds exactly like a loose injector hold down bolt in the video. Did it blow black smoke, loss of power etc?

 

It did everything offensive to humanity. Just listen near each front wheel with the hood closed and you'll know where the prairie dog is barkin'. Warning - just torqueing the injector back down will not cure the damage that occurs with a loose injector.

First, order at least one set of injector O-rings for the offending stick (I ordered 8 sets). [LINK] Once you've identified which injector bolt is sloppy loose, you'll need to pull the glow plug, then the injector. The injector will likely come out by hand, with no prying on the bracket. Now the icky part: You need to clear the oil from the cylinder (Mity Vac works great) and really inspect the cup. If you don't see anything obvious, puff up the degas bottle to 10-15 PSI and watch for coolant dripping in the cup. Even a tiny amount is bad... search for my thread titled "Stinky's Stick-up".

If the cup survived the combustion pressures, buy a lottery ticket... this is your lucky day. Install the new O-rings and pay particular attention to the copper washer on the tip ("bump" side away from the injector). Follow the procedures for installing an injector.

If you say "But it's #7 and it's a bugger to get to." I feel your pain... I replaced all 8 cups when #8 was damaged by that sound.