No, I haven't. Might be a good idea. Will have to find pics of what it looks like done correctly.

 

The fuel pressure test you were talking about should show
if you have it installed correctly or not.

Sean

 

How bad can a cracked CAC boot make my truck miss? My upper boot on the hot CAC has two cracks on the outside. Just checked it out and one of the cracks has made it through to the inside in a couple of tiny spots. I put my hand over the crack while idling to seal it off and didn't notice a change, but then, the truck idles real good.

 

The fuel pressure is fine - never got below 55. The IPC and IPR numbers check out - IPR idles at 30%.

I've got to do something real stupid today. A while back, I committed to hauling a 1,500 lb. staircase from Houston to Austin on Friday. Have to pick it up today. I recommitted last week after signs that my truck was getting better. Usually not a problem to cancel, but he's rented a crane for that morning - lots of people/money would be wasted.

I did a test run the other night hauling a car 50 miles down to my brother. The truck really struggled between 45-60mph with the load, but with only the trailer, it struggled much less.

While the staircase weighs much less, it's length requires that I use my gooseneck trailer, so it ends up being about the same weight, and both ways instead of a light return load.

I made a similar run before doing this last work limping the whole way, but I'm worried about this one. I'm about to hook up my gooseneck for a test run to see how it pulls empty.

 

IPR should be at 23/24 at idle, you may have a leak somewhere

 

Yes, I think that was the dead cold percentage. After I was driving around today, noticed it was more like 22% at idle.

 

OK, now I've found another air leak. Right where the plastic air intake fits on to the turbo, it has about a 2 inch long crack on the bottom, right alongside the band for the screw clamp. Would that cause a miss/loss of power?

 

Well, I was saved. My customer postponed his shipment today. I now have another week to try to get my truck running right before I have to pull a trailer.

Still hoping someone has experience with CAC tube and air intake leaks. I have a tiny hole on the upper hot CAC boot and a long crack on the air intake right at the turboo inlet. Know I need to replace them, trying to understand how bad they'd make my truck run - I doubt they are the sole cause of the stumble/missing I'm getting, but they could be. If it's doubtful, I want to take the time to find the air intake at a junk yard rather than pay top dollar, and I'll look at aftermarket CAC boots, if they offer an advantage. If it's likely that those leaks are causing my problems, I'm going to Ford right now.

 

I really doubt your air leak is causing a stumble, normally just causes a low boost condition. Those boots are a weak spot on these engines. Mine also look ugly. Riff Raf has some nice ones that everyone seems to like.

Just for the record, the PCM and the FICM will "compensate" for a low injector/s to smooth out the engine. I think the speed that you have the stumble is right where the PCM and FICM have trouble smoothing out the engine. Hope that makes sense. I only think this because mine has the same problem, only less severe. Right around 50mph with a slight load on the engine I get a small miss that I believe is an injector. Once I get over 60mph it's smooth as glass. I think that's the "soft spot" and maybe the PCM and FICM do very little to compensate under that condition. This is just a guess though, I could be completely wrong.

Also, before I replaced a known bad injector the miss was the worst around that speed under a slight load.

Hey maybe we are onto something. BTW the Ford IDS has the capability to turn OFF the compensation too make it easier to identify a failing injector.

.

 

I would think bad injector as well except that when I pull the wire on each one, I can hear a definite difference in the idle. But, maybe that's not a definitive test.

Was thinking about doing a compression test, then I saw this old post by Cheezit "start truck pull oil fill cap and see if it smokes like a fright train. If not most likly not a compression issue."

My truck doesn't smoke out of the fill tube.

 

Might be worth the cost of a diagnostics at a Ford
shop that knows diesels. Just diagnostics only.


Sean

 

Yeah, I paid them $250 once already. Their recommendations were to replace #7 injector, do the blue spring, and replace the fuel pump, which I've done.

But still, I agree with you. Tried to get into 3 different dealers here this week and all were too busy. Did go back today and talked to the guy that diagnosed it the first time. He suggested that another injector might be out because I drove it for a while before changing out the fuel pump. He says checking fuel pressure at the regulator does not tell you how much pressure is going to the injectors. It measures how much is coming from the pump, so I might still have a problem between the regulator and the injectors. I took the regulator apart again and checked the oring on the brass fitting as he recommended. Looked OK to me.

I'm calling them again tomorrow. The service writer said he'd call me when they could get me in, but maybe a squeaky wheel will get more grease.

 

Cracks in the cac tubes and boots would definitely cause low power.....not the stumble though.

 

I can't really argue with any of this.

I will say that it's a balance test, which means that there are some cylinders that are stronger then the others. Normally an injector is to blame since that's what supplies the fuel to make the power.

I would not rule out a fuel delivery problem. The fuel does go through the heads to get to the injectors.

Also there is a check valve in the fuel fitting that goes into the head.


.

 

If you do get in have then give you a printout of the power balance
and post it here.
I don't agree with the service writers comment about the pressure
for the most part. That being you can have lower pressure at the
end of the line when under a high flow condition. That is why the guys
that put in the really BIG injectors use a regulated return system.
However in stock I don;t think that will ever be an issue. The regulator
sets the pressure that all the points past it will see. Unless there is a
high flow demand and like I said stock won't have that problem.

How ever this is my opinion and everyone is entitled to have there own.


Sean