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Need Some help

Turdle

Lowrider
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It's Vacuum leak. I can hear it at the back of the engine when I open the throttle a real quick whistle. Can't pin point it. I smoked it and can't find a leak. What's the chances it's the intake gaskets? Alot of the vacuum lines are buried under that crazy intake.


Just a hunch, could it be the line running to the brake booster? There is a lot of vacuum there.

Check right where the brake booster vacuum enters the booster. move that connector around to see if you hear a difference in the vacuum sound. Also, check the vacuum source connection for that hose, and, the booster itself could develop a leak.
 


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Kidd7

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Thanks, I'll check that out. I'm going to pick up a PCV and replace those 2 hoses off the T; they are worn some & I have no idea how old the PCV is. I'll report back.
 




J_C

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Except for the hoses being old and potentially fragile, you can pull them off the intake (or other end) and plug/block that port, or pinch (some of) them shut to see what it does to your fuel trims.
 




Kidd7

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Except for the hoses being old and potentially fragile, you can pull them off the intake (or other end) and plug/block that port, or pinch (some of) them shut to see what it does to your fuel trims.

Why didn't I think of that??? Shut down for today, my wife needs it for work tomorrow. I tried propane, no increase in RPMs. I replaced the PCV, 'T', & hoses; I smoked from the brake booster to the intake & through the hose to the booster. There is still a hiss at the back of the engine. I then sprayed starter fluid around and no change in Revs. Crazy. I'll be back at it again. Thanks for all the help so far.
 




Kidd7

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Ok, I was traveling and left the truck with my mechanic. He smoked it and left it under pressure and it never leaked. Can someone enlighten me to the snap trottle test and what the voltage should be on the MAF? thanks.
 




Kidd7

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I verified my fuel trims are still high, around +10 both banks. I unplugged the MAF, it idled a little rough, but the fuel trims settled around 0. The readings I was seeing from the MAF seemed a little questionable. I replaced it with a reman Motorcraft unit. The flow rates look much better. I pulled the ECU fuse and let it sit then drove it. Now it seems to drive better, admittedly possible placebo effect. Fuel trims are still around 10.
I'm thinking I'm down to fuel delivery. Filter is new and I tested fuel pressure a while back.
Advice?? Should I look at injectors and the fuel pump? Is there something I'm missing here?
Thanks.
 




J_C

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I don't know what fuel trims do during an ECM relearn nor how much you've driven, and would wonder about bad gas.

Combine all these and I'd try topping off the tank with new fuel, add some fuel injector cleaner, and drive it a while. However previously you thought you heard a vac leak, whatever became of that? Still the noise or no?
 




Kidd7

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I left the truck with my mechanic while I was traveling. He smoked it and held it under pressure and there were no leaks. I heard some air noise at the back of the intake area only when I opened the throttle quickly, he stated it is probably turbulence in the intake as air rushes in. I also talked to him about the odd shifting, he, like you, talked about the ECU relearning and this is Ford's early stages of adaptive learning. He is not able to clear the adaptive learning. So maybe it is residual. My wife has been driving it this week and she thinks its better also.
 








Kidd7

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I did check the ECU connector. and ohmed out the O2 sensor wires while wiggling them around. One theory I started with was a bad connection / broken wire causing the O2 signal to fall out. I have not looked at the other square connector yet, but will do soon. Wife has stated the truck has been running well. I'm planning on taking for a long-ish test drive this weekend.
 




Kidd7

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OK, I checked the fuel delivery, the flow rate was about 3 GPM, within spec for a V6. Filter is clear. Then I checked pressure again. I had checked the fuel pressure months ago and it was over 60 psi then, I did not see what happens to fuel pressure when throttled at that time. This time idle fuel pressure was only 50 psi and when you open the throttle quickly it would drop below 40 psi. I replaced the fuel pump and the pressure is at 65 psi and only drops a 1 or 2 psi under quick throttle change. It's been driving much better since the change, we'll see how the next few weeks go.
 




Kidd7

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The fuel pump/ sending unit has fixed the stalling problem, but the tranny shifts like crap. It doesn't seem to shift into O/D, revs are pretty high on the freeway. It also throws a tranny code intermittently. I'm working with a tranny mechanic, but going to start a new post on the tranny issues.
 




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