Injector knock
minor injector knock got worse. I now have hard start, louder knocking and loss of power. Here is what I've done so far...
Rebuilt fuel bowl / new filter Isolated knock to #2 cyl - stethoscope on top of injectors - unplug injectors one at a time w/engine running - measured temperature at each port on exhaust manifold All point to the #2 cyl Replaced injector with reman Still knocking.... Returned injector and got a new one Still knocking....(power does seam much better) Did a fuel pressure test (at idle) and getting 55 psi (I checked out at fuel pressure test kit at the parts store and the bypass valve was leaking on the gauge so I did not test it under load, but I am getting 55 with the leak). Removed UVC harness and did a visual check and an ohm test All good... Did another ohm test with UVC harness installed from com pin to each positive injector pin. All good... Still knocking... The only odd thing I have found is a lack of oil coming out of #2 injector at idle, all other injectors looked normal, I'm not sure what happens at higher RPMs. So that about sums it up, it's still knocking. Any ideas?:-arrgh Sincerely, Injection Dejection |
{cracking knuckles}
While many may have chased this beast, I lived in a high-hide and documented it's behavior patterns - National Geographic style. You may already know some of this - but I have to walk through all of it to make sure nothing is skipped over: I don't know how many miles you put on the truck between disruptions of the injector. I can tell you air in fuel or oil will make the injector knock as it passes through the guts, with #2 and #7 getting first dibs on the air in fuel. I have read many things on #8 knock being attributed to air in fuel - but #8 has a different form of the air-in-fuel problem (momentary pressure drop because of firing order). #1 and #2 don't like air in oil, they are the highest point on the dead-head ICP oil line. Saying all of that, you need at least 50 miles on the truck after pulling the injector - just to get all the air out. I've had situations where I had a cling-on in the engine for over 75 miles. I've learned going out on the highway and bringing the throttle to the ground Fred Flintstone style abbreviates the air purging process. Air in fuel can have many sources, but a proper and thorough Hutch mod typically puts all the usual suspect in the big-house. Here's the question that may raise an eyebrow: Have you ever noticed if it seems to get better right after a fill-up? A higher fuel elevation in the tank puts more pressure on the fuel pick-up, so it is less inclined to suck air. 55 PSI fuel pressure at idle is good, but the real questions is... what happens at WOT? If you can't monitor the FP while driving, then you can't conduct an air-in-fuel test the easy way. A big drop in fuel pressure at WOT is strobe lights, a trumpet riff, and the Rockettes high-stepping across the gauge - trying to raise the alert that you have air in fuel, a clogged fuel system, or both. I have bigger-than-stock injectors, and my FP never dips more than 5 PSI at WOT. When I had issues with the fuel line before the pump, I'd loose as much as 20 PSI at WOT because of a poor hose fitting, and as much as 40 PSI because of fuel restriction. Air in oil is a more dastardly creature, I would avoid going near its lair until you're assured it's not air in fuel that climbs into the upstairs room to get your sticks knocked up. |
I had pretty much the same symptoms on an engine, but it was cylinder 8. The noise went away completely with the injector disabled. What I was convinced was injector knock turned out to be a bent crankshaft. Just sayin' . . .
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Total disaster cannot be ruled out yet, but I've found many of my woes in the past have been things other than parts in the short-block. I've had a knock in #7 since I bought the truck - 80,000 miles ago.
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The only odd thing I have found is a lack of oil coming out of #2 injector at idle, all other injectors looked normal, I'm not sure what happens at higher RPMs. Not sure about the mileage on your rig but these beasts require attention to the fuel delivery at some point. As mentioned, Hutch Mod and I'll throw in the RiffRaff FPx regulated return with CVD (check valve delete) fittings. |
That's some quality troubleshooting guys. Subscribed.
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I haven't brought this up, assuming you are torqueing the injector bolts properly. I shouldn't assume, so here it comes: You cannot elbow-torque an injector. Drifting from the torque spec will certainly cause the symptoms you are describing. I paid dearly for that little lesson.
Have you tried the UVCH link in my signature? It's a bit more thorough with the wiring to the injectors. |
have you compression tested the cylinders?
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It's been a couple of weeks off from head-butting my injector knock. But my excuses have grown old. Here is where I am.
I have been using Torque App w/ford enhanced, but get no codes. I downloaded car gauge pro, performed a buzz test (sounded good) and received a P1272 high side to low side open I ohm tested from the IDM connector, according to to this link GB Remanufacturing - Tech Bulletin #103 All tests were within specs (Performed all three tests). I have put on over 200 miles since I changed or removed the injector. I haven't done a compression test so I'll need to find an adaptor for that, I don't think the rental kits at the auto parts stores are set up for the 7.3's. On the fuel pressure at WOT, I agree I need to check that, but if the knock is present at idle and my idle pressure is good, then my brain (or lack of) tells me that isn't the issue. Oh yeah, I did torque the injector bolts to 120 in. pounds. I did the hutch & harpoon mod a couple of years ago. What am I missing? |
Fuel pressure: While I'm sure you were diligent with your Hutch mod, it is still best to conduct some tests to be sure no air is in the fuel. You can have a ton of air in the fuel and good FP at idle. It's WOT that really tests the fuel pump and the integrity of the fuel lines. I had perfect fuel pressure at idle... but not so much at WOT - I had to double-clamp the fuel line out of the tank.
Have you seen the Torque Pro PID thread on the forum? Are you monitoring ICP/IPR/FIPW? Did you spin the pushrods to make sure none were bent? Are there running issues with the truck, or is it just knock? Smoke at startup? Did you flip the oil filler cap over the snout to do the hover test? #1 and #2 frequently don't have oil coming out of them immediately after draining the oil rails. It takes time to get the air out of the system and for oil to shoot out of either of those. If you covered the VCs before the air was purged, you wouldn't see if #2 has oil shooting out now. When did the knock start? Did something change or did you do any work on the truck at that time? |
Tug- I have wondered how this product would do on a diesel. One of its claims is reduced air. Maybe a buckzooka reload will be in order. Haven't found out if its diesel rated yet. http://youtu.be/4rG97UuVgmQ
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Just what wanted to hear, if I don't figure something else out I will drop the tank (after I burn off 30 gallons of fuel).
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Originally Posted by liquidlounge
(Post 14970465)
Tug- I have wondered how this product would do on a diesel. One of its claims is reduced air. Maybe a buckzooka reload will be in order. Haven't found out if its diesel rated yet.
Originally Posted by Rigormortise
(Post 14972952)
Just what wanted to hear, if I don't figure something else out I will drop the tank (after I burn off 30 gallons of fuel).
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