Fuel tick/knock

Lumberjackchuck

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So I’ve had this annoying ticking/tapping that happens between 1300-1700 rpm when I’m hitting the throttle pedal.

It’s kind of hard to diagnose though since it really only happens when I’m driving.

But I’m pretty sure it’s injector or pump related since if I take my foot off the pedal it goes away and as soon as I apply it, it comes back.

I had a really loud fuel knock from an injector that was leaking when I first fired up my rebuilt engine. This is a much lighter tapping/ticking noise.

What do you guys think? Does it sound like a pump issue if it’s happening at specific RPM? Or could it be another leaky injector? I’m not having any white smoke or anything
 

KansasIDI

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Believe it or not, an exhaust leak on a turbo IDI engine, pre turbo, sounds very much like a lifter or injector malfunctioning… non turbo engines have a more standard exhaust leak sound…
 

Lumberjackchuck

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Believe it or not, an exhaust leak on a turbo IDI engine, pre turbo, sounds very much like a lifter or injector malfunctioning… non turbo engines have a more standard exhaust leak sound…

Interesting, because the sound goes away when I get to the rpm that the turbo lights off. I wonder what the exhaust pressure is like before that.

Also, I don’t think it’s a lifter issue. I’ve already pulled valve covers and all my lifters are rock solid and rockers are in good shape. Plus I don’t think those would care about the load/fuel to the engine.

I wish there was an easy way to post a video of the sound. It’s always so hard to diagnose a noise from a video because the audio is usually crappy anyway.
 

Cant Write

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Believe it or not, an exhaust leak on a turbo IDI engine, pre turbo, sounds very much like a lifter or injector malfunctioning… non turbo engines have a more standard exhaust leak sound…
This, I was 100% sure I had an injector issue, specific rpm range, the whole 9 yards. Tried to cure with ATF.

Was under the van one day and soot marks at a crack in the Y pipe. Huh....did I feel dumb. Stopped worrying and let the soot plug it up. I’ll worry again when the exhaust drags down the highway cookoo
 

Lumberjackchuck

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So this quiet, intermittent tick developed into a much more discernible knock accompanied by some white smoke. I was actually able to produce the noise parked in neutral and revving the engine.

Was able to narrow it down to the Cylinder #2 injector by cracking injectors 1 at a time and revving the engine (making a huge mess in the process).

Since I’ve already sent these back to be fixed several months ago, I think I’m going to try a stock injector instead. The stage 1 injectors are proving to be finicky.

I also think I’m going to retire the pretty R&D fuel return rails. They’re beautiful and haven’t leaked, but they’re not practical when you have to repeatedly pull injectors out to trouble shoot them.
 

Nero

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Who built the injectors? Just curious.
 

Lumberjackchuck

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Who built the injectors? Just curious.
R&D stage 1. Heard nothing but good things about them, and he fixed them up right away the first time I had an issue free of charge. They’ve been problem free for several months since, but I don’t feel like bugging him again.

In the end, I don’t know if it’s an issue with the IP that’s causing these injectors to malfunction, even though all 3 malfunctions have been in different cylinders. What else can I expect when running a heavily modified engine on this truck? Bound to face problems and trouble shoot them to overcome. I’ll give you guys credit for still running these trucks, you gotta be stubborn AF.

I figure the best path forward is to try a reputable set of re-manufactured injectors and see if that solves my problems.
 

Nero

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I’ll give you guys credit for still running these trucks, you gotta be stubborn AF.

Freakin' nailed it.

I encourage you to at least call him and run it by him about what's going on, he'll at least be able to steer you in the right direction. Guy is genuine. I called him earlier today to check on the status of my heads. He was definitely direct about when he'd get to them.
 

Lumberjackchuck

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I got a set of Russ injectors in the truck today and dang! It is much better. Knock is gone, it doesn’t have that slight hazy white smoke on cold starts anymore, and the exhaust doesn’t stink. See if you can tell which injector was the one that was knocking.

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But, that mystery rattle/slight tick is still there at 1500 rpm when I hit the throttle. It seems a little quieter. But I’m leaning towards it probably being an exhaust leak as some of you mentioned. Maybe I can dial into it with a stethoscope and pin point it.
 

Nero

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I'm glad you got some of the issues fixed. You should still reach out to Justin, see what he suggests about the injectors.
I'm curious to see what he says. Especially since I have a set of his stage 1 injectors I have ready to use...
 

Lumberjackchuck

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I'm glad you got some of the issues fixed. You should still reach out to Justin, see what he suggests about the injectors.
I'm curious to see what he says. Especially since I have a set of his stage 1 injectors I have ready to use...

Last time I talked to him he said the injectors were ‘finicky’… if they all work for you then that’s awesome, hopefully you get it paired with one of his IP’s.

I will say there was noticeably more power with the stage 1 injectors, it definitely could roll some coal too.

But my truck definitely runs smoother with the rebuilt set from Russ. I’m hoping they last a long time.
 

Nero

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I got one of his pumps too. If the injectors don't pan out for me I plan on getting a set from russ. Used a set of his in my in laws truck. They run amazing.
 
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