6.7 injectors might be going bad

**Rockwerx** · 11-13-2014

Too many people are hung up on installing larger injectors into diesel engines IMO. The rule of thumb building diesels is Air before fuel. This means turbo before injectors. Even if your injectors are on the way out I would save for a turbo and manifold first. Lots of guys fried their 6.7 engines when they first came out...head gaskets mostly. This is because they installed a hot tune and then larger injectors while running the stock manifold and turbo...bad combination. Air BEFORE fuel and THEN tuning is the way to go IMO. Stock turbo is maxed even at stock level.

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**Polaraco** · 11-13-2014

Originally Posted by Rockwerx

Too many people are hung up on installing larger injectors into diesel engines IMO. The rule of thumb building diesels is Air before fuel. This means turbo before injectors. Even if your injectors are on the way out I would save for a turbo and manifold first. Lots of guys fried their 6.7 engines when they first came out...head gaskets mostly. This is because they installed a hot tune and then larger injectors while running the stock manifold and turbo...bad combination. Air BEFORE fuel and THEN tuning is the way to go IMO. Stock turbo is maxed even at stock level.

Heh That's exact;y how I see it too. Get the most out of what you have then go forward.

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**Wildkarrd RRD** · 11-14-2014

Originally Posted by Rockwerx

Too many people are hung up on installing larger injectors into diesel engines IMO. The rule of thumb building diesels is Air before fuel. This means turbo before injectors. Even if your injectors are on the way out I would save for a turbo and manifold first. Lots of guys fried their 6.7 engines when they first came out...head gaskets mostly. This is because they installed a hot tune and then larger injectors while running the stock manifold and turbo...bad combination. Air BEFORE fuel and THEN tuning is the way to go IMO. Stock turbo is maxed even at stock level.

I agree, and if I could I would certainly do it in that order. But I have a hard time buying stock injectors now just to spend more money on 50 over nozzles later. That is the beauty of custom tuning. I can get the 50's now, and tune the fueling down to match the VGT. Is it preferred? Not really, but it saves a little bit of money in the long run... and the effort of trying to convince the wife to let me spend money on just an upgrade. She's all for upgrading if a part fails, but if it's not broke it doesn't need upgraded yet

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**Rockwerx** · 11-14-2014

Before you swap out your injectors I would make sure they are the problem. It could be a few other problems.

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**Wildkarrd RRD** · 11-14-2014

Originally Posted by Rockwerx

Before you swap out your injectors I would make sure they are the problem. It could be a few other problems.

I've checked everything I could think of that would cause it. Any other ideas? I have been paying attention and anything over 20 ksi rail pressure is where it starts white/light grey smoke. Coolant level right where it's been since the headstuds. Oil level is exactly where it always is....

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**Rockwerx** · 11-14-2014

I would start with the easy cheap stuff like fuel filters. Plugged filters can cause a lot of the same symptoms. Weak lift pump. Then a weak relief valve (the more times it pops open the weaker they get) on the common rail. After that, stuff starts to cost a lot. Worn CP3 or worn injectors could also be the problem.

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**Polaraco** · 11-14-2014

Originally Posted by thewildkarrd@doublerdiesel

I've checked everything I could think of that would cause it. Any other ideas? I have been paying attention and anything over 20 ksi rail pressure is where it starts white/light grey smoke. Coolant level right where it's been since the headstuds. Oil level is exactly where it always is....

Did you stop with the Archoil?

So you are saying you have 20K of rail pressure at idle? Isn't that a bit high? I forget, but I thought it was supposed to be closer to 10K at idle. Or is that where it starts to smoke?
@AccurateDiesel

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**Wildkarrd RRD** · 11-14-2014

Filters have less than 5k miles on them, but won't hurt to replace. Fprv can't be weak since it's shimmed to 30k. (Bought 2 valves, found relief on one on the bench, then installed new one) Fass pump is still showing me 16 psi idle, 13 wot. CP3 itself has no problems pushing up to 28 ksi as was commanded.

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**Wildkarrd RRD** · 11-14-2014

Originally Posted by Polaraco

Did you stop with the Archoil?

So you are saying you have 20K of rail pressure at idle? Isn't that a bit high? I forget, but I thought it was supposed to be closer to 10K at idle. Or is that where it starts to smoke?
@AccurateDiesel

Still running archoil at every fill up. Idles at 6ksi starts to smoke at 20 ksi.

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