Injector rattle...

[BDaugherty]

I realize that there are a couple of similar posts right now, but they are dealing more with the FCA.



My question: What is injector rattle? What is the cause and when does it warrant injector replacement?



I notice that when I run my truck up to 2100RPM or so and then shift gears, I get a clatter before the RPM's drop. It's worse cold and also worse if my TST is adding any timing. The sound that I'm referring to is distinctly different from the sound the engine makes with added timing when cold or under load.

 

[Slow Six]

I had a similar rattle on my 03. Ended up with new injectors.

 

[JJPage]

I would suspect the TST, mine acted similar, almost as loud as an AK47 under my hood. Anybody riding with me would give me an "inquiring" look, I would just shake my head.



When I sent my R37 in for the upgrade(four new levels/choices), the rattle went away, never to return.

 

[BDaugherty]

My TST is less than a month old so I would assume it has the latest programming. Also, the TST exadurates the rattle, but it is still there either way. I miss the cold engine protection feature of my old juice with attitude on my '01 truck.

So, if I have the injectors run on a test bench, will that show any potential problems that could be causing the rattle?

 

[JJPage]

you could have an injector contribution test performed without removing them from the head. Not sure that will explain your rattle, but it may single out a weak or underperforming injector or two.



Yes, to be certain, remove the injectors and have a certified Bosch tech with the appropriate test equipment check them out. I would not be quite so quick to start borrowing trouble, If the TST amplifies the rattle, then that tells you it is a result of added timing, whether by actual advance, duration, or the increased fuel delivery.



Run some ashless 2 stroke oil in your fuel, quart of 2 stroke to a full tank of fuel. That will definitely quiet the injectors down, but unless the rattle is extreme I wouldn't be too concerned if no other symptoms.

 

[LNaugle]

The noise is common on trucks with chips or tuners that incease fuel rail psi... the noise is louder because fuel and engine are cold. (especially older tuners and chips because of the way they were making the extra power) have one question though... does it have a little longer than normal crank time when cold? Whatever u do... i do not recommend 2 stroke oil in the fuel! That is a lil 2 old school for these new injectors, i recommend Stanadyne fuel treatment and nothing else. Ihavent found anything that comes close in comparison AND i havent had a customer come back and say he didnt at least get 100 more miles per full tank. Cost is like 5 bucks!

 

[JJPage]

There are quite a few folks, including myself, who have been using TCW3 formula two stroke oil for several years, every single tank fill, without any negative affect that I'm aware of. This is in our 5. 9's, the newer 6. 7's are designed for the ULSD, the OP, I believe is referring to his 03.

 

[cerberusiam]

Injector rattle is really misnamed, it is ignition rattle. In reality, it is cylinder pressures spiking high and fast due to the shape of the injection pattern.



The ECU jacks with timing when the negine is cold for emissions purposes. The colder it is the more advance you get to keep smoke down. The more advance you get the more complete the burn and the higher cylinder pressures spike. Not to mention the shape of the injection events change somewhat when cold so it is not a true pilot and main event it is more 2 main events to aid warmup.



Fueling boxes just aggravate the tendencies that are already there, then, we wonder what is falling off the truck now. You will get this with good or bad injectors, good or bad tips, etc. However, worn tips are going to flow more fuel and usually not as exact as good ones so that will aggravate the tendencies to rattle even more.



the addition of additives like oil serve a 2 fold pupose, lubing the low clearance sparts in the fuel system better than ULSD, and, the oil slows down the burn and limits pressure spikes. The additives raise the cetane but at certain times lowering produces more even power with less noise.



There is literally no difference between 5. 9 and 6. 7 injector and absolutely no reason not to add either 2 stroke oil or even non detergent motor oil for extra lube. The additives contain the same lubricating properties as oil with even more refining for different aspects. Doesn't neccessarily mean they are better, just different.

 

[LNaugle]

Well i may be wrong and will be happy to admit it, but it seems like the toleranco on injector tip to plunger is MUCH tighter on common rail injectors than previous... I know for a fact that if you pant the plunger with a permanent marker that it will not go back in the tip. So... maybe the fuel dilutes the oil enough, but would really like to take one apart that someone has been using oil for extended time just to see... .

 

[cerberusiam]

I know for a fact that if you pant the plunger with a permanent marker that it will not go back in the tip.

Dip it in oil and it will slide back in with no problem. The residue from the marker is akin to the 7-10 micorn crap in the fuel being forced thru at 10k psi. It will go thru but not without consequnces. The molecules in diesel are larger than the molecules in plain dino oil and they go thru fine. The ULSD unfortunately has a lot of those long charge large molecules refined out during the process to rid the fuel of sulphur.



As long as the oil is non detergent and relatively free of additives that are abrasive it works fine.



What is really old school is thinking that ATF in the fuel is doing any good. The additves combine with any free water and create acids that etch the crap out of tight tolerance components. The abrasives inherent in ATF for friction modifiers are just like running sand thru the system. Bad, BAD, BAD!!!