3rd gen RATTLE issue has been determined

triton

triton

Scarlet Fever
Joined
May 30, 2007
Messages
5,497
In talking with Exergy, they've had this issue brought to them before. They got with engineers at Bosch Motor Sports about the problem and found it was something they've been looking into also.

I can't relay all the exact terminology but, basically it's caused by the pilot injection or lack of it. I always kinda assumed that was it but, thought it was because of having larger injectors and the pilot was putting out more fuel than it should during that event.

Well, Bosch said it's a elimination of that event causing the rattle we're experiencing. Exergy wasn't on the same page with Bosch but, has now determined they're most likely correct. Something to do with psi at idle and not enough fuel being able to get through to start the pilot event.

It causes no damaging effects on the motor other than a annoying rattle. He said we've just turned our 3rd gen's into 2nd gen's that don't have that third event. The only possible way to fix the issue right now is a stand alone that can bump up the pilot injection.

Bosch is working on this issue but, until a new/different nozzle design is worked out... it's just something we have to deal with. I've been there done that and just turn my radio up a bit louder.

So, for the many who have questioned the infamous rattle, I hope this helps to put your mind a bit more at ease.
 
Well, Bosch said it's a elimination of that event causing the rattle we're experiencing. Exergy wasn't on the same page with Bosch but, has now determined they're most likely correct. Something to do with psi at idle and not enough fuel being able to get through to start the pilot event.
Click to expand...

What do you have that is eliminating the pilot event?

--Eric
 
ENafziger said:
What do you have that is eliminating the pilot event?

--Eric
Click to expand...


larger injectors. Something to do with the hole sizes the pindal<<< ?? I believe and not having enough psi at idle. Most of it went over my head so I'm not being exact. Maybe Weston can explain it in better detail ??
 
SINNER said:
The pilot does not turn off unless you are running a stand alone so keep looking for someone who is CORRECT in their diagnosis.

Scope view of Cummins CR injection events. Pilot is always active. - Competition Diesel.Com - Bringing The BEST Together
Click to expand...

I suggest you call and talk to Greg at Exergy then. I doubt between them and Bosch they're incorrect. It's not being turned off electronically. It has to do with psi's at idle and/or low rpm's. It might be active but, the fuel isn't getting through.
 
Gregg Spoolstra is one smart guy, he definatly knows his common rails. He isn't known for bullchiting.
 
I might be a dumb plumber but if you are firing the solenoid, it's active. Big nozzles or not there is NO WAY that even a stock pump could not keep up with the pilot at idle yet still maintain enough pressure for the truck to run at WOT.
 
I can see it. Because of the high amount of degrees BTDC there is insufficient heat in the cylinder to ignite the fuel at the intended time so it "rattles" because the fuel is injected then has to wait till later in the cycle or until the main event ignites it. Thats why it goes away with boost.

The stock tips have small enough orifices that it lets the fuel ignite at such high advance but when you enlarge the orifice it doesn't have the same amount of energy behind it.

Good find!:clap:
 
SINNER said:
I might be a dumb plumber but if you are firing the solenoid, it's active. Big nozzles or not there is NO WAY that even a stock pump could not keep up with the pilot at idle yet still maintain enough pressure for the truck to run at WOT.
Click to expand...

I didn't post this to argue about it, believe what you will. I just relayed what I was told about it. I'd tend to believe someone that's been doing it for over 20yrs and Bosch engineers over anything that's been posted.

I personally went through every system in my truck over a 2 to 3 year period in search of the issue. Nothing I changed or did corrected it. It was mentioned that Bosch has also recognized the issue and is in the works of finding a solution. It's not solenoids or electronics... it's in the nozzle and it's components designs.
 
ENafziger said:
What do you have that is eliminating the pilot event?

--Eric
Click to expand...

SINNER said:
The pilot does not turn off unless you are running a stand alone so keep looking for someone who is CORRECT in their diagnosis.

Scope view of Cummins CR injection events. Pilot is always active. - Competition Diesel.Com - Bringing The BEST Together
Click to expand...

They don't mean that the pilot event is eliminated electronically but mechanically. The conditions are not correct in the cylinder for ingition when the orifice size in the tips is modified.
 
I believe you're on the right track Bignasty. He did say that such a little amount of fuel gets through during that event, that it basically just goes puff instead of cabang ! By the time the main event kicks in, the pilot injection is gone.
 
It may be that, because the solenoid is actuated so quickly for the small amout of fuel, that in stock form there is sufficient time for the lower rail pressure to fill the space inbetween the pintle and tip orifices for a correct spray. With larger tip orifices and the same pintle pass through volume there is insufficient time for the low rail psi to pass enough fuel by the pintle to fill the same void and push it out the tip orifices at an effective pressure.

Think of a garden hose. If you have a small nozzle on the hose, a short burst of the spigot will shoot water a good distance where with no nozzle the same short burst would just peder out the end.
 
triton said:
In talking with Exergy, they've had this issue brought to them before. They got with engineers at Bosch Motor Sports about the problem and found it was something they've been looking into also.

I can't relay all the exact terminology but, basically it's caused by the pilot injection or lack of it. I always kinda assumed that was it but, thought it was because of having larger injectors and the pilot was putting out more fuel than it should during that event.

Well, Bosch said it's a elimination of that event causing the rattle we're experiencing. Exergy wasn't on the same page with Bosch but, has now determined they're most likely correct. Something to do with psi at idle and not enough fuel being able to get through to start the pilot event.

It causes no damaging effects on the motor other than a annoying rattle. He said we've just turned our 3rd gen's into 2nd gen's that don't have that third event. The only possible way to fix the issue right now is a stand alone that can bump up the pilot injection.

Bosch is working on this issue but, until a new/different nozzle design is worked out... it's just something we have to deal with. I've been there done that and just turn my radio up a bit louder.

So, for the many who have questioned the infamous rattle, I hope this helps to put your mind a bit more at ease.
Click to expand...
First off, I am far from arguing about it. I am just doubting the information you posted is correct. I tend to read and comprehend what was written. So the fact that you claim it's lack of fuel pressure or volume that is causing this just does not add up.

TheBigNasty said:
They don't mean that the pilot event is eliminated electronically but mechanically. The conditions are not correct in the cylinder for ignition when the orifice size in the tips is modified.
Click to expand...

I see where you are coming from but at the pressures these injectors fire at idle, I seriously doubt that the spray pattern is so poor the fuel wont burn. Timing would seem more likely as the measured amount of fuel is certainly getting into the cylinder faster with larger nozzles. The problem with that is I have heard trucks with fairly large injectors, including mine with 0 rattle, and trucks with considerably smaller injectors that clearly have a additional rattle.
 
I have what could be considered fairly large nozzles and I haven't noticed any significant rattle either. I'm just saying I could see what they are trying to say.
 
I had the same size of EH nozzles as Triton does,and I had no rattle.Lets hope my new injectors that Exergy are doing larger than my last set won't rattle.
 
What about 03-04's that I believe only have 2 events? Intresting way of looking at it. Thanks for the post.
 
The 03-04's have a pilot injection still, its only purpose is noise reduction, I don't have mine anymore

Sent using tapatalk from my HTC Aria
 
TheBigNasty said:
It may be that, because the solenoid is actuated so quickly for the small amout of fuel, that in stock form there is sufficient time for the lower rail pressure to fill the space inbetween the pintle and tip orifices for a correct spray. With larger tip orifices and the same pintle pass through volume there is insufficient time for the low rail psi to pass enough fuel by the pintle to fill the same void and push it out the tip orifices at an effective pressure.

Think of a garden hose. If you have a small nozzle on the hose, a short burst of the spigot will shoot water a good distance where with no nozzle the same short burst would just peder out the end.
Click to expand...


You nailed it. That is basically what Greg told me. Makes total sense to me.

Sinner, if you know of another definite reason..... what is it? Many have it and many have wondered so, I thought I'd post what I found. I have posts here back to 07 about it and there's never been a "qualified" answer until now... IMO.

Howling, as many already know extruding isn't very exact. Bad radius's, all holes not exactly the same...etc. Our nozzles may have come out different after the process. That's a good reason for some to have it and others not.
 
I know Greg and I am not doubting him but that diagnosis does not make sense. A single injection event in a 2nd gen is louder because all of the fuel comes in at one time in a single event and in the timming set for it to fire. With a multi-event cr you start inj at the same time as that 2nd gen maby even advanced a little more butthe shot is so small it doesnt cause noise. So if you loose that pilot injection all you get is the main event that is way less timming then what the pilot would be thus decreasing injection noise. I can take the stand alone and with a single injection event pull back timming until it is just as quiet as a pilot injection system, the noise is in the timming.

IMO going off what I know of having both the stock ecm's and working with a stand alone the noise comes from the pilot injection having a whole lot of timming in it, once you go bigger nozzle you are upping the size of the pilot shot creating more injection pressure with that shot causing more noise.

Timming makes injection noise, less timming takes it away.
 
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