Yea I kinda get that if I interprete your sound effect descriptions, I just got used to it. Actually thought it was kinda cool, but I'm strange that way.

 

So do you get the dropping stumbling when coasting to a stop or slow light trottle? Or were you refering to the high idle(nothing ridiculous probably 1000 rpm)that dissappears with full brake application? I know that Matt live tuned for you and wondered if he made any of the above less noticable? I went with Matts upgraded VGT 40 with a 65 compressor wheel and see 30 pounds of boost. What boost do you see with your fixed 64compressor wheel? How high do your egts go with your setup? I really appreciate your reply, just looking for the best all around(street/occasional towing)set up, be it variable geometry turbo or fixed unit like you run. Is that a ball bearing turbo?

 

The coasting sound is what I get, I don't really get the high idle that you describe. I still have it though, I got used to it. I see pretty well stock boost levels upwards of 31 psi max at just one time. It'll get up to 1200, but then it tends to hold that temp even going up a pretty steep hill. I like the turbo for towing and I do that pretty often. The only issue is that you have to keep the tach pretty high as everything has been shifted upwards, but once you get used to that, it's a dream to tow with it.

 

Yup...Get the high idle till I come to slow down. It isn't a normal high idle though, it hacka clak a clakka. Kinda makes the truck wanna keep rollin. I have to apply more brake than normal till I get under 15mph. No one seems to be able to modify the fueling to fix it. I don't like it at all. If you drive in a lot of stop and go traffic, it would drive me nuts. Yes, you get used to it. I guess if the guys that sell these things put a disclaimer on the box that said the injectors did this, most would be hesitant to buy them. BUT......every other aspect of the upgraded injectors ROCKS! I haven't done a true MPG test, but I swear it is doing better on mileage.....I can cruise down the freeway at 70mph on flatland only pushing a few pounds of boost. When I hammer it....my dually hauls *****. ~Brad

 

Yeah I agree 100%. I wish that somebody would of made the quirks of bigger injectors public so I could of weighed that into my decision. Looked everywhere and there is not a peep about these quirks. Oh well, at least we are getting it out there to help others make more informed decisions b4 upgrading injectors. Don't get me wrong, my rig is crazy fast, but had I known about the rough running charactoristics of them, might of went another route. Being that I opted for 190s probably exagerates the symptoms a little more, but I guess everything has its pros & cons. Bad Brad, do you get the stumbling when coasting to a stop?

 

yeah, I have a hard time describing the sound in words, But im sure it is the same thing you are experiencing. The sound it makes is kinda cool, kinda like a big cam in a hot rod....sorta....It's the trouble idling down wanting to "keep rolling" that just aint right. There are definitely some other folks on here that have the same issue. Im sure some will chime in. Im off to Cabo in the morning...Adios amigos!

 

I've never had the rough running issue though, just the sound, either that or I didn't interprete it as rough running. The sound itself wouldn't have weighed that much in my decision, but if I had the rough riding it would have. However, I have fried what little hearing I had with blasting Billy Squires a little too loud(still do).

 

Yeah I have the same high idle thing when trying to slow the truck down. The RPM's usually stick at 1000 and the truck wants to keep driving. I don't like it but have gotten used to it and just apply more brake. I talked to Matt the other day and he is going to make some adjustments to hopefully fix this issue. Besides that bigger sticks are great and with my SDT SCT power and the truck runs like a champ.

 

The coast-down cut-out sound is an attribute you will see with any properly modified aftermarket 6.0 injector.

As with any HEUI injector, there is an oil-fired piston in the top of the injector that pushes down onto a fuel plunger. This fuel plunger sits at the top of the fuel "barrel" and is what forces the fuel out of the nozzle into the cylinder.

The diameter of the fuel plunger and the stroke length it travels dictates how much fuel it can move. There are two ways to increase the size of an injector- increase the diameter, or increase the stroke length. Increasing the diameter of the plunger also causes a reduction in injection ratio- the ratio of oil pressure to fuel pressure; which drops the injection pressure. Lowered injection pressure causes poor fuel atomization, so in order to enlarge the injectors almost all manufacturers increase the stroke length.

In order to increase the stroke length, there is an air bleed hole in the side fuel barrel. No matter how much length is added to the travel of the plunger, no amount of fuel will be injected until the plunger drops past the bleed hole and blocks it off. One of the very first modifications to the injector, regardless of size, is to block off that specific bleed hole.

When the hole is blocked, this essentially adds about 15mm of injectable fuel. This injectable fuel starts injecting before the FICM anticipates the injection event, because the FICM assumes that the first small bit of injector stroke is deadband, such as it is in a stock injector. With the hole blocked, the injection event starts sooner and effectively adds 15mm^3 of unknown fuel every time the injector fires.

This isn't a problem when any amount of load is induced on the motor, and why the cackle doesn't happen until coast-down, as 15mm is a tiny bit of fuel and can easily be compensated for with tuning. However, regardless of tuning in the PCM, this prevents the FICM from being able to fire the injector with LESS than an a 15mm shot; because otherwise it would simply calculate not to fire at all.

Under very small loads, 15mm is enough to continue to accelerate the engine. The FICM senses this, and since it is unable to trim the injection event further, it starts randomly dropping injectors out of the firing sequence in order to bring the engine back to the commanded speed. What you are hearing is actually a module-induced random misfire.

It is of no harm, but it does seem to bother some people. This is something we will be able to recalibrate for when the FICM tuning is released with the new tuner

 

thanks Matt

 

COOL^. Thanks Matt great info! Rep points on this one.

 

Persoanlly I LUV the "hot-cam" sound. Only had the "pulling issue" once or twice where I had to break a little harder.

Stay Tuned
Amp

 

I see alot about tuning the fuel system with a FASS and RR but has anyone tried to tune a fuel system with an Airdog and raptor fuel pump to a RR? Is it the same? I would imagine it is easier because of the adjustment screw on the fuel pump to adjust pressure. Should I still put the RR 2 psi below the fuel pump pressure?

Anyone done this?

 

FASS is a self regulating fuel pump. You have a spring(50 or 60 psi(have to ask for this one)) and it regulates the fuel pressure according. You don't have to adjust it on the pump itself.

 

I plan on putting in an airdog with a raptor pump which has an adjustment screw on the side.

Any one tuned one of these with a RR?