First time posting on this site, i have to say this site is amazing always have found stuff that has helped me. Well im hoping someone could explain whats houng on with my truck. First and foremost the truck is a 1999 2wd 5 speed 3500 2nd gen cummins and it has a cold air intake and a intake horn, edge ez, 50hp injectors, new H. O vp44. The truck has 307k miles and runs amazing and has no issues. But when im driving on the highway at a steady speed around 80mph the sound in the engine bay will change every 15-20 seconds it is most deffinetly the sound of combustion changing and or the injection timing changing. The truck will have the typical knocky 24v clatter that sounds kind of like a machine gun but every 15-20 seconds that knocky sound will totally disappear and the engine sounds so smooth at this point, after about 5 second, sometimes a little longer it goes back to the klattery machine gun sound for another 15-20 seconds and then back to the smooth sound. It is most deffinetly the sound of combustion and not like valves or anything like that im 100% sure of that. Its like the ignition timing is changing and changes the engine sound. Exhaust note doesnt change its all under hood noise . Has anyone ever seen this or have a clue at how and why it does this? I wish i had a way to view the timing commands in real time and see if their is a correlation in timing changing and the sound changing. It would be nice to find a way to make it have that smooth quiet tone all the time while on the high way it would deffinetly keep some decibels off  

Talked with my friend he put the supplied key in it. Figured he did , hes they type of guy that does stuff right. So if its not the key and i watch engine load and it changes while  cruising on flat ground at a steady speed what should i look for then?  And if it doesnt change then what lol? 

quadzilla zillaraider was a wire tap box.  It is pre adrenaline. makes power, no adjust-ability iirc.

Oh i know it doesnt have any adjustability im trying to figure out how to wire the map sensors to it the harness has 2 wires coming out of the lead that is for the map sensors and im confused as to how i wire 2 wires into two 3 wire plugs. I know one wire will be a jumper between the two plugs but im confused on where the two wires from the harness will go to each map plug male and female the last pic is of quads adaptor and it looks like theirs either 3 or 4 wires going to the two map plugs. I checked from the start of the harness and its deffinetly only 2 wires supplying the map sensors that were once their. I wish i could find someone that has this same tuner and be able to see a picture of there harness with the plugs wired to it thats all i need and i can get this wired back up so i can use it for a little bit and put it up for sale and then put that towards an adrenaline

So i just found this picture its an xzillarator harness but for a ford and the map sensor plugs just have one wire in, a jumper to the other plug and one wire out so it shouldnt be too different on the cummins i just have to figure out what pins do what

@Mopar1973Man should i buy this 

@Mopar1973Mani also found this one

Too old that's a version 1.0 without tuning abilities.

The first one i sent you has the iquad and is a v2 was sent out to quadzilla and passed all the tests it has a new harness and iquad

 With your scanner hooked up look at the engine idle speed and the percent of.load at idle. That will give a clue to the health of the injectors. 

 Engine should idle at 800rpm and load should be roughly 5%. If there is no load at idle and the idle fluctuates it indicates the injector pop pressure is low. 

 There is also a possibility it could be something in the ecm.

Be aware the injectors can wear to the point idle load will drop to 0% and idle speed could be as high as 900 RPM as I seen on one truck I replaced injectors on.

Injectors are newer 50hp idk how new but ive always kept good filters and changed them regularly as well as use hot shots diesel extreme every few thousand miles as well as sometimes motuls diesel purge. Ill hook the scanner up when i get home and see but according to the das my idle is right around 800 i know thats really not accurate but ill see in a couple hours. Also i came up with this theory about that other tuner i have theres only 2 wires supplying the map sensors so the wires should go to the pin that is the map signal and the jumper wire would be the supply voltage. Im just trying to get it wired so i can sell it. I bought the first adrenaline i sent you its the v2 with iquad i got it for 425$ it was sent to quad for a test and passed all the tests and came back with a new harness and i quad. I know @Mopar1973Man said it was too old, i belive you were looking at the second one i sent for 300 the first one i sent was 500$ and had iquad and was the newer model

With the little displays yeah too old. Should use your cellphone or mobile device likat a tablet. I'm pretty sure you could change out the display for the radio head (BT/WiFi) then update the firmware to get to version 2. Just easier to get a unit with the radio head and just plug in.

Edited March 28, 20241 yr by Mopar1973Man

The one i got links by bluetooth and the guy said it was updated to v2 so it was probabily the older one at one point but with the iquad i can see everything on my phone and tune it right?, and i plugged in my scanner and truck idles at 815-820rpm i didnt see any fluctuations higher than 825 it stayed right around 815-820 majority of the time. The load i dont think is true every vehical ive ever had it on at idle was 0% it says "calculated load value"  and while driving it didnt give the best readings fluctuating weirdly and glitching almost its not the best scanner its a OBDlink MX+

I saw this guy got a flip out pioneer radio and was able to link his iquad to it ill probabily end up doing something like that

I didn't even realize that there was an iquad and iquad plus lol i just read that the iquad plus will work with any adrenaline module. Its like 200 bucks so maybe ill just end up getting that instead of the radio. Either way atleast ill be in the adrenaline family now and be able to monitor and change things. The guy i got it from did say it had the v2 software

 Being the idle is above 800 and the load is at 0% your injectors may be weak. If you don't trust that scanner can you borrow one from somewhere? Just to get you an accurate reading. When my injectors were bad my truck idled at around the same as yours and showed 0% load at idle. I believe they were the oem injectors with 150k+ on them. Generally that don't last much past 100-120k miles.

I think we had a prior thread on here about an IAT sensor that was overheating, melting from a leaking intake valve. Valves can be funny and rotate or walk around causing leakage. Pull the IAT and look for heating or build up and clean it.

 

BTW, the Silverado 4.3l is an easy fix. Ozone builds up in the distributor cap. Just drill some vent holes in the distributor base.

29 minutes ago, Doubletrouble said:

I believe they were the oem injectors with 150k+ on them. Generally that don't last much past 100-120k miles.

 

First, I am not singling you out @Doubletrouble, but I am curious as to why there is so much emphasis placed on replacing injectors at 100,000 - 150,000 miles.   Also, I don't understand the engine load / increasing idle concept that is displayed on the Quadzilla tuner relating to poor performance of injectors.  The only tuner that I have used is the Smarty S03 during the last 50,000 miles of my OEM injector life.

 

On my personal truck, I ran the OEM injectors for 303,000 miles.  I only changed them out because I thought it was time and they had served me well.  The engine rpm had never changed at idle throughout the life of the injectors.  Fuel economy was always very good, the power was very good, the exhaust was clean (for this era of engine), and the engine always started fine in cold weather right up to the time that I replaced the injectors.  In fact, when I replaced the injectors with RV275's, I really couldn't tell any performance difference other than the RV275's delivered a little more torque on the low end, but engine idle was the same - smooth, and at the same rpm,

 

The OEM injectors (303,000 miles logged) are shown in photo below.  In my opinion all of the injector tips looked very clean for the miles logged - no evidence of poor performance on any of the injectors.  The appearance of the other four injectors looked the same as the two injectors in the photo.

 

- John

 

 @Tractorman, I don't feel signed out at all. All opinions are welcome here. Just trying to help a fellow 2nd gen owner out. @Mopar1973Man may be able to explain the relation of idle to weak injectors better than I can.

 My theory is this: the injectors fire when the pump pressure overrides the spring of the injector. Springs get weak over time, I think we can all agree on that. With as many cycles as these springs see in a lifetime there is no doubt they will loose some tension which in turn changes the timing of the injection event. Weak springs will fire sooner (advance) over time.

 Also, the internal needle and seat inside the tip will also wear and not seal as well as when new.  They will begin to leak.

 I've driven large diesel trucks for many years. Injectors do wear out, go bad and cause issues. 

 When I changed my injectors I went with 100hp from DAP, I noticed immediately that it would start up a bit faster in the colder weather, when it was warm out even quicker.

 That has just been my experience. 

Specs according to Dodge FSM

 

Minimum pop pressure 293 bar (4,250 PSI)

Maximum pop pressure 327 bar (4,750 PSI)

Set pop pressure - 310 bar (4,500 PSI)

 

Then the engine load has hit zero because the pop pressure is too low and the ECM no longer can control the set idle speed being the injectors are popping open too early and too long and idle control is lost. If all 6 injectors were pulled you find when tested like mine at 150k miles DAP tested mine and they were at 850 RPM and zero engine load which brought mine down got 240 to 260 bar. Which is unusable timing is totally off and too advanced in timing. 

 

Hence why when I had these 7x0.010 injectors built I opted for 320 bar for longevity and better spray. So far I'm still idling at 800 RPM at about 6-7% engine load so the injectors are still within timing and not popping open too early.

 

Like I'm learning with Quadzilla tuning 290 bar injectors are a PITA being they are right at the breaking point of failure and over-advanced by about 4 to 5 degrees and require a tune that is retarded. My tune has to have more advancement being I'm set above 310 bar so I've got to add more advancement being I'm about 2 to 3 degrees retarded. All are based on the 310 bar set point of where the timing will be. 

Edited March 29, 20241 yr by Mopar1973Man

 Thanks @Mopar1973Man, I couldn't have explained it that well. 

That's what I know after working with DAP on my current injectors. Which I'll admit I'm pushing past 100k limit because I was set higher than 310 bar. 

 

I've got a trophy injector in my tool box I was the only person that could hear the fact there was one injector popping wrong. This was on a Case backhoe. The injector was missing a hole. 

 

Yes I'm very sensitive to picking up on bad injectors by ear.

@Doubletroubleand @Mopar1973Man, I appreciate your prompt replies.  I agree on many of your points regarding the life of an injector over time - specifically the weakening spring (lower pop pressure) and the internal needle and seat wear.  I also understand that the injector tip holes can erode over time. 

 

I am in touch frequently with two other Dodge truck owners - one with a 1999 Cummins and the other with a 2002 Cummins.  The '99 has 295,000 miles on the original injectors.  I have recommended that he replace his injectors.  The '02 has has 185,000 miles on the original injectors.  Both of them still perform well and both of them have not experienced any change of engine idle rpm.  So, what gives here?

 

@Mopar1973Man, is it possible that this engine load / rpm change that you refer to is more evident with aftermarket high horsepower injectors and not with stock OEM injectors?

 

Just my opinion, but I think the average life span for new OEM injectors for this era of engine would be closer to 200,000 miles. 

 

Thank you both for your input.

 

- John

 

Edited March 29, 20241 yr by Tractorman

 I don't completely disagree agree with you @Tractorman, the oem injectors will run a long time. To a person that owns one for a long period of time the change would be minute. The big issue long term is that if an old injector were to fail in a worse fashion it would suddenly dump fuel like mad into a cylinder and wash it out scarring the walls and wiping out the rings. Now there is a rebuild needed. 

 Alot of what we do is preventative maintenance. These engines will last a very long time if cored for and the warning signs taken seriously. Not saying that this scenario will be on every injector at a given milage but it does happen. 

 The prevention is worth the expense.

 Back to the OP's original issue. I see that he has an H.O. vp44 pump. Could that have an impact on the timing changing as he states? @Mopar1973Man may be able to answer that, myself I don't know for sure. Just a thought.