What is canbus fueling? What is wiretap? Max timing on a 24v?

[Ravewolf]

As the title states, I'm not sure what either one of these is. I've tried Iooking them up on here, and on Google, but no dice. I come from a gasser background, so idk heads or tails with my truck. All new to me. If anyone can explain any of this, I'd appreciate it. Thanks! 

[Mopar1973Man]

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What is canbus fueling?

 

CANBus fueling is what to can produce on just the ECM alone. Typically most all tuners come up to about +60 HP CANBus only fuel. The VP44 and ECM have rules. The VP44 can understand a value 0 to 4,095 for fuel map. This is the limit of fuel for the CANBus.

 

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What is wiretap?

 

Wietap is typically used to now exceed the limit of the ECM / VP44. You now are tapping the fuel solenoid wire and commanding the fuel pulse to hold an extra 1,200 to 2,200 us (microseconds) more than what CANBus can do alone.

 

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Max timing on a 24v?

 

Quadzilla allows max timing of 32° BTDC timing. As for each case, max timing can be less. Timing is based on the injectors, injector pop pressure and the amount of fuel being injected into the cylinder. More fuel and larger atomization droplets then more timing is needed. The Smaller the mist the less timing. IAT also plays here warmer it gets less timing is needed. In a nutshell, you trying to find the optimal amount of time to heat the fuel, to make it go BANG so it making the most power. This can be seen two places either in MPG logs (accuracy) or Engine Log (gross errors).

 

Like the last time I checked on my truck the max timing without bucking was about 27° BTDC. But that was back with the 7 x 0.0085 injectors. I've not checked with 7 x 0.010 @ 320 bar. 

[Ravewolf]

So I've read some of your posts, and noticed you don't like using wiretap. Is it bad? More stress on the pump? I would imagine you'd want as much fuel from the ECM as possible before wiretap, correct? 

Also, since we're on the subject, what is pop pressure? 

[dripley]

Injectors are set at a certain pressure to pop off. The VP supplies that pressure to overcome the spring holding the injector closed. Pretty sure 310 bar is an average pressure on a new injector. 1 bar = about 14.5 psi, about 4500 psi. You can get them set higher and when they wear they will get lower in pop pressure. This is where controling timing with a Quad is good to have. 

[Mopar1973Man]

21 minutes ago, Ravewolf said:

So I've read some of your posts, and noticed you don't like using wiretap. Is it bad?

 

No. My wiretap dumps out so much power that the tires break loose. I've got to keep turning down the level to keep the tires under it. I've ran a wiretap on my last VP44 with the entire life and it had many years of the Edge Comp on 5x5 and then the Quadzilla and it life ended at 243k miles. Timing piston failure (P0216). Matter of fact I was heading over the bridge in Ontario laid a bit too deep in the throttle and BAM! 

 

24 minutes ago, Ravewolf said:

More stress on the pump?

 

Not really. You just hold the fuel solenoid a mere extra 1,200 microseconds up to 2,200 microseconds. This translates to 1.2 milliseconds and 2.2 milliseconds. Yeah, the pump is pushing just a bit more but rotor failures are extremely rare. 

 

26 minutes ago, Ravewolf said:

I would imagine you'd want as much fuel from the ECM as possible before wiretap, correct? 

 

Correct. You want to start out on levels 2 and level 3 and figure out your CANBus fuel map and then you can stack on the extra ponies of the wiretap. You should have a clean smoke free tune on CANBus only. Then you can stack on the wiretap and tune it for what you like. Mine hazes slightly yet but I like the power for passing on the highway.

 

Like this morning 2 cars and a semi-truck. The rearmost car squeezed me out I laid on the throttle and passed the nose of the semi at nearly 90 MPH no problem. Whipped back in my lane and unwound the Mighty Cummins. 

3 minutes ago, dripley said:

Pretty sure 310 bar is an average pressure on a new injector.

 

Most injector builders seem to favor 305 bar. Bottom limit is 293 bar. Doesn't give much room for longevity. This is why I've opted for 320 bar which words super this winter no starting issues. I know the pop pressure is failing on my injectors already. Even got to recalibrate the MPG display and add more to the percentage offset. 

 

[dripley]

45 minutes ago, Mopar1973Man said:

 

Most injector builders seem to favor 305 bar. Bottom limit is 293 bar. Doesn't give much room for longevity. This is why I've opted for 320 bar which words super this winter no starting issues. I know the pop pressure is failing on my injectors already. Even got to recalibrate the MPG display and add more to the percentage offset

Hey, at least I was close. You shuold be proud I am paying attention.

[Mopar1973Man]

1 minute ago, dripley said:

Hey, at least I was close. You shuold be proud I am paying attention.

 

You are paying attention. So how much did it cost you? 

[dripley]

4 minutes ago, Mopar1973Man said:

 

You are paying attention. So how much did it cost you? 

Only time my freind, only time. 

 

The truck runs like a scalded dog with MAP fixed. Just wish the HG was done. Time off coming up, not sure how much though.

[Mopar1973Man]

1 minute ago, dripley said:

The truck runs like a scalded dog with MAP fixed.

 

Right on!  Finally got it fixed!

 

1 minute ago, dripley said:

Just wish the HG was done. Time off coming up, not sure how much though.

 

Get your ducks in a row...

[dripley]

Just now, Mopar1973Man said:

 

Get your ducks in a row...

Trying but the CFA folks are holding me back bad.

[Me78569]

It is also important to point out that wiretap fueling is hard to control and the resulting fuel tends to end up with EGT issues when you push duration as far as it will go. 

 

Using bigger injectors and less duration means you will make the same amount of power, but with less egt and better mpg.  Key thing to remember is the point of being able to control timing is to get your injection point tuned to a specific place in the rotation of the engine.   The more duration you have the longer your injector spray and the more * of rotation the engine has for that injection event.  

 

You want to inject as much fuel as possible in the shortest period of time to keep things efficent. 

 

My memory is hazy at this point, but I believe at WOT commanding full canbus and an additional 2400us worth of wiretap puts you at or near 90* of crank rotation from start to finish of your injection event.   Thats ALONG time injecting fuel.