I'm getting ready to put Siemens Deka (Mototron) 60LB Injectors in my truck, and had a few questions...

Which tables to change

1. IFR vs KPA

2. ?

Also, these are going into a 2002 engine with return style system with boost.

Thanks

David

 

IFR table is the main one. You will need to tweak the VE table and pulse width table, but if you start with the IFR table you can work around the others.

IFR with those injectors and a return style fuel system will be 72.30 accross the board.

 

yep...change your offset voltage line of 13.5 to somewhere in the neighborhood of .52 to .55. Blend from there on the voltages above and below. Obviously change the IFR to 72.3. You may (probably) need to bring down the min inj pulse table to some lower numbers. Tweak the ve back into spot. You'll still have some stupid idle AFR due to the size of the inj's. But if you like closed loop don't sweat it.

 

All ive done so far is IFR 72.3 ,Offset table, and right now 1.14 pw. Still need some work but I have them working in my N/A 5.3 with 216/220 cam...

 

I have tunercat, and the stock IFR was 3.1 g/sec (I think it was g/sec, I know the value was 3.1)

Tunercat has a calculator in the tools section, and I entered 72.5lbs and hr and it converted that over and it came out to be 9.1g/sec

I entered that into my tables, hit the key, and had no problems with it starting, really couldn't tell that it had different injectors in it.

Moss

 

We just got done tuning a truck with those injectors with a trick turbo,went really well
Scale the IFR table and you will need to work with injector offset ETC.

 

Bare with my newby questions....

Shouldn't the returnless systems be scaled, say from 72.3 - 79.9 at 80 KPa?

How is the offset adjusted, i mean is there a set # or deviation from stock?

I look at that table and get very confused....

 

All of the above guys seem to have the "return" style is like mine so it will have the same number through the entire column.

From what I have read if it is a "returnless" system then you would scale them as you posted.

The 60lb Seimens Deka/Mototron injectors have very different "dead" times from the stock injectors that is why they require changes to the battery voltage(in EFI don't know what it is called in HP) table.

 

Right, I (barely) understand the offset importance but am unclear where or what changes are necessary. It's a huge table. Also, the voltage on the '05 fluctuates a lot, the voltmeter (dash) reads low until a load is applied and then output increases....

am I way off here?

 

Voltage plays a factor in dead times because as the voltage decreases the amount of time it takes the injector to open increases. Think of it like a "Boost-a-Pump" in that when it increases voltage to the fuel pump you get more fuel. The injectors with increased voltage open faster so you get a little more flow given the same pw time.

Example:

Lets say it takes your injector 1ms(millisecond) to open at 12V. If you increase the the voltage to 14V it only takes 0.8ms. So if you pcm commands 10ms and there was no voltage correction then at 12V it would actually only pulse the injector 9ms(10 - 1) but at 14V it would pulse it 9.2ms(10 - 0.8) because the injector would open faster. That is why you need to know the dead times at all the given voltage range. The same goes for different injectors because they have dissimilar dead times.

Example:

Lets say the stock injector has a dead time of 1ms and the 60lb injector has a 2ms dead time. The pcm commands 10ms to get 9ms because it takes into account the dead times for the stock injector of 1ms. If you switch to an injector that takes 2ms to open then the vehicle only sees 8ms because it does not know the new injector takes 1ms longer to open. That would give you a lean condition. The pcm would always be making its correction wrong because of the wrong dead time put into its programming.

You can try and tune around that but if you go to an area with different elevation or temps the pcm would always be fighting to try and adjust the a/f because of the wrong info.

Someone else can either confirm this or give a better explanation.