Hi All

I wondered if you might be able to help me out with a fuel trim issue..

I have recently installed a TT system on my Stock LS1 Vette. I upgraded the stock injectors to the Racetronix Delphi 42lb/hr @43.5psi "009" disc style.

After scaling the IFR table to compensate for the higher flow injectors, I notice that the PCM is pulling a great deal of fuel (LTFTs are -ive 10 to -ive 15) to maintain stoich while cruising around.

I have not touched the VE table or MAF ....

I understand that this type of injector is much quicker than the stockers to open and close. Does anyone have experience tuning with these injectors?

For example do people adjust the "injector offset timing" for this type of injector?

I can always scale the IFR table higher than the calculated value until the LTFTs sit at or around zero but I wondered if I might be missing something...

Any help or comments are certainly appreciated.

Dave

really need more information like what you guess the flywheel HP is and what the inecjtor part number is
If those are 42 lbs at 43 PSI rail pressure and LS1 uses around 60 PSI then those 42s are now like 50 plus lbs are you sure those are not too large since that is about 25% more flow then if a fuel rail of 43 PSI.

The PCM was designed to use a average pulse width time of around 3 mSec for part throttle. the longer on time gives the PCM better control and when you start forcing PCM to use shorter on times you put more load on CPU to keep spending clock time in recommanding injectors.

Remember the voltage offset is a delay time after PCM commands pulse width so if you set that too long or too short then injector could be coming on before or after ign coil has fired off the sparkplugs so I'd require the vendor who sold you these to supply what offset time should be.

I'd drive the injector flow values of IFR with larger values to drive it leaner and then see what the average pulse width time is.

A injector that was flowing 42 lbs with a 58 PSI rail pressure using the 80 % duty cycle rule could handle 540 flywheel HP so you can see if your injectors are really 50 lbs that would be
640 flywheel HP, so is your engine require that much injector flow ?

Hi
Thanks for taking the time...

I would expect the system to make around 575 flywheel+ when correctly tuned.
I am running 10psi wastegates with a meth/water injection system (comes on at about 5psi).

Part Number of the injectors is Delphi 01D030B.

I currently have the injectors scaled for the 58psi fuel rail on the LS1. This gave me a flow rating of 48lbs/hr (or 6.18gm/sec at 100kpa in LS1edit).

Great info on the delay time. I had misunderstood the function entirely...
The engine does hesitate slightly under mild acceleration (which is very irritating). Perhaps a result of the timing issue between spark and injector pulse.

Pulse width at tick over is 2.27ms and then up to 11ms at WOT.

I now have a request into the vendor for additional info on the injectors.

It sounds like I have a combination of issues to resolve with these injectors.

Thanks
Dave

That part number seems to be too short, normally on side of them will be the complete part #.

Either as tuned or/and injectors too large since inj pulse width is below the avg 3 Msec and its max is no where near WOT which is about 15-20 mSecs
At WOT if your not seeing 65-75% duty cycle then injectors are too large for most engine conditions

You do not want them to be commanded ON at the wrong time as you knock if they are too early or late od when sparkplugs are commanded on.

OK
I took a closer look at the injectors today. There is nothing else but maybe this helps:

This is from the RACETRONIX website-
Part Number Delphi 01D030B (Lucas old 5208009, Lucas New 621031, Delphi old D3181AA) ???
Maybe you have worked with some of these?

Regarding pulse width, I screwed up in my previous post.
I am seeing injector pulse widths of 19.5mSec at 4,000 RPM (this is with 10psi of boost). this puts me at a 67% duty cycle.

Here is the quote from the LS1edit doc regarding the offset table.

"4.2.6 Injector Offset
The injector Offset Table is used to compensate for the time delay in opening the injector. This is the base time used for every injector cycle. The calculated Pulse Width for the needed fuel is added to it. It is in Milliseconds."

My understanding from reading this is that the offset will impact both the length of the pulse and also the timing of the fuel delivery.

The question is how much faster are these injectors than the stock Bosch type and is it something you have ever had to worry about when tuning?

P.S. No answer from Racetronix yet, but their sales team are out of the office this week

Dave

You can find that injector as
http://teamzr1.com/injectortypes.html

or at the top of forum use seach function for
injector
where I have posted about 40 threads on them

They are 42.29 lbs/hr at 43 PSI rail pressure and 445 cc/min

Yes being the coil of the injector might take xx time to react and open and close then PCM is adding that to the pulse width so that the time that coil reacts then the remainder of PW time would be the correct flow time.

Coil could be faster then what stock was and its offset table values but also could be a slower reacting coil.

The vendor which is Lucas ( I do not use them I do not think they are very good at spraying well as duty cycle increases, nor do I like Racetronic products ) has to be the one who says what that coil reaction time is