wh944

Hello from Vienna in Austria :-)

I drive a Porsche 928 GT with implemented Rotrax compressor blowing about 9-10 PSI. Setup was performed by Victor from VCB. Sharktuner PEMs are installed in the LH and EZK.
Since a few days I am a happy owner of a Sharktuner. WBO2 with AFR-Meter is installed (MTX-L from Innovate).
Now I am about to perform some fine tuning using Sharktuner and Sharkplotter.
I do not know what injectors are used in my car, but need the related parameters for Sharktuner's 'Fuel Parameter Page' (lb/hr and injector opening time).
I took two pictures from the injectors.
Does anybody know what injectors these are?
Greetings and excuse for bad english :-)
Wolfgang

Speedtoys

You installed them, they came with the car, or did they come from Victor?

What does the Sharktuner say right now, their size is?

Can you rotate (they will) one to find the part number stamping on one?

Like this:
www.flickr.com/photos/28804666@N08/shares/ahZ85o

wh944

They came from Victor. I messed up with the 'fuel parameter page', but think there was 45lb/h and injector opening time 1,25. Car was running much too rich immediate after startup for about 45-60 seconds.
I will have a closer look and try to find the part-numbers.

wh944

Have been to the car and had a closer look. The numbers seem to be removed. Maybe Victor's business secret? The injector may be overpainted and originally yellow.

Speedtoys

How does it read -after- 45-60 secs?

Cold start, or warm start?

Have you been driving it since the install? If so..get a photo of the Fuel Parameters screen from the ST... while idling warm, after the 45-60 sec startup. Curious what the Trim Adjustments are.

If you changed the injector size, im sure Victor can just tell you what they are..

wh944

After 45-60 seconds after cold(!) start when closed loop kicks in the shark idles around Lambda 1 (or AFR 14,7)..
The install was in 2013 and I drove the car for about 6 thousand miles since.
I tried to contact Victor without success :-(
I can post more technical infos (Fuel Monitor, etc..) on Saturday.

Speedtoys

Ok, cool. So you changed the injector size by mistake?

Did not download the PEMs before making the change?

IMHO, 36# injectors are fine for that, 24s are edgy..if the PN is removed, they may be 'modified' from their original configuration to be larger.etc.

wh944

The car was running rich at cold start since 2013 and hat some flat spots when driving (i think running to lean).
I saved the LH and EZ maps from the PEMs before doing any modifications, but the fuel parameters were not saved as I expected :-(
On Saturday i will perform more tests. What should i set for 'injector opening time' on the sharktuner fuel parameter screen?

Speedtoys

Very odd that injector size/etc not in there.

Ill see if I can point some help this way.

Rob Edwards

Without the numbers and the red-on-yellow-maybe painted, impossible to tell what they are. They kinda look like Bosch 30-pounders but I wouldn't trust that without the numbers. My 30's are Bosch 0 280 150 558, I use an opening time of 0.85 msec with these.

Marti

If they are are the Bosch motorsport 30 lb version the opening time is 1.19ms . Very difficult to tell without a part number as they all look the same. The Bosch 30lb injectors I have are definitely not painted red so maybe that is the key to understanding the size?

Speedtoys

^^No, the PN is key, or the word of the supplier.

Not uncommon to be altered internally, PNs removed, then changed color.

However, as an example, if the ST says 19#, but they are really 24#, you will see Trim corrections of about -15#, and you get an idea of what they really are. 19/24/36/42 are the 'general' sizes IIRC.

FredR

Being interested in the subject matter I had a number of chats with Victor about his setup. I know his injectors are bigger than my 30lb injectors which I felt were easily big enough to support his output levels. His basic kit ran boost to about 5 or 6 psig so if you are running 10 psig then presumably you will have his intercooler option fitted. For whatever reason my brain tells me that Victor chose to use 42lb injectors with that option.

If you have a given tune and you set the opening time incorrectly this has more impact at idle/low rpms. At 6000 rpm there are 100 revolutions every second - one rev every 10 milliseconds. Given the injector opening time is likely in the region of 1 millisecond, not hard to see why for a given tune the correct opening time is critical at low rpms given at idle every rev lasts about 100 milliseconds. If your 928 is equipped with a NBO2 sensor presumably the issue gets further complicated as this will try to compensate for any over or under fuelling in the programming.

Sean Ratts runs a VCB setup but which version I know not. Maybe he can offer you some insights if he sees this thread.

Finally, if you saved the original programme files [as you should have] then you simply reload them from your laptop unless you corrupted them first and then saved them. If you change something in ST2 that change is automatically written to the PEM- you recover by loading the the version saved on file thus why every time you make a change always save it with some kind of log file reminder as to what you did and why.

wh944

Thank you FredR!

Yes I have the intercooler option fitted and i think there are 42lb injectors installed. (The sharktuner 'fuel parameter' said custom 45,7 at a opening time of 1,25). But car was running much too rich the first second after cold start in the morning. Often it died immediately after cold start and could not be restarted because of flooding :-(
I think I will reset the fuel parms to 45 and 1,25.and try to reduce 'cranking pulse width' and the 'warmup map'.

BTW, do you still have contact to Victor?
Thanks also for the tip to contact Sean Ratts.

FredR

With ST2 and a WBO2 at your disposal sorting this out should be rather easy. Just remember the trick is adjust one thing at a time to test for impact. The cranking pulse width may be suspect- remember when cranking the supercharger is doing nothing and injector pulses on each crank need the same amount of fuel as the stock 928 but you have injectors that have over twice the stock capacity. You also have a system operating at about 48 psig but the nominal capacity is based on a pressure of 43 psig if my memory serves me well so that has an increment of 5% over the nominal capacity not that it is an issue I would stick with the nominal rating of 42 and only change the mapping if all else fails. If you increase the opening time you will get more fuel- not what you want at the moment.

The trouble with these things is that if you reset one parameter incorrectly to fix one symptom you may well end up with something else subsequently going out of optimal tune. I used to contact victor through the persona message feature- we have not seen much of him in recent times.