Raceboy

Denso ones can be used when O-rings are changed, though installing them takes a bit more effort.

If anyone's interested, I have almost new Bosch 315cc @ 3bar 12Ohm injectors, these are newer, "pencil" style:

alexjc4

Thanks Peep that's good to know, I just remembered I have some cleaned and flow matched 370cc low impedance Densos in a box somewhere too.

Anyway, for now, I'd be glad enough just to max out the standard injectors

alexjc4

Peep, if I want to run the low impedance injectors (I have a resistor pack) would I need to modify the anything for the flyback? On this old thread it looks like you need to solder in some diodes, or does VEMS come with that as standard now?
http://www.vemssupport.com/forum/index.php?topic=76.0

ras62

Looking at your original comments you say ITB is what you want to fit in future and the stand alone ECU is there to support this idea. As far as I can understand your rebuilt engine is stock apart from a hotter cam, therefore the standard rev limit must be used. Given that ITB work best at over 7k I dont see the benefit of installing them on a rev restricted motor which puts a ? on the need for a stand alone ECU?
You may well find that fitting slightly uprated injectors with a Schofield remap is the best way forward.

alexjc4

Good point on the ITBs, you'd want to build the engine for the revs. As I said I might go TPC/Eaton/Roots or even Rotrex supercharger or Turbo, so lots of options are open in the future, even VRAM.

The benefits I see in going to a standalone are; response, idle control (with a lumpy cam), drive-ability, removing the AFM, and when the time comes, coilpacks and wasted spark or even COP - and of course kicks and giggles.

Most people that map ecus, regardless of make, will figure out a Speed Density or Alpha-N hybrid system and be able to map this system, whereas you are very limited for choice with Motronic chip tuners. With the logging and wideband02 that comes with this ecu, I can map the fueling a fair amount myself - and easily swap out injectors and recalibrate.

alexjc4

Injection:
Q: Is the standard DME fully sequential injection or partly bank or simultaneous fire? If the latter what conditions does it move from one to the other? This may be slightly redundant with the very high duty cycles the standard injectors will run meaning it may as well be CIS as high load - but is more relevant when larger injectors are fitted.
A: From searches on this forum, Porsche technical documentation (noted to be unreliable in this sort of detail) simply references pulsed, sequential injection is used. But not it this is full time (i.e if it changes to bank fire), or how it is timed against crank position. It seems the distributor hall sensor may only be used at start-up to establish TDC on #1 cylinder, after that the crank trigger is used for all timing info and knowing TDC on #1 it would be able to run timed sequential injection.

Q: What size are the standard injectors and what power level will they support?
A: The part number is known 0-280-150-731 and the 3bar flow is known 194cc/min, however the operating (3.8bar) flow is not known and two reputable sources differ - Geoffrey suggests ~250cc/min and rule of thumb Bernoulli derived calculation gives ~220cc. Either way I think Geoffrey and others suggest dyno proven limit of 300bhp for standard injectors, which seems a lot for the injector size, based on the standard BSFC based calculations available online but there is no reason to doubt the veracity of Geoffrey's results.

Q: If required what are readily available upgrade injectors?
A: Denso's with minor alteration can be fitted (I have a range of these). Alternative bosch part numbers seem hard to come by. Peep has some s/h 0 280 155 831 (std fit for Volvo S60 S80 V70 XC90), High Impedance, 315cc @ 3bar replacements. These seem to ebay new for £50 per injector which is fairly reasonable.

Q: Are mods to ecu required to run low impedance aka "low-z" injectors, assuming appropriate "resistor pack" is added to injector loom.
A: ?

ECU inputs:
Q: What TPS can be used
A: The part from an "Opel Omega A 2.0" is adaptable with the fabrication of a bracket.

Q: What AIT/MAT can be used to replace the one in the AFM
A: ?

Q: Is EGT sensing desirable and is it retrofittable to PnP unit?
A: For mapping this may not be essential, but are there any other benefits to using this as an input to the ecu?

Q: Knock sensing, how well does the VEMS knock sensing work and how should it best be configured to manage knock
A: The ecu will be delivered with conservative ignition timing. The knock sensing configuration in VEMS allows band pass filtering and time windowing and configurable response strategy in terms of how much and when to pulling timing. How can this be tested and verified as reliable? I understand that tuning to up-to-knock by ear on aircooled motors is very hard due to noise levels, I do have standalone knock detection equipment (Phormula Knock) perhaps that should be used for mapping and the VEMS for "last line of defense" engine protection against bad fuel etc in day to day running. Views welcome on this?

Hardware and wiring:
Q: What is the best position to take off the feed for the MAP sensor; pre or post throttle? is there an existing vacuum hose that can be tee'd into?
A: Since it's a MAP sensor and the M stands for Manifold - after the throttle seems the obviously place, but where exactly?

Q: Whats a nice way to wire the old AFM plug for the new AIT/MAT sensor (neatly and reversibly)
A: ?

Q: How to wire wb02 and map sensor?
A: wb02 will come with it's own loom back to the ecu, the map sensor will come with a suitable "hard hose" back to the ecu. both will run through the firewall with the factory loom down to the ecu.

Q: Simplest effective replacement for the AFM?
A: ? I'm thinking: measure and make straight pipe of similar dimensions to the AFM and source "top-hat adapter" to bolt to the std airbox, OR use a bent pipe and a pod filter a-la Ninemeister.

alexjc4

Things I've confirmed or I am just assuming Peep will setup for me in the base map (Peep please set me right if I've go anything wrong here):

• Setting injector dead time (aka latency, aka null time, aka blast off time) for standard injectors in line with DME dead time table.
  
• Configure injector sequential vs batch fire operation as appropriate
  
• Apply AIT vs ignition retard and AIT vs fuel adjust tables similar to standard DME
  
• Configure knock detection and responses in VEMS
  
• Configure cold start, hot start and cranking mechanisms
  
• Configure reasonable "tables": VE table (RPM vs MAP), AFR target table (RPM vs MAP), Ignition table (RPM vs MAP). Q: will there be any Alpha-N (aka TPS vs RPM) blending? this is something that may well be needed depending on the stablity of MAP at low low due to the lumpy cam.
  
• Perform O2 sensor calibration on supplied unit
  
• Provide extra earth wiring to enable switch to coilpacks later
• Setup dwell times to drive coils safely

PhatPhlatSix

Sure thing. If you can upload the hex images, send them to me via email. Otherwise we can read them on my burner.

As you stated, part throttle maps on the Motronic are 3D, whereas WOT and closed throttle are 2D.

Dan

PhatPhlatSix

Couple comments here Alex.

1) Be careful about adding load resistors to low impedance injectors - their performance will be compromised as you're dropping voltage across the resistors. Also, high-impedance injectors on an output stage meant for low impedance injectors is also a bad thing because normally the injector-driver outputs a high current until the 'peak' current is reached, and then drops to the 'hold' current. If it never achieves the 'peak' it may not drop to the 'hold' and thus burn itself out.

2) I have a spare adapter for my MAF kit that converts the square 964 airbox hole to a large round one. You can have this and then sll you then need is a length of silicon hose....

Dan

alexjc4

1)Yeah that's an interesting one I've heard that caution perivously. My Nissans (which all these random sets of 6 injectors I seem to have gathered come from) have a mix of high and low impedance but are all interchangable with the addition of a resistor pack. The ecus are in reality all setup for high impedance injectors. The GTR runs low impedance 440c with a resistor pack, the GTST runs high impedance without, but it's widely accepted to run low impedance + resistor pack. I guess it comes down to whether the ecu runs the injectors genuinely as peak hold or saturated. I guess the Nissan ecus (of the 90s at least) run all injectors as saturated and simply add resistors to allow fitment of low impedance peak hold injectors where that is more convenient (i.e they don't use the peak hold control mechanism regardless of impedance). But my understanding is these 964 stock injectors are high impedance ie saturated so the drivers should be able to cope with the sustained load, no?

2)thanks man that's fantastic, I'll be in touch to grab that when the time comes.

Also thanks to the heightened levels of neuron activity this project has stimulated, I've managed to find my Moates 28pin chip burner, which I mislaid two house moves ago and I had feared gone forever, so I'll read those chips and email you the bins, can you pm me your email.

ghhally

There's a sample map for 964 on the KMS website. Download the software and the map and you're good to go as a base.

ghhally

Bought the 55 pin-connector and wil make short harness into KMS md35

alexjc4

Thanks ghhally it's interesting to look at different tuning software to see what the common factors are and the terminology that is used.

I've had a quick look and have some observations, these aren't positive or negative, just trying to test my comprehension of the information in the "map":

1)it looks more like a "start up map" rather than a tuned "base map". So it may be meant to simply get the car running and idling safely, and to let you drive to the dyno. For example if you compare the WOT ignition curve with the one on Steve Wong's website the ignition is quite retarded especially between 2500rpm to 4000rpm.

2)the load axis for both fuel and ignition is based on TPS with "a MAP correction", so there's no VE or target AFR tables, just fuel demand in milliseconds for a given TPS vs RPM, this fueling would then be modified based on the MAP.

3)there is no CHT base ignition retard specified.

4)injection is trimmed for by % for CHT up to 60DegC (for cold start), and air temp by % with -10% from 60Dec up (I assume this is AIT rather than ambient temp).

5)injector latency is configured in a 2d table vs battery voltage (in milliseconds) with 0.440ms at 14v (normal operating voltage, i think)

6)There is a air pressure correction table which zeros at 1015mbar and applies % correction - I assume this is barometric correction for ambient air pressure, not the MAP correction (MAP compensation, I think is based on a formula - this is often called Map "multiplication").

7)Idle is controlled by fuel (rich lowers rpm, lean raises rpm) and ignition (retard lowers RPM, advance raises it), but not the idle valve.

Ducks964

Keep up all the good information. I need to learn as much as possible before I start my VEMS install. I am hoping that a friend and local speed shop (with 4 wheel dyno) can help. I have the added challenge of the supercharger to contend with. Don't want blow up an engine.

alexjc4

Not wanting to go down a rabbit hole on this but, can I just offer the following quotes from a thread from a while back:

And this dyno plot from rothsport fron a 964 motec + jenvey itb + cam job



Myth busted?