MikeScarab28XLT

This is my old ECM, original from 1993 HEX 9550.

This i have read out from the ECM.
Tomorrow i read out the new modified ECM and a HP500 ECM.

MikeScarab28XLT

Now i have the programm MEFIBURN for some month and i have read out some engines.
Now i have see some differences in programming Mefi1 and mefi3.

HP500EFI MEFI3 the Main Spark in RPM/MAP are going up strade, like a old Sparkmodul from thunderbold. 35.9 over 5000RPM Fuel goes up to 5000 than up to 6000
502EFI MEFI1 use a loop over 3600RPM x1RPM to UPPER RPM 5000RPM. 30,5 over 5000RPM (Limiter 5080RPM) Fuel goes up to 4800 than up to 5200



Now my idea for my ECM MEFI1, what do you think ??

Limiter 5200RPM

Loop 0,00417
upper RPM for Loop 4800RPM
= 5,00


Main Spark
3600/100 29.9
3600/90 28.1
3600/80 32.0
3600/70 35.9

BPW vs MAP/RPM
4400 2.70 4.20 6.40 7.50 8.60
4800 2.60 4.20 6.30 8.00 9.20
old
5200 2.70 4.10 6.10 7.30 8.60
new
5200 2.70 4.20 6.30 8.00 9.20



??????

MikeScarab28XLT

Or is it better only

Loop 0,00417
upper RPM for Loop 4320RPM
= 3.00

+29.9=32.9 over 4320RPM and MAP 100

MikeScarab28XLT

So im back from testrun.

The 34* give 0.75* Nock Retards, so im ending with 33* and no Problems.

Slope 0.0045 end 4300
Tabel 29.9* /100MAP
9.2 Fuel with 30PSI

4970RPM with 30" Bravo LAB

Griswald

Why is the fuel pressure so low? Should be at least 43psi. I would bump up your fuel pressure and turn the bpw down a bit. You're working the hell out of those injectors at 9.2ms.

dbkski

iTrader: (1)

I believe Mike has an early 90's 502 EFI. That should be an engine that used 38 psi as opposed to my late model 502 MPI that uses the higher
fuel pressure(42 psi). As you pointed out, 30 psi is way too low.

MikeScarab28XLT

Hello yes i have a engine from 1993. I buy some new standart fuel pressures and testet them with the gauge (mercruiser fuel press tool) and allways 32 psi.
With 34 psi the boat are slower.


The bpw is it testet ore a calculatet number ? I dont now what i put in for better higher rpm.

What are better: test with more psi ? Ore more bpw ? Ore more psi and less bpw ?

Griswald

Are you tuning with a wideband O2 so you can monitor air/fuel ratio? Others may chime in but in my opinion, you're driving the injectors too hard at wot. Most injectors are built to run at 80% duty cycle which in my experience translates to a max of 8.0bpw. Pushing them into the 90% range could potentially lead to failure. And, at WOT... that could be disastrous for your motor. I don't know what your motor combination is or if you're just trying to improve the tune on the stock setup. However, if it were me, I would raise fuel pressure and try to get the duty cycle of the injectors down a bit. The only way you can do this effectively though is to monitor af ratio with a wideband O2 as you're running the boat. To raise fuel pressure you may also need to install an aftermarket regulator so you can adjust.

MikeScarab28XLT

Hello Griswald, thank you for the replay.

I like to tune the stock setup from the old model. The 9.2BPW are from the stock ECM with 4800RPM. But the stock goes than down to 8.0 at 5000RPM. My idea was to holt the 9.2 to 5000RPM. But i can make more PSI, i have a manual adjustable fuel pressure regulator and go to 8.0 but i dont now what to do with the rest of the BPW Tabel.
I have Imco Thumber Power Exhaust and i have no Air Fuel Ratio meter.

At time i run PSI30 (32) and BPW all at stock. Only the small change on 5000RPM to 9.3BPW and the Lope total 3* ending on 4300RPM and 29.9* on MAP100 at 3600RPM. No Nock retards.

I have record files from diacom with twin record and i have ECM files with the programming i have make.

MikeScarab28XLT

I have test a little bit more PSI (32PSI) with 9.2 and the speed goes down.
I have test with the 31PSI and more BPW 9.5 and the speed goes down.

Is the BPW are fix from 4800 to 5000RPM ??? Ore what BPW at 4950 i have ?


Hello Griswald,
do you think the injectors are damged if i drive WOT for only 5 Minutes ?? I can only drive for only 5 to 8 Minutes at WOT on my river.