Recording Wrong RPM on ECM

[fallflight]

Please look at this one. It is from the same trip, literally 2 min after the other that you looked at.

Goes into closed loop much more.....what changed?

[EagleMark]

I don't know? BLM are in ballpark now.

Couple things I did notice was:
1. EGR went to 100% after log started and stayed there, do you have EGR? PCM is running as EGR is open.
2. Batterey voltage and fuel pump voltage are very low at 12.1 and 12.3? These ECM like 13.7 to 14.1, this can change a lot of things including fuel pressure and deleivery.
3. CCP was also active, do you have CCP?
4. Your always in drive, probably good?
5. Your brake is always on, not sure what that would cause in this PCM? DFCO or Deceleration Enleanment? Not sure...

[fallflight]

No CCP and EGR has a blocking plate on the intake. I can see your point about deceleration enleanment as the boat cannot possibly have a brake. This could cause some problems. It is funny as I noticed while datalogging in my driveway (No river cruise today) that voltage was only at 12.1, but was thinking that PCM/ECM was regulating this voltage for smooth electronics operation......just my thoughts. I will, however, look into the alternator as I know it is charging on the amp gauge but volts are low. This could be the reason for crappy idle.

In your opinion, should I commission someone to write a bin that takes more of these oversights into consideration? Would someone do that for a fee? I want this PCM to run smooth, like it did in the 93 Chevy truck these parts came from. Maybe someone already has....I cant be the 1st person to put this application into a boat with 8625 PCM.

I learn more and more about this but still am ignorant to the tuning world. I am an oldschool carb guy by nature. IS there any literature out there that would help me understand? Keep scrubbing the internet, but havent found much.

I welcome your opinions. THANKS

[EagleMark]

When I see datalog voltage that low I have to find out why and fix it. It's still low at 2000 RPM so something is wrong, full charged battery is not 12 volts, it's 13.1 volts, with an altenator it should go no more then 14.1 volts. Some relays need 12.0 volts to turn on!

Then think of the electric fuel pump motor, DC, more volts more pressure and volume.

Code 44 is still set, don't see a reason for O2 Lean condition now?

I rarely get involved in tuning by mail and this PCM is not one I have a lot of experiance with. In person I do almost anything and I would do it hands on, no issue. But I would suggest Dave W here as he is into these PCM heavily.

[Six_Shooter]

Fully charged battery is 12.6.

2.1 volts per cell, 6 cells, 12.6V.

[EagleMark]

Batteries or school may be different in Canadia ay? I went to school and it was 2.2 volts per cell in 1976... just charged my EFI test bench and 100% was 13.1?

Or it could be a metric equivilent again or elevation?

But I had to Google it and the world is once again full of misinformation and your right, 2.1 volts per cell, up to 2.45 volts per cell?

A) Recharging: 2.3 to 2.4 volts per cell. (May depend on slight
differences and whether North America or European administration).
B) Floating: In service but neither charging of discharging, just
waiting with a full reserve, 2.15 to 2.17 volts per cell.
C) Discharging: For very long periods while battery supplies 'all it's
got', 2.0 volts per cell.
D) As the last percentage of the battery capacity is used the voltage
will then tail off rapidly; how quickly depending on the load at that
point. Lights will be dimming etc. voltage will drop to 11.0 volts and
below.
The six cell (auto service) equivalents for these are;
A) 13.8 to 14.4 volts.
B) 12.9 to 13.0 volts.
C) 12 volts
D) Voltage tails off .............. nothing left.If battery is charged normally for a normal time period (not
overcharged) then allowed to stand for say 10 to 24 hours and then
shows around 11.3 volts it is most likely useless!

[Six_Shooter]

Nothing to do with Canada Vs US, or Metric Vs Imperial, Volts are Volts.

In EVERY automotive electrical article, text, informational package etc I have read, glanced at, been a part of, had read to me, etc, it's 2.1V per cell and 12.6V for a fully charged automotive battery.

If JUST charged your battery, it will be resting at a higher voltage. To charge a battery, you must have a charge voltage of 13.6V, 1V higher than full charge voltage. The battery voltage will remain higher for a short period of time, once the charger is removed, usually around an hour, though I've seen some batteries stay high for longer. Many will return to their fully charged state of 12.6V in as little as 20 minutes.

[EagleMark]

My shop teacher must have told us the full charge after charging because it has always worked, now I have to run around and test batteries next day...

[PJG1173]

according to the documentation that came with my new delphi alternator I installed last night
12.6v 100%
12.4v 75%
12.2v 50%
12.0v 25%
=< 11.8v deeply discharged

No CCP and EGR has a blocking plate on the intake. I can see your point about deceleration enleanment as the boat cannot possibly have a brake. This could cause some problems. It is funny as I noticed while datalogging in my driveway (No river cruise today) that voltage was only at 12.1, but was thinking that PCM/ECM was regulating this voltage for smooth electronics operation......just my thoughts. I will, however, look into the alternator as I know it is charging on the amp gauge but volts are low. This could be the reason for crappy idle.

In your opinion, should I commission someone to write a bin that takes more of these oversights into consideration? Would someone do that for a fee? I want this PCM to run smooth, like it did in the 93 Chevy truck these parts came from. Maybe someone already has....I cant be the 1st person to put this application into a boat with 8625 PCM.

I learn more and more about this but still am ignorant to the tuning world. I am an oldschool carb guy by nature. IS there any literature out there that would help me understand? Keep scrubbing the internet, but havent found much.

I welcome your opinions. THANKS

I run the 8625 PCM on my s10. it isn't hard to tune some of these little things out. EGR was the first thing I did when I first started tuning. turned out to be real simple. I just zero'd the EGR tables our and set the enable temps high. you may need to adjust your OL AFR table since your engine runs cooler than what it was origionally programed for (Open Loop AFR vs. Temperature vs. Vacuum). this might help when it drops to OL. I can tell you that my autometer tach reads about 300 rpm higher than what TunerPro is displaying. I wonder if the low engine/exhaust temp is messing with the readings on the O2? have you lowered the temp to go into closed loop yet?

[dave w]

Guys,

I am not emulating. Only datalogging. I am going to attach files involved. I attached 2 log files, while short can show what it is doing.

note BLM

Also how low the O2 sensor is reading both in closed loop and open (Reminder that this boat does have an 02 sensor)

Thanks! Thanks! Thanks! Thanks! Thanks!!


I PLAN TO EMULATE.....Still trying to understand how this whole system works

I looked at the "By myself.xdl". The first think I noticed was a constant sprak retard of about 20 ~ 22 degrees all the time in the data log! I've looked at hundreds of data logs, and spark retard all the time is a huge problem! Is it possible there is a V6 memcal not a V8 memcal in the PCM? Maybe the Knock Sensor is not being used? I think the knock retard needs to be fixed, then figure out what else needs to be done. The knock retard can be disabled in the PROM to help with troubleshooting.

dave w

[EagleMark]

For data logging "Knock Retard" instead of "Battery Voltage". The bin must be change at L51FE to support this.

It is battery voltage with wrong conversion... it's a hack not done in bin.