camens ecu

[n16boo]

hi looking for any advise...

had the car on the laptop yesterday with an engine builder, and on the realtime display the voltage meter was flucturating between 14 & 12.6 volts regardless of load so he suggested alternator was shot so once home i removed and took to have checked and it tested all ok so back i came refited and then checked the main cable to the starter solinoid from the alternator and the ignition lamp and feed leads, all seem fine.
ran up the engine and i was getting 14.2 volts at the alternator and 13.7- 13.8 volts in the car at the master switch ...

i dont see anything untoward however just wondered if anyone else have had this with either camens or another brand?

[Unweder]

You are 1/2 a volt amiss you should be getting the same voltage using the same earth/ground point dont blame the Canems ECU or software yet sort the voltage offset be it power or earth cable issue

[stevieturbo]

n16boo said:

hi looking for any advise...

had the car on the laptop yesterday with an engine builder, and on the realtime display the voltage meter was flucturating between 14 & 12.6 volts regardless of load so he suggested alternator was shot so once home i removed and took to have checked and it tested all ok so back i came refited and then checked the main cable to the starter solinoid from the alternator and the ignition lamp and feed leads, all seem fine.
ran up the engine and i was getting 14.2 volts at the alternator and 13.7- 13.8 volts in the car at the master switch ...

i dont see anything untoward however just wondered if anyone else have had this with either camens or another brand?

Instead of changing random wiring.....if you are seeing a lower voltage somewhere, then you need to look at the wiring where you believe you are getting that reduced voltage.

Is it really a problem ? maybe, maybe not.

I'd be more worried if voltage critical items like coils, injectors, fuel pump etc were not getting a nice stable voltage.

[n16boo]

thanks for your comments, the drop in voltage at the master switch is due to umpteem items feeding off of the switched on live pole,correct or not its been the same for some 30 years so im not changing it now ;-) the alternator takes its feed from the otherside which is fed from the battery and the battery and alternator voltages are stable,
the engine builder has summond me back for a rerun as the intermitant voltage in to the ecu is making the ecu misbehave and the fuel maping is way out compared to the dyno bench run...,

fingers crossed i have found the issue in that the ecu earth to the battery had a spade joiner connecting 2 cables and this was loose so im hoping this was distorting the earth signal as it gets a harsh life with vibrations and heat being its a stage rally car!!

[stevieturbo]

n16boo said:

thanks for your comments, the drop in voltage at the master switch is due to umpteem items feeding off of the switched on live pole,correct or not its been the same for some 30 years so im not changing it now ;-) the alternator takes its feed from the otherside which is fed from the battery and the battery and alternator voltages are stable,
the engine builder has summond me back for a rerun as the intermitant voltage in to the ecu is making the ecu misbehave and the fuel maping is way out compared to the dyno bench run...,

fingers crossed i have found the issue in that the ecu earth to the battery had a spade joiner connecting 2 cables and this was loose so im hoping this was distorting the earth signal as it gets a harsh life with vibrations and heat being its a stage rally car!!

The alternator powers everything when running. You should have a good supply cable from alternator to any critical power supply/fuse boxes.

It really does go without saying, ALL grounds need to be very good. Battery to chassis, battery to engine, chassis to engine. And obviously any ecu grounds need to be to a suitable solid ground location.
Whether that's deemed on the engine, chassis, battery, people have differing views. But do not skimp on grounds or assume they are good. ALL to good clean bare metal.

Most ecu's should be very tolerant of varying supply voltages. That's not a big deal.

If injector dead time data is not good, then varying voltage can massively affect their operation. And even if it is good...you need to fix any varying voltages.

However, due to wiring either goodness, badness, inconsistencies etc etc....just because you see say 12.5v at your ecu, doesn't mean the injectors see the same, or coils, or fuel pump.
Really if there is bad wiring, insufficient cable size or quality, poor quality connectors/connections/fuses etc etc, that needs fixed.

[E-bmw]

As has been touched on above the 14.odd volts is the supply voltage from the alternator, the 12.odd volts is the supply voltage from the battery.

In itself, this is telling you that the alternator output isn't always getting into the car's electrical system.

Remove, clean, tighten, ensure all main electrical connections between the 2 parts of the system are good and not just visually.

It is entirely possible that you may have touched the connection causing the issue, but just double check everything or as Stevie says you won't get the desired results & could waste more time/money at the tuners.

[GreenV8S]

stevieturbo said:

Most ecu's should be very tolerant of varying supply voltages. That's not a big deal.

If the voltage fluctuations are being caused by grounding problems and any sensors or actuators are grounded separately then could cause eratic behaviour.