Hi All,
Finally got my car running better 74 914 2L FI. Thanks to all for suggestions. It turns out it was most likely the main power wires loose to my battery (fixed). Fuel was on and off.
I noticed something else when setting my idle.
When I turn on my headlights my RPM's drop. I recently acquired a 912E and it does the same thing, though not quite as much. I attached some pictures, just because I like threads with pictures better.
A. Could this be my Battery?
B. Grounds?
C. All the above?
D. Other_________?
Click to view attachment
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Full Version: Electical Draw ? Lowers RPM ? 914 and 912E
When you say "RPM drops" do you mean the Tach reads lower RPM or the engine itself slows down when the lights are on?
The increased load on the alt means that more HP is required to turn the alt thus the drop in RPM. But headlights shouldn't drop it too much? Massive amps and subs it sure will~ 200 amp loads, the car near stalls!
Jon
Jon
Most likely your electrical systems (both cars) need some cleaning and freshening. Resistive grounds and corrosion on terminals will increase the amperage of normal loads.
Disconnect all ground terminals, clean and reassemble. Wire brush the fuse panel terminals. Check the alternator wire for lumpyness under the insulation. This will indicate corroded wire. Wire has a life span. It is less than 40 years...
If you do not know the date of the last time the battery cables were replaced... Replace them. Put in a new ground strap on the tranny.
Do all this and the alternator should work better along with the rest of the electrical system.
Basically you do an electrical tune up...
Disconnect all ground terminals, clean and reassemble. Wire brush the fuse panel terminals. Check the alternator wire for lumpyness under the insulation. This will indicate corroded wire. Wire has a life span. It is less than 40 years...
If you do not know the date of the last time the battery cables were replaced... Replace them. Put in a new ground strap on the tranny.
Do all this and the alternator should work better along with the rest of the electrical system.
Basically you do an electrical tune up...
So, might help to better understand what is actually causing the RPM drop in order to find a solution, I am not entirely sure it is just load on the engine from the alternator.
D-jet sort of leaves you totally blind when it comes to diagnosing issues but on my megasquirt equip car I was seeing the same RPM change when I kicked on the headlights. Its pretty obvious when looking at the megasquirt dashboard what was happening as when the headlights went on 2 related things happened.
1. system voltage dropped slightly
2. mixture leaned out slightly
In my case the RPM change was due to the mixture change, which in turn was due to having a slightly shorter injection pulse, which was due to reduced system voltage. Thankfully Megasquirt has a setting to compensate for this exact thing, but if this is the case for you i think your only option with d-jet would be try and reduce the voltage drop as much as possible.
If you have a wideband sensor, see what is happening to your mixture with the headlights on, and/or see if the system voltage at the relay board drops when the headlights are on.
D-jet sort of leaves you totally blind when it comes to diagnosing issues but on my megasquirt equip car I was seeing the same RPM change when I kicked on the headlights. Its pretty obvious when looking at the megasquirt dashboard what was happening as when the headlights went on 2 related things happened.
1. system voltage dropped slightly
2. mixture leaned out slightly
In my case the RPM change was due to the mixture change, which in turn was due to having a slightly shorter injection pulse, which was due to reduced system voltage. Thankfully Megasquirt has a setting to compensate for this exact thing, but if this is the case for you i think your only option with d-jet would be try and reduce the voltage drop as much as possible.
If you have a wideband sensor, see what is happening to your mixture with the headlights on, and/or see if the system voltage at the relay board drops when the headlights are on.
Had the same problem. Like Mike says, clean all the grounds, replace where necessary. I also added a second battery ground cable from the - battery post to the engine. RPMs have never dropped with lights, blower, or amp...
It's a paradox.
Lower rpm= less charge= lower injector voltage= lower rpm= less charge= lower injector voltage= Lower rpm= less charge= lower injector voltage= lower rpm= less charge= lower injector voltage= Lower rpm= less charge= lower injector voltage= lower rpm= less charge= lower injector voltage= Lower rpm= less charge= lower injector voltage= lower rpm= less charge= lower injector voltage= Lower rpm= less charge= lower injector voltage= lower rpm= less charge= lower injector voltage= Lower rpm= less charge= lower injector voltage= lower rpm= less charge= lower injector voltage= Lower rpm= less charge= lower injector voltage= lower rpm= less charge= lower injector voltage= Lower rpm= less charge= lower injector voltage= lower rpm= less charge= lower injector voltage= Lower rpm= less charge= lower injector voltage= lower rpm= less charge= lower injector voltage= Lower rpm= less charge= lower injector voltage= lower rpm= less charge= lower injector voltage= Lower rpm= less charge= lower injector voltage= lower rpm= less charge= lower injector voltage= Lower rpm= less charge= lower injector voltage= lower rpm= less charge= lower injector voltage=
Lower rpm= less charge= lower injector voltage= lower rpm= less charge= lower injector voltage= Lower rpm= less charge= lower injector voltage= lower rpm= less charge= lower injector voltage= Lower rpm= less charge= lower injector voltage= lower rpm= less charge= lower injector voltage= Lower rpm= less charge= lower injector voltage= lower rpm= less charge= lower injector voltage= Lower rpm= less charge= lower injector voltage= lower rpm= less charge= lower injector voltage= Lower rpm= less charge= lower injector voltage= lower rpm= less charge= lower injector voltage= Lower rpm= less charge= lower injector voltage= lower rpm= less charge= lower injector voltage= Lower rpm= less charge= lower injector voltage= lower rpm= less charge= lower injector voltage= Lower rpm= less charge= lower injector voltage= lower rpm= less charge= lower injector voltage= Lower rpm= less charge= lower injector voltage= lower rpm= less charge= lower injector voltage= Lower rpm= less charge= lower injector voltage= lower rpm= less charge= lower injector voltage= Lower rpm= less charge= lower injector voltage= lower rpm= less charge= lower injector voltage=
Brad Anders also found that fine-tuning his idle mixture reduced the RPM drop with electrical load noticeably.
(Scroll down to where he talks about voltage or electrical load affecting the idle.)
http://members.rennlist.com/pbanders/idle.htm
--DD
(Scroll down to where he talks about voltage or electrical load affecting the idle.)
http://members.rennlist.com/pbanders/idle.htm
--DD
QUOTE(Mike Bellis @ Dec 17 2013, 03:09 PM) 
Most likely your electrical systems (both cars) need some cleaning and freshening. Resistive grounds and corrosion on terminals will increase the amperage of normal loads.
Disconnect all ground terminals, clean and reassemble. Wire brush the fuse panel terminals. Check the alternator wire for lumpyness under the insulation. This will indicate corroded wire. Wire has a life span. It is less than 40 years...
If you do not know the date of the last time the battery cables were replaced... Replace them. Put in a new ground strap on the tranny.
Do all this and the alternator should work better along with the rest of the electrical system.
Basically you do an electrical tune up...
I have replaced the ground on the battery and tranny ground strap. I will clean the grounds and fuse box. Thanks!
QUOTE(JamesM @ Dec 17 2013, 03:17 PM)
So, might help to better understand what is actually causing the RPM drop in order to find a solution, I am not entirely sure it is just load on the engine from the alternator.
D-jet sort of leaves you totally blind when it comes to diagnosing issues but on my megasquirt equip car I was seeing the same RPM change when I kicked on the headlights. Its pretty obvious when looking at the megasquirt dashboard what was happening as when the headlights went on 2 related things happened.
1. system voltage dropped slightly
2. mixture leaned out slightly
In my case the RPM change was due to the mixture change, which in turn was due to having a slightly shorter injection pulse, which was due to reduced system voltage. Thankfully Megasquirt has a setting to compensate for this exact thing, but if this is the case for you i think your only option with d-jet would be try and reduce the voltage drop as much as possible.
If you have a wideband sensor, see what is happening to your mixture with the headlights on, and/or see if the system voltage at the relay board drops when the headlights are on.
Good suggestions. I do have a Innovate wideband MTX-L installed. I will check this. Thanks!
QUOTE(jim_hoyland @ Dec 17 2013, 03:21 PM)
Had the same problem. Like Mike says, clean all the grounds, replace where necessary. I also added a second battery ground cable from the - battery post to the engine. RPMs have never dropped with lights, blower, or amp...
Where did you connect the ground to the motor?
QUOTE(thompson-mfr @ Dec 17 2013, 04:25 PM)
QUOTE(jim_hoyland @ Dec 17 2013, 03:21 PM)
Had the same problem. Like Mike says, clean all the grounds, replace where necessary. I also added a second battery ground cable from the - battery post to the engine. RPMs have never dropped with lights, blower, or amp...
Where did you connect the ground to the motor?
One of the screws on the fan housing
QUOTE(Mike Bellis @ Dec 17 2013, 03:09 PM)
Most likely your electrical systems (both cars) need some cleaning and freshening. Resistive grounds and corrosion on terminals will increase the amperage of normal loads.
Disconnect all ground terminals, clean and reassemble. Wire brush the fuse panel terminals. Check the alternator wire for lumpyness under the insulation. This will indicate corroded wire. Wire has a life span. It is less than 40 years...
If you do not know the date of the last time the battery cables were replaced... Replace them. Put in a new ground strap on the tranny.
Do all this and the alternator should work better along with the rest of the electrical system.
Basically you do an electrical tune up...
....The most "neglected"maintenance!!
(nice 912-E)
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