SPO2454 - Ammeter ?
 

Hello everyone... First of all I have learned a ton and used this site along with SCOF Site to help me understand and even make improvements on my MKIII. I have owned my SPF for 3months and have put 1000miles on! Love the car as I am the 2nd owner. It currently has 22k miles on it, MFG'd in 2007.

==> I can use some feedback/help on how my Ammeter behaves. Wondered if this is normal. Here is a pic of the Ammeter (with Master Pwr OFF)... See the needle is to the LEFT of "Zero".

CAR OFF observations:
1) With Master PWR OFF Ammeter rests slightly NEG.
2) With Master PWR ON Ammeter rests slightly NEG (same as with Master PWR OFF)
3) I checked for "Parasitic" type current draws... and have 0 m-ohm draw. So none measured.

For reference I added: NOTE: I have a 1 Wire Alternator (No VR) .
- Added New Alternator (Powermaster 105amp), the old one tested fine so I keep it as a spare. It's an identical replacement.
- Added a 8ga GND wire from the Alternator GND to the BAT-/Chassis frame.
- Added the Ammeter stabilizing "fix" : RED 12ga wire from ALT+ to BAT+.
- Added New RED Top Optima , use Battery tender with PWR Mstr OFF. Battery is always at 12.6-12.7v before starting .... so battery seems good.

==> The Ammeter has always been erratic to me, but wonder if this is normal?
Note: Car is wired so with Ignition "ON" , Headlights/Running Lights are always "ON".
1) Once car starts, Ammeter moves positive as depicted in pic 2 RED Line for a few mins. Then moves back to slightly NEG (like the first pic).
2) As I continue to drive, more than 5mins or so.. Ammeter drops ,more Neg to look like pic 3 RED Line, with Lights ON.
3) Then when Fans are ON and Lights ON needles drops further to look like pic4 RED Line.
I can drive 20-30mins and the needle stays negative or moves closer to pic 2 Red Line Left of "Zero"??

Is my Ammeter out of calibration because it doesn't rest at ZERO?
Is this NORMAL Behavior or something else going on?

Feedback suggestions are welcome.....

My Car is: SPO2454 Cobra MKII 427SC. It has a Roush427SR, 4BBL 770cfm Holley & TKO600 with MSD Disty & 6AL MSD box ...

I'm guessing your ammeter is a little off.

With the master switch off, I'm guessing the position of the needle is the true zero, which looks like the right side of the indicator needle.

If you have the lights on without the engine running, the needle should be more negative.

Just after starting it, the needle sholuld be somewhat positive for a little bit, and then drift back towards "0"

If the ammeter reacts this way, I'm guessing it's OK, just that the indicator is a little off. And, If you don't like the way the gauge looks, replace the gauge.

If it doesn't react this way, then the gauge maybe bad, and therefore replace the gauge.

Just went through this with my SPF.
Your ammeter is telling you that you’re running your car off of the battery. Your alternator is either not operating properly or you have a wiring problem and the charge is not getting to the battery. Easy to test.
With all switches off, connect a multimeter to the poles of your battery and see what your battery voltage is. Should be around 12.6 volts. If not, battery needs a charge or is going bad.
Now turn on the engine and read the battery again. Should read between 13.7-14.7 volts. If not, then your alternator is not putting out enough current to keep your battery charged. Or the charge isn’t reaching the battery from the alternator. Put the multimeter on the one wire pole at the back of the alternator with the engine running. Should read between 13.7-14.7 volts. If not, alternator needs replacement.
A third culprit, and one that happened to me is that the fuse box wiring under the dash was loose and the charge wasn’t getting from the alternator to the battery. Not fun chasing that one down. Had to have a shop that specializes in hot rod wiring find that one.
And my ammeter always rests on the left side of the center Mark even when no draw is present. Has done that since new, 11 years ago.
A cheap multimeter will help you isolate the cause.

Thanks Anthony & jhv48 ...

I will check the Voltage to the battery during running soon... Before I did this , I decided to look at my fuse box wiring and see if anything is loose or looks bad.
- I checked all the GNDs on the car .. they were rock solid. Including the Dash GND.

In my Fuse Box , noticed a couple of things I'd like feedback on ...
1) The Voltage Stabilizer (top left corner of Fuse Box) appears to have a few loose connection? See the pic 1 ... at RED Arrow..
2) The Wire crimp on Fan 2 looks like it was overheated? See pic2 .. at RED Arrow. Fan 2 works fine as does Fan1 , Should I fix this?
3) I cracked the Turn Signal Relay plastic case removing it to look at the Voltage Stabilizer circuit. Need to replace it .. see pic 3... It's a Tridon 3247402 , 2-Prong Relay ... Any suggestions on a better replacement with a better plastic case?

I would check the fan connection closer. Be sure the female coupler is tight on the male connector. Tough to see from the photo but check the wire crimp on the female connector. Might be loose. The flasher cracked because of the spring clamp that held it on the fuse panel. Easily replaced at any automotive parts store. Can’t make out the other photo well but appears to be the fuel gauge power Wiring going to the 10V step-down. BTW: I have a Wiring Diagram for your car if interested.
The AMP meter is not a precision instrument. When you are crusing with the RPM’s above 2000 and the lights on and fans kick on, you will see the gauge dip negative momentarily, but the alternator output should be feeding everything at that RPM. With a little extra showing on the gauge usually. I would suggest not bothering to look for a problem until it presents itself in this case. The battery sounds well charged for your description. don’t fix it if it ain’t broken. I suggest you become acquainted with the way your car operates and make note of any differences when they occur. If you got into another Superformance I would guess that it would operate “different” than yours but not necessarily “better”. Look for something odd happening to determine a problem.
Blas

Thanks Blas .....

I have a wiring diagram from you. it came from the prior owner ..I have been using it !!!

Here is a closeup of the 10V step down .. the wires are soldered at 90degrees and they are not not shorted/touching... is there a better fix for this?

Okay all.... Here's what I did and my findings....

1) Tightened the Voltage Stabilizer connections... crimped and compressed the female connector for a tight fit... It's definitely better...
2) I pulled Fan 2 wire out of fuse box.. compressed the wire connection as well as the female connector .. reinstalled it.
3) Checked the 10V Fuel Gauge step down wires.. spread them apart to assure no opportunity for shorting. There is at least a 1/16 inch space between tabs..

Then...
- Measured the battery voltage before starting: 12.6-12.7V
... Started the car .. at idle cold with choke ~1200 RPM ..
- Lights are ON (Always ON when car is running) .. Ammeter is slightly Positive (Right) of Zero, similar to original Pic1 in first post.
Battery Voltage measured 14.6-14.7V ...

So .. I think my Alternator and charging is working... my Ammeter is most likely a little out of calibration...

Will run the car tomorrow and measure battery voltage after it warms up.. with Lights ON and Fans running ... then report back the results...
I'll also must add a new Turn Signal Relay since I broke the cheap case..:mad::mad::mad::mad::mad::mad:

Again .. many thanks for the guidance and advice!

Connections look like all the others on the 10v stepdown. No need for concern. You might check the snugness of the two wire posts on the drop down fuse panel. Don’t over tighten or you will pop the post off the tray. I never liked the ny-locks used there. A nice brass nut wit lock washer is a better choice.
Blas

I have the EXACT same meter. It rests at the EXACT same place as yours when the key is off...

Here's the Lucas ammeter that was going into my car (it's not period correct for an early 289, so I'm using a different one). Note....still in box.

Looking like the "zero" error isn't unusual :D



Cheers!
Glen

Here's my Smiths gauge with the battery out of the car. The needle was always slightly to the left of zero. Even when the gauge was sitting on the kitchen table.:cool:

http://38.134.118.239/ampgauge001.jpg

I was told the Lucas amp meter were period correct for the 427 cars. My gauge sits a little to the left of zero as well. I guess this is normal?

No, it's not normal. It just means all of our Lucas and Smiths stuff is basically POS gauges to begin with, albeit with ridiculously high price tags.:cool:

Thanks everyone for the reassurance & confirmation.....

As promised I just took the SPF out today ... fully warmed it up and I have some data to share....
1) Needle behavior seems normal... initially it moves to the RIGHT of Zero after starting.... but eventually rests back to left of Zero while running....
2) Voltage to Battery when started up at about 900RPM .. is 14.5-14.6V ... this is with Lights ON and car running since my car is wired for Lights ON when ignition is ON.
3) Voltage to Battery after running the car on the road so it's fully warming with Lights ON Battery voltage is 14.2-14.3V ... then when I turn Fans ON the voltage measures 13.7-13.8V... I assumes this is because they draw some many amps....
4) Ammeter when Fans are ON drops then gradually creeps back up to just Left of Zero.. which is normal given the Smiths Ammeter gauge.
5) When I shut the car off, turn OFF the Master PWR Switch ... Battery reads 13.2V ...

Couple of conclusions ...
- My Powermaster 105amp Alternator is putting out higher amperage (since my Voltage is 14.6-14.7V at initial 1200RPM), since I ran a Heavy 8gauge GRD from ALT directly to chassis Battery Neg. This moves my Ammeter needle to POS .. more than previously. I got this from SCOF website.
- I did fix some marginal connections, not sure that helped much... however it's better than before so I feel more secure.
- I noticed now my Tach is more accurate ... at low RPM''s my Smiths Tach would read ~1100RPM, yet my timing light would read ~900RPM... now the Smiths Tach is within 100RPM of my Timing light (still slightly lower but much closer).

BTW .. Blas thanks for the schematics !! Invaluable to me a novice MKIII owner. I also checked the Screws in the Fuse Box and all were locked in place tight so no need for me to try tightening any.

Again.. please accept my thanks for all the encouragement, insight and feedback... this makes driving the SPF even more enjoyable and spirited!!

Stay safe all and thanks!!

Looks like the anomaly concerning the zero error has been around for a while ;)

Here's the vintage Lucas ammeter that is now fitted to my car....

Attachment 34940

Zero error been around for a long time!

Cheers
Glen

OP and comments seem to provide good rationale for voltmeters instead of ammeters. LOL

Both work fine but you need to learn how to interpret the information each gives you.

After my recent melt down under the dash, I got rid of the amp meter and replaced with a volt meter. Not sure if the newer cars are wired different. On mine (1436) the main output wire from the alternator goes to the fuse panel, from the fuse panel to the amp meter, then out to the solenoid. So all the power was running through the dash!
I removed all those wires and ran the main output wire from the alternator (bigger wire) to the solenoid, then I ran a new wire from the solenoid to power the fuse panel. Installed a new volt meter and hooked a switched wire to it.
http://www.clubcobra.com/photopost/d...27_210600.jpeg
http://www.clubcobra.com/photopost/d...510_160928.jpg
http://www.clubcobra.com/photopost/d...505_135147.jpg

I would recommend you loose that master foil fuse and buy something a bit more modern. Go to an after-market stereo shop and get a glass fuse and holder or a Maxi-fuse and holder at an auto parts store. What kind of meltdown did you have?
Blas

Hey Blas,

Yes, I agree with the updated fuse. I had some picked out on Amazon, but I didn't do it.
Well, it is kinda interesting the way it happened. Keep in mind my car is 1436, has over 50k miles, and I have never had electrical issues once I tossed out the 50amp alternator. There is only one reason why I think the main wire from the alternator to the fuse panel got so hot, it melted the insulation on the wire, the nylon lock nut plastic, and melted the glue on the post and basically melted the fuse.
I had just my carb back on the car and had the AF meter hooked up which I have used many times in the past. I had recently upgraded the head lights ( come to find out they are the same watts as the original, just brighter)and also the small running lights inside the headlight housing to brighter ones.
I took the car out for a ride with the AF meter on. I have always used it during the day and never at night. The AF meter takes a bit power to heat up. Once the car was warm and the AF meter was running, I set out for a ride. I forgot I needed to get gas, so I stopped and shut everything down. After gasing up, I reheated the AF meter, turned on the lights and took off. I don't recall exactly what happened when I was driving, but the AF meter shut off, so I restarted it. This happened a few times, but I really didn't think too much about it. As I was driving I could smell plastic buring thinking some DipS was just bring plastic. As I pulled in the driveway I could still smell it. I dropped the fuse panel and saw the melted wire etc.
So the only thing I can think is between the headlights and AF meter trying to heat up, the alternator was putting the power in, but the small stock wire could not handle it.
As I mentioned above, I put a 8 gauge wire from the alternator to the solenoid, then I used the one amp meter wire to power the fuse panel that comes off the solenoid.
Scott