unusual problem.need some ideas??

dwhiskie

New Member
Sep 18, 2004
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Theres 2 grounds from my - batt termanal. 1 to the block and 1 grounds with the 1 that comes out of the harness to the inner fenderwell behind the battery. The problem is, When this is hooked up, the idle will jump up about 500rpms and stays there when I turn on the headlights but the car runs great. If I take this ground off, It idles rough and has a miss but the rpms dont change when I turn on the lights. All the other grounds are where they are suppose to be. Any ideas as to what the problem could be?? So far, nobody has been able to figure it out. Any help would be great.
 
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It sounds like you're talkin about the EEC's ground. In OEM form, it has what looks like a glass fuse holder about 6" from where it bolts to the inner fender.

Jrichker has posted pics of this before.

Good luck.
 
As JRichker has said in the past...its a good idea to upgrade your grounds. So, if you are experiencing engine RPM change by turning on the headlights (I think I read that right?), you have something fishy going on electrically speaking. May want to search (or jrichker may post) on upgrading the grounding setup.

Just my $0.02. Hopefully someone who knows more than I will post up about it.

EDIT: BTW, HISSIN knows more than I, lol. But Jrichker or TMOSS would be your electrical super heros. :nice:
 
srothfuss said:
The ground next to the battery on the driver inner fender is the EEC ground. Without it connected, the computer is probably not too happy...

Edit: Here is JR's post on grounds In my 3G install thread

The eec ground is there and hooked up. Theres another blk 4g comming from the neg batt and is mounted in the same place as the eec ground. If its not suppose to be there and I remove it then the engine has a miss/stumble as I slowly up the throttle but the rpms dont change when I turn on the headlights. I am completely stumped on this one??
 
dwhiskie said:
The eec ground is there and hooked up. Theres another blk 4g comming from the neg batt and is mounted in the same place as the eec ground. If its not suppose to be there and I remove it then the engine has a miss/stumble as I slowly up the throttle but the rpms dont change when I turn on the headlights. I am completely stumped on this one??

Thanks for the link. I noticed in the first pic, there is the smaller eec ground and it also looks like there is a bigger wire on there to."that looks like mine" but in a couple pics down its shows the same area without the batt and it looks like there is only one wire "the eec ground"
 
criticman said:
But isn't he (aren't you) saying that with it hooked up, you have the weird RPM increase when you hit the headlights?

But yeah, you need that sucker hooked up.

With the other larger ground hooked up, Thats when I get the raise in idle speed. One other thing I noticed is if I turn the headlights on before I start the car, it doesnt effect the rpm`s as much.
 
Have you messed with the wiring at all since you have owned this stang? Not trying to point fingers, but if wires are missing, someone did something to them (or they were abducted - always an option lol).

Something is obviously not right though, regardless of if your grounds looks like the ones pictured or not. You are having issues when electronics are turned on (and depending on when they are turned on).
 
criticman said:
Have you messed with the wiring at all since you have owned this stang? Not trying to point fingers, but if wires are missing, someone did something to them (or they were abducted - always an option lol).

Something is obviously not right though, regardless of if your grounds looks like the ones pictured or not. You are having issues when electronics are turned on (and depending on when they are turned on).

No, I just put a new motor in but I had this same problem with the last motor to. I just discovered that this larger ground is where the problem is from but now just got to figure out why.
 
Dump the codes and see what the computer says is wrong…

Here's the link to dump the computer codes with only a jumper wire or paper clip and the check engine light, or test light or voltmeter. I’ve used it for years, and it works great.

See http://www.troublecodes.net/Ford/
OR
See http://www.mustangworks.com/articles/electronics/eec-iv_codes.html

IF your car is an 86-88 stang, you'll have to use the test lamp or voltmeter method. There is no functional check engine light on the 86-88's except possibly the Cali Mass Air cars.

Codes have different answers if the engine is running from the answers that it has when the engine isn't running. It helps a lot to know if you had the engine running when you ran the test.

Trouble codes are either 2 digit or 3 digit, there are no cars that use both 2 digit codes and 3 digit codes.

For those who are intimidated by all the wires & connections, see http://www.actron.com/product_detail.php?pid=16153 for what a typical hand scanner looks like. Normal retail price is about $30 or so at AutoZone or Walmart.

Or for a nicer scanner see http://www.midwayautosupply.com/detailedproductdescription.asp?3829 – It has a 3 digit LCD display so that you don’t have to count flashes or beeps.. Cost is $35.

I suspect you may have problems with the signal ground for the ECT, ACT, TPS, EGR and MAP/BARO sensors. They use a separate ground from the power ground for the alternator.
 
jrichker said:
Dump the codes and see what the computer says is wrong…

Here's the link to dump the computer codes with only a jumper wire or paper clip and the check engine light, or test light or voltmeter. I’ve used it for years, and it works great.

See http://www.troublecodes.net/Ford/
OR
See http://www.mustangworks.com/articles/electronics/eec-iv_codes.html

IF your car is an 86-88 stang, you'll have to use the test lamp or voltmeter method. There is no functional check engine light on the 86-88's except possibly the Cali Mass Air cars.

Codes have different answers if the engine is running from the answers that it has when the engine isn't running. It helps a lot to know if you had the engine running when you ran the test.

Trouble codes are either 2 digit or 3 digit, there are no cars that use both 2 digit codes and 3 digit codes.

For those who are intimidated by all the wires & connections, see http://www.actron.com/product_detail.php?pid=16153 for what a typical hand scanner looks like. Normal retail price is about $30 or so at AutoZone or Walmart.

Or for a nicer scanner see http://www.midwayautosupply.com/detailedproductdescription.asp?3829 – It has a 3 digit LCD display so that you don’t have to count flashes or beeps.. Cost is $35.

I suspect you may have problems with the signal ground for the ECT, ACT, TPS, EGR and MAP/BARO sensors. They use a separate ground from the power ground for the alternator.

I have a scanner but it wont let me do test while running. I got code 67-(neutral safety switch) but there isnt anything wrong with it so dont know how to fix that. On my last motor my TPS was having a problem. I would set it then once I started the motor it would change so I had to add a seperate ground to signal return (pin 46) I tapped into that #46 wire at the computer and grounded it where the computer is grounded under the carpet (pass side by kick panel)
 
Ran koeo and this is what it says
22,63-TPS is set right and goes from .98v to 5.40v 64,35,67-nuetral safety switch-It works so I dont know what to fix? Cant run koer test with code 67
 
Hmm...auto or manual? I got code 67 once, I think...no clue though.

I know mine, when following directions that came with code scanner, required me to tap the gas, hold it over x rpm for a few seconds, or something like that...