New Alternaor Causing Missing, Stuttering, Backfiring?

[Ishman 306]

I recently replaced my alternator with a 3G 130A and removed my voltage regulator (x-police cars had them for the alternators they used). After I hooked the battery back up, and fired it up, the car immediately idled at like 500 rpm and was about to die. I have driven it probably 400 miles since then, and can't figure out whats going on. The problem comes and goes randomly and at all rpms (maybe except WOT). When its there and you hit the gas the starts to miss and act like its running on fewer cylinders and sometimes at constat rpm starts to buck around. ANYONE PLEASE HELP ME WITH THIS ONE.

The only thing I can think of is maybe I need that voltage regulator on the car even though the 3G is an internal regulated?

Here is done:
1. EGR deleted at plenum and block off plate (been like that for years)
2. set TPS (new) but can't get more than .40 volts no matter how far I turn it?
3. recently cleaned off and taped up wired going to the WOT (A/C replay)--before alternator upgrade

 

[jrichker]

Here's what the alternator wiring is supposed to look like electrically with the
exception of the black/orange wire from the battery post side of the starter
solenoid to the alternator. You should have a 4 gauge wire & 130--150 amp fuse in place of that wire

Diagram courtesy of Tmoss & Stang&2birds

See the following website for some help from Tmoss (diagram designer) & Stang&2
Birds (website host) for help on 88-95 wiring
http://www.veryuseful.com/mustang/tech/engine

http://www.veryuseful.com/mustang/tech/engine/images/IgnitionSwitchWiring.gif

http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif

http://www.veryuseful.com/mustang/tech/engine/images/88-91eecPinout.gif

The secondary power ground is between the back of the intake manifold and the
driver's side firewall. It is often missing or loose. It supplies ground for the
alternator, A/C compressor clutch and other electrical accessories such as the
gauges. Any car that has a 3G alternator needs a 4 gauge ground wire running
from the block to the chassis ground where the battery pigtail ground connects.

Picture courtesy of timewarped1972

Are you getting 14 volts while the engine is running? Have you had the charging
system checked at your local auto parts store? Most of them will do it for free.

If there are no mistakes in your wiring, 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.

 

[Ishman 306]

Thanks for the help.

I will run the codes again when I get home. Before I started trying to fix it I had codes 42 and 92 I think.


HEGO sensor circuit indicates system rich (left side) and (right side).


FYI in case it matters I am running a cobra computer and mass air and 24's.

What does this mean?

I will try and look at the wiring when I get home and pull codes again to double check. Thanks for the help, and keep any suggestions coming.

Scott