130 amp install problem....

I have installed the 130 amp alternator, and I am still haveing problems at idle. I have 1990 LX 5.0, and I have added pulley's, and even a smaller alternator pulley and it still drops way low at idle... can some one please help????

did you gheck it with a good multy meter?? cuz you the factory guages are a guesstimate, also make sure your tensioner is not worn out allowing the belt to slip.Chris

What about a new power wire? The stock wiring is barely adequate for the stock alternator, let alone the 130 amp one. I know, I fried my wiring with my 3G alternator. When I installed the new positive power wire, my amp gauge jumped up a whole notch...

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1966 Mustang, 351w -- Best ET: 13.4@105.3, street tires,blown tranny
2002 F150 XLT Supercab, 4.6L automatic -- my GF stole it!
1991 5.0 Notchback - daily driver

<font size=-1>[ This Message was edited by: 66stang on 2/11/04 8:46am ]</font>

You did not say what transmission you had in your mustang. The automatic transmissions cause the engine to idle slower (especially with stock torque convertor)than a manual transmission will idle. 86-93 Mustangs were notorious for the lights dimming at idle. This condition is more pronounced on auto transmission cars.

At one point, I had underdrive pulleys on my 89 GT (automatic) with a electric cooling fan. I killed the battery one day running the AC and idling the engine for an extended period of time (the electric cooling fan added to the load). Engine temp was rising when idling in traffic too. I went back to the belt driven fan and standard sized crank pulley to spin the alternator faster. Eventually converted over to a 130 amp 95 Mustang alternator on the cheap which finally resolved the dimming issue.

Think about your electrical load. Do you have an aftermarket stereo with additional amps that loaf along pulling 10-20 amps even with the volume turned down? Do you have aftermarket high wattage head lights and other added lighting. Now think about the AC for a minute-The standard in dash ventilation fan draws nearly 10 amps in high speed, the magnetic clutch for the AC compressor uses several amps just to keep the clutch engaged.

Personally, I think that most underdrive pulleys are best if used on the drag strip or non-air conditioned manual transmission cars. Underdrive pulleys work pretty good on some manual transmission cars on the street (depends on how small they actully made the crank pulley and how big they made the water pump and alternator pulleys). Underdrive pulleys work good on the drag stip on a properly cooled down engine. It doesn't help to have underdrive pulleys if your engine temp is 20 degrees hotter with them when you want to put your foot down on the street.

EFI Mustangs use more juice than the 79-85 carburator models did but the alternator never got upgraded. Note: A 130 amp alternator only puts out something like 25-35 amps at idle. Some aftermarket alternators do better at idle. You would have to hook up a alternator load tester to see what it puts out at idle.

Let me get off my soap box and shut up before I start sounding like a nut. Regards Lyle

Guys: What about the plug on the harness at the alternator? I got a Pep Boys alternator that came with a replacement plug that was supposed to be soldered onto the harness, but never got to it. The factory plug was not melted per se, although it was also not brand new looking. But I'm getting low readings at idle with lights &amp; accessories on. Could the plug be at fault? (Aside from the fact that i'll never get another @#$%$$#@ Pep Boys alternator). I've read about the plug being prone to melting but are they also a source of poor connectivity?

You can get a new plug at www.pa-performance.com

with those 1wire hookup alternators what do you do w/ all the other wires (the 2sets) that plug into the stock alt.?

scorcher you just take the wires that used to connect to the alt. tape them and stick them down by the head light. The power master that I installed in my 88 came with a big red wire that connected directly from the new 1 wire alt to the batt. Chris

i got a 130amp alt for a 97 taurus 3.0L (same as 95 mustang) and my lights still dimmed at idle but not as much. the i went to an electronics shop and got 8 feet of 4 gauge wire and two lugs for the ends. then i ran it off the back of the alt in front of the radiator and around to the starter synanoid (batery side) and now no more droping voltage with radio amp electric fan a/c