Bad idle, no power, alternator/power issues?

[Falcon3]

Hey all, my battery died a couple times in the last month, tested the batt, it was ok, alternator showed only 13v output so decision was made to replace alternator (Denso reman)

After replacement, at the batt it showed 13.7v charging, OBDii showed 13.3-13.4

However about a week after I did the alternator, I got a horrible rough idle, the thing barely runs, dies at stop lights, pretty bad black smoke from tailpipe (ecu going full rich). It surges and chokes when driving and even the transmission shift points are messed ok. Battery still shows 12.4-12.6 at rest, however the alternator voltage at idle fluctuates between 12.4-13.9.

I have checked all the grounds and positive leads. Used a multimeter on the main cables to the fuse box and to/from battery to alternator, there’s no voltage drop and no obvious corrosion.

Could this be symptoms of a bad voltage regulator? I imagine the fuel pump/ecu/injectors would have a difficult time managing the wildly fluctuating voltage from the alternator to keep the rig running. Did I get a bad Denso reman?

 

[riceandpho]

might need to clean out the throttle body and maf sensor so your truck can re idle. disconnect the battery again and leave it off for 30 mins,

when you start it up, leave all ac and fan off, let the truck idle at least 15 mins.
also you'll need to re initialize the windows

 

[Falcon3]

might need to clean out the throttle body and maf sensor so your truck can re idle. disconnect the battery again and leave it off for 30 mins,

Thanks for the reply. I ended up changing out battery and alternator, checked all connections and grounds- nothing. Changed the plugs (they were fouled on all cylinders from running rich), cleaned TB and MAF, double checked all vacuum lines. Still runs like shit.

It will start and run sometimes for a couple minutes just fine, then like a switch is flipped, RPMs drop and goes full rich. Giving it throttle just makes it misfire faster, not run smoothly.

 

[Captsolo]

Any codes?

 

[00GTvert]

I'm having the exact same problem with my 2005 V6 4WD. I just came in from the garage after replacing the battery and alternator with autozone products. The first start up after the swap didn't initiate a cold start/high idle which is abnormal but voltage at the terminals was near 14.5ish (analog multi meter). After idling for a few minutes voltage dropped to right around 12 which tells me its running off the battery. The car idles weakly and doesn't want to rev. Idle doesn't change much whether AC is on full blast or completely off. Everything is tight and the ground off the battery cable looks good and is tight. Dash is not reporting any CEL. Did I get a bad alternator from A-zone?

 

[riceandpho]

did you guys make sure you plug all connectors back in completely?
also check the alt-s fuse 7.5 amp

 

[00GTvert]

did you guys make sure you plug all connectors back in completely?
also check the alt-s fuse 7.5 amp

I just swapped in a 2nd autozone alternator. No improvement. Low idle, doesn't want to rev. Volts at the battery terminals show mid 12's. There is no CEL and the battery "icon" is lit like it should be when the key is in run position indicating the fused link is OK.


As far as I know there's only one signal plug and the power that gets bolted to the brass post. Both of those are on....

None of the fuses look burned/black. I pulled a few of the 7.5's and they all looked identical.

Why isn't it throwing a CEL for low voltage?

Should I try a part from Advance or Napa?

 

[00GTvert]

OK...my issue for the most part appears to be resolved.

Turns out the replacement alt I installed was in fact charging but it was idling so low voltage at the terminals was mid 12s. Once RPMs were raised to 1K it began charging normally. I cleared the TB/IAC and reseated the plugs. The truck had to learn how to idle and is now driving normally. I hope this helps someone in the future.

 

[riceandpho]

i wonder if you changed your belt too, old belt might be just stretched out a little, even when i did a temp alternator fix, i check my belts and made sure it still good. the oriley alternator functions like the factory, voltage stayed at 13.5-14.0, only had it in for a week before my high output alternator is different, uses an inch shorter belt.