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So, I noticed that my factory alternator seemed to be getting weak, so I opted to go high output with a 220 amp alt. I notice that the new alt is running kind of similar to my factory on. Once the car warms up and idles down, my voltage goes from 14.2-14.5 down to 12.5. Similar to my old alt. Only difference being that when I tap the gas the new alt jumps back up much faster and stable than the old one.

But this voltage drop is messing with my remote start, and I'm starting to think I need to find out more about the voltage regulator. On an 03 duratec, is the regulator internal in the alt, or is it in the PCM or ECU?

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So, I noticed that my factory alternator seemed to be getting weak, so I opted to go high output with a 220 amp alt. I notice that the new alt is running kind of similar to my factory on. Once the car warms up and idles down, my voltage goes from 14.2-14.5 down to 12.5. Similar to my old alt. Only difference being that when I tap the gas the new alt jumps back up much faster and stable than the old one.

But this voltage drop is messing with my remote start, and I'm starting to think I need to find out more about the voltage regulator. On an 03 duratec, is the regulator internal in the alt, or is it in the PCM or ECU?

AltCgWagn_zps2bfa144e.jpg

 

Just did this one today, chart by carchip recorder and I put in XL format. Warm engine idling with all power except rear defog maintains over 13V and holding.

 

Factory alt 126K miles on it. This should be normal for DOHC. If you do not hold this value, it is not the reg. It is the alt not spinning fast enough or weak alt.

Amps rated at ~6,000 engine rpm not at normal run rpm or idle. I would check to be sure pulley is the right one, otherwise maybe something using a lot of juice.

Likely not the bat at fault unless it is really bad.

 

Best on this one.

 

-chart-

 

-

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I did notice that that the pulley on the new alt is smaller, but that would actually make it turn faster, thereby creating more power even at idle. And once I even tap the throttle, voltage immediately jumps to 14.2-14.5. I can turn off all electronics, including eatc, stereo, amps, and all lights. Still 12.5 at low idle. And battery is still very strong, about two years old on front battery, about 3 years old on isolated rear deep cycle battery.

Should I be contacting the new alt manufacturer? I just put it in last month, and is been this way since I fired it up. Just finally tracked my remote start problem to this. Now I'm annoyed enough to deal with it.

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I did notice that that the pulley on the new alt is smaller, but that would actually make it turn faster, thereby creating more power even at idle. And once I even tap the throttle, voltage immediately jumps to 14.2-14.5. I can turn off all electronics, including eatc, stereo, amps, and all lights. Still 12.5 at low idle. And battery is still very strong, about two years old on front battery, about 3 years old on isolated rear deep cycle battery. Should I be contacting the new alt manufacturer? I just put it in last month, and is been this way since I fired it up. Just finally tracked my remote start problem to this. Now I'm annoyed enough to deal with it.

If the new alt has smaller pulley, the belt may be slipping.

And I do not see how the alt has anything to do with remote start.

-chart-

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I find that graph very interesting Chart, compared to my Explorer the voltage is low.  Explorer read a steady 14.5-14.9 volts with the old alternator, no matter the load. New alternator is exactly the same, always above 14.5 volts, even with headlights on, blower on max, and radio cranked.  Just shows the difference between vehicles, you never seem to get above 14 volts, the Explorer never seems to drop below 14 volts. 

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The new pulley is only about 25% or so smaller, and the belt still feels good and tight. Even took a bit of force to get it on. I don't notice any flickering or dimming lights.

As far as the remote start, the current programming/wiring monitors the vehicle voltage, watching for the straight battery voltage, the dip in bat voltage during cranking, then the spike in voltage as the alt takes over and charges. It will continue to keep the car running as long as the vehicle voltage is high enough, which I think is around 13 volts.

When the car is cold started, it immediately rises to roughly 1200 rpm. The voltage is strong at 14.2 volts at that rpm. As it warms up, the first drop in rpm comes down to roughly 750 rpm. This is where the voltage drops to 12.5. The remote start sees this drop, assumes the car has stopped running, and kills power so as to not kill the battery.

I can re wire it to hook directly up to the tach and reprogram it to work, but I feel like that's not solving the problem of the voltage being low at idle.

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Check that your PCM harness is good and tight at the firewall. Mine has this issue where it keeps coming loose and causes all sorts of electrical issues. I replaced the alt twice thinking that would solve the problem and it didn't. My PCM harness is getting loose again right now. As soon as the weather goes above 60 degrees I'm going to put some threadlocker on the retaining bolt.

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The new pulley is only about 25% or so smaller, and the belt still feels good and tight. Even took a bit of force to get it on. I don't notice any flickering or dimming lights.

As far as the remote start, the current programming/wiring monitors the vehicle voltage, watching for the straight battery voltage, the dip in bat voltage during cranking, then the spike in voltage as the alt takes over and charges. It will continue to keep the car running as long as the vehicle voltage is high enough, which I think is around 13 volts.

When the car is cold started, it immediately rises to roughly 1200 rpm. The voltage is strong at 14.2 volts at that rpm. As it warms up, the first drop in rpm comes down to roughly 750 rpm. This is where the voltage drops to 12.5. The remote start sees this drop, assumes the car has stopped running, and kills power so as to not kill the battery.

I can re wire it to hook directly up to the tach and reprogram it to work, but I feel like that's not solving the problem of the voltage being low at idle.

Clearly someting is wrong. I now get why the remote quits. I get average of 4 readings 5 seconds apart warm idle in gear.

13.13V with full elect load.

13.61V with only the engine and no added usages.

 

Your cold idle should be a bit higher than my hot and in gear. My pulley is 3 1/8" dia at the flange. So unless someone had put underdrive pulley on the carnk things do not add. Maybe some heavy load but highly likely not heavy enough to pull the alt down.

 

-chart-

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Check that your PCM harness is good and tight at the firewall. Mine has this issue where it keeps coming loose and causes all sorts of electrical issues. I replaced the alt twice thinking that would solve the problem and it didn't. My PCM harness is getting loose again right now. As soon as the weather goes above 60 degrees I'm going to put some threadlocker on the retaining bolt.

I remember you talking about that in another thread. IIRC, you gave the location as well as another couple details about that harness. Could you point me in the direction of that thread, or the PCM harness?

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Clearly someting is wrong. I now get why the remote quits. I get average of 4 readings 5 seconds apart warm idle in gear.

13.13V with full elect load.

13.61V with only the engine and no added usages.

Your cold idle should be a bit higher than my hot and in gear. My pulley is 3 1/8" dia at the flange. So unless someone had put underdrive pulley on the carnk things do not add. Maybe some heavy load but highly likely not heavy enough to pull the alt down.

-chart-

I'm not completely understanding what you're telling me. You saying that smaller pulley on the new alt is too small? Or that is probably something else entirely, like a loose PCM harness? Or that somebody has possibly put an underdrive pulley on my motor before I got it? The last one is doubtful, based on the model, mileage, and condition when I bought the car, though I won't rule it out.

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I'm not completely understanding what you're telling me. You saying that smaller pulley on the new alt is too small? Or that is probably something else entirely, like a loose PCM harness? Or that somebody has possibly put an underdrive pulley on my motor before I got it? The last one is doubtful, based on the model, mileage, and condition when I bought the car, though I won't rule it out.

A smaller alt pulley whould help it charge at idle. As a 2003 it has PCM contol of volts, but that is a very small adjustment. Mostly for air temperature but it also can reduce charging for WOT to boost max power for a short time.

 

Added a pic of voltage range for testing. This for cars using PCM adjusted volts output. The center wire from the Alt (Lite blu/Red) is the adjusting wire signal. It indicates 0-3volts in both testing modes. For cars that do not adjust like my '01, they just ground that wire and that is that. You could just cut that wire and ground it on the alt side and terminate pcm adjusting and make it like older years. My Lin Cont using the same alt does not adjust. They do not have a center wire in the harness and nothing connects to that terminal on the alt. Guess there is no reason to reduce charging on WOT for that one. And the Intech spins the Alt 50% faster than the DOHC.

 

Best of luck.

 

-chart-

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I had the same problem with multiple high output alternators. I would try what chart said by grounding the PCM wire. Either that or go back to a stock alternator =/

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I remember you talking about that in another thread. IIRC, you gave the location as well as another couple details about that harness. Could you point me in the direction of that thread, or the PCM harness?

 

Here's how you get to it:

 

Remove the cowling on the passenger's side. The yellow arrows show the clips and bolts you need to remove. Be careful with the evap line (green arrow.) You don't have to worry about the red arrow. That's an '04+ Vulcan specific part.

 

valve_arrow.jpg

cowl_screws.jpg

 

Once the cowling is off you have easy access to the PCM harness on the firewall. Pretty easy to spot - lots of wires going into it. You also gain access to the cabin air filter behind the strut tower. If you've never changed it now might be a good time.

 

cowl_removed.jpg

 

Hope that helps!

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So, I noticed that my factory alternator seemed to be getting weak, so I opted to go high output with a 220 amp alt. I notice that the new alt is running kind of similar to my factory on. Once the car warms up and idles down, my voltage goes from 14.2-14.5 down to 12.5. Similar to my old alt. Only difference being that when I tap the gas the new alt jumps back up much faster and stable than the old one.

But this voltage drop is messing with my remote start, and I'm starting to think I need to find out more about the voltage regulator. On an 03 duratec, is the regulator internal in the alt, or is it in the PCM or ECU?

Curious what method you used to remove the Alt.

AltBolts_zpsb8adbd8a.jpg

I had mine loose but not off to do some other work. I modified the bolts to make it easier next time.

On the bolt I shortened, pays to put the nut on before cutting it off and then remove the nut to strighten the thread in the cut area.

Of course, I cut mine on my lathe and filed the thread end for a bevel.

-chart-

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Let me start this by saying that I initially found the lower voltage at idle minutes after I installed my new alt alt a month ago. That's when I saw 12.5 volts at idle. I let it go because I had other things to tend to. When I got home last night, I checked it via obd port again, and got down to 12.5 volts, but seemed to be holding there. Then I decided to check on the PCM harness.

Here's how you get to it:

Remove the cowling on the passenger's side. The yellow arrows show the clips and bolts you need to remove. Be careful with the evap line (green arrow.) You don't have to worry about the red arrow. That's an '04+ Vulcan specific part.

valve_arrow.jpg

cowl_screws.jpg

Once the cowling is off you have easy access to the PCM harness on the firewall. Pretty easy to spot - lots of wires going into it. You also gain access to the cabin air filter behind the strut tower. If you've never changed it now might be a good time.

cowl_removed.jpg

Hope that helps!

I actually just popped the hood and tracked some wire, and found the most logical ( and in the end, right) harness. Luckily, on an 03 duratec, the "red arrow item" is nonexistent, and creates a perfect hole to stick a hand and socket wrench into, without removing the cowling. Bolt definitely seemed lose. I think it took about 2.5-3 or so turns before it stopped. I thought it helped, judging by the 14.2 volts I got at idle afterwards on my obd port.

Wrong.

I let the car cool down for a couple hours, and came back out and tried again. Initial start, nothing electrical on, got 14.5. Then it dropped idle, and slipped down to 12.4-12.5. Decided to load it down. Turned on headlights, foglights, ac, and stereo, and dome lights. Voltage dropped to 11.7. Touch the throttle, jumped to 14.2 immediately. Headlights brightness dependant on rpm.

Something is definitely wrong here. When i get home tonight I'll get in there again, this time with a multimeter direct on the battery instead of the obd. I want to rule out the route of my Big 3 upgrade as the issue. But if it still fails, I'll be contacting the seller of my alt.

Chart, this is the method i used. Didn't cut any bolts. Just took some jingling and jangling. Book calls for 6 hours to replace alt on my duratec. I'm confident with this method I could do it in two.

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Update: just got home. Checked both batteries while connected and while isolated. Both batteries are over 12 volts without charge. Start car, without electronics on, voltages are slightly over 12, with them on, 11.7.

These tests were with a multimeter. But they match the obd scanner.

I've already emailed the seller of the alt, waiting reply. I'm truly inclined to believe that it's a weak alt at this point.

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You don't happen to have an underdrive pulley do you?

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You don't happen to have an underdrive pulley do you?

No underdrive pulley to my knowledge. I bought the car 8 years ago with 41,000. The shape I bought it in would make me highly doubt the previous owner put one in.

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Speaking of underdrive pulleys again, Chart, is that 3 1/8" measurement from the crank pulley or from the alt pulley?

Probably won't hear back from db electrical on my alt until Monday. Figure I could look at a couple things while I'm waiting.

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Speaking of underdrive pulleys again, Chart, is that 3 1/8" measurement from the crank pulley or from the alt pulley?

Probably won't hear back from db electrical on my alt until Monday. Figure I could look at a couple things while I'm waiting.

Adding a pic. Shows how it is measured.

 

Since I can't remember things, I take pics to remind me.

 

Hard to believe you underdrive is available for G-4 DOHC. It is made on a shaft with large LH threads to screw into the crank. All one part.

 

-chart-

 

OK added overdirve pulley for Alt. This is from common V-8 rear drive Ford prod. Approx 50% faster rpm of Alt. Belt length different of course. Does not address why your Alt does not charge it idle though. The Alt can stand the speed. My Lin used a larger crank pulley and medium dia alt pulley for 50% faster Alt rpm compared to '03 DOHc, according to Alldata. For that car, it has redundant lights so lots more load to run at idle. The 130A Alt is common from Lin, most rear drive V-8, DOHC. Different mounting, same parts.

 

-chart-

Edited by -chart-

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My factory alt has the same 3 1/8" pulley. The ** alt still in the car has roughly 2 1/2" (its tougher than it seems to get an accurate measurement without removing the part).

Haven't had a chance to measure the crank pulley (my 2 1/2 year old requires attention too haha) yet, but it looks big and black. Or, "factory looking". Haha ill measure that in a little while.

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My factory alt has the same 3 1/8" pulley. The ** alt still in the car has roughly 2 1/2" (its tougher than it seems to get an accurate measurement without removing the part).

Haven't had a chance to measure the crank pulley (my 2 1/2 year old requires attention too haha) yet, but it looks big and black. Or, "factory looking". Haha ill measure that in a little while.

Measured pulley dia with belt pieces around it with caliper.

 

See pic attached, and % change from DOHC standard pulley.

 

The crank pulley will not be easy to measure.

My pulley collection from JY scrap pile.

 

And as to removal of Alt from G-4. I did one on G-3 way back and I took the pulley off inside the engine bay with an electric impact. Made it easy. Same putting it back. My old pre WW-II Ingersol impact still ticking. Inherited it from my dad. Life saver for working on cars.

 

-chart-

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Why did i not think of my caliper? Ugh. Children make it difficult to concentrate sometimes... haha

Well, scratch that. No way I can get the caliper in there without unbolting something, which I refuse to do without the new alt in front of me.

Now, what about grounding out that wire? Are there any risks in doing that? If I do it, I plan on doing it in a way that will make it easy to reconnect the wire if necessary. But will it potentially mess anything up grounding it out in the first place? Or is it a pretty safe bet?

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Why did i not think of my caliper? Ugh. Children make it difficult to concentrate sometimes... haha

Well, scratch that. No way I can get the caliper in there without unbolting something, which I refuse to do without the new alt in front of me.

Now, what about grounding out that wire? Are there any risks in doing that? If I do it, I plan on doing it in a way that will make it easy to reconnect the wire if necessary. But will it potentially mess anything up grounding it out in the first place? Or is it a pretty safe bet?

 

ChargingDiag_zpsd9bc3ab5.jpg

This is the diag of the system on years that do not adjust the volts but just gound the center wire in the PCM. If you cut this wire and ground the end going to the Alt and leave the end to the PCM open, it should disable the PCM control of the Alt and make it like the '01 that I have that does not control that. There must be some reason they run the wire to the PCM and just gound it, but it leaves the option open to do PCM control with the same wiring harness and alt plug in future years. Someday I am going to put my volt meter plug in the power port on the '03 and do WOT and see where the volts goes. It needs some exercise anyway.

-chart-

 

-

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So I got a battery tester, and used it to determine that my primary battery and starter are definitely good. The alternator seems to be checking out as well. My auxiliary battery seems to have a little bit of a high charge on it, but not so much that I'm concerned. However, I disconnected the auxiliary battery from the charging system, started the car, and checked voltages. Still 11.7 volts at low idle. So chart, your idea is next up tomorrow night. I've traced the PCM control wire to the top of the motor, where I'll cut it and ground it. I figure this way, if it doesn't work or if it has negative results, it'll be easier to reconnect the original circuit. I'll let you know how it turns out.

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