Took my car out today for the first time. Twice I had the speedometer and Tach gauge sweep to zero and check engine light come on. I had my hand held connected, which froze after the gauges sweep with voltage at 12.1. I did not notice any change in car performance. After 2 seconds the gauges went back to normal. When the car is hot, voltage drops to around 12.4 but once you bleep the throttle, it goes to 13.5 or when the car starts running and things start cooling, voltage goes to where it should be. Right now I will run cooling ducts and see how that goes.
Voltage dropping at WOT pulls. Need Help!
- Thread starter 04Mach1Blurr
- Start date
:read: hmmmm intresting! i would like to know how you fixed it
OP,
You originally posted about lack of volts at WOT and in post #21 your saying lack of volts at idle and normal when blipping the throttle. Am I following correctly? What size lower do you have. Additionally, if I understand my tuner correctly voltage table can be modified in the tune to command more or less voltage across the rpm range. Have you checked to see if they are out of whack?
You originally posted about lack of volts at WOT and in post #21 your saying lack of volts at idle and normal when blipping the throttle. Am I following correctly? What size lower do you have. Additionally, if I understand my tuner correctly voltage table can be modified in the tune to command more or less voltage across the rpm range. Have you checked to see if they are out of whack?
I was reading this thread...
http://www.svtperformance.com/forum...ly-please!&p=14152797&viewfull=1#post14152797
Perhaps excessive shaft runout/bouncing brushes are the reasons for poor output at high rpm??? Not sure why a cobra would be more suceptable to this vs. any other appliaction, maybe it just because cobra owners datalog and are aware of the issues.
http://www.svtperformance.com/forum...ly-please!&p=14152797&viewfull=1#post14152797
Perhaps excessive shaft runout/bouncing brushes are the reasons for poor output at high rpm??? Not sure why a cobra would be more suceptable to this vs. any other appliaction, maybe it just because cobra owners datalog and are aware of the issues.
I figured I would go ahead and get a new ford unit today since it's warrentied anyway and they actually ordered it and sent it to my shop and that alternator was the first one I sent back with a bent shaft! I just laughed and called them and he was like are you serious wtf I'll get another. So hopefully I'll get it tomorrow and throw it on this weekend and hopefully be done with this shit
Update*
So I had a buddy take my car to his shop today to do some more investigating. Went again with the stock alternator pulley on the new OEM alternator and made sure it was on there well. The car drove and idled in the 13s. And at WOT it went as low as 12.7 which is better, but not great. I also found out that from the battery to the ECM, the car is dropping about .3/.4 volts. I also believe that my kill switch i was using as a power distribution block was having an effect of not being completely in line and allowing full current. So my buddy just cut a piece of metal and made a temporary power distribution block and that is also what helped.
Main take away*
Car is loosing volts from the battery to the ECM. What is the fix? Is it simply upgrading the power wire?
So I had a buddy take my car to his shop today to do some more investigating. Went again with the stock alternator pulley on the new OEM alternator and made sure it was on there well. The car drove and idled in the 13s. And at WOT it went as low as 12.7 which is better, but not great. I also found out that from the battery to the ECM, the car is dropping about .3/.4 volts. I also believe that my kill switch i was using as a power distribution block was having an effect of not being completely in line and allowing full current. So my buddy just cut a piece of metal and made a temporary power distribution block and that is also what helped.
Main take away*
Car is loosing volts from the battery to the ECM. What is the fix? Is it simply upgrading the power wire?
Mine is always in the mid to low 13's under normal driving. Once I go wot, it's in the 12-12.3 range. I was told this is ok. Once your volts drop below 12, then it's time to address the issue. Maybe this is wrong?
My tuner is wanting 13s, but is saying he will see how it does with the 12.7 volts. When its charging, it should be almost 14.1
I see 13.5 while driving, and 13.0 at WOT with my terminator swapped mach. Thats on a hot day with the daytime running lights, fogs, radio, and a/c going. It is a little higher in colder weather without so much draw on the alt. I had to replace the stock failed alt with the 160 amp ebay one and so far so good.
OP,
Remember you lose voltage across connectors from the battery poles to the PCM. My voltage is ALWAYS .5v higher at the battery than at the PCM, not much you can do about it. With that said my Aeroforcetech reads 13.5v-14.4v. Did your tuner check your command voltages in the tune as I eluded to in my last post?
Remember you lose voltage across connectors from the battery poles to the PCM. My voltage is ALWAYS .5v higher at the battery than at the PCM, not much you can do about it. With that said my Aeroforcetech reads 13.5v-14.4v. Did your tuner check your command voltages in the tune as I eluded to in my last post?
He was reading off the PCM i believe, when I get a spot on the dyno I will have him check the command voltage you are talking about. Any ideas on upgrading the wiring from the battery to the PCM/ECU?
Doing so would require a full harness replacement.
Doing so would require a full harness replacement.
OP typically when these cars data log low 12s high 11s for battery voltage under WOT 99% of the time it's an alternator problem. I've personally had alternators that put out mid 11s under WOT. At night you could even see the headlights dim when you went WOT.
My current setup, auto parts store life time warranty alternator, with stock pulley and stock lower puts out around 13.1 ~ 13.2 volts at WOT and around 13.6 in normal driving. I'd say your 12.7 is pretty close and decent. When you get closer to 12.0 or mid 11s I'd be worried.
BTW - I do have upgraded grounding cables from the motor the frame. Instead of that little steel braid I have 4 gauge cable. I also have an upgraded heavy duty cable from the alternator to the distribution fuse box next to the battery.
My current setup, auto parts store life time warranty alternator, with stock pulley and stock lower puts out around 13.1 ~ 13.2 volts at WOT and around 13.6 in normal driving. I'd say your 12.7 is pretty close and decent. When you get closer to 12.0 or mid 11s I'd be worried.
BTW - I do have upgraded grounding cables from the motor the frame. Instead of that little steel braid I have 4 gauge cable. I also have an upgraded heavy duty cable from the alternator to the distribution fuse box next to the battery.
Mine always start's out in the 14's, but after the car is driven awhile the volts will drop a bit. I've never heard anyone that has there volts stay consistently in the 14's after the engine is warm and the car has been driven awhile.
I sure hope we can figure this shit out soon. So far I've tried 3 ford alternators all new grounds and upgraded my alt to fuse box feed and today on the way home it stayed between 13.1 - 12.5 and when I cracked it it saw 11 and I wanted to drive it into the trees.
Mine oscillates into the 14's after being heat soaked as you describe. That's in cab so add another .5v at the battery poles ad previously described. I'm running a 170a Billet Tech, non adjustable and internal regulator.
I pulled the trigger and bought a mechman 170. Once I get it (4-6 days to build) I'll do a full write up with details of readings also.
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