Voltage problem at WOT, possibly leaning car out??

[KevinB]

Hey all, heres what the car is doing: At WOT my volts are dipping into the high 11 volts area. I think this is causing my car top lean out. At the end of the track, my 02 volts are in the 720's. At the start of the track, they are in the 790's. My car is running 11.40's at 30psi using 65# injectors and a brand new Walbro pump. It was doing this when I had 009's and an older hp pump. I thought I was just maxing that stuff out so I upgraded the injectors and replaced the pump. Still doing the same thing! BTW...the pump is hotwired of course!

Looking at DS files, my car is going to 11.9 volts. Could this cause my leaning out?? I have a newer Caspers complete wiring harness, new Caspers ground and positive battery cables. I also have a ground strap going from the battery to the frame, and firewall to bell housing bolt along with the extended grounds. Also have changed battery and alternator. Would a volt booster help this? I just ordered one from Caspers. Any other solutions? I also suffer from very slow windshield wipers and power windows. Actually the windows are pretty much at average speed I guess.

Thanks in advance

Kevin

 

[disco stu]

I am having the same problem. I am reading 14.2V until I get to about 10 psi, the it drops to 11.9V I though maybe the belt was slipping, so I put a 63" belt on it. I have tried a new 140A alternator, exactly the same thing. I have a new Caspers harness, the grounds on the harness are on the sock locations on the back of the head, and have added a large additional ground from the battery to chassis, and a 8 awg from the dash frame to the battery. I have a new ground to the engine. The positive and charge back wire are new as well. I am going to try a volt booster, but not sure that will fix my roblem since the alternator should regulate itself to greater than 11.9 volts.

I have no idea. There is no way I am maxing out the alternator, but what do I know. I would like to buy an amp clamp for my Fluke to see what it is drawing WOT, but they are very high.

The additional draw I have over stock are low imp injectors, a dual spal, a double pumper with 2 340's and an engine oil cooler with a 10" fan.

Hope we can figure this out.

 

[wagon]

I had this problem myself. I was running a FAST unit, and had to keep upping the fuel. I have 72# injectors, and I still couldn't get enough fuel in a mid 12 sec run. Jack Cotton noticed that my volts were dropping to low 12s, high 11s at the top of the run. I threw in a volt booster, and had to bring the fuel back down in the program because it was so rich. So, to answer your question: Yes, this could be causing you to lean out.

 

[KevinB]

Wagon....Thanks, I ordered a booster, we'll see if that solves it! I did a search and found pros and cons of the boosters, but I think this is the only thing that can solve my problem. That was the answer I was looking for....the booster solving problems similar to mine.


Disco Stu...are you running a booster?

 

[disco stu]

Nope, but I am bout to be. I am running out of places to find a problem area to fix.

 

[wagon]

You're welcome. I hope it fixes your problem like it fixed mine. You too disco stu. Post the results.

 

[disco stu]

Well the wasn't fixed with the volt booster, not that I fully expected it too. But at least I will have it when I do get my original problem knocked out.


Looking at my data logs, when I go WOT voltage gradually drops down. So bu the time I am at the end of 2nd I am at about 10.9. Haven't let it go any faster than that and there no need to since I can see where it starts nosing off.

I am not sure WTF the problem is.
New battery.
New power and grounds, and additional grounds.
All possible places I can think to do voltage drops are good.
And my main harness is only a couple of years old.
And yes, the dummy light is good.
Had it load tested but they could not load it over 60A.

I guess I will throw another new alternator at it. Or maybe a big hammer will fix the goddamn thing.

 

[badboy86gn2]

sounds like your alternator is taking a dump

Johnny

 

[TurboTR]

Really though, it's a normal fact of life for the volts to go down at full load. If you have enough fuel pump and injector to begin with it should not be a problem, for a reasonable voltage drop of course. EFI systems are compensated for voltage; the system volts goes down, the controller sees it and the inj pw widens to compensate.

TurboTR

 

[disco stu]

Really though, it's a normal fact of life for the volts to go down at full load. If you have enough fuel pump and injector to begin with it should not be a problem, for a reasonable voltage drop of course. EFI systems are compensated for voltage; the system volts goes down, the controller sees it and the inj pw widens to compensate.

TurboTR

I am used to that, but when voltage goes down in the 11 volt range things start to worry me. The FAST was showing almost 20% batery correction. I sure the volts would have continued to drop if I continued any farther WOT.

I had the alternaor tested on the car and it was deemed good.
BUT I took the alternator to Texas Alternator to have it tested. Even though at full speed on their machine is about 2500 engine RPM, the voltage and amperage under a load was quickly flickering off if it was ran on the tester for a few minutes. So, looks like a rotor or a regulator.

I have a warranty on my alternator, and got a replacement.

And now I have a full 14+ WOT rock steady, no volt booster.

Just beause a part is new, or it tests well initially, that does not mean it cannot be faulty.
I should have had it tested at an alternator shop to begin with. The Midtronics and other handheld testers are alright most of the time, but an old school load tester and an old school alternator guy is better.

Good luck to the rest of ya'll and thanks for the help. And thanks to Hogie for recommending this shop.

 

[TurboTR]

I've always seen mid 12's at wot. Glad you found the problem!

TurboTR

 

[Mike70gtx]

I was having same problems. Did the heavier Caspers wire from the alternator and battery. I got a 160 amp alternator at Advance Auto part # DL1400-6-4. Not sure what it goes to, maybe later model Chevy. I did a search and someone recommended it. Fits right on, just don't use one of the support brackets. I also have the 200 amp kit to rebuild by old one, but I messed it up the first time, so I had to get the one at Advance so I could get back on the road. I also added Casper's CCCI hotwire kit. More volts to the coil. After you know you have good wires, I think a higher output alternator was the answer. I also did the coill booster too. Between the two I'm running good.

 

[KevinB]

UPDATE:

After installing the Casper's volt booster, I think my problem is solved. Unfortunately my local track was closed last night, but I did manage a few highway pulls. At the track, my O2's went down to the low 700's. Without touching anything tuning wise, my O2's last night on the highway at 100+mph were in the 820's. Also had some bright headlights at WOT

 

[WH1]

Good to hear, I'm experiencing the same problem and am currently waiting on my volt booster to arrive. I hope it fixes mine like your's did.