Surging voltage question

Squid4life

Well-Known Member
Joined
Jul 5, 2004
Okay, now thta I "solved" the low oil pressure issue, I have a voltage issue.

When the car is running, the fuel pump sounds like it is surging, and when driving at night the gauges and headlights surge as well. I have all the grounds from the pass side attached to a stud on the intake manifold. I have the FP hot wired, so I am thinking it may be my alternator.

All lights go bright-dim-bright-dim in about half-second intervals. Also every once in a while on the Tlink when accelerating the voltage goes down, not up. But the fuel pump does raise psi with boost psi (verified only to about 5)

Sound like bad alternator, or ground?
 
Squid4life said:
......... When the car is running, the fuel pump sounds like it is surging, and when driving at night the gauges and headlights surge as well. I have all the grounds from the pass side attached to a stud on the intake manifold. I have the FP hot wired, so I am thinking it may be my alternator. ......... Sound like bad alternator, or ground?

Does the voltage fluctuate on your scantool or just go down and stay down?
Belt slipping?
Battery checked and verified?
Alternater checked at your local parts store?
 
I just pulled it off, had it tested at 8 places. Yes, 8. Two said it was good. One said it was marginal, but so was their BRAND NEW one! The rest said it was bad but couldn't really say why. I am reinstalling it, checking more grounds/connection again, then drive it to them to load test that way.

Belt is new and the idler keeps it nice and tight. Haven't had batt tested but seems ok.

When accelerating, voltage drops then comes back up. The big thing is the lights flutter as well as the FUEL PUMP. You can hear the fuel pump do the high-low pulsate, not steady like it should be.
 
"""Second point might be to verify that the small brown wire to the alternator from the volt lite in the dash is always hot. Sometimes that circuit will be intermittent and cause the alternator to charge/not charge.""

What wire are you talking about? I have the following wires:
1. Alt hot to harness
2. Hot wire for fuel pump
3. The regular alt connector

4. A mysterious wire that doesn't seem to attach to anything. Is this the wire? Pic attached.
 

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Squid4life said:
4. A mysterious wire that doesn't seem to attach to anything. Is this the wire? Pic attached.

That aint a mystery wire, its the brown wire that must connect to the alternator to make it charge.
Top right hand side under that loom is where its at.
If you had a multimeter, you would see that the alt wasnt charging with that wire unplugged.
I can post a pic of my alt.
BW
 
You can see in the pic, this is where it plugs into
BW
 

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Sorry, Bryan, I should have been more clear. The plug pictured in the very front (thumb/pointer finger) is the one you are talking about, and it was hooked up. I though we were all talking about either one not pictured, or the one on the right bottom, non insulated plug (middle finger and ring finger).

I had it hooked up, the alt was charging, but was surging. Even made the fuel pump surge :eek:

Through some checks it seems my rectifier and possibly the diodes are bad internally. I am getting AC volts at the battery connections...

I can get the correct alt locally for $100 from Auto Zone, but am going to try another place I can get stuff at cost still. I would like to rebuild it, but can't seem to find a rebuild kit for it. turbo buicks has an upgrade kit for $79, but I need it ASAP. We'll see.

Thanks again!!!
 
Squid4life said:
............. I am getting AC volts at the battery connections........
Ouch! :eek:
Have the battery checked. Could have damaged it (??)
 
With new alt, AC voltage at 2000 rpm is nothing, however sitting not running it does read AC voltage. (27.3 if I remember right)

Alt fixed the surging lights and fuel pump.

Now time to fix a knock problem.... :mad:
 
Glad to hear the alt fixed you up.Make sure your knock isnt only a loose Grd on passenger rear head,or exhaust hitting somewhere.If your numbers are in line from say a scanmaster reading,chances are something may be hitting.
 
Squid4life said:
........... Alt fixed the surging lights and fuel pump. ......... Now time to fix a knock problem.... :mad:
With the new alternator resulting in good voltage, you may just need to tune a bit to get of the knock.
 
Oil pressure is holding at ~12 hot idle in gear. Lights and fuel pump no longer pulsate. Car is quiet (too quiet after having open THDP!!!).

Yeah, I am still trying to figure whether it is real or false knock. I need to put some race fuel in and see if it goes away, but just filled the tank this weekend with 91. When I was at the exhaust shop with the rear end hanging my exhaust touches the mufflers to the driveshaft, and you can see it has rubbed recently while driving. Also, the rear upper control arms are VERY close. I need to get underneath with weight on the rear to see if it can hit the driveshaft, or anything else and cause falsse knock. I get knock on the knock gauge and TLink.

I'm getting there... :rolleyes:
 
Believe me, if your seeing knock, then its really there.

Ive never heard of the exhaust hitting the driveshaft causing false knock.

What i would check for first is... Good 7/32 check valves on the intake, one is right next to the egr and the other is inline leading to the charcoal cannister.
Then make sure you have good fuel pressure.

How much knock?
BW
 
Strange thing is I get knock at launch, then it goes away. I get a little knock at launch, then again when it shifts sometimes, but it goes away and I run it WOT to about 100 MPH and no knock. I have read that the knock is real if it gets progressively worse, but false if it starts, then goes away.

I have a 91 octane chip in from Eric, running 91 octane, with about 2-3 gallons of 110 left in there. I also tried a "booster" from my buddies race shop. It is a home brew that has toulene, and two other ingredients that I forget. (you have to have an ATF license to get one of them... :eek: ) It is supposed to raise 91 to 99.5 octane.

I still got knock with this. I know I need try it on pure 110, but still had a full tank so I did the additive.

Bryan, you don't think that if something is hitting (tailpipes hitting control arms/ mufflers hitting driveshaft) that if it "sounds" similar to knock the knock sensor may pick it up?

I have a few runs saved from Tlink, but I am not very good at deciphering it totally yet and troubleshooting with it. If anyone wants to take a look at it, let me know.
 
Squid4life said:
All lights go bright-dim-bright-dim in about half-second intervals.
This is caused by a bad capacitor. Its job is to filter ac voltage. It costs about $5.00 at the dealership. It's the little black rectangular thing that connects between the regulator and the rectifier. There's almost never a need to replace the generator. You can usually fix it by replacing the rectifier,regulator,capacitor,or brushes.
 
Bryan>>>""What i would check for first is... Good 7/32 check valves on the intake, one is right next to the egr and the other is inline leading to the charcoal cannister. Then make sure you have good fuel pressure.""

I have the check valves in place, tested before installed. Both have the white/gray away from the hard lines. Fuel pressure is good at idle, plus raises with boost.

I am still getting knock, but I am only seeing it on TLink and on the gauge. It is REAL bad during spin. I go from a roll at 30 or so and the tires spin, sometimes get wheel hop and it gets worse. I installed the airbags this am, and now get wheelhop like a MF'er. What kind of pressure is normal in each side?

I also found my driveshaft was hitting the muffler. Here is a pic or two. You can see in pic one the driveshaft has been rubbing the muffler. In the second pic, you can see the DS is about an inch away from the muffler, and you can see it has beat the edge of the muffler in the past pretty bad. The corner of the muff is beat down, plus the second "groove" or dent is from the DS balance weight than just so happens to be right there as well. I am surprised the weight is still attached.

A few questions:
1. What should my TLink setting be warmed up at idle?
I know the TPS settings, but mainly need IAC setting. And does it need to be IN closed loop to set it, or just warmed up hit closed loop, then back to open to set it. Mine won't stay in closed loop at idle.

2. Why does my boost gauge say 13 but TLink says 9 PSI of boost?

3. How many PSI of air in the bags is typical. This wheelhop is killing me...
 

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I have a few Tlink runs if anyone want to take a shot at it. They are short/small. (about 2000 bytes each) :confused:
 
Squid4life said:
A few questions:
1. What should my TLink setting be warmed up at idle?
I know the TPS settings, but mainly need IAC setting. And does it need to be IN closed loop to set it, or just warmed up hit closed loop, then back to open to set it. Mine won't stay in closed loop at idle.

2. Why does my boost gauge say 13 but TLink says 9 PSI of boost?

1. To set IAC, your car should be warm and in closed loop .......
Shoot for 20-30 on the IAC counts.
Is the TT chip not an open loop chip?

2. Did you change to a 3 bar MAP?
 
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