New battery won't last

[02BLUR]

My old battery died, so I got a new one. Then I did the "cap replacement" on the ECU. Now the battery has died again (after about a month). While the car was running, I disconnected the battery and the car died. So its running off the battery (which would also explain high RPM sputter). The alternator checks out fine. (old battery was shot, I just attempted to recharge that one). Its gotta be the ECU. I looked at my solder job and cleaned it up again, but still the battery won't last. Ideas please. Thx

 

[steve]

On a 1G the ECU has nothing to do with the alternator other than to consume its electrons.
If your battery isn't charging you need to check that system out. How do you know that your alternator is fine?

Steve

 

[02BLUR]

Thats not what I read, http://www.tmo.com/howto/ecu1g/caps.htm He is saying its directly related to the alternator. Ever since I started F'in with the ECU, this happened.

Took it to Schucks and they brought out there tester and proved the alternator was fine.

Oh, and just now I put in the recharged battery and put in the ECU and started it up, and #1 cylinder is pissing fuel all out the exhaust manifold and it runs only on 3 cylinders. Compression is 145,145,130,145. I think this time I REALLY screwed up the ECU.

And I read the battery voltage while it was running - only 12.7V, the alternator is doing nothing.

 

[steve]

Thats not what I read, http://www.technomotive.com/howto/ecu1g/caps.htm He is saying its directly related to the alternator. Ever since I started F'in with the ECU, this happened.

You'll have to point it out to me because there is only one reference on that page to the alternator and it talks about how clean the output is.
I'm basing my comments on my knowledge of 1G's and from double checking with the circuit diagrams. I'm pretty sure (like 99.9%) that the ECU has no interaction with the alternator on a 1G, 2G are a different story. On them the ECU controls the output to manage engine load and emmissions.

And I read the battery voltage while it was running - only 12.7V, the alternator is doing nothing.

That was more along the lines of what I was looking for. It's clear from the fact your only seeing 12.7v that although the alternator may be working your not seeing it at the battery. The usual cause is the 80A alternator fuse is blown but there are two other fuses to check as well, the 30A sublink #4 and the 10A fuse 11 can cause charging problems.

Steve

 

[02BLUR]

I'm trying to find diagrams on my backup manual, I dont' see where the ECU connects, either. This just doesn't add up. After I put those new caps in, I went driving, then I floored it and the water light, brake light and battery light all came up just for a second. So i checked the alternator and it was working fine. But then the battery died.
And of course, now, it only runs on 3 cylinders and smokes like mad. I need a beer

 

[huafist]

Steve's right. on a 1G, there is *0* - repeat, *0* interaction between the alternator and the ECU. If the alternator tested fine but you're not seeing it at the battery, it's something ELSE in the system. Forget about the ECU for a minute and check fuses and relays.

 

[LAUNCHED]

Did you check the alternator fuse? I didn't see what car you have but in a 2G its 100amp and a 1G its a 80amp.

And yeah forget about the ECU, that has nothing to do with your problem. Seems to me like you are digging too deep when its most likely something simple.

CRAIG

 

[02BLUR]

90 Talon TSI AWD

Yep, I checked that 80A fuse, it looks fine.

Ok I'll go check more

But then I'm afraid to run it with the #1 blowing raw fuel out of the exhaust manifold. Smokin all over

Here's a neat little video of it.:
(but this is the other prob of not firing on cylinder #1, oh and the leaky exhaust manifold, guess I know now where it leaks now!) See, you gotta see the positive side of things!

http://www.zero2blur.com/leak.mpg (1MB)

 

[LAUNCHED]

Check all your connections to your alternator as well, sometimes the connections will get build up on them and it will charge intermittedly and your battery will not be getting a sufficient charge will your lights and such are on.

Another thing to check is the connections/plug in below the battery case itself. Have you changed your tranny or anything lately? Intercooler piping?

CRAIG

 

[SlowSpyder]

put a voltmeter across the battery while the car is running and you should get atleast 14 volts. If not then you have a voltage drop on the ground or insulated side such as bad connections or possibly something is wrong with your alternator