Imprezor

OK I have a VERY weird problem with my LS VTEC on my Civic CX 93.
I just built the motor this past July, and everything is great in the mechanical area, but I seem to have some electrical issues.

After buliding up the motor and getting the car going (with a new battery), everything was great, then, about 2 months later, I started to have the problem. The firts clue I had about the problem is that one day the car wouldn't start because the battery was dead, no charge. I had a friend help me out with that, got the engine running, and went home with no probs. Took the battery to the dealer and had it charged again. Meanwhile the car also started not to run strong as it usually does (LS VTEC with PR3 pistons, not a beast but you know). I mean, ECTs, oil pressure, everything is fine and the car does not hessitate or anything but just looses power. Usually VTEC kicks in really hard and when it is not running strong you can just tell the VTEC went in out of the sound but there's no kick. Now, after going down a long hill, holding the car back with 2nd or 3rd gear, when I get to the bottom of the hill the car runs great, really strong. The car usually runs strong also after just warming up to temperature, but I mean just after because a little later when I've been driving for a while it won't run strong again. The difference is HIGHLY noticeable, specially here in Venezuela where there are lots of mountains and hills.
From time to time it just wont start, I mean battery charge is so low that the starter wont move the engine, and I have noticed that if I drive with the engine at a higher RPM than I usually do (since the car has a lot of torque for the weight, I usually don't have to push it too far to get to drive like a normal person) and instead of going 1500-2000 RPM I drive in the 3000 - 4000 range, the car will always start after turning it off, but if I drive in the normal RPM range as I would if the car had not probs, then it won't start.

I'm thinking its a bad alternator, everything points to it but what does a bad alternator have to do with the car not running strong???? I mean, I'm not really good at electrical stuff but I don't find a relation betweem both.

Sadly I don't have a voltimeter, so I haven't been able to measure battery voltage with the engine on and off but, what voltages should I be reading?? Again, its a Civic CX 93 with a LS VTEC (alternator comes from the original B18B which is a 94 engine I believe).

Sorry if I extended too much in the post...

THANKS IN ADVANCE TO EVERYBODY THAT CAN GIVE ME A HAND

Imprezor

uppp

anyone please

Mbenztech

I would say it's the alternator. Your saying if you drive in high rpm, then the car will start after sitting overnight. That's probably due to the fact that at high rpm your alternator is putting out enough voltage/amperage to charge the battery and run the car. Change it or take it to get tested. Just my 0.02 cents.

Imprezor

OK I agree with everything you say. And, what do you think about that and the engine not making the power it should be making? I mean not running strong.

I'm leaving to the beach right now as soon as I get back I will have the alternator rebuilt (since getting a new one is like hell of a problem here in Venezuela) and I will get back to you hopefully taking VTEC to 8300 and kickin *** hehehehe hope so

IF ANYONE HAS ANOTHER OR THE SAME OPINION PLEASE WRITE SINCE I WANNA HEAR EXPERIENCES AND STUFF.

zcar4me

Invest in a decent voltmeter/multimeter. Trust me, a decent one will last for a long time, and you'll be surprised, especially dealing with older cars, how much you will use it.

Definitely sounds like a bad alternator. And poor voltage will cause havoc with several sensors, hence the poor performance when the battery is discharged. You should have very close to 14V at the battery when the car is running, and 12V when the car is off. And with your new meter ...check your grounds as well. You should have less than .5 ohms from the chassis ground to the negative battery terminal.

Imprezor

Well today I had a chance to have a multimeter in my hands and started to do some testing. Batt voltage with the car off was 12.65V (battery was just slowly charged overnight). With the engine running voltage was 13.2V. Now checking for continuity in the alternator's + big wire (from the alternator nut all the way to the bolt in the fuse box) there was some points (depending where I put the contact probe) where I had no continuity, it was like at some points there was no contact between the wire and the alternator. Then I checked for resistance and I can't remember the number but it was lot higher than 0.5 ohms. I concluded that there was a energy loss between the wire and the alternator and that means the connector. The ring shaped connector that goes into the alternator bolt (the one at the alternator end of the big + wire) and that is clamped there by the nut was all rusty and like burned up, the same with the nut, so I honed the **** out of it and the nut too till it was clean and shinny. I also aplied some SQ electronic cleaner and as soon as I started the engine again battery voltage was 14.14V.

So I'm as happy as hell and the engine is finally running damn strong and kickin ***, I will keep an eye on the problem and keep on measuring voltages and get back here if anything comes up, so the solution can be confirmed and people can use my experience as possibilities when having a similar problem.

Thanks to you all