Beretta.net

If you're seeing a consistent drop in voltage (noticeable) on the volt meter everytime you "get on it" then I would say your alt is having trouble keeping up. This is sounding more and more alternator related to me. The radio, clock etc, are always the first things to cut out along with the lights when an alt is weak, shorting, or dying.

Yeah, but 3 alternators and those troubles have been there throughout my ownership of the Z for the most part. This is something different. My car has always had weak alternator charging, especially in warm weather. I can remember back to even when it was still fairly new, taking it to the dealer and they couldn't find anything wrong with the charging system. Typical position of the volt needle on my gauge when engine is up to temp in summer, is the half mark to just under half. In winter it will usually fall between the higher 2 marks and well above the half mark. If I happen to be on the battery, the gauge will be at the mark just before the bottom red zone or just below, and it may only go there during idle sometimes, if I had say the radio up, turn signal, fans blowing, etc. I would often stick it in neutral for long stops, just so the alt would keep up to stay off the battery level. But it has done this for many years. So I have always assumed it was just a characteristic. Who knows, maybe it was fucked up since it was built. I have no idea. But when this happened, that gauge bottomed out! Even on a battery that shouldn't have happened. So to me it acted like the ECM lost all power, but so did other systems. Even the door locks refused to work properly right afterwards (as I turned the ignition off and back on). My guess would have been a massive temporary short. But that also should have blown something, or left a trail, something. This is just annoying.

Anyway, as I said before, I would normally agree with you. But I still think this new symptom is a different issue or problem altogether. It may be compounded by the fact that the charging system seems improper however. Hell I don't know.

One thing is certain. It wasn't doing this last week. LOL

I just think something may be leaking to ground. It could be a coil. As I said, I will do some checking of the coils hopefully tomorrow, pulling them and doing ohm measurements. See if I find anything odd.

No blown fuses, and no engine codes of any kind. Stumbling idle, YET no problems with WOT!! Stinky exhaust at idle too when its acting up, very noticeable rotten egg, way more than normal. I suppose I could pull the alternator off the base (if its the same AMP size?) and try that... *shrug

All sensors are original parts. I have never changed ANY sensors on the engine since I bought it new. Yes, even the O2 sensor. As I have not had any codes to suggest otherwise....? Why would I change something that apparently works? Or did.

Rotten egg smell from your exhaust is usually a sharp indicator of a failing/failed Cat.

I seriously think you must have a draw somewhere. Something is drawing hard enough on your Alt's that it sounds like the battery is shouldering part of the work load sometimes while the car is running. A massive short is unlikely. I'd say your alt stopped charging (from your description of events and the needle reading) and the battery was running very low. Then the alt started charging again. This is definitely an electrical issue.

A bad/weak ICM or coil has never ,in my experience , caused the other failures you speak of. Honestly, I'd have made them give me a different new car , if I just bought it and no problems could be found to explain it. gently caress that. Lemon Law anyone?

There's ONE other possibility but it only fits a very small portion of the problem. Your alt gauge (in other words your cluster) has been jacked up from day one.

IF that was so, then "normal" would read "low" on the gauge and dead would read well below Red. So you may have a failed alt and think not due to a shitty cluster you've grown accustomed to "reading wrong" from day one.

Possible , but not extremely likely imho.

***EDIT***

Note: If the Cat is bad (ie: clogged) it WILL cause the stumble you're experiencing for sure. It should NOT , however, cause the electrical issues. Get a ball peen hammer (king kong 20 lb maul not required for this test,lol) and crawl under the car. TAP lightly to medium power on the bottom side of the Cat. Usually if bad or broken up , you'll hear what sounds like marbles in a jar or gravel bouncing around. If you hear that, the Cat's toast and screwing up your power, mileage and running abilities.

But if the cat was clogged, wouldn't that also affect WOT? Even more so in fact? My WOT runs are just the same as they have been for a long time. Smooth, powerful and throaty. I jumped on it today even, took it clear to 90 in no time at all, but once back down to 55 at cruise, you could feel the occasional shudder.

Makes no sense to me. I get what you are trying to say, but something tells me its more than just a possible alt issue. As I said, when the (for lack of a better word) event when the radio even got affected, it only happened once. I happened to be looking at the dash when it happened, and saw the volt gauge literally fall down past the red, the engine quit, the radio went silent, but the key was still "on". I put it in park, turned it off (locks feebly tried to unlock but failed to unlock all the way)waited a moment then restarted the engine. If the battery was truly near dead, it shouldn't have started at all. But instead it fired right back up and the volts were back to normal. This happened on last Friday, while crossing the international bridge up here. It wasn't till this week that the stumbling has been more often and more pronounced. Before that, I wasn't stumbling at all. Starting to wonder now if that event is what led to this problem. Like some sort of short in the system damaged something else.

But again, who the hell knows.

Not to mention a clogged cat would not normally just show up and be bad at once...? Wouldn't that be more of a gradual problem?

Do you have two 02 sensors? One up on the manifold and one just before the Cat? If you do, the O2 sensor is either bad or the cat is. The rotten egg smell is DEFINITELY a bad Cat thing, trust me. You could have experienced a massive jolt to the electrical system, but from where is the 64,000 question isn't it? A short that powerful would almost HAVE to have come from your charging system. Is it possible it fucked your ECM up? Maybe. But you obviously ran the codes and got the code 12 and the Cat code. That would indicate the ECM is still somewhat doing it's job anyhow.

From your description, I'm quite sure your Cat is shot. May not be clogged, but it's coming apart. The "rotten eggs" smell is a very sure indication.

The random miss at idle and cruise speeds could be as simple as faulty O2 sensor input. 9 times out of 10 an bad 02 will NOT throw a code.

What is throwing me is the volt meter readings, the stereo mishap , and the stuttering all happening together. To me , these things are all intertwined.

Humor me, and have the alternator in the car tested at a parts house, or two even for multiple results. See if it tests good or bad. If it tests good , then one less thing to consider. You say you've traced all grounds and connections relating to the alt. , so that's covered. We'll go from there.

I'm truly thinking you have a faulty rectifier or diode. I'm betting the alt tests out either borderline or bad.

Unplug your high resolution crank position sensor and see if the idle smooths out. Its the three pin wide plug just above the AC compressor the sensor itself is behind the crank pulley.

SuzukiGhostRider wrote:Do you have two 02 sensors? One up on the manifold and one just before the Cat? If you do, the O2 sensor is either bad or the cat is. The rotten egg smell is DEFINITELY a bad Cat thing, trust me. You could have experienced a massive jolt to the electrical system, but from where is the 64,000 question isn't it? A short that powerful would almost HAVE to have come from your charging system. Is it possible it fucked your ECM up? Maybe. But you obviously ran the codes and got the code 12 and the Cat code. That would indicate the ECM is still somewhat doing it's job anyhow.

From your description, I'm quite sure your Cat is shot. May not be clogged, but it's coming apart. The "rotten eggs" smell is a very sure indication.

The random miss at idle and cruise speeds could be as simple as faulty O2 sensor input. 9 times out of 10 an bad 02 will NOT throw a code.

What is throwing me is the volt meter readings, the stereo mishap , and the stuttering all happening together. To me , these things are all intertwined.

Humor me, and have the alternator in the car tested at a parts house, or two even for multiple results. See if it tests good or bad. If it tests good , then one less thing to consider. You say you've traced all grounds and connections relating to the alt. , so that's covered. We'll go from there.

I'm truly thinking you have a faulty rectifier or diode. I'm betting the alt tests out either borderline or bad.

I did not run any codes. I have not even had a code since all this began the past week. In fact I haven't thrown a code since the trip to Indy. Pretty sure that one was a tran slip.

Well obviously something died. I can't imagine a cat puking one day and being just fine before. That doesn't compute.

3X00-Modified wrote:Unplug your high resolution crank position sensor and see if the idle smooths out. Its the three pin wide plug just above the AC compressor the sensor itself is behind the crank pulley.

I will give this a shot today, see what happens. That at least is an easy test, but what does that do? Force the engine into MPFI mode all the time? Should that also throw a code?

Thanks guys.

No it will not throw a code, its more for high resolution spark advance, and also used for missfire detection due to rough running, MPFI is done by the cam position sensor, so thats another you could unplug to see what it would do, and that may or may not throw a code, I cant quite remember that. Either way, both unplugged it will still run fine.

My bad Ace. I was thinking of another thread a guy mentioned a Cat code in. Sorry.

94 is also OBDI essentially, so no cat monitoring O2, that was only on 96's

Yeah, I realized his was a '94 after I posted. I had been thinking it was a '95-'96.

Ok ACE, just thought you had the old plugs and not any of the high mileage newer plugs. I sure don't miss changing plugs twice a year. I'm running AC platinums now.

Good lord. I can't imagine that at all. Why would you even have a plug you can buy that requires a 5k interval change? crap you would be doing that on damn near every oil change!
As for "old plugs", I am using the same brand and model of plug that originally came with the car.. And I'm quite confident they could easily last a 100k. Every set I have ever pulled has always looked good, even after lots of miles.

That was on my old 90 3.1L. I'd been running the old style plug all my driving life and it was nothing to do that in the old days. Those plugs would have a .05 gap increase after 5k and the longer you went the larger the gap. Let me tell you that I could change the plugs on that thing with my eyes closed(I put over 100k on that car). Guess I could have went to 10K, but that was too much gap for me.

Rotten egg smell, electrical woes, there is some gremlin there, I tend to agree with mike. If you aren't getting a good spark at low engine speed, that will cause the cat to bind up and give you the sulfur smell.

You either have a weak spark issue that evens out at high rpm, which makes sense, or a serious electrical problem causing weak spark.