car battery & system problems,plausible?

....?     So where do the dead parts come from, ecu gives them wrong voltage? I don't understand what the problem is. The entire ignition system is replaced with new parts, now after 1 test drive it has the same symptom's and I'm yet to test them, broken elec components. I get at least readings of current to them and at ignition, but its stopped at the hall sender (again). Brand new it sent a strong spark when the key turned to ON, I could then start the vehical for tests. The next thing is a low idle (idle regulator new) which is probably an o2, air sensor; this stalled the vehical. The ecu IS compensating whilst tuning...good, but the individual elec parts are being knocked out via..something. This is essentially the problem. Unless there is some way the ecu is able to ..? then there's no other option that I can see! The coil new, might have sent a bad current to the new hall sender and survived it but all in all its the only reasonable explanation I can find. Earths are large cables, checked.

How are you testing the sensor? How do you know it is not an ignitor or IgCoil or wiring or connector breakdown? You know it is a failure of spark and not fuel/injectors? Is it a 5V sensor and is it getting 5V or more than 5.5V etc? And your alternator never exceeds (say) 15V nor do your car electrics? (Ground faults can cause voltage differences of several volts. That can cause voltages above 16V - especially on vehicles with external body/chassis mounted voltage regulators.) Have you checked the alternator for shorted diodes that pass -ve voltage, or open diodes? I suggest taking it to an auto electrician. IMO that will cheaper and your simplest option.

I would venture to suggest that inexperience is causing you to go over the top in testing and draw the wrong conclusions. An experienced auto electrician might well have come across your problems before, know the answer and sort it out immediately. Out of interest two things come to mind instantly apart from the aforementioned alternator. Bad grounds (earths) have been a particular VW problem since the early 80s. Substituting cheap cheap coil plugs and causing grief.

I agree. Mostly testing connectors as the info on sensors WAS on my tablet but it got switched off before I could read and apply, now its just memory. Which is one of the tests, the current from the battery, through to the component has this one reading for current and others have differing voltages for their specific use, usually less but an info sheets required for those. Basically the vacume/digifant systems, current/battery, mechanical parts and general servicing and cleanliness are being tended until the problems found. The advice brought by forums helps find ways to fix quicker but not always right so this forums question was why a 'short' could make a difference, surprise, its not as direct as a bad battery. Thanks fellas. As the score is . Everything I poke a stick at has an answer. The problems have other factors of cause. Nothing I've fixed has any reflection/asscociation of the next problem fixed. The tests from ecu show everything is in order. Forum tricks get applied anyway and I'm running out of reasons why I can't Start the van with no where else to turn. No power seen from the new hall sender. Something's blown it up, but the currents path to it didn't blow up the rest of the new components. ?? Checking starter motor. Can back flow. Checking solonoid for coal filter, zero v reading. Replacing hall sender, and it will start after...but I won't risk blowing that one up $130 a pop. Eg tests. Ignition ON. Battery 12.7 To coil 12.5 Coil lead to dizzy 12.4 ICV 12.6 Air flow 5.0 Throttle 5.1,4.6,0 Blue 5.1 Black 12.5,0.2,0 Etc

You say current testing which worries me. But I presume you mean voltage. (Essentially current is irrelevant - unless a fuse blows or heat/smoke occur.) Some sensor supply voltages may be 5V (usually +/- 0.5V) - eg, AFM, MAP etc but have varying signal voltages or even have 'digital' (pulsed) outputs. Others vary eg - temp. What signifies correct operation usually requires datasheets and specific test conditions. The behaviour of some sensors depend on the type. EG - a reluctor module will only output whilst rotating (usually a pulse). A Hall Effect module should be low or high (or rather, grounded else floating unless pulled up to 5V or 12V via a resistor etc) but a Hall Effect ignitor (like a reluctor or any ignitor - EXCLUDING CDI and some systems) should only pulse low for a brief time - usually less than 10mS.    And you should NEVER read the voltage (or resistance) of some sensors - eg, O2 sensor elements - as that will destroy the sensor (or trigger airbags etc). Take it to an auto electrician. Otherwise search VW and other forums for the specific detail you need.

Yes, later I'm might be able to find exactly how to TEST parts. Now is just to find bad wires, wrong readings (its all I can do anyway!) Just enough to try out the ecu, if it is at fault-if not that only leaves the alternator. All fuses checked, earths cleaned etc. Testing the hall sender;    I've no idea how to, maybe with tiny instruments. Thanks for the volt guages. Essentially the hall sender can't be a major blame of not working from what your saying, its finer role is Dependant on volts/ecu and functioning vehical. It is just the way I'm getting it fixed. But what ever blew it up twice is ...... A bleep! This new ones gone (and now that I think of it in much the same circumstances) but I haven't tested it, just a volt check 0. Both times the vehical is (low)idling and the van just stops. The senders just don't work after. I got the impression the earth just failed.     The starter motors off and its got damage with cogs, solenoid needs a test....and the alternator when working. My whole guess is it is some sensors, unclean connections, unseviced parts, leading to bad timing and compensated by the ecu thus things go wrong. Elecs need the experts.

The voltages you posted look fine to me. Not that I know what Blue & Black refer to, but the the others look fine depending on the situation. Like I said, the alternator is easy to test unless it has faulty diodes. If it's stalling at idle, are you sure the idle speed is high enough, or that the battery and its connections are good? Idle speed should be easy to adjust.    If it's bad timing, adjust it. That;s not a bad sensor issue unless it is erratic. But bad timing won't blow components - it will only blow the engine.

I should elaborate, it runs(ran) rough with an intermittent dip, almost stalls, every 10sec. I replaced the idle reg and removed that but it still hits a spot and trips over itself, so it defenitly needs timing and sensors replacing to give the ecu time to find the right fuel injection and idle speed(currently too low,erratic). The battery's new....just keep fixing things till nothings on list. Just rementioning the strong spark at ignition ON only, I was thinking maybe a fuse could've let that in?! To think a working engine gets one of those at the some time, the flux would burn something out. ..fuse or exposed wire..or....

So you've checked the fuel pump & filter and its pressure? And the air filter? And compression, timing, splugs, & valve timing & clearances? Injectors have been cleaned? Strong spark at IGN ON. Do you mean when you first turn on the ignition. That should not happen. If the ECU controls the spark, then it's likely to be a faulty ECU. Else it's some contamination (shorting wires etc) or a failed ignitor etc component.

That sounds like it... Yep the first time I tried with all new ignition line up the test of sparky1 was out to see function, so because I've only got one set of arms, I recorded the event..there's a sec from turning the key and zap. I've checked its earth..had it out to clean,clean as...electrical function. I can send it off for return in a flash. I can't do valves etc just haven't got those tools yet.