car battery & system problems,plausible?

A reversed pole. A crossed wire or cable.

Take the starter out of the car and test it.

OK..to wrap up the immo was sorted by REPLACING it which is legal and the starter works. The problem was traced back to the pin which inserts from the ignition barrel and ignition switch, the pin can't poke far enough into the groove its meant for .... how about that. Why that is, IS beyond me, but now I start it with a screw driver because it may be the reason for fluctuations. Its poping on and off at random at full key insertion (whereas before it wasn't in far enough) so starting was hidden behind this guise. I guess responsible for it..... Thanks for the assistance (I might try an out of town garage next time it gets this weird again!.)

custum wrote: I might try an out of town garage next time it gets this weird again!

NO!!! As some wise dude said on page 1, an auto electrician - not some bluddy mechanic. That was suggested in the same (early) reply as the possibility of intermittent connection, and advice to break and make all involved connections. After that comes systematic checking - like jumping wires or switches, or testing voltages (usually with a test lamp to provide some load). Faulty ignition power should have been found quite quickly. (... by a clever person or auto electrician - but not mechanics that can't diagnose a bad battery connection after 3 weeks...)

I sympathize and agree, but I was joking- I'd never see THEM. Had I found a link between ignition switch, starter motor and hall sender AND went to an auto electrician (and what dim person wouldn't!) to test the many hall senders for a working one, HE said 'to go to the mechanics' as they use the computer equipment related to these types of things,(mainly referring to my van prob) he in fact couldn't test them (professionally), only ohms test with difficulty. He did get readings from them; alas they don't work!, but all in all a busted planetary gear in the starter was the only REAL damage to blame. I guess there's something there for all of us. I get another hall sender this week so it will really resolve the replaced parts I ordered in which was basically they entire ignition system, but they had to be serviced anyway due to the years of nowt. Will go to them if it goes though. Fingers crossed!.

I still don't see why the hall sensors keep failing. If it was intermittent (IGN) contact I can imagine ECU damage (as did the aforementioned mechanic that eventually blew the ECU from repeated trial&error testing having totally missed the problem - bad battery terminal connections), but the Hall should be buffered thru the ECU. Even bad vehicle grounds should not cause damage thru alternate paths (cables, signal ground wires) as Halls are (always?) isolated from chassis. And I would have expected an autoelec to simply rotate the dizzy or slide some ferro-metal thru the Hall slot (or magnet past a non-vane sensor) with a 5V supply to a vane Hall sensor, and then check the output with a DMM (resistance) else rig a 12V test light or load. (They should respond to vane slots else magnets; the short "dwells" of (say_ 6-9mSecs being done by ignitors or the ECU. But I have known of bad autoelecs. However bad mechanics fixing electrical related problems seem to be greater in abundance. And since modern car faults are often electrical, autoelects are a better first bet. And IMO electrical faults have to be discounted before chasing mechanical or "performance" problems, tho mechanical failures themselves (timing, compression, bearings, pumps, leaks, even splugs) should be reasonably obvious.

......welcome to my bad circus show......!!):) The plausibility you've mentioned about the ecu causing it IS suspected but I don't know how to relate it, yet I was sure the immo had a lot to do with it, and then the odd out of place things seem more the culprit's than the suspects....whatever it is/was can be identified with a culmination of the little wrong things making one large wrong .. to the normal operation of the vehical. The ecu reading it, and compensating for it, adjusting the normal setting too far. A mechanics job. Once upon a time i considered car battery's 24v, now I know they're 12v but that is as far as I go electrically.

Nah... ECUs are from that selfish part of society - they might cause the engine to blow, but not their own sensors and attachments. Exceptions (to the latter) are if components break down - eg an ECU resistor shorts (ha!) or moisture bypasses it so the Hall (Hell?) sensor output transistor blows thru over current, or its 5V regulation to the Hell sensor fails. Even blowing the engine is difficult. The EMS will probably sense faulty injectors that can hole pistons & burn valves (thru lean-out) etc. In fact the latter reminds me of a common modern scam where people sell components to enrich or lean fuel mixtures. I thought that was long dead but last year I saw a 2011 edition of Trucks! or similar that used the old resistor in AFM or MAP sensor line to increase the performance of the engine by tricking the ECU into supplying more fuel except that they were using an LM317 voltage regulator. Of course that is total crap and I found that its website's info on DIY had been removed. However when searching I found many "recent" sites proposing the same crap. And its lucky it doesn't work... It seems many have used it to REDUCE the fuel supplies and if it did work, many engines would blow due to excessively lean mixtures. I don't know if such proposers are merely idiots or ignorants that do not confirm results, or if they make money selling the parts (eg, a 5c resistor or $2 317 circuit for handfuls of dollars) or if they hope the industry makes money from the damage. It's another modern equivalent of mechanics kinking oil-pressure lines (to increase oil pressure for increased performance engines - ha ha!) or draining carbies if not using vehicles for extended periods. The repairs for those tricks made good money for mechanics. (If your kinked oil-line engine survived, it proved that oil pressure is largely irrelevant or that higher output engines work well with lower oil pressure at the bearings.) If people are silly enough to think that merely fitting bigger injectors means more power, I guess they'll easily be sucked in to hose scams. (It was bad enough when people fitted excessively large carbies - it wasn't until they tested that they'd fine the worse fuel consumption with LESS engine performance. Of course we'd see the black exhaust fumes. And bikes removing exhaust baffles...)

Isn't it place a block of steel in the engine to boost pressure?? All I remember was when fuel injection first came out we were told to remember that the injectors were coupled with electronic management (and the other alternative of just injection...or something) so any alternative wasn't going to be because of this. Placed on the wall around the 80s and many grumbles were heard as out went the 'good system'. I just learned from the 'VW man' today my ecu can be remapped (sure just basically, but when I get a turbo an upper hand on the item is all you need) AND that my blown hall sensors are from the No30 relay. Already replaced I got another. The ecu WOULDNT account for the damage. So the system is largely maintanence free as far as im concerned, good as is.

custum wrote: Isn't it place a block of steel in the engine to boost pressure??

I've heard some tall ones, but not that one (like how tf would it?). Nah - engine oil pressure is determined by the big end bearings. Hall sensors do not require a relay. From what I understand, the No 30 relay (pn 165 906 381) is the ECU relay meaning it supplies power to the ECU. It's a 5-pin relay which is essentially a normal 4 pin SPST with an extra output 86a being 86 via a diode. (Why not simply wire the diode externally?) If relay 30 supplies the Hall, what provides the 5V required for the Hall? (Or is it NOT a 5V Hall sensor?) If I had the wiring diagram I could confirm the above. And yes, because of O2 sensor or equivalent feedback, changing sensor air flow & pressure or temperature signals will not effect performance. Same with injectors - UNLESS the original injectors are undersized. Remapping is required along with the need to change the O2 sensor target (assuming it's wideband) or ignoring the O2 sensor altogether and relying solely on air/fuel mappings.