Unable to diagnose 1998 Polo "one day no power, unable to idle, VAG-COM has no codes"

   #21  

platydog2

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I appreciate your suggestions Jack.
I have to be away for a week now, but when I get back I will find look at this on the VCDS and let you know.
What is hard to understand is that the idling/power problem just happened, out of the blue, one day when it was started up.
I have worked on cars of all sorts since the 70's myself, so I am well trained to notice things well before they go to crap, but there was nothing to warn me on this one. Feeling humbled by an old VW Polo!
:)
David
 
   #22  

AIB Wolfgang

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Uuuppps:D
Sorry, bad translation.

It looks like no clue will work as expected:thumbs:
 
   #23  

Jack@European_Parts

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David,

Yeah been tinkering with toys since the 70's myself and stuff bites me in the ass too.

I do not know everything and I'm bound to screw something up pretty routine, usually it's my poor writing skills or what it seems to be lack of empathy when I write comes across like an asshole.

You will find it don't worry.
 
   #24  

platydog2

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   #26  

platydog2

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Hi Jack,
Been away, so only now can I get back to trying all the suggestions.
So probably going to be a holiday period job!
David
 
   #27  

platydog2

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Hi everyone,After further investigations, swapping parts in and out, and checking and replacing etc, I have found out what caused my sudden running/power problem in my 1998 6N1 Polo.Embarrassingly, it has turned out to be a faulty Hall sensor in the distributor. The car now has usual startup, running and power etc.Since, in hindsight (always valuable!), the fact that it ran OK (when parked) above 1500rpm I was fooled into thinking spark was OK - Spark plugs, cables, and ignition coil were all fine, and there was spark from all 4 leads when I looked originally, but it was actually poor or intermittent spark on cylinders 2 and 3 when I looked again more carefully. Strangely, cylinders 1 and 4 fired just fine, and I think that they allowed enough ignition balance and power to have the engine ‘run’ apparently OK at higher rpm, but in fact it was with almost no increased power capability (like turning on A/C), so I got well fooled. So when I replaced the distributor (that includes the Hall Sensor) and it ran perfectly again. So that explains also the suddenness of the original problem - the Hall sensor failed (to a partly? working state). And the symptoms could then be fitted to any number of possible sensor /other failures if I thought about it hard enough :-( On this 1998 model Polo the ECM must be early enough that the VCSD is not covering all the sensors, it does not seem to monitor the Hall sensor, so a scan could not help me of course (reacll that there were no codes appearing). Hindsight says I should have done much better basic troubleshooting way back, before jumping into all of the other possibilities. So I am suitably shamed !For those of you who offered suggestions or want to check, many many thanks for your ideas. (and in response to suggestions: Jack, there were no obvious restrictions for intake or exhaust; I checked the throttle body, it was a little tight on the cable, but looesen-ing did not allow it to do adaption, also is no EGT sensor on this model, and changing out MAP sensors made no difference along the way. Wolfgang, I tried your suggestions too with no effect. Ad MartinSx your suggestions all were tried but of course with little effect given the distributor being the cause of things.One aspect remains of interest, though now that things are running OK it’s really just for interest / noting - I can’t get a successful VCDS throttle adaptation, whether I use the 001 or 098 codes.

Anyway, many thanks to all of you who responded with suggestions! I am resolved to be more careful with basic checks in the future!

David
 
   #28  

Jack@European_Parts

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Makes sense to me since this car has no G28 and relies solo on G40 for ignition pulse, so indeed could act in such a manner like as if bad coil etc. & evade a DTC!
 
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