Hi there, I'm new here and would love to hear some advice or guidance on what may be at fault with my car. I have a '98 Mk3 gti 8v (agg engine) and recently broke my collarbone mountain biking. I didn't drive my car for 6 weeks, (started it once about 3-4 weeks ago and it went fine). Went out to go for a run as soon as the doctors said I was good to go and the battery was flat (no surprises there). So I got a pal over to give me a jump start and it just cranked away. With a bit of a check I noticed there was no spark or fuel. At this point I started to trawl the forums and found all the threads about fuel pump relays, ignition coils, engine speed sensors and ecu relays. So, I fitted a new coil and fuel pump relay and got another jump start- it fired up straight away. I then went for a drive and after about 15-20 minutes it died on me and wouldn't start again, even with a jump. At this point I was far enough from the house to call out the AA. The AA guy checked it out and couldn't get it going but he noticed that the electrical feed to the distributer hall sensor (I think) was reading as 3 earths and thought I had a wiring fault. He didn't think the engine speed sensor was at fault because my rev counter is fine. So, since then I have cleaned up all the earth contacts I could find and am getting a new battery delivered today. I'm pretty sure the battery is goosed but wouldn't expect that to be the cause of it stalling even with the lights on ( they weren't dimming at all when it stalled). Anybody got any ideas? I was thinking ecu relay next but the instument readout is all fine. (EDIT) I've just fitted the new battery and no joy (as expected). To add to the post, when I turn it over the oil light starts flashing, I can't remember if this is normal. The fuel isn't priming now. Could I have blown the new fuel pump relay? It wasn't a vw one- from gsf. To add, I also just noticed that the tacho doesn't move while cranking. Would this suggest the crank/engine speed sender? Would that stop power to the distributer hall sender?
Did the guy test the hall sender wiring with it still connected to the dizzy? Id disconnect the plug from the distibutor (hall sender) and test the 3 pins on the plug for continuity to earth. At least one pin should have continuity to earth... Neil.
the rev counter should move when cranking (I'm pretty sure anyway, definitly on a MK2 is it different on a MK3??) could well be a dead hall sender or wiring fault along the line. Does the AGG have a crank sensor, probably about time for it to be replaced if it does! Last of all, flashing oil light on ign/cranking is normal, since the oil pump is driven by the engine I would expect oil pressure to be low when its not running best bet is to have VAG-COM plugged into it, see if the ecu is winging about anything.
If there's no spark or fuel and the rev counter is registering on cranking then it's most proably the crank sensor that's duff.
cheers for the responses guys. The AA guy tested the hall sender plug whilst disconnected- he didn't think it was a dizzy issue. I've been looking at the crank sensor and it is a mess. Someone has done a botch job on it before I got the car. 4 inches of bare wire (all 3) right into the sensor. They've been kept apart with what looks like chewing gum and insulating tape!!!! I'm amazed the car has been ok for the 18 months I've owned it. Hopefully that's the issue, I'll get into changing it now. looks like you have to remove the front engine mount bracket to get at it, is this tricky? It looks it.
A mate is going to give me an old laptop tomorrow and I have the usb cable around here somewhere so I'll plug it in and see what it spits out.
yeah to do the crank sensor the front engine mount bracket needs to come off, not hard though just get a jack under the sump, crack off the top mount nut/bolt and jack the engine till it lifts off the mount. Then its a few bolts that hold the front bracket to the block, same bolts that hold the starter motor in.
cheers, will do. Hopefully that will sort it out. I'm a bit worried that they couldn't get the old one out before and thats why they did the dodgy job on it, we'll see.
OK, got the thing changed! bit of a footer getting the allen bolt out but it came eventually, so new camshaft sensor = still not starting :-( It won't have done any harm though the thing was a mess. To re-count, I've put a new coil, battery and fuel pump relay in there and now the sensor. What I find odd is that it went for a wee while after doing the coil and fuel pump relay. Is it possible that the goosed battery knackered the old and new fuel pump relays? I don't know how these things work, do they just wear out over time or can you break them? I'm a bit stumped now to be honest. Will get the vagcom thing on the go tonight. Check this out for a laugh- the old sensor!
Hi again, when you say "continuity to earth" I'm not sure what you mean (not much of a car electrics person!) I do have a basic multimeter, is that all I need to test this?
set the meter on continuity, thats when if you touch the two prongs together the needle goes right over or if it's a digital meter it will read 0, put one lead to a good earthing point and then touch the other lead to each pin in the plug in turn.
Update, I tried jumpering the fuel pump relay and the fuel pump still wasn't priming so that rules that out.
could be the alarm/immobiliser not allowing the car to start and cutting the fuel pump off? Its the red and yellow one I think. Also make sure that the allen bolt holding the crank sensor is tight as well.
I made sure the allen bolt was tight. I'm not sure if it even has an immobiliser? My keys don't have any visible electronics in them so I'm guessing not. If it does where would it be? I've heard that if it was an immobiliser issue that the car would start and then cut out after a couple of seconds anyway. I checked wiring conector to the hall sender and one of the wires has continuity to earth. Spoke to a mechaninc and he reckoned it is probably the distributer itself.
OK. Just plugged vagcom in. It threw the G28 code at me as expected, I then cleared it. Now the fuel is priming but it still won't start. Turned it over a few times- Rev counter is registering on cranking. Then did the engine check again with vagcom- no faults found! Tried all the individual MK3 specific tests (01,02,03, 08 up to 56) and got no codes. This is getting infuriating now! Suggestions anyone?
if its a 98 it should have a factory immobilisor, chip is in the key. there is a transponder ring round the ign lock, and a control box under the dash somewhere. have you tried querying the immob part of vag com?
Hi there, I checked the immobilser in vagcom, it came up with "00546 data wiring faulty - implausible signal" I cleared it and tried starting the car a few times, the code never came back. I wondered if it might have been related to the engine speed sensor? Would the code not come up again when I tried to start it after clearing it?
OK. spoke to a mechanic, he reckons I've bought a duff coil that's lasted 20mins and then failed. So, back to the shop me-thinks!
