wehey Posted January 25, 2016 Report Share Posted January 25, 2016 (edited) As the title says. My tdi starts perfectly when cold but when hot it will occasionally really struggle. It will take 10-20 sec of cranking before it fires up. 90% of the time it's fine tho and this problem seems really random. No fault codes are showing. Any ideas folks? Edited January 25, 2016 by wehey Quote Link to comment Share on other sites More sharing options...
Skezza Posted January 27, 2016 Report Share Posted January 27, 2016 Does the glow plug light up, when not starting? It could be relay 109. They're affected by heat, well the older ones are. Quote Link to comment Share on other sites More sharing options...
wehey Posted January 27, 2016 Author Report Share Posted January 27, 2016 44 minutes ago, Skezza said: Does the glow plug light up, when not starting? It could be relay 109. They're affected by heat, well the older ones are. Hiya... Yes the glow plug light always comes on whether the engine is hot or cold. I have seen the 109 relay pop up in various discussions before although I can't say I have a clue what it does lol I will do some more googling and find out more. Ta ? Quote Link to comment Share on other sites More sharing options...
Skezza Posted January 27, 2016 Report Share Posted January 27, 2016 Double check that it does. I'm not exactly sure what Relay 109 does, because it's referred to as so many things: Glow Plug Relay, Fuel Pump Relay, Main Power Supply, ECU Relay.... All you need to know is that if it's failed, your car will not start, no matter how much you crank it. However, the issue with relay 109 is that it's failure is caused by heat stressing the internals. The original design was very poor, resulting in poor solder joints failing over time due to heat. Heat stresses the solder, causes it to crack and then the car doesn't start. The problem is, as I said, heat is the catalyst, so in the cold, your car may well start fine, so you think nothings wrong. You'll pull up on a motorway services and then it won't start. I had this issue for 12 months. Car starting fine in the morning, then pulling in the shops and it not starting (occasionally), wait 10 minutes and it starts again. One day, I pulled into a petrol station, and it wouldn't start at all. After an hour waiting, cranking with no luck, I angrily bashed the fuse box and there was a flicker of the glow plug light. The car started and I made it home. The new Relay's don't suffer this issue. Just make sure yours is the newer relay, otherwise a few years down the line you'll have this problem again. Oh and it doesn't leave a fault code. Quote Link to comment Share on other sites More sharing options...
wehey Posted January 27, 2016 Author Report Share Posted January 27, 2016 (edited) 100% certain that the light does come on. i had to stop for a few mins today and I made a mental note to check for the light before starting. The light came on and the car struggled to start. It's very random and doesn't happen every time?? is the relay specific to the Lupo/Arosa or will any VW 109 relay fit? Going to look online for one. EDIT: just found this http://www.ebay.co.uk/ulk/itm/252266235103 Edited January 27, 2016 by wehey Quote Link to comment Share on other sites More sharing options...
Sausage Posted January 27, 2016 Report Share Posted January 27, 2016 Engine temperature sensor, lazy starter motor? Is this only since the remap or before also? Quote Link to comment Share on other sites More sharing options...
RachB Posted January 28, 2016 Report Share Posted January 28, 2016 I had a similar issue with my Arosa. I would be driving along and the car would lose all power (not ideal when you are doing 90 in the outside lane ), I would pull over and wait about 5 mins and then it would start again. If I tried starting it straight away the car would make an horrendous judder and allsorts of lights would come up. This started off as an intermittent problem which ended up happening every other day. I got the lads at the garage to plug it into the diagnostics machine and it came back with no codes So I turned to my best pal Google. After finding people with exactly the same issue I would read the thread and they didn't have answer . The lads at the garage said it was most likely my fuel pump but I'm a cheap skate and had read somewhere about 109 relay (fuel relay). Got myself one ordered from eBay (about £9 delivered) and fitted it. Absolutely no issues since. I took apart the old relay and at first glance it looked fine but after a closer inspection it was slightly corroded inside. It's definitely worth a try to see whether it will fix your problem. Quote Link to comment Share on other sites More sharing options...
wehey Posted January 28, 2016 Author Report Share Posted January 28, 2016 Thanks Rach that really helped. yesterday I had a similar thing happen for the first time, but at slower speed. i was following a learner at about 10-15mph in 2nd gear. They indicated to pull over to the kerb and so I put my foot down to drive round them. All of a sudden the engine just died, for about 1-2 seconds, then came back to life and has been fine since. i will order up a 109 relay as its relatively cheap especially if it works ? Quote Link to comment Share on other sites More sharing options...
Skezza Posted January 28, 2016 Report Share Posted January 28, 2016 The pattern parts are easily as good as the OEM ones btw, just make sure it's the newer revision which has a far better design. Quote Link to comment Share on other sites More sharing options...
wehey Posted January 28, 2016 Author Report Share Posted January 28, 2016 Just 1 more question......I have seen a 4 and a 5 pin version for the VW. Is it the 4 pin that I need? Quote Link to comment Share on other sites More sharing options...
RachB Posted January 28, 2016 Report Share Posted January 28, 2016 http://www.ebay.co.uk/itm/Number-109-ECU-Fuel-Pump-Relay-Audi-Skoda-Seat-Diesel-357-906-381-A-357906381A-/171236977827?hash=item27de84eca3:g:tIMAAOxyVaBS9A95 This is the one I got. 1 Quote Link to comment Share on other sites More sharing options...
wehey Posted January 31, 2016 Author Report Share Posted January 31, 2016 So I ordered the relay and am waiting for it to arrive. i was out driving today and had covered about 7miles. Was travelling at about 25mph when the engine completely cut out. i pulled over, waited about 30 secs then tried to restart. The glow plug light DID come on and after a bit of cranking it fired up and I made it home. so I think that the problems I have been having are related. Something has been breaking down slowly over the last few months, starting out with hot starting problems and now progressing to cutting out whilst driving. i am really hoping that it's this relay..... Quote Link to comment Share on other sites More sharing options...
Sausage Posted January 31, 2016 Report Share Posted January 31, 2016 It probably is... Quote Link to comment Share on other sites More sharing options...
RachB Posted February 1, 2016 Report Share Posted February 1, 2016 Sounds like mine, fingers crossed! Quote Link to comment Share on other sites More sharing options...
wehey Posted February 1, 2016 Author Report Share Posted February 1, 2016 Relay arrived this morning and will be fitting this afternoon ? Its been a bit of a "squeeky bum" drive to work this morning lol Quote Link to comment Share on other sites More sharing options...
RachB Posted February 1, 2016 Report Share Posted February 1, 2016 I always knew my car would start as he loves me - Honest Quote Link to comment Share on other sites More sharing options...
wehey Posted February 1, 2016 Author Report Share Posted February 1, 2016 (edited) So....time for an update. Fitted the relay and drove 3-4 miles to warm it up. Parked up and waited 5 mins. Tried to start the engine and exactly the same problem. 10-20 secs of cranking to get it to start !!!! So what next guys and gals. If it were a petrol I would know exactly what to do, but modern diesels baffle me lol Any ideas on what to check next? Edited February 1, 2016 by wehey Quote Link to comment Share on other sites More sharing options...
Skezza Posted February 1, 2016 Report Share Posted February 1, 2016 Changed the air filter lately? Quote Link to comment Share on other sites More sharing options...
wehey Posted February 1, 2016 Author Report Share Posted February 1, 2016 Air and fuel filter were changed 3k ago Quote Link to comment Share on other sites More sharing options...
Sausage Posted February 1, 2016 Report Share Posted February 1, 2016 Your conking out says electrics like the relay or maybe ecu, your non starting hot says cranking speed too low. Vagcom might be able to measure live data for cranking speed. No fuel is injected below a certain rpm i think and the maps for fuel are different for hot and cold. What is your battery voltage ignition on, engine off? Was that relay a snug fit in the socket? Quote Link to comment Share on other sites More sharing options...
wehey Posted February 1, 2016 Author Report Share Posted February 1, 2016 (edited) 19 minutes ago, Sausage said: Your conking out says electrics like the relay or maybe ecu, your non starting hot says cranking speed too low. Vagcom might be able to measure live data for cranking speed. No fuel is injected below a certain rpm i think and the maps for fuel are different for hot and cold. What is your battery voltage ignition on, engine off? Was that relay a snug fit in the socket? I agree that it seems to be electrical as when it conks out it literally dies instantly, no spluttering or stuttering. Reading elsewhere online for similar symptoms the crank sensor pops up regularly? Battery voltage with ignition off is 12.63v and with ignition on its 12.22v The relay seemed like a good fit but was hard to really tell as access was limited. do you think the problems are related? Edited February 1, 2016 by wehey Quote Link to comment Share on other sites More sharing options...
wehey Posted February 1, 2016 Author Report Share Posted February 1, 2016 (edited) It's just so random. On Saturday I drove 80 miles without it missing a beat, then on Sunday it conked out after 6 miles. i can handle the starting problem, but the conking out is frightening as you instantly lose breaking and power steering ? Edited February 1, 2016 by wehey Quote Link to comment Share on other sites More sharing options...
RachB Posted February 1, 2016 Report Share Posted February 1, 2016 NNNNOOOOOOO!!! I was really hoping that this would have sorted it. 1 Quote Link to comment Share on other sites More sharing options...
Sausage Posted February 1, 2016 Report Share Posted February 1, 2016 Well at least you started with the cheapest possible solution. The engine cutting out and the hot starting may or may not be related but probably are. You need that vagcom lead asap though. OK quick search finds this: That was fuse box connections , other likely options are crank position sensor flaky. Quote Link to comment Share on other sites More sharing options...
wehey Posted February 1, 2016 Author Report Share Posted February 1, 2016 I have just ordered that lead ? Just out of curiosity, what will it be able to tell me that a normal diagnostics (handheld type) tool can't? Quote Link to comment Share on other sites More sharing options...
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