Maverik Posted October 15, 2013 Share Posted October 15, 2013 Hi Folks, Got around to changing out the injectors on the 90 (Disco 200tdi) and when running the performance does seemed to have increased, but now I've got a starting issue. After 12hr + of non use, I find that on start-up for a good 10-20 seconds the engine is pretty lumpy like she's starting with one cylinder down. It clears itself after said 20 seconds or a tad quicker I think if accelerator is nudged. Injectors where old re-furbed units with "bosch" nozzles. new copper sealing rings, with properly cleaned sealing faces in head, after a good blast to Edinburgh via Glasgow the problem persists after initial thoughts of it could be an air lock. I've not noticed any other symptoms really she could be smoking a tad more, but she's always been a bit smoky on start-up. No leaks or sounds that I've noticed new. Anyone got any thoughts? Cheers Mav Quote Link to comment Share on other sites More sharing options...
TheRecklessEngineer Posted October 15, 2013 Share Posted October 15, 2013 I'd say air lock too. Given that you've disturbed the injector leak off lines while the injectors were replaced, I'd be looking there. Quote Link to comment Share on other sites More sharing options...
reb78 Posted October 15, 2013 Share Posted October 15, 2013 My BMW does something similar after its been stood a while. The chaps who service it for me reckon it might be a leaky injector, so it takes a moment to come up to pressure and then runs fine from then. Quote Link to comment Share on other sites More sharing options...
Maverik Posted October 15, 2013 Author Share Posted October 15, 2013 Regarding an airlock, I cracked the nuts on top of the injectors, it is possible there some air trapped in the spill rail do you think? - with the injectors running at 200bar I would have thought they self bleed though... A new thought has popped into my head, could the timing now be out a bit? if the FIP was adjusted to account for the "old/worn" injectors...? Quote Link to comment Share on other sites More sharing options...
Maverik Posted October 15, 2013 Author Share Posted October 15, 2013 My BMW does something similar after its been stood a while. The chaps who service it for me reckon it might be a leaky injector, so it takes a moment to come up to pressure and then runs fine from then. Hmm, a work colleague recons that is the problem too... I'm in denial as fault finding the dodgy injector will take me all week... Quote Link to comment Share on other sites More sharing options...
CwazyWabbit Posted October 15, 2013 Share Posted October 15, 2013 If you still have one of your old injectors why not swap one injector a day to see if the problem disappears? If it's a dodgy injector you'll know which one... Quote Link to comment Share on other sites More sharing options...
Rangy35 Posted October 15, 2013 Share Posted October 15, 2013 If you crack the fuel supply lines one by one while the engine is running lumpy you will know immediately which injector is causing the concern, it will be the one that makes no difference when cracked. I think it is a injector, not a air lock. Quote Link to comment Share on other sites More sharing options...
TheRecklessEngineer Posted October 15, 2013 Share Posted October 15, 2013 Regarding an airlock, I cracked the nuts on top of the injectors, it is possible there some air trapped in the spill rail do you think? - with the injectors running at 200bar I would have thought they self bleed though... A new thought has popped into my head, could the timing now be out a bit? if the FIP was adjusted to account for the "old/worn" injectors...? They do. Eventually. Meanwhile the air in the injector line compresses causing retarded timing and lowered fuel delivery. Leaky injector perhaps - didn't consider that. I'd swap an old injector in one at a time. Quote Link to comment Share on other sites More sharing options...
Maverik Posted October 15, 2013 Author Share Posted October 15, 2013 If you crack the fuel supply lines one by one while the engine is running lumpy you will know immediately which injector is causing the concern, it will be the one that makes no difference when cracked. I think it is a injector, not a air lock. I'd agree, but I'm not sure I'd have time to get through them all before the thing self primes and starts working as it should, it seems to take in the region of 6-12hrs for the problem to show up again... I think it will be the trial and error with pulling an injector out at a time jobby... Quote Link to comment Share on other sites More sharing options...
reb78 Posted October 15, 2013 Share Posted October 15, 2013 Thats the problem with these faults. Like you say, you'd have to be quick to get to the injectors and probably only get one cracked at a time! With the BMW, I've lived with it as whenever it gets to the garage, there are no faults logged and the injector pressures are all fine by then. I have no idea if it is affecting economy on it, and the performance is very good anyway. I suppose you could try a bottle of injector cleaner and see if that improves things? It might free off a sticky injector. Quote Link to comment Share on other sites More sharing options...
Maverik Posted October 15, 2013 Author Share Posted October 15, 2013 Thats the problem with these faults. Like you say, you'd have to be quick to get to the injectors and probably only get one cracked at a time! With the BMW, I've lived with it as whenever it gets to the garage, there are no faults logged and the injector pressures are all fine by then. I have no idea if it is affecting economy on it, and the performance is very good anyway. I suppose you could try a bottle of injector cleaner and see if that improves things? It might free off a sticky injector. Injector cleaner I think would be wishful thinking, I just happened to have a new spare injector, which I'll start the swap out with tonight, hopefully by Friday I'll have found the faulty one... and coincidently rule faulty injectors out... Quote Link to comment Share on other sites More sharing options...
Maverik Posted October 16, 2013 Author Share Posted October 16, 2013 ok, So pulled Number 1 injector out last night, and slipped in a brand new "odd" injector I'd picked up a few weeks ago. On starting the engine after installation I was really surprised how long it took for the injector to self prime and start up, I was expecting around 10+ seconds as per what I had been experiencing with the problem, but nope, I don't think I counted to 2 before it kicked in. Going to the motor this morning, was ice on the windscreen so it had been a cooler night than most, there was a slight lump but cleared within a second, nothing at all like had been happening the past few days... Out of the 4 refurbished injectors this one looked the ropiest so I put it in No1 slot... fingers crossed I might have found the issue - due to it starting up reasonably well this morning, I'll keep it in another day to see how she gets on. Quote Link to comment Share on other sites More sharing options...
Maverik Posted October 17, 2013 Author Share Posted October 17, 2013 Confirmed, to be No1 being the issue. On closer inspection of the injector, the fuel return port seat is damaged obviously letting air leak back into the injector. An interesting note to make sure your spill rail is in good fettle as if it isn't any kind of air leak point could cause rough starting issues. Quote Link to comment Share on other sites More sharing options...
CwazyWabbit Posted October 17, 2013 Share Posted October 17, 2013 Result makes a change for it to be the first one you changed Quote Link to comment Share on other sites More sharing options...
dailysleaze Posted October 17, 2013 Share Posted October 17, 2013 The workshop gods were smiling on you there Quote Link to comment Share on other sites More sharing options...
reb78 Posted November 16, 2013 Share Posted November 16, 2013 Strange this. I've just changed my injectors and have a very similar fault. Rough starting, but definitely improved performance when running. If I give it a tiny prod on the accelerator it clears straight away. Quote Link to comment Share on other sites More sharing options...
Maverik Posted November 17, 2013 Author Share Posted November 17, 2013 Strange this. I've just changed my injectors and have a very similar fault. Rough starting, but definitely improved performance when running. If I give it a tiny prod on the accelerator it clears straight away. Yeah same problem, sounds like you've got leak back happening, did you renew the leak off banjo bolt copper washers? - and how's the health/fitment of your leak off pipes? Quote Link to comment Share on other sites More sharing options...
reb78 Posted November 17, 2013 Share Posted November 17, 2013 Yep. New washers and new pipe - except one section that I replaced 6 months ago. I might replace that first, just in case. I nipped the banjo bolts up a tiny bit last night, just in case, but don't want to over tighten them! Quote Link to comment Share on other sites More sharing options...
Maverik Posted November 17, 2013 Author Share Posted November 17, 2013 I've not got a picture to hand, but I did you notice that the seats for the fuel return ports where nice flat... that's what was wrong with my duff one. the previous owner had been a little rough getting them out obviously and they'd mangled with a spanner the actual seat, to the copper couldn't deform enough to fill the wee gap. Strangely, the gap must have only been very small as diesel fuel didn't leak out, but obviously air was getting in... Quote Link to comment Share on other sites More sharing options...
reb78 Posted November 17, 2013 Share Posted November 17, 2013 It's funny. I do recall one being marked, but thought it would still seal ok. I'll have a closer look later. If it is a problem, I wonder if a spot of loctite under the washer would seal it? Quote Link to comment Share on other sites More sharing options...
Maverik Posted November 17, 2013 Author Share Posted November 17, 2013 It's funny. I do recall one being marked, but thought it would still seal ok. I'll have a closer look later. If it is a problem, I wonder if a spot of loctite under the washer would seal it? That could work, also go and flick your Haynes manual for the screw down torque on the banjo bolts, just in case you're being a whimp Quote Link to comment Share on other sites More sharing options...
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