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X1 E84 N46N hard start or long crank after short rest
01-08-2023, 19:25 PM,
Post: #1
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X1 E84 N46N hard start or long crank after short rest
Am at my wits end trying to resolve a hard start issue N46 engine. The engine starts ok when hot or cold but has difficulty firing when rested from hot for 5+ minutes.
1. Cam/crank sensor - no luck 2. Tried with eccentric shaft disconnected to disable valvetronic 3. Tried throttle valve 4. Checked temp sensor when hot all plausibl 5. Fuel pump - strainer clean, seems to deliver fine What else could I look at or retest? Only thing I can think of is dme but I doubt thus. I would appreciate some suggestions. |
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01-08-2023, 19:58 PM,
Post: #2
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RE: X1 E84 N46N hard start or long crank after short rest
Is there spark and injector pulse? If yes, any chance for a fuel vapour lock? I don’t know the engine very well.
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01-08-2023, 19:59 PM,
Post: #3
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RE: X1 E84 N46N hard start or long crank after short rest
Hi ,some ideas
1) Check fuel pump relay ,i dont remember if this car has ekps. 2)Check or replace spark plugs 3)Remove one of two camshaft sensors before shutoff the car so the valvetronic open the valves full and then you can shutoff the car leave it around the time(5+min) as you say and then check if the car start normal |
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02-08-2023, 03:06 AM,
(This post was last modified: 02-08-2023, 03:09 AM by willisodhiambo.)
Post: #4
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RE: X1 E84 N46N hard start or long crank after short rest
(01-08-2023, 19:58 PM)liviu2004 Wrote: Is there spark and injector pulse? If yes, any chance for a fuel vapour lock? I don’t know the engine very well. There is because it seems to fire but not prope4ly. Vapour lock seems plausible but I can't see where it would develop. Worth investigating (01-08-2023, 19:59 PM)fireblade9 Wrote: Hi ,some ideas These I tried. This car has no fuel relay, except the one inbuilt into the junction box. Ill try another i see. . Plugs were already replaced and vvt already tested by removing eccentric shaft sensor as that also sets vvt to max open. |
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23-08-2023, 05:12 AM,
Post: #5
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RE: X1 E84 N46N hard start or long crank after short rest
Problem still not solved. SO far tested with replacement pump, injectors and rail, battery. Same issue. 10-15min rest always results in a long crank hard start. I have no plausible explanation for this behavior. Strange some of these problems
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23-08-2023, 07:04 AM,
Post: #6
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RE: X1 E84 N46N hard start or long crank after short rest
Have you checked compression when it long cranks/hard starts when hot? Have seen one or two with piston rings sticking, although I seem to remember these were N42.
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23-08-2023, 07:10 AM,
Post: #7
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RE: X1 E84 N46N hard start or long crank after short rest
Why don't you graph as many parameters (for example using ISTA expert mode) as you can during normal startup and during this issue then??? We would at least have something to investigate. Now should we be listing all possible reasons for engine not starting here???
On diesel I would say 90% clogged injectors. Never seen this on petrol a engine, but it could be possible that someone was putting crappy gas into it to clog them. But then it is CLEARLY visible in certain parameters on the graphs!!! You could also at least stop cranking this "long" crank before engine starts and check whether spark plugs are wet, etc. Now NOTHING we can think about AT ALL!!! |
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25-08-2023, 07:24 AM,
(This post was last modified: 25-08-2023, 07:28 AM by willisodhiambo.)
Post: #8
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RE: X1 E84 N46N hard start or long crank after short rest
(23-08-2023, 07:04 AM)tonemoz Wrote: Have you checked compression when it long cranks/hard starts when hot? Have seen one or two with piston rings sticking, although I seem to remember these were N42. Not checked compression yet but opened the cylinder head and checked integrity of the gasket. Was OK. The issue is only present when car rests for 10-15min. Cold start OK, restart any time before about 10min OK, restart after say 1hr - OK. However, let me do a compression test I see. (23-08-2023, 07:10 AM)Node Wrote: Why don't you graph as many parameters (for example using ISTA expert mode) as you can during normal startup and during this issue then??? We would at least have something to investigate. Now should we be listing all possible reasons for engine not starting here??? While cranking the engine tries to fire but does not succeed and reties a few times. Occasionally it stops and stalls then fires the second time like nothing happened. Fuel refreshed and the problem has existed for the last one year!! The symptoms point to insufficient fuel delivery. And now that I think about it let me confirm that the injectors are on the correct plug and not mixed up!! |
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