D15B 3 Stage Vtec rough idle when warm
#1
D15B 3 Stage Vtec rough idle when warm
Hello folks, Im having some weird issues with my ek lately. Ill start off with some background story.
few weeks back i came home from work (4-5km drive) and parked the car outside my home. An hour later when i tried to crank the engine, it wouldnt start. sounded like as if engine wasn't rotating, it had a monotone starting sound from which i was implying that either there was no fuel/spark or the timing belt was broken.
For the next two three days (I had been trying to crank the car after every 4-5hrs) the car had same cranking sound. On the fourth day the I felt as if when I start to crank my engine, the engine did rotate to some extent so i pressed the throttle and let it crank for 15-20 secs. Surprisingly the car started but it had rough idle which lasted for the next 2-3 mins only. I went to the gas station right away and got a full tank. At that point I noticed that the fuel gauge would show only half full tank. Since then I have been using my car 10-15 kms daily and the fuel gauge is fixed at 1/2- 3/4 level at all times even when the fuel was low.
Now recently the car has stared to idle rough but only when the engine has warmed up. Car feels perfectly fine to drive revs up till redline in S mode. the fuel filter was changed merely 2000kms back, throttle body was serviced 1000kms back, injectors were cleaned 2000kms back.
Now where should I start with troubleshooting. and sorry for wordy english!
few weeks back i came home from work (4-5km drive) and parked the car outside my home. An hour later when i tried to crank the engine, it wouldnt start. sounded like as if engine wasn't rotating, it had a monotone starting sound from which i was implying that either there was no fuel/spark or the timing belt was broken.
For the next two three days (I had been trying to crank the car after every 4-5hrs) the car had same cranking sound. On the fourth day the I felt as if when I start to crank my engine, the engine did rotate to some extent so i pressed the throttle and let it crank for 15-20 secs. Surprisingly the car started but it had rough idle which lasted for the next 2-3 mins only. I went to the gas station right away and got a full tank. At that point I noticed that the fuel gauge would show only half full tank. Since then I have been using my car 10-15 kms daily and the fuel gauge is fixed at 1/2- 3/4 level at all times even when the fuel was low.
Now recently the car has stared to idle rough but only when the engine has warmed up. Car feels perfectly fine to drive revs up till redline in S mode. the fuel filter was changed merely 2000kms back, throttle body was serviced 1000kms back, injectors were cleaned 2000kms back.
Now where should I start with troubleshooting. and sorry for wordy english!
#5
Re: D15B 3 Stage Vtec rough idle when warm
okay ill start with it this weekend, what should be the value? I have a spare fuel pump with me which was recently taken off from 05 skyline (350gt), will it work on my ek?
and what about the guage problem, how to fix that? on an empty tank it comes down to 1/2 mark and when i fill it up it only goes up till 3/4 level.
and what about the guage problem, how to fix that? on an empty tank it comes down to 1/2 mark and when i fill it up it only goes up till 3/4 level.
#6
Re: D15B 3 Stage Vtec rough idle when warm
During the 2-3 days when my car wont start and cranked in a monotone, I showed it to a mechanic who opened the engine oil cap and peeked inside, only the first valve rocker was moving up and down, the ones right next to it weren't moving. He said that the camshaft is broken. And i actually thought he might be right for the time being.
Any idea why this monotone cranking thing happened all of a sudden??
Any idea why this monotone cranking thing happened all of a sudden??
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#8
Re: D15B 3 Stage Vtec rough idle when warm
During the 2-3 days when my car wont start and cranked in a monotone, I showed it to a mechanic who opened the engine oil cap and peeked inside, only the first valve rocker was moving up and down, the ones right next to it weren't moving. He said that the camshaft is broken. And i actually thought he might be right for the time being.
Any idea why this monotone cranking thing happened all of a sudden??
Any idea why this monotone cranking thing happened all of a sudden??
You have the 3 stage motor so not all the rocker arms will be noticably moving at any one time. Various vtec's (e-vtec and vtec) lock in additional rocker arms. So if you are not in vtec mode (high rpm performance, not all the rocker arms are engaged. If I am comprehending the 3 stage motor correctly in my head, in e-vtec mode there should be two sets of rocker arms not engaged, then in regular mode, one set of rocker arms not engaged, then finally in vtec mode the last set of rockers arms engage and all of them move.
I hope that makes sense of what you were seeing.
I suspect there is issues with your fuel pump thus the problems starting and also the incorrect gauge representation from what is likely a stuck float.
I highly doubt your Nissan fuel pump is going to fit your Civic. It might be doable with some fabrication and modification but it is not very likely a direct swap.
Testing your fuel pressure should indicate the bad fuel pump. If I recall correctly I think you should be in the range of 40 PSI at the fuel rail but I haven't looked that up in awhile.
#10
Re: D15B 3 Stage Vtec rough idle when warm
In e-vtec one set of rocker arms will look like it's not moving being the small lobe just to prevent pooling. Normal mode, the slightly moving arm locks with the moving arm and both arms should move, then on vtec mode the arms then lock with the vtec middle arm that's also on the lma, still both arms move.
My mistake. Of course that's assuming the layout is the same as a normal vtec or e-vtec setup. I haven't actually had the pleasure of seeing the rocker arm assembly of the 3 stage D15B. My brain didn't put it together properly.
Thanks Tony.
Of course the point you were making is that one arm will appear not to move as it's on the barely opening lobe during e-vtec mode. Which coincides with what the mechanic saw.
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Honda CRX / EF Civic (1988 - 1991)
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09-06-2016 01:38 PM