WhyOne?
20-05-2010, 04:34 PM
As I am sure many of you will know, Y1 developed a misfire about 3 weeks ago.
The misfire was easy (and repeatable) to provoke - just put the engine under load by depressing the throttle and the car would misfire. If the car was driven with a very gentle throttle foot, it appeared to run normally.
A strange (to me at least) feature of this malady was the cars reluctance to store error codes. The ECL would flash but more often than not, no error code would be lodged. Those that did get recorded were mainly related to multi-cylinder misfires. I did, early on, get a cylinder #1 misfire code which initially led to the suspicion that the coil pack in this cylinder being defective. (Cylinder #1 is in the rear bank, nearest to the offside of the car and reletively commonly damaged by water ingress via the vent/duct which runs across the rear of the engine compartment glass 'bubble').
I took the car to my local(ish) Honda dealer and they set about trying to diagnose the problem. After about 10 days (and trying things suggested by myself via ideas proposed here & unearthed on Prime, they were no closer).
The plugs looked fine, it was felt unlikely that all 6 ignition coils would break down at once, the ignitor unit had been swapped with one from another car & it was all looking a bit grim. Next item to swap out was probably going to be the ECU!
I had to temporarily bring the Honda dealers research to a halt as I had promised my eldest son I would take him to his end of school ball in the NSX (he so wanted to go in the NSX rather than a stretch limo...I must have done something right bringing him up!!!!)
I collected my car from the Honda service dept. and they had no further news. Problem still present (though a new ignition coil had arrived at my request & they had experimented with moving this from cylinder to cylinder to no avail).
They were now awaiting a call from Honda technical.
I drove the car very gently for ~30 miles, max revs 3000rpm.
The fuel warning light came on - I never usually let the fuel get this low, but I have been distracted by the misfire. I stopped & filled the car up.
I drove another 6 or 7 miles, again very gently.
No sign of a misfire at all today so far.
I was heading to Simon's (NSXGB) house, as he had very kindly agreed to help me swap plugs, ignition coils & ignitor unit from his car to mine to once and for all establish if the problem lay with any of these components. About 3 miles away I thought I should induce the misfire just to remind me what to do once we had swapped parts from Simons car.
In 2nd gear, 2000rpm I accelerated hard to ~4500rpm. No misfire.
I backed off and accelerated hard again - this time to about 5500rpm. No misfire.
I tried again, this time running up to 6500rpm - no misfire!!!
I couldn't get the car to misfire!
Because of this, there was no point swapping Simon's parts into my car.
I was of course I am pleased that the car was working properly again. But part of me was worried - at least up until this point the problem was consistent - we had a problem to solve!
Having apparently done nothing worried me that the problem would return.
BUT, I had of course done something.....I had filled the car with fuel.
So this set me wondering about the quality of the fuel in the car. I always use fuel from one of the major retailers - Shell, Esso, Texaco, BP. But the fuel in the car was (I am ashamed to say) ~5 months old! I spoke to both Kaz & the garage about this & both accepted that this could conceivably be the reason Y1 was misfiring, but here was some scepticism from both.
There was something else though - and this had not occurred to me at the time until Kaz mentioned it. There is a small valve in the fuel cap which normalises the pressure between tank and atmosphere. I normally get a small hiss when I remove the fuel cap, but when I filled the car up the other day, there was an almighty 'whooosh!' as I released the cap.
It seems possible to me that the valve wasn't/isn't working properly - I have prodded & poked it since and it was certainly not easy to move (I have since fitted a new fuel cap).
It seems to me that this could explain the misfire - remember this only occurred when the engine was under load - if there was a partial vacuum forming in the fuel tank as the fuel level decreased, it would be increasingly difficult for the fuel pump to draw fuel from the tank - especially under hard acceleration.
I have driven Y1 nearly 500 miles since refueling that day a week ago. Everything has functioned perfectly - not a hint of hesitation or misfire (much touching of wood!)
Was it due to degraded fuel, a dodgy valve or something else altogether? I suspect I will never know!
I must thank the community here on NSXCB for all their help, support and advice - so many of you have been generous with your time, advice, bits of your cars etc. etc!!!! This makes owning this wonderful car even more of a pleasure.
Most especially (in no particular order) I must particularly thank Simon (NSXCB), Paul (NSX 2000), Gary (Hagasan), Andy (at VTEC Direct) and of course, Kaz.
I should also thank the service department at Geo Collins Honda, Herstmoceaux. They took the car in at no notice despite being fully booked, spent what time the could on the car, wouldn't recommend buying new parts before finding the root cause of the problem, and were happy to follow up idea's relayed from the good people on NSXCB - I know many service dept's wouldn't do this.
:)
The misfire was easy (and repeatable) to provoke - just put the engine under load by depressing the throttle and the car would misfire. If the car was driven with a very gentle throttle foot, it appeared to run normally.
A strange (to me at least) feature of this malady was the cars reluctance to store error codes. The ECL would flash but more often than not, no error code would be lodged. Those that did get recorded were mainly related to multi-cylinder misfires. I did, early on, get a cylinder #1 misfire code which initially led to the suspicion that the coil pack in this cylinder being defective. (Cylinder #1 is in the rear bank, nearest to the offside of the car and reletively commonly damaged by water ingress via the vent/duct which runs across the rear of the engine compartment glass 'bubble').
I took the car to my local(ish) Honda dealer and they set about trying to diagnose the problem. After about 10 days (and trying things suggested by myself via ideas proposed here & unearthed on Prime, they were no closer).
The plugs looked fine, it was felt unlikely that all 6 ignition coils would break down at once, the ignitor unit had been swapped with one from another car & it was all looking a bit grim. Next item to swap out was probably going to be the ECU!
I had to temporarily bring the Honda dealers research to a halt as I had promised my eldest son I would take him to his end of school ball in the NSX (he so wanted to go in the NSX rather than a stretch limo...I must have done something right bringing him up!!!!)
I collected my car from the Honda service dept. and they had no further news. Problem still present (though a new ignition coil had arrived at my request & they had experimented with moving this from cylinder to cylinder to no avail).
They were now awaiting a call from Honda technical.
I drove the car very gently for ~30 miles, max revs 3000rpm.
The fuel warning light came on - I never usually let the fuel get this low, but I have been distracted by the misfire. I stopped & filled the car up.
I drove another 6 or 7 miles, again very gently.
No sign of a misfire at all today so far.
I was heading to Simon's (NSXGB) house, as he had very kindly agreed to help me swap plugs, ignition coils & ignitor unit from his car to mine to once and for all establish if the problem lay with any of these components. About 3 miles away I thought I should induce the misfire just to remind me what to do once we had swapped parts from Simons car.
In 2nd gear, 2000rpm I accelerated hard to ~4500rpm. No misfire.
I backed off and accelerated hard again - this time to about 5500rpm. No misfire.
I tried again, this time running up to 6500rpm - no misfire!!!
I couldn't get the car to misfire!
Because of this, there was no point swapping Simon's parts into my car.
I was of course I am pleased that the car was working properly again. But part of me was worried - at least up until this point the problem was consistent - we had a problem to solve!
Having apparently done nothing worried me that the problem would return.
BUT, I had of course done something.....I had filled the car with fuel.
So this set me wondering about the quality of the fuel in the car. I always use fuel from one of the major retailers - Shell, Esso, Texaco, BP. But the fuel in the car was (I am ashamed to say) ~5 months old! I spoke to both Kaz & the garage about this & both accepted that this could conceivably be the reason Y1 was misfiring, but here was some scepticism from both.
There was something else though - and this had not occurred to me at the time until Kaz mentioned it. There is a small valve in the fuel cap which normalises the pressure between tank and atmosphere. I normally get a small hiss when I remove the fuel cap, but when I filled the car up the other day, there was an almighty 'whooosh!' as I released the cap.
It seems possible to me that the valve wasn't/isn't working properly - I have prodded & poked it since and it was certainly not easy to move (I have since fitted a new fuel cap).
It seems to me that this could explain the misfire - remember this only occurred when the engine was under load - if there was a partial vacuum forming in the fuel tank as the fuel level decreased, it would be increasingly difficult for the fuel pump to draw fuel from the tank - especially under hard acceleration.
I have driven Y1 nearly 500 miles since refueling that day a week ago. Everything has functioned perfectly - not a hint of hesitation or misfire (much touching of wood!)
Was it due to degraded fuel, a dodgy valve or something else altogether? I suspect I will never know!
I must thank the community here on NSXCB for all their help, support and advice - so many of you have been generous with your time, advice, bits of your cars etc. etc!!!! This makes owning this wonderful car even more of a pleasure.
Most especially (in no particular order) I must particularly thank Simon (NSXCB), Paul (NSX 2000), Gary (Hagasan), Andy (at VTEC Direct) and of course, Kaz.
I should also thank the service department at Geo Collins Honda, Herstmoceaux. They took the car in at no notice despite being fully booked, spent what time the could on the car, wouldn't recommend buying new parts before finding the root cause of the problem, and were happy to follow up idea's relayed from the good people on NSXCB - I know many service dept's wouldn't do this.
:)