Well I took my Q to the Dealership to have them replace the Knock Sensor and 02 sensors. I got the car back an everthing worked fine for about a day. Then the miss and stumbling started. The car still had good power at WOT but any other time the car was defineately running a little lope-y. The CEL light came on for cyl #1 and I took it by a mechanic friend who recommended replacing the plugs as it was simplest and easiest to do. The car still misfired saying cyl 1 was the culprit. So we go and buy a new coilpack and the problem still persists. This is when we do a compression test.
The test came back with good numbers (180-200) on all the other cylinders except number 1 which was at around 100. The Mechanic now wants to say the car has a bad exhaust valve. It could be possible, but I've never heard of that being a problem on the VH. (or many other nissan engines for that matter) Not only that, but the car idled smooth as butter before the knock sensor job and even the following day afterwards. Gas mileage was great too, but now that the misfire has developed the gas mileage is as expected, crap.
I'm kinda stuck as far as what to do now. Not saying the valve isn't a problem, but this car has never overheated or ran hot before. It's ran smooth for the complete time of ownership with very few problems. The engine does have 180k on it, but I'm not seeing how this would be a big issue for the car. I see Qs on this forum with far more miles.
YG33 Misfire after knock sensor replacement
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maxnix
- Posts: 22627
- Joined: Mon Jul 22, 2002 8:11 pm
- Car: 1995 Infiniti Q45
1995 Infiniti Q45t
2000 Infiniti Q45
Re: YG33 Misfire after knock sensor replacement
Maintenance history? OCI?
Re: YG33 Misfire after knock sensor replacement
If the problem started just 2 days after the dealer did the 02 sensors & knock sensors......why didnt you immediately take it back to them to figure out ??????
180,000 miles on engine could just be breaking in, or just getting ready to break,period.All depends on prior routine maintenance being timely performed from very early in the engines life......getting a neglected engine for a good part of its life from the previous 1,2,3+++ owners and all of a sudden current owner{you} babies it with frequent service,even using premium synthetic fluids,etc cant erase years and miles of accelerated wear due to prior poor/very little routine maintenance having been performed.
180,000 miles on engine could just be breaking in, or just getting ready to break,period.All depends on prior routine maintenance being timely performed from very early in the engines life......getting a neglected engine for a good part of its life from the previous 1,2,3+++ owners and all of a sudden current owner{you} babies it with frequent service,even using premium synthetic fluids,etc cant erase years and miles of accelerated wear due to prior poor/very little routine maintenance having been performed.
Re: YG33 Misfire after knock sensor replacement
I think it is a bad coilpack. It may be on a different cynlinder
Re: YG33 Misfire after knock sensor replacement
The car was acquired with about 97K miles on it two years ago. Awesome interior that still smelt like a brand new Q with hardly any cosmetic defects. When i got the car plugs, belts fluid and many other nick nacks had been changed. The car ran perfect and performed perfect when we had it. Since then the car has been maintained very well with routine oil changes and we recently did the Knock sensor and all that as mentioned.
Reason we didn't bring the car back to the dealership immediately is because that is a 2 hour drive from where I live. I don't wanna drive the car that far with it running as it is. Is there anything I should look at that could point me in the direction of solving this issue? The car idled fine before doing the knock sensors and such. But then about two days after we did it, the misfire developed. I like to think that issues arising around the same time as previously done work are related to the work. But I could be wrong. Just seems weird cause you never hear of these cars having valve problems.
Reason we didn't bring the car back to the dealership immediately is because that is a 2 hour drive from where I live. I don't wanna drive the car that far with it running as it is. Is there anything I should look at that could point me in the direction of solving this issue? The car idled fine before doing the knock sensors and such. But then about two days after we did it, the misfire developed. I like to think that issues arising around the same time as previously done work are related to the work. But I could be wrong. Just seems weird cause you never hear of these cars having valve problems.
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Q451990
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Re: YG33 Misfire after knock sensor replacement
If you had a dead miss on that cylinder due to no spark, it's possible that the unburnt fuel on that cylinder has washed the rings clean, causing your compression issue. When you did the compression test, did he do a trial after squirting oil into the cylinder? That should isolate rings vs. valves.
I'm assuming they didn't remove the coil packs or valve covers at the same time as your knock sensor service?
Coil pack failure is extremely common on that version of the Q. Usually a misfire will almost "roam" from one cylinder to another - especially after they've been pulled. The most reliable fix has been to replace all 8 at the same time. They're available from online sources for about $83 each.
http://www.orderinfinitiparts.com/parts ... mCallOut=1
Oh, and if you ran it for a while between the time you changed the plugs and changed the coil, it's possible that the plug is fouled on that cylinder. I would check it to make sure it looks nice and clean...
Good luck!
Heath
I'm assuming they didn't remove the coil packs or valve covers at the same time as your knock sensor service?
Coil pack failure is extremely common on that version of the Q. Usually a misfire will almost "roam" from one cylinder to another - especially after they've been pulled. The most reliable fix has been to replace all 8 at the same time. They're available from online sources for about $83 each.
http://www.orderinfinitiparts.com/parts ... mCallOut=1
Oh, and if you ran it for a while between the time you changed the plugs and changed the coil, it's possible that the plug is fouled on that cylinder. I would check it to make sure it looks nice and clean...
Good luck!
Heath