Low RPM Engine Knock and vibration in the interior dash

[tmay2624]

OK...I have been dealing with this for some time and it is getting worse, I don`t believe its fuel related because I have been through just about every fuel related solution I can find. (Without a complete fuel system tear down for cleaning)

When we start from a slow speed or a stop, more so when engine has warmed up, we get a short burst of extreme knocking (between 1100 and 1800 rpm) and the car also feels like it shifts into too high a gear causing vibration of the dash board. Sounds like the timing chain is slapping, though I have no experience with that, and I`m getting concerned. I have had it to the dealer and they said 3 techs drove it and could not get it to do it, we drove the service manager around and it was very mild knocking at the time and he said he couldn`t hear it. As soon as we get 30 miles down the road its back. I think we are going to try another service dept.

My concern is Timing Chain, I know that can cause some serious damage and the dealer said if something was wrong with the chain it would code, I`m not getting any codes.

Any Information or past experience with an issue like this is appreciated. I have read through the forum and saw the post about the tension-er for the timing chain and was wondering if that may be my issue. I wanted to exhaust anything else I could check that may be cheaper!...I just dumped $1650.00 into the front end and need some recoup time.

So to be more precise.....will a timing chain issue code?
Maybe I need the fuel system professionally cleaned, if that is possible?

Thank You.....this forum has saved me loads of money and headaches.

Tim

[zebelkhan]

Originally Posted by tmay2624

When we start from a slow speed or a stop, more so when engine has warmed up, we get a short burst of extreme knocking (between 1100 and 1800 rpm) and the car also feels like it shifts into too high a gear causing vibration of the dash board. Sounds like the timing chain is slapping

I don't think this is fuel related, not quite. You should also be able to hear the chain slap at idle or start-up so I don't think that is your problem either. It sounds like engine is doing this only under load. Then it is more than likely a timing issue which is controlled by the knock sensor. If you are not using premium gas, I recommend start there first. If you already are then knock sensor replacement would be my next choice.

[tmay2624]

Originally Posted by zebelkhan

I don't think this is fuel related, not quite. You should also be able to hear the chain slap at idle or start-up so I don't think that is your problem either. It sounds like engine is doing this only under load. Then it is more than likely a timing issue which is controlled by the knock sensor. If you are not using premium gas, I recommend start there first. If you already are then knock sensor replacement would be my next choice.

Thank you for the input....the dealer was telling me if it were the knock sensors it would code, but I`m not having the best luck with the dealer they don`t seem to want to help. I will definitely look into knock sensor replacement.

[tmay2624]

Originally Posted by zebelkhan

I don't think this is fuel related, not quite. You should also be able to hear the chain slap at idle or start-up so I don't think that is your problem either. It sounds like engine is doing this only under load. Then it is more than likely a timing issue which is controlled by the knock sensor. If you are not using premium gas, I recommend start there first. If you already are then knock sensor replacement would be my next choice.

When I started it up first thing this morning I did notice a knocking that lasted about 1 - 2 seconds at most and dosn`t do it at idle at all after that initial cold start.

Thanks for your input.

[zebelkhan]

You mean after the initial cold start it does not do it at all, even under load? If that is the case then many are suffering from that rattling noise. Check your oil level. It maybe something as simple as low oil level.

[tmay2624]

Originally Posted by zebelkhan

You mean after the initial cold start it does not do it at all, even under load? If that is the case then many are suffering from that rattling noise. Check your oil level. It maybe something as simple as low oil level.

No, I`m sorry for the confusion, I get a knock for a second on cold start, nothing at idle after the cold start, and while parked revving the engine will not cause knocking either. The knocking I was referring to in my earlier post is under a load and low RPM that you thought might be the knock sensor and not the timing chain because of it being under load when it knocks. I think I`m going to do the knock sensor with a spark plug change because I`m getting close to needing plugs anyway and hopefully that will take care of my issue. If not I`ll be back with an update and in need of more ideas!....

[Capt Ni-Mo]

I've been trying to figure out this issue on my Murano also. I changed the plugs last weekend and it did not seem to help. It is hard to trouble shoot because it only does it at take off under very light acceleration but it does seem to do it more often right after start-up when taking off. To describe it on mine; I would say it sounds like a lifter rattling for a second or 2 but I dont think it has to do with the valves. If you have any luck diagnosing the issue please report back. This does seem to be a common issue nobody has really pinned down yet.

[Eric L.]

Right, you have two issues here.

The cold start knocking noise is pretty normal - its valve chatter that is common on a lot of Nissan VQ engines. It happens on both my Maxima and Murano, and I've always used Mobil One 5w30 and Nissan factory oil filters.

The noise under initial acceleration (load) is probably a bad knock sensor or excessive carbon buildup (which functionally increases compression). On my Maxima, a bad knock sensor would *not* throw a code, since I replaced it once on a whim and found the old one was dead as a doornail (but no check engine light). Not sure if this is the case on the Murano. There are ways to test the resistance of the knock sensor if you have the factory manual. In the meantime, see if the knocking goes away with premium unleaded. I have never heard of a timing chain issue on VQ engines with proper lubrication.

Originally Posted by tmay2624

No, I`m sorry for the confusion, I get a knock for a second on cold start, nothing at idle after the cold start, and while parked revving the engine will not cause knocking either. The knocking I was referring to in my earlier post is under a load and low RPM that you thought might be the knock sensor and not the timing chain because of it being under load when it knocks. I think I`m going to do the knock sensor with a spark plug change because I`m getting close to needing plugs anyway and hopefully that will take care of my issue. If not I`ll be back with an update and in need of more ideas!....

[turbizzy]

You should have the tech roadtested overnight for a day or two and let them hear it.

[lgt]

So have you tried premium yet? I find it kind of funny that in so many words the manual says the tune is for premium, but you can run regular. I'd like to know how the ECU deals with knock. It shouldn't knock that bad, but it's worth a try. I try some injector cleaner too. I sugest Redline.

[tmay2624]

Originally Posted by turbizzy

You should have the tech roadtested overnight for a day or two and let them hear it.

I have an appointment Oct 12th with a well known high performance shop in the area for the knocking. I had my tech change the knock sensor when I had it in for plugs and the low RPM knock is still there.

[turbizzy]

Well how'd it go?

[tmay2624]

Well I have had my Mo in 3 different shops one including the dealer and its looking like my knocking issue could be timing chain related. The best mechanic in our area said he can do the timing chains, tensioner, guides, ect....plus the water pump while he is in there for $1590.00, The dealer is at $2000.00 excluding the water pump.. They were also mentioning it could be the variably cam sprocket so I could be looking at A LOT more money. ($900.00 ea)

( So far I have had the plugs replaced and the knock sensor, $600.00 P&L)

My question is about the variable cam sprockets, is there a diagnostic that can tell if they are bad?

The shop that quoted me the $1500.00 said he wants to look into the issue more and have me leave the Mo with him a couple days so he can become more acquainted with it before tearing into it. It is a very well known high performance shop in my area and has an outstanding reputation, pricey but good.

Thanks!!

[turbizzy]

There is a way of tested the VTC sprockets and involves monitoring the intake valve timing sensor angles and comparing them to factory specs under certain conditions.

I supposed a faulty VTC sprocket could cause a knock issue but i would assume the ECM would flag a code if so. Have you been to the dealer yet? I think its time...

[tmay2624]

Originally Posted by turbizzy

There is a way of tested the VTC sprockets and involves monitoring the intake valve timing sensor angles and comparing them to factory specs under certain conditions.

I supposed a faulty VTC sprocket could cause a knock issue but i would assume the ECM would flag a code if so. Have you been to the dealer yet? I think its time...

Yes, they had it and couldn't replicate the knock and as soon as we got 30 minutes away it was back with full force. I will be near the dealership on Thursday and will stop in again.