Super-Mystery Engine Noise

[munkmunk]

Leased new EX35, which has really annoying mystery engine noise. Tech's can't hear it. I will skip the usual whining, and just say that if Infiniti fails to resolve the issue, I will return it under lemon law provisions.

Here are the facts: - Cyclical, mechanical engine noise (almost like a Diesel, or sticky lifter) heard at slow speeds (0-50 MPH), between 1k-4k RPM, under engine strain (from a stop, up a hill, etc). - Unpredictable. Occurs in hot and cold conditions, both weather and engine. - 92 Octane fuel always used, including different brands in different cities. - Detected at ~275 miles. Still present at ~1,200 miles. - Cannot be heard when increasing RPM's in Neutral, or under engine breaking. Only under vehicle movement. - Sound not present on another new EX35 with 1 mile on odometer.

Anyone have any bright ideas? Great car, hate to return it, but this is unbearable.

[bosh]

Leased new EX35, which has really annoying mystery engine noise. Tech's can't hear it. I will skip the usual whining, and just say that if Infiniti fails to resolve the issue, I will return it under lemon law provisions.

Here are the facts: - Cyclical, mechanical engine noise (almost like a Diesel, or sticky lifter) heard at slow speeds (0-50 MPH), between 1k-4k RPM, under engine strain (from a stop, up a hill, etc). - Unpredictable. Occurs in hot and cold conditions, both weather and engine. - 92 Octane fuel always used, including different brands in different cities. - Detected at ~275 miles. Still present at ~1,200 miles. - Cannot be heard when increasing RPM's in Neutral, or under engine breaking. Only under vehicle movement. - Sound not present on another new EX35 with 1 mile on odometer.

Anyone have any bright ideas? Great car, hate to return it, but this is unbearable.

Sure - I had similar symptom, but the sticking tapping noise would only occur at over 4000 rpm under load (in drive).

Fix - ITB07-007c - Back flush the heater core to remove gray silicone debris.

Ok - the dealer double back flushed it - worked for 1 day.

The symptom return at 2000 rpm.

Fix - dealer replaced the heater core - unfortunately manual stated 4.5 hours of labor. It actually took 10.5 hours - Dealer reported it to Infiniti, who will modify the time required to fix it. (Bottom line - you will have to leave EX there for 2 days - after the second visit)

And I'm a very happy camper

[munkmunk]

The dealer now assures me that this is a timing issue. He recommended that I try fuel additives.

Adding an octane booster did smooth out the noise, but it is still there, and I can't imaging driving this thing for another 30k-50k with it.

What sort of issues could be plagueing the engine timing?

[JCL622]

The dealer now assures me that this is a timing issue. He recommended that I try fuel additives.

Adding an octane booster did smooth out the noise, but it is still there, and I can't imaging driving this thing for another 30k-50k with it.

What sort of issues could be plagueing the engine timing?

sounds like they're trying every shortcut before needing to do anything that requires time/labor. demand that this be taken care of, or if they prefer, that you'll just contact Infiniti HQ directly because the vehicle was leased and you expect the customer service that is supposed to be representative of a luxury brand such as infiniti

[munkmunk]

Pretty much. I will give them 2 more days before escalating directly to Infiniti.

[SteveTheTech]

Octane boost is not a valid fix. It just isn't an answer.

The heater core noise threw me for a wicked loop when I first heard it. I started pulling the dash board apart before I was actually able to realize that is the sound from the heater core. This is not to say this is munkmunks noise.

I have a really odd ball request for you to make of the Infiniti dealership.

Please ask them to try the Exhaust Timing Learning procedure that is outlined on page 19 of the EC section of the esm. It's a shot in the dark but an exhaust cam that is slightly out of time but not out enough to set a trouble code.

Since the car has such a low amount of miles on its clock that would be my first try.

[munkmunk]

They retarded the timing as much as possible, within factory spec, which has almost eliminated the noise. Could the Exhaust Timing still be an issue? Could it be the issue if retarding engine timing resulted in improvement?

[jmess]

Octane boost is not a valid fix. It just isn't an answer.

The heater core noise threw me for a wicked loop when I first heard it. I started pulling the dash board apart before I was actually able to realize that is the sound from the heater core. This is not to say this is munkmunks noise.

I am having the local dealer check my car out. When I talked to them about the strange noise I had been hearing and the heater core tech bulletin they said they have never had an EX with this issue before. My 08 was part of the first batch from japan.

[SteveTheTech]

They retarded the timing as much as possible, within factory spec, which has almost eliminated the noise. Could the Exhaust Timing still be an issue? Could it be the issue if retarding engine timing resulted in improvement?

It could be. Retarding the timing was one of our little tricks for dealing with octane variation and some case by case issues. The only time I have personally ever done this was on an I35 and that was only 3*. Some of the G guys swear by adjusting the timing for power but I personally think the computer having final say is more likely to be right than anything I can do for it. If the battery goes dead or the computer was reprogrammed the EXT learned position might be off as well as the Closed Throttle, and Idle Volume.

This type of adjustment is also not a legitimate permanent fix. If they are adjusting the timing that is a strong indicator of something. To me having you say that it changes the noise means that either the engine timing is not correct but before digging into the mechanical timing I would be looking at the EXT first then I would check compression.

[ljb5966]

I have about 6500 miles on my car and it just started making a grinding/clicking noise when accelerating hard - it would not make the noise if I drove it like a 4 cylinder, but that is not why I own this car. I brought my car in and they thought it was going to be the power steering, but it was not. They listed the technical bulletin ITB07-007C - Back-flush heater core. I have only had my car back over night, so we shall see if that fixes the issue - so far, so good. Bring your car in and tell them about this technical bulletin. It should correct your problem.

[munkmunk]

Let me know if that fixes it.

[mcouper11]

Have a 2010 with 200 miles -- ready to trade it in. As described on another post, has a loud whine sound under acceleration or up incline. Even kids asking what's up w the car. Got a feeling they're not going to figure it out or will tell me it's normal. Will take any suggestions/advice.

[SteveTheTech]

Is that a 2010 EX that you have? I really like what they changed in the center display. Congrats. :dtumb

The very high pitched noise (~20k Htz) under any load is coming from the ECM and cannot be fixed just yet. This has been going on for a little while and they are working on a repair for it that does not involve altering the airflow near the ECM case. The ecm like any computer needs to be cooled off and as Nissan learned with the 2000 Sentra recall (ECM was wrapped in foam to keep it quiet) which lead to the ECM cutting out and having all types of issue when it got too hot.

There should be a repair in the future but there is not a whole lot that can be done about it right now. Although the frequency is pretty high the volume is fairly low in comparison to the average radio volume.

Hang tight though they are working on something.

[mcouper11]

Yes - 2010. Great vehicle, aside from the noise. Actually sounds like its coming from the underneath the car from either front or rear passenger wheels. As you can see, hard to articulate what it sounds like or where its coming from -- all I know is that Ive never heard a sound like it on a brand new car (or even an old one for that matter). Seriously considering trading it in if it persists.