Hey guys. I Just picked up my ne '06 MT and noticed a little pre ignition noise when accelerating from 2000 rpm in 2 nd gear. I have been braking her in as per the 4000 rpm rule. Is this normal? I have heard of some guys having there timing off from the factory. Like I said it happens when your low on the rpms and give it a good dose of pedal. Any insight would be great!! Thanks.

 

WOW!! I did a search on this topic and am learning way too much about ignition and clutch noises. Sounds like Infiniti needs to do some better R&D in these departments...

 

I have it too and can tell you at 1500 miles it's not going away after the break in period.

Maybe I made a mistake getting the 6MT. I had a 03.5 5AT sedan and would say the auto transmission is excellent. Maybe a little slow on the downshift, but when accelerating quickly the shifts were hard and quick. And no knocking at all.

On the + side I think the coupe handles much better. Love the exhaust note and the interior improvements. And of course it looks much nicer

 

i've taken my vehicle into the dealership for this issue and they retarded my timing from 15 degrees to 13 base... this did not help much at all... here are the reasons why:

1) summer fuels - these have an inherently different makeup than winter fuels and are more prone to pre-ignition... their octane rating is the same, but the variables in the equation used to find minimum octane differ... the equation is (R+M)/2... the Research Octane Number, or R in the equation, is a measure of the gasoline's ability to resist knock at low speed under relatively mild operating conditions, such as city type driving... the Motor Octane Number, or M in the equation, is a measure of the gasoline's ability to resist knock at high speeds and under severe operating conditions, such as towing a boat or climbing steep hills... the average of these two numbers defines how well the gasoline will resist engine knock under most conditions...

that said, the problem with summer fuels is the R portion of the equation...hence the reason you're getting detonation at lower RPMs... couple that with the ambient temperature being much higher in the summer and you have spark knock... now, *some* fuel manufacturers will have a good R portion in their summer mix and a lower M portion... if you put a tank of their fuel into your ride, you'll get detonation at higher RPMs...

2) Infiniti (Nissan) advances the timing on these engines like mad to pull every ounce of HP out of the motor that they can... so, even with the base retardation of my timing to 13 degrees, the ECU senses me stomping the skinny pedal and advances my timing to match... hence the reason i still have spark knock... it makes me very uncomfortable to know i'm riding around on the edge of my engine's capacity at all times... even though it has knock sensors to retard the timing once it starts banging, that doesn't stop the initial damage done... and i've seen pistons burnt out from spark knock...and even heard of a fella slinging a rod from detonation... (granted he was FI at the time and engine ran lean)

all in all, you're only recourse is to make damn certain that you're running the highest octane possible and a reputable fuel... i also recommend getting yourself some Chevron Techron additive and running it as directed... you can get this at any Chevron gas station...

 

I don't think a little bit of knock is actually going to hurt the engine, but thanks for the dealership info I won't bother mentioning it to them. The less they touch the car the better.

BTW tops I'm keeping this car 4 or 5 yrs which should be like 60-70K miles so not really worried about long term engine reliability.

 

think what you want... but, *any* detonation damages the engine... it's an uneven burn across the cylinder head pre-ignition... the heat generated can burn a hole in the piston even if there is only one instance of it...no repetition necessary...

 

I agree. The G is not a long term keeper. It's a fun car but the build quality is not there.

 

Engine knock in our VQ's shouldn't happen at all. I know the temptation is to just put up with it, but any pre-ignition is bad to some degree and also affects your gas mileage too.
Keep your eye on it and change fuels to see how others perform. You may find that you got a substandard tank of gas (or even low octane fuel. )
I know how you feel about the dealer touching your ride, I hate it too, but having him check the timing shouldn't take much, then at least you can rule that out too.

G/L
C.

 

You mean your G, right?

 

^+1

Preignition can be a real bad thing. I didn't know it was common. I've never heard a peep from mine and I run 91.

 

echephron,

That sucks they would pull timing on your engine. Thats the wrong fix.
Pre-ignition means ignition before spark. So what they did not only doesn't fix the problem, it reduces power and efficency.

There are two really good ways to adress pre ignition.
1) Use a colder plug.
2) Switch to a similar heat range plug that isn't platinum.

Platinum is a very good catalyist. in fact, platinum is often used in combustion systems to create light off in conditions where ignition would normally be difficult.

Very much the same reason why platinum should not be used in nitrous systems. nitrous is even more sensitive to platinum and is touched off very easily.

If possible, go back to your dealer and ask them to set your timing back to normal and then install 1 step colder plugs. They only need to read the service manual to know the proper procedure but it sounds like they were either lazy or didn't want to give you a new set of plugs.

Tony

 

Preignition will often show itself by staining the inside of the lower plenum intake runners with a brown burn residue.

Its not very common, but it certaintly happens.

Since you are in Canada you could be using a completely different chemistry of 91 octane. (Be glad you don't live in California. We must have the worst mystery gasoline chemistry you can pump into a car. Out here its just a mixture of any oxygenated hydrocarbon concoction that can be made to burn.

Cold Canadian air inlet temperatures can also quench off hot plugs and this would help you out a lot...

 

I have it below 2000 in 2nd when accelerating from a slow roll.
I have about 210 miles now and for now I just try not to drive there.
I have yet to put gas in it and am running it down to very low because I got the car in philly and don't know how good that gas station they used was.
I am thinking with Sunoco 94 in the car it will be fine. I always ran this same gas stations gas in my Evo and never had a problem.

Oh and off-topic, I will be talking to you Tony in the next couple months.

 

I'm not in Canada and my car does the same exact thing. There was another thread with a number of people with 06 6MT having the same issue.

I wonder if it has anything to do with the skyrocketing gas prices. I notice all the pumps talk about alcohol content now. Can I blame Bush? I love to blame him for everything. I just hate him that much

 

Thanks Tony!!! Voice of reason! I learned something new today!! Always a pleasure to read your replies!!!