Ask the Car People.SM


Infiniti I35 Maintenance and Repair

594 messages,  Last post on Jan 13, 2013 at 8:58 PM

You are in the Infiniti I30/I35 Forum.

What is this discussion about? Infiniti I35, Sedan

Messages Page 57 of 61

#552 of 594 Re: 2003 I-35 [wilson16] by Mr_Shiftright HOST

May 12, 2011 (1:33 pm)

Replying to: wilson16 (May 12, 2011 12:58 pm)
If it sounds like a chain dragging under the car when you accelerate, this could be detonation (pinging) and it is *very bad* for your engine, if it persists and is frequent and loud. (a little 'ping' for a split second is okay).
 
Just buy the best gas you can for starters, like Shell or some other name brand, and see how it affects the noise. If it diminishes or goes away, you are on the right track. If it doesn't, you'd best see a mechanic to determine if it is really severe detonation requiring engine adjustments, or if it's some other noise not related.
 
In any event, don't postpone acting on this. Severe detonation will punch a hole right through the tops of your pistons.
 
The noise you are hearing are the internal parts of your engine rattling around---literally.

#553 of 594 Re: 2003 I-35 [wilson16] by atma97

May 15, 2011 (11:33 am)

Replying to: wilson16 (May 12, 2011 4:54 am)
Knocking sound in acceleration is a symptom of gas with low octane or engine running too lean. One should always use a premium gas for I35. If knocking sound exists after a couple premium gas tanks, then knock sensor need to be replaced ($50 part). For saving on gas, I am adding 3 oz of pure acetone into a 14 gal gas refill and saw mpg increase more than 3 mpg. I am doing this with my own risk but the car is running at its best. At 160,000 miles with a luxury and smooth ride, I could not find a just reason to get rid of this car and get a more luxury and trendy one. Hope not to keep driving this one for another ten years.

#554 of 594 Re: 2003 I-35 [atma97] by Mr_Shiftright HOST

May 15, 2011 (11:45 am)

Replying to: atma97 (May 15, 2011 11:33 am)
Acetone has been shown in rigorous clinical tests to have no affect on gas mileage, and is also corrosive to paint and rubber, so you could confidently abandon it with no worries. I personally never recommend using it. Probably you're experiencing normal variations in MPG and most of us don't have the patience to really measure and calculation out all the variables.
 
Your suggestion about a knock sensor is definitely worth looking at and thanks for mentioning it.

#555 of 594 Re: 2003 I-35 [Mr_Shiftright] by wilson16

May 16, 2011 (9:23 am)

Replying to: Mr_Shiftright (May 15, 2011 11:45 am)
I have heard there may be more than (1) knock sensor in the 03-I35
Can you tell me where the location or locations would be and is it something I can change myself

#556 of 594 Re: 2003 I-35 [wilson16] by Mr_Shiftright HOST

May 16, 2011 (6:06 pm)

Replying to: wilson16 (May 16, 2011 9:23 am)
No just one. Looks like a bit of a job. Book says 3.5 hours for a mechanic. It seems to sit (from the diagram I've got) in the valley between the two cylinder heads--so under the intake---about 2/3rds of the way back. It's also a pricey little devil--not something you'd want to be guessing about. List price close to $200 bucks tho' I'm sure you could shop around and do much better.

#557 of 594 Re: 2003 I-35 [Mr_Shiftright] by wilson16

May 17, 2011 (4:10 am)

Replying to: Mr_Shiftright (May 16, 2011 6:06 pm)
Well as such as all the parts for Infiniti. If the premium gas doesn't fix the knocking that I'm getting what would the signs be for a knock sensor going bad or about to. Are there any other places I might check to solve this problem

#558 of 594 Re: 2003 I-35 [wilson16] by Mr_Shiftright HOST

May 17, 2011 (9:05 am)

Replying to: wilson16 (May 17, 2011 4:10 am)
Well it would be good to get a "second ear" on this noise to make sure we're barking up the right tree...unless you are POSITIVE it's pinging.
 
Anyway the knock sensor is supposed to correct for pinging--it's supposed to "hear it" and retard the engine timing. The question then becomes--is the knock sensor working or not, and if it IS, why isn't the engine responding to the signal?
 
DESRIPTION: The knock sensor is attached to the cylinder block. It senses engine knocking using a piezoelectric element. A knocking vibration from the cylinder block is sensed as vibrational pressure. This pressure is converted into a voltage signal and sent to the ECM.
 
So in theory we could also have an electrical connector issue, or an ECM issue.
 
Unfortunately I cannot find any description of how to diagnose and test for a bad knock sensor. I would presume a good repair shop with a CONSULT-II scanning device knows how to do this.
 
They used to say "you don't have to be a rocket scientist to figure THAT out"--but you know, sometimes I wonder

#559 of 594 Re: 2003 I-35 [wilson16] by atma97

May 18, 2011 (2:49 am)

Replying to: wilson16 (May 17, 2011 4:10 am)
There are other reasons for the engine to knock when the car has high millage. Car might run too lean or too hot. Lean might due to dirty fuel injections or weak fuel pump. Hot might be caused by back up pressure from bad catalytic converters. I would exam spark plugs to figure out how lean the engine runs.
 
Knock sensor is bolted to the center of the engine, underneath intake manifold body. As soon as removing the intake manifold upper and lover parts, you will see the knock sensor sitting right on the engine. You will need a new set of manifold gasket though. It might be a good idea to change valve cover gaskets and spark plugs when you have full access to these locations. The whole tedious job requires patience, try not to over tighten the bolts on this engine block. Hope you will have another 100k miles on your car after this job.

#560 of 594 Re: 2003 I-35 [atma97] by wilson16

May 18, 2011 (4:36 am)

Replying to: atma97 (May 18, 2011 2:49 am)
Do you think the noise I may be hearing could be the timing chain getting loose or already that way. I've noticed that when you rev the motor you hear a clanging sound or when you shut the motor off

#561 of 594 Re: 2003 I-35 [wilson16] by Mr_Shiftright HOST

May 18, 2011 (8:49 am)

Replying to: wilson16 (May 18, 2011 4:36 am)
Sure could be chain noise from a bad tensioner. Usually you'd hear this more when the engine is 'slack' than when it is being revved but this could be diagnosed with a mechanic's stethoscope.

Messages Page 57 of 61

To POST a message, please Sign In.

Advertisement

Browse by Category

Browse by Vehicle
   View All Vehicles

Browse by Board
Browse by Topic
View All Topics

Edmunds Community

Advertisement