Knocking! Help me?

L

lestat13

Member
After some reading on the other forum, people were talking about knocking and blowing motors and stuff..... got me paranoid. So driving around tonight with a friend of mine in his turbo volvo I setup my dashhawk to alert me every time I knocked 1.0 (which I am assuming is one knock). Holy s***, I could not believe how much I was knocking in 5 and 6 gear when I was not ramping up or WOT.
 
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excuse my ignorance . . . what is a knock? Also how bout investing in an engine mount. Made a huge difference in my car and they are cheap / quick install.
 
coyfish said:
excuse my ignorance . . . what is a knock? Also how bout investing in an engine mount. Made a huge difference in my car and they are cheap / quick install.
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What does it have to do with Motor mounts.

I think this is normal. What gas do you use?
 
Check your gas octane rating, stations have different blends some have higher ethanol blends. Some work better with the MS3 turbo than others.

http://en.wikipedia.org/wiki/Engine_knocking

The knocking might be from a low grade or cheap blend of 91 octane gas. Try a quality station and see if you can get 93 octane and see of that clears up the knocking.
 
I always use 93 octane, usually from the same BP station... actually think I've only gotten gas maybe 3 or 4 times somewhere else since I've bought the car cause it's right by my house.

I am just worried that maybe the knocking is damaging my engine so please post up any info you have. Consider this my bump.

Also, this may help in diagnosis. I noticed that it really only happens in 5th and 6th gear, but it doesn't happen accelerating below 5psi or a wot. It does seem to happen mostly at a part throttle situation or when slowing down off of wot or near wot. I was getting boost cut too, but I am not afraid of the that cause it won't blow up my engine.

Thanks for the info so far, let's keep it going and hopefully save me and someone else a motor.
 
What is your mph when you hear it? You might just be going to slow for the gear that your in when it happens is what I'm thinking. I doubt that its detonation.
 
niz55 said:
What does it have to do with Motor mounts.

I think this is normal. What gas do you use?
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The man clearly stated he was not sure what a knock was hence his thinking it might be related to motor mounts and the engine knocking about or something.

For the coyfish: Engine knock is the sharp, metallic sound caused by the pre-ignition of fuel as it is compressed in the cylinder; a result of burning gasoline with too little octane.
 
Is it a constant knock or just hit or miss? I would think the ECU would pull timing. I assume the MS3 has a knock sensor.
 
It does have a knock sensor and you are not going to hear it like you think. THe ECU can adjust for 89 octane if it needs to, not suggested but it will. I have been running 89 octane in my CX7 with zero problems for 2 years.
 
Appreciate the help Donas. I try to learn the most I can from these forums but some people make it very difficult :(.
 
lestat13 said:
After some reading on the other forum, people were talking about knocking and blowing motors and stuff..... got me paranoid. So driving around tonight (aggressively) with a friend of mine in his turbo volvo I setup my dashhawk to alert me every time I knocked 1.0 (which I am assuming is one knock). Holy s***, I could not believe how much I was knocking in 5 and 6 gear when I was not ramping up or WOT.

How much does this hurt the car? More importantly, what can I do about it? Performance mods are only sri, dp, rp.
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I don't think it is too big of an issue, I mean, somebody can prove me wrong on this, but when I had my Sentra Spec-V I has having some major knock issues, but if it gets bad, your ECU will throw a check engine light. As long as there is not a cylander missfire, you are okay. Also, do you boost high under 3000 rpms? Like floor it in 6th gear when you are only going 50mph? Just wondering, you can be honest if you do.
 
The best power is to be had with the ignition as advanced as possible without damaging detonation. Knock is the most likely under the conditions you described, high gears, fairly low RPM and lotsa throttle. The ECU advances the timing a bit until it hears one or two knocks on the sensor and then backs if off a little. This is normal - it's the ECU doing it's best for you.
 
Just make sure you are running the proper fuel and in the right gear for that speed. Anything further take it in and show them what it is doing.
 
lestat13 said:
After some reading on the other forum, people were talking about knocking and blowing motors and stuff..... got me paranoid. So driving around tonight (aggressively) with a friend of mine in his turbo volvo I setup my dashhawk to alert me every time I knocked 1.0 (which I am assuming is one knock). Holy s***, I could not believe how much I was knocking in 5 and 6 gear when I was not ramping up or WOT.

How much does this hurt the car? More importantly, what can I do about it? Performance mods are only sri, dp, rp.
Click to expand...

From all the data logs I've seen, the disi absolutely knocks on a regular basis in stock form. Regardless of the gas used. That said, I see that as a huge issue! IMHO, it is probably one of the main factors preventing people from making big power!

Not sure if anyone has figured out what the cause is, but it does seem to happen mostly around 3-4000 rpms. Hopefully the aftermarket will come up with something to address this sooner rather than later...
 
SuperStretch18 said:
From all the data logs I've seen, the disi absolutely knocks on a regular basis in stock form. Regardless of the gas used. That said, I see that as a huge issue! IMHO, it is probably one of the main factors preventing people from making big power!

Not sure if anyone has figured out what the cause is, but it does seem to happen mostly around 3-4000 rpms. Hopefully the aftermarket will come up with something to address this sooner rather than later...
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Alot of the knocking issues I've heard about were in the low RPM's when people are high boosting. I haven't heard too many problems once the engine gets past 3k rpms. I have actually seen it run alot more efficient (a/f ratio) at those RPMS. I think the car could run a little leaner below 3000 rpms and that would take care of alot of the issue.

all cars knock, its the misfires that people really need to worry about. or some very very bad knocking.
 
Alexsered said:
...I think the car could run a little leaner below 3000 rpms and that would take care of alot of the issue.

all cars knock, its the misfires that people really need to worry about. or some very very bad knocking.
Click to expand...

Do you mean richer? If it's knocking, then the cylinder is hot enough to cause combustion without a spark. I imagine you would need extra fuel to cool at those points.

We'll have to disagree that knocking isn't an issue. It's just an added strain on our bottom ends...
 
Wow, this thread really took off in the 12 hours or so it's been here. Thanks for all the helpful information.

I try to never stomp the throttle, especially in high gears, unless I am already boosting 5+psi. Squeezing it seems to be the way go for sure! I try my best to keep boost under 5psi when under 3k rpms and when I cross 3k, I try to make sure I am at wot. These are things I have heard (whether they are right or wrong) that are better for our engines.

When it knocks, I don't hear anything. I don't know if there is a difference between knocking and pinging and just knocking, but it doesn't sound like there's a ping (but after about 90mph with the wind noise how could you hear it??). I know it's knocking because my dashhawk starts flashing. It was the worst in sixth gear when boosting (pretty much at all) at anything other than wot or no throttle. 3-4k rpms seems to be the prime range. Once in sixth gear I pulled off wot slowly and it went knock knock knock.... about 6 times on the dashhawk -- I was at about 5-10psi around 3-3.5k rpms.

If our engines are chronic knockers, that might explain why rods are going. Any more information for this thread is GREATLY appreciated. I will continue to do some research and take some datalogs and get back to you.
 
I reiterate - the ECU uses the knock sensor to adjust the timing to the best it can be. It advances to knock and then pulls back slightly. It needs to hear the knock to know where it is. The DashHawk just shows the few clicks it needs to feel out the best setting.
 
can you plot the data? I've seen knocking in other cars recording data such as knock vs time and its very quick blips on the chart. I would think that if it was held constant for an amount of time (which I'm not sure what that time would be) it would mean you have an issue?

possibly you get ever so slight blips of knock and the ecu is doing its job to adjust timing, fuel etc.. Since you've asked your DH to indicate an event occurred it does ...but not the length and time u know what i mean..? I don't own a dash hawk so maybe it does indicate this for you...

edit: I jsut read Rotus8's response and sounds like he was saying what i was thinking...
 
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