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Discussion Starter #1
Hello folks,
I'm wondering if anyone else has heard spark knock on their 4 cyl. Terrain or 'nox. Mine started at about 3,000 miles (now @ 4,000) and progressively got worse until it was bad enough to where the dealer could hear it (first trip to the dealer ended up no problem found). This is the first Equinox they've had with this problem, so they called GM for diagnostic help. GM tells them to perform a top end engine cleaning and recommend top tier gas only for this vehicle.

Well, my first thought was what a load of crap. But after the cleaning, the spark knock is gone... for now. I'm concerned about the long term issue of dealing with this. Has anyone else had any similar issues?

Quite frankly, I'm not too keen on having to search for top tier gas stations anytime I need fuel.
 

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Considering the 'Nox engine has around 11 to 1 compression ratio, I'd even burn 91 octane in it too. That's a lot of compression to keep happy in order to keep the engine from knocking.
 

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crazytalk said:
Hello folks,
I'm wondering if anyone else has heard spark knock on their 4 cyl. Terrain or 'nox. Mine started at about 3,000 miles (now @ 4,000) and progressively got worse until it was bad enough to where the dealer could hear it (first trip to the dealer ended up no problem found). This is the first Equinox they've had with this problem, so they called GM for diagnostic help. GM tells them to perform a top end engine cleaning and recommend top tier gas only for this vehicle.

Well, my first thought was what a load of crap. But after the cleaning, the spark knock is gone... for now. I'm concerned about the long term issue of dealing with this. Has anyone else had any similar issues?

Quite frankly, I'm not too keen on having to search for top tier gas stations anytime I need fuel.
Having some light spark knock in our 'Nox, developed the problem around 3500 mi. It's gotten better in the last 200 mi.. BUT, we have been using Shell most of the time, which IS a "toptier" brand. I posted about this issue a few weeks ago and others have griped about it. Me thinks this will be a bigger pain as time goes on. Expect more gripes as more vehicles are out there and miles pile up.

First trip to the dealer resulted also in "no issue found" as the day I took it in was cooler than usual. I didn't hear it either but it's knocked a few times, every lightly, on warmer days. The knock sensor is working though as you hear it for a split second but it goes away quickly. A friend who works for Delphi and knows a lot of the ECM software guys in his office says that this can happen when winter blend is switched over to summer blend gasoline. His suggestion was give it a few tanks.

Summer is coming so that will be the test if indeed this has vanished. And no, I do not want to use 91 octane when the manufacturer explicitly states you only need 87 octane. There is no reason to use a higher octane fuel if the engine is working properly.
 

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I agree 100% on sticking with 87 octane. My 4 cyl hasn't shown any knocking symptoms yet in 3,700 miles - "knock on wood" !
 

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tnmats said:
And no, I do not want to use 91 octane when the manufacturer explicitly states you only need 87 octane. There is no reason to use a higher octane fuel if the engine is working properly.
The manual states "at least 87 octane". If the engine is knocking, and you want that fixed then higher octane is the answer. Is knocking a problem? No, not really. But it can be annoying. If you talk to any mechanic that's been around since before everything was fuel injected and computer timed, then you'd know that a little knock was actually a sign that an engine was timed correctly for the best performance.

If higher octane does not fix the knocking, then there could be other problems. Talk to your dealership more after trying this suggestion if you still hear knocking.
 

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Something also to consider, is that engine knock can be caused by the gas stations switching between winter and summer blend gases.
 

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Discussion Starter #7
tnmats said:
Having some light spark knock in our 'Nox, developed the problem around 3500 mi. It's gotten better in the last 200 mi.. BUT, we have been using Shell most of the time, which IS a "toptier" brand. I posted about this issue a few weeks ago and others have griped about it. Me thinks this will be a bigger pain as time goes on. Expect more gripes as more vehicles are out there and miles pile up.
I found the thread you spoke of. I'm going to post a link to it. I think it's important to get this issue some publicity.

http://www.equinoxforum.net/index.php?topic=674.msg8104#msg8104
 

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Narg said:
The manual states "at least 87 octane". If the engine is knocking, and you want that fixed then higher octane is the answer. Is knocking a problem? No, not really. But it can be annoying. If you talk to any mechanic that's been around since before everything was fuel injected and computer timed, then you'd know that a little knock was actually a sign that an engine was timed correctly for the best performance.

If higher octane does not fix the knocking, then there could be other problems. Talk to your dealership more after trying this suggestion if you still hear knocking.
I don't know what mechanic you've been talking to, but pinging/detonation can be very bad for an engine. It can result in burned pistons, problems with the ring lands on the piston, bent rods etc. It just depends on the severity. Carbon buildup in the combustion chamber, which can raise compression, can cause detonation. If it happens close to TDC or slightly after, it can cause problems with the rods and bearings. Pinging should not be taken lightly because it can be very detrimental.

I would definitely be trying a better fuel first. If it continues, then have a talk with the dealer. Many things can cause pinging/detonation.
 

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Any knocking in an engine definately isn't a good thing. If you hear that the the timing needs to be turned back a degree or two. You talk to anyone that is into high performance engines and they will tell you that the best performance is just on the edge before the knock occurs. That's how we run our drag cars, they will actually run slower when the knock occurs!!
 

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carguy332000 said:
Any knocking in an engine definately isn't a good thing. If you hear that the the timing needs to be turned back a degree or two. You talk to anyone that is into high performance engines and they will tell you that the best performance is just on the edge before the knock occurs. That's how we run our drag cars, they will actually run slower when the knock occurs!![/color]
Indeed, it changes the entire dynamics of the crank, con rods and pistons' timing.
Knock or ping is something you definitely want to keep to a minimum.
 

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JLF said:
I don't know what mechanic you've been talking to, but pinging/detonation can be very bad for an engine. It can result in burned pistons, problems with the ring lands on the piston, bent rods etc. It just depends on the severity. Carbon buildup in the combustion chamber, which can raise compression, can cause detonation. If it happens close to TDC or slightly after, it can cause problems with the rods and bearings. Pinging should not be taken lightly because it can be very detrimental.

I would definitely be trying a better fuel first. If it continues, then have a talk with the dealer. Many things can cause pinging/detonation.
I've been using quality gasoline, namely Shell at a high-volume station locally. We're giving it a tank or two to see if this subsides. If not, then it's back to the dealer. I'm betting this a larger occurrence with these 4 cyl. SIDI motors than I thought but likely a "growing pain" as more of them get into the real world. I expect an ECM update if enough of us complain about it. My friend at Delphi did some more digging with his ECM software brethren, and according to them DI engines are run somewhat lean on purpose to boost fuel efficiency but are a bit more prone to predetonation too because of this.

For now I'm monitoring it. The knock occurs at lighter throttle in slower-speed traffic. For example, when the car is gently accelerated after a stop light in heavy city traffic. No MIL lights but something is going on. Blip the throttle a bit more heavily and it's gone. I'm not surprised to experience this with a car with 35,000 mi. on it but not 3500 mi.

Maybe all the 'Nox needs is a good ol' Italian tune-up. ;D
 

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Its funny you mention the "Italian tune up" because VW recommends that their DI cars be driven above 3500 RPM for up to 20 mins to burn off excess carbon. It actually is in their patent paperwork.
 

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bballr4567 said:
Its funny you mention the "Italian tune up" because VW recommends that their DI cars be driven above 3500 RPM for up to 20 mins to burn off excess carbon. It actually is in their patent paperwork.
Is that in the VW owner's manual? It definitely isn't in any GM owner's manual I've seen. And do you have a patent number for the VW filing? I'd like to check that out.
 

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Stumbled across this earlier:

http://www.cadillacforums.com/forums/cadillac-srx-second-generation-forum-2010/190115-direct-injection-carbon-buildup.html
http://forums.rennlist.com/rennforums/997-forum/556680-dfi-motor-carbon-build-up-possible.html
http://forums.vwvortex.com/zerothread?id=4518993

sounds like there is a lot of grumbling about DI and carbon build up, but it seems to be at higher mileage than what is causing our spark knock.

Do a Google search of "excess carbon build up vw di". Lots of interesting stuff pops up.
 

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tnmats said:
Is that in the VW owner's manual? It definitely isn't in any GM owner's manual I've seen. And do you have a patent number for the VW filing? I'd like to check that out.
It was on vwvortex. It was a photocopy of the actual paperwork IIRC. This was a few months ago when I read it.
 

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bballr4567 said:
It was on vwvortex. It was a photocopy of the actual paperwork IIRC. This was a few months ago when I read it.
Doing the Google search I found what you were describing. The link is in my post above. One anecdotal point is the GM DI/Turbo engine wasn't having this issue but that's just one comment from one owner.
 

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Yea, I saw your second post after I just posted. lol
 

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Discussion Starter #18
tnmats said:
Stumbled across this earlier:

http://www.cadillacforums.com/forums/cadillac-srx-second-generation-forum-2010/190115-direct-injection-carbon-buildup.html
http://forums.rennlist.com/rennforums/997-forum/556680-dfi-motor-carbon-build-up-possible.html
http://forums.vwvortex.com/zerothread?id=4518993

sounds like there is a lot of grumbling about DI and carbon build up, but it seems to be at higher mileage than what is causing our spark knock.

Do a Google search of "excess carbon build up vw di". Lots of interesting stuff pops up.

Well, that's not a very encouraging long term outlook, but good info none the less. My dad has a Pontiac G5 with the 2.2L Ecotec. He runs the cheapest gas he can find and has since mile 1. Says it runs like a top and he's a former auto and diesel mechanic so knows a little about engines.
 

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The 2.2 Eco is a different animal. It is lower compression, and not Direct Injection - I believe.
 
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