Low load / low RPM knock
Thread Starter
Joined: Nov 2010
Posts: 3,489
Likes: 859
From: Salt Lake City, UT
Low load / low RPM knock
I'm having a weird problem that I've just begun to work on, but thought I might get some feedback anyways. I get some very audible knock between about 1800 - 2500 RPM at low - mid throttle. It's isolated just to those scenarios. Full throttle at low RPM's is fine. And any throttle at high RPM's is fine as well. There's a knock plugin with the Torque app that provides knock count and the timing that's pulled but it only works at full throttle. I've monitored knock at full throttle across the whole RPM band and very seldom get anything. And when I do, it's very minor, usually pulling timing by 0.5 degrees which is pretty much in the range of background noise. I also replaced the knock sensor (with OEM) for good measure. So yeah, nothing at full throttle and like I said, nothing noticeable at partial throttle at high RPM (although that scenario is kind of rare anyways).
When I hear it, I either increase/decrease throttle, after which is goes away, or stay in a high RPM range. If I stay in the low RPM/throttle range, the knock disappears after a second or two, presumably due to the ECU pulling timing.
My plan is to try the following:
Change gas to a different brand. I'm currently using Shell Nitro+ 93
If the knock persists, I'll try race gas and see if that reduces or eliminates it. That's not a long term fix since that stuff is expensive and it's kind of ridiculous to have to use race gas in a TL
I'll be using Ktuner to log knock and report that to the tuner. When I told him about the problem that's exactly what he suggested. He said it could be that timing is too aggressive in that particular range. However, the low throttle response is way better than it was when the car was when it was stock so I'd rather not go that route unless I can't eliminate it otherwise.
If anyone's had this problem or has additional suggestions I'm all ears.
When I hear it, I either increase/decrease throttle, after which is goes away, or stay in a high RPM range. If I stay in the low RPM/throttle range, the knock disappears after a second or two, presumably due to the ECU pulling timing.
My plan is to try the following:
Change gas to a different brand. I'm currently using Shell Nitro+ 93
If the knock persists, I'll try race gas and see if that reduces or eliminates it. That's not a long term fix since that stuff is expensive and it's kind of ridiculous to have to use race gas in a TL
I'll be using Ktuner to log knock and report that to the tuner. When I told him about the problem that's exactly what he suggested. He said it could be that timing is too aggressive in that particular range. However, the low throttle response is way better than it was when the car was when it was stock so I'd rather not go that route unless I can't eliminate it otherwise.
If anyone's had this problem or has additional suggestions I'm all ears.
Senior Moderator
Joined: Feb 2006
Posts: 21,392
Likes: 2,181
From: Space Coast, FL
I'm thinking it could be an issue with the injectors not misting/spraying properly. With 250K miles there def. is some wear on them.
Also monitor your IAT's when this happens. I Hate Cars in the 3G section found in the summer months the car would heat-soak and pull timing. The solution was the ultimate cooling mod which helped quite a bit. Some folks also used the thermoblock manifold gaskets to help reduce temps and they help, however some have reported the cheap ones melt over time!
Last though, are you sure it's knocking and not something else like a bad upper/lower trans mount bouncing around under light acceleration?
Also monitor your IAT's when this happens. I Hate Cars in the 3G section found in the summer months the car would heat-soak and pull timing. The solution was the ultimate cooling mod which helped quite a bit. Some folks also used the thermoblock manifold gaskets to help reduce temps and they help, however some have reported the cheap ones melt over time!
Last though, are you sure it's knocking and not something else like a bad upper/lower trans mount bouncing around under light acceleration?
Thread Starter
Joined: Nov 2010
Posts: 3,489
Likes: 859
From: Salt Lake City, UT
If it were injectors, I think I'd see worse mileage. But mileage and performance is great. But yes, they're certainly old. Maybe I'll see if I can find some cheap used ones on eBay just for good measure.
Yes, IAT's have been all over the board. It doesn't seem like there's much consistency between IAT and knock. So I'm not suspecting that. I have a P2R intake manifold gasket and the coolant bypass so IAT's are usually only 10F higher than ambient.
I haven't ruled out rattling of something else such as mounts, heat shields or plastic trim. But it definitely sounds like your classic textbook knock.
I hooked up KTuner and took about a 20 minute drive. It only registered 2 knock events and that was at high RPM. I got my coolant up to 212F (at which point the cooling fans kick on) and gave it full throttle up hills at 1500 - 3000 RPM and could never get it to knock. However, I did that after I ran a can of Seafoam through it. Maybe that helped. I'm not a huge believer in Seafoam but figured I'd give it a try since Walmart had it on sale for $5. I also put a can of Gumout multi-system tuneup in the tank, and had burned through about half the tank before I ran along with KTuner. So maybe things improved between those two. I also switched from Shell to Chevron. I'm driving Uber tonight and find that the knock typically happens after a few hours of driving. We'll see what happens.
Yes, IAT's have been all over the board. It doesn't seem like there's much consistency between IAT and knock. So I'm not suspecting that. I have a P2R intake manifold gasket and the coolant bypass so IAT's are usually only 10F higher than ambient.
I haven't ruled out rattling of something else such as mounts, heat shields or plastic trim. But it definitely sounds like your classic textbook knock.
I hooked up KTuner and took about a 20 minute drive. It only registered 2 knock events and that was at high RPM. I got my coolant up to 212F (at which point the cooling fans kick on) and gave it full throttle up hills at 1500 - 3000 RPM and could never get it to knock. However, I did that after I ran a can of Seafoam through it. Maybe that helped. I'm not a huge believer in Seafoam but figured I'd give it a try since Walmart had it on sale for $5. I also put a can of Gumout multi-system tuneup in the tank, and had burned through about half the tank before I ran along with KTuner. So maybe things improved between those two. I also switched from Shell to Chevron. I'm driving Uber tonight and find that the knock typically happens after a few hours of driving. We'll see what happens.
Thread Starter
Joined: Nov 2010
Posts: 3,489
Likes: 859
From: Salt Lake City, UT
So it looks like it was some excessive timing. Or at least that's what fixed it. Despite what I did above, I was still getting some knock but only after the engine had been running for a few hours. However, when I ran the stock map there was no knock whatsoever. We dropped the timing down just a couple degrees in the 1800 - 3000 RPM / 20-40% load areas and it disappeared. The tuner said I might notice a very small difference in torque at those ranges but I haven't noticed anything (other than a lack of knock 
).
I'm still wondering if there's some other problem and that pulling timing back a bit is just a band-aid. I suppose not since the timing is still higher than stock. And there are no other symptoms. Long term fuel trim is excellent - usually right on 0. Very rarely beyond +/- 2. So I don't appear to be running lean. Mileage and output are both great. Still, it didn't seem to be having this problem at first. The timing has been set at those increased values for a while now. We're going to keep an eye on it and see if it comes back with the new lower values. If so, there might be something else wrong.
).I'm still wondering if there's some other problem and that pulling timing back a bit is just a band-aid. I suppose not since the timing is still higher than stock. And there are no other symptoms. Long term fuel trim is excellent - usually right on 0. Very rarely beyond +/- 2. So I don't appear to be running lean. Mileage and output are both great. Still, it didn't seem to be having this problem at first. The timing has been set at those increased values for a while now. We're going to keep an eye on it and see if it comes back with the new lower values. If so, there might be something else wrong.
Pro
Joined: Apr 2016
Posts: 687
Likes: 118
I'm having a weird problem that I've just begun to work on, but thought I might get some feedback anyways. I get some very audible knock between about 1800 - 2500 RPM at low - mid throttle. It's isolated just to those scenarios. Full throttle at low RPM's is fine. And any throttle at high RPM's is fine as well. There's a knock plugin with the Torque app that provides knock count and the timing that's pulled but it only works at full throttle. I've monitored knock at full throttle across the whole RPM band and very seldom get anything. And when I do, it's very minor, usually pulling timing by 0.5 degrees which is pretty much in the range of background noise. I also replaced the knock sensor (with OEM) for good measure. So yeah, nothing at full throttle and like I said, nothing noticeable at partial throttle at high RPM (although that scenario is kind of rare anyways).
When I hear it, I either increase/decrease throttle, after which is goes away, or stay in a high RPM range. If I stay in the low RPM/throttle range, the knock disappears after a second or two, presumably due to the ECU pulling timing.
My plan is to try the following:
Change gas to a different brand. I'm currently using Shell Nitro+ 93
If the knock persists, I'll try race gas and see if that reduces or eliminates it. That's not a long term fix since that stuff is expensive and it's kind of ridiculous to have to use race gas in a TL
I'll be using Ktuner to log knock and report that to the tuner. When I told him about the problem that's exactly what he suggested. He said it could be that timing is too aggressive in that particular range. However, the low throttle response is way better than it was when the car was when it was stock so I'd rather not go that route unless I can't eliminate it otherwise.
If anyone's had this problem or has additional suggestions I'm all ears.
When I hear it, I either increase/decrease throttle, after which is goes away, or stay in a high RPM range. If I stay in the low RPM/throttle range, the knock disappears after a second or two, presumably due to the ECU pulling timing.
My plan is to try the following:
Change gas to a different brand. I'm currently using Shell Nitro+ 93
If the knock persists, I'll try race gas and see if that reduces or eliminates it. That's not a long term fix since that stuff is expensive and it's kind of ridiculous to have to use race gas in a TL
I'll be using Ktuner to log knock and report that to the tuner. When I told him about the problem that's exactly what he suggested. He said it could be that timing is too aggressive in that particular range. However, the low throttle response is way better than it was when the car was when it was stock so I'd rather not go that route unless I can't eliminate it otherwise.
If anyone's had this problem or has additional suggestions I'm all ears.
Pro
Joined: Apr 2016
Posts: 687
Likes: 118
I'm having a weird problem that I've just begun to work on, but thought I might get some feedback anyways. I get some very audible knock between about 1800 - 2500 RPM at low - mid throttle. It's isolated just to those scenarios. Full throttle at low RPM's is fine. And any throttle at high RPM's is fine as well. There's a knock plugin with the Torque app that provides knock count and the timing that's pulled but it only works at full throttle. I've monitored knock at full throttle across the whole RPM band and very seldom get anything. And when I do, it's very minor, usually pulling timing by 0.5 degrees which is pretty much in the range of background noise. I also replaced the knock sensor (with OEM) for good measure. So yeah, nothing at full throttle and like I said, nothing noticeable at partial throttle at high RPM (although that scenario is kind of rare anyways).
When I hear it, I either increase/decrease throttle, after which is goes away, or stay in a high RPM range. If I stay in the low RPM/throttle range, the knock disappears after a second or two, presumably due to the ECU pulling timing.
My plan is to try the following:
Change gas to a different brand. I'm currently using Shell Nitro+ 93
If the knock persists, I'll try race gas and see if that reduces or eliminates it. That's not a long term fix since that stuff is expensive and it's kind of ridiculous to have to use race gas in a TL
I'll be using Ktuner to log knock and report that to the tuner. When I told him about the problem that's exactly what he suggested. He said it could be that timing is too aggressive in that particular range. However, the low throttle response is way better than it was when the car was when it was stock so I'd rather not go that route unless I can't eliminate it otherwise.
If anyone's had this problem or has additional suggestions I'm all ears.
When I hear it, I either increase/decrease throttle, after which is goes away, or stay in a high RPM range. If I stay in the low RPM/throttle range, the knock disappears after a second or two, presumably due to the ECU pulling timing.
My plan is to try the following:
Change gas to a different brand. I'm currently using Shell Nitro+ 93
If the knock persists, I'll try race gas and see if that reduces or eliminates it. That's not a long term fix since that stuff is expensive and it's kind of ridiculous to have to use race gas in a TL
I'll be using Ktuner to log knock and report that to the tuner. When I told him about the problem that's exactly what he suggested. He said it could be that timing is too aggressive in that particular range. However, the low throttle response is way better than it was when the car was when it was stock so I'd rather not go that route unless I can't eliminate it otherwise.
If anyone's had this problem or has additional suggestions I'm all ears.
Long story short, I took mine in for High oil consumption, Acura approved the fix at no cost to me, and the noice has never happened again. AFTER I SPENT TIME AND MONEY trying to diagnose the issue. If this sounds like your issue,
YOU must have 3.7 Engine
Make appointment for an oil consumption test at dealer
If your car is making that noise it will fail the test (using more than 1qt. of oil per 1000-1500 miles)
Acura will rebuild the short block of the engine at no cost to you.
https://acurazine.com/forums/showthr...8&goto=newpost (here is the link)
I drove mine in Sport mode during the test, and Ive heard many taking measures in their own hands to ensure they fail the test to get the work done.
my engine runs like new.
Hope this helps;.
Racer
Joined: May 2013
Posts: 283
Likes: 16
From: Under the stars
There area few threads about this, and if its the same thing I know your pain! We all thought it was knock sensor or fuel related. Turns out for many of us it was called piston slap. SPECIFIC to the 3.7 engines. This was caused by carbon build on due to faulty o-rings. Luckily Acura has extended our warranty to fix whats called "Oil Consumption Exceeds Client Expectations. So its a domino effect. Carbon build up, cause o rings to not do their job properly and oil is getting in places it shouldnt and gas doing the same. This knock was usually heard after a start up with moderate load between said RPMS. It was always present for me after a warm start. never a cold start. So lets you wake up in the morning,, you stop at the store. When you get back to your car after the store and you drive away THATS when it would happen. Is this the case with yours? So many were certain it was fuel related....
Long story short, I took mine in for High oil consumption, Acura approved the fix at no cost to me, and the noice has never happened again. AFTER I SPENT TIME AND MONEY trying to diagnose the issue. If this sounds like your issue,
YOU must have 3.7 Engine
Make appointment for an oil consumption test at dealer
If your car is making that noise it will fail the test (using more than 1qt. of oil per 1000-1500 miles)
Acura will rebuild the short block of the engine at no cost to you.
https://acurazine.com/forums/showthr...8&goto=newpost (here is the link)
I drove mine in Sport mode during the test, and Ive heard many taking measures in their own hands to ensure they fail the test to get the work done.
my engine runs like new.
Hope this helps;.
Long story short, I took mine in for High oil consumption, Acura approved the fix at no cost to me, and the noice has never happened again. AFTER I SPENT TIME AND MONEY trying to diagnose the issue. If this sounds like your issue,
YOU must have 3.7 Engine
Make appointment for an oil consumption test at dealer
If your car is making that noise it will fail the test (using more than 1qt. of oil per 1000-1500 miles)
Acura will rebuild the short block of the engine at no cost to you.
https://acurazine.com/forums/showthr...8&goto=newpost (here is the link)
I drove mine in Sport mode during the test, and Ive heard many taking measures in their own hands to ensure they fail the test to get the work done.
my engine runs like new.
Hope this helps;.
My car is currently waiting for the fix and it makes the knocking noise you mention.. This only happens when the engine is hot.. it didn't make any knocking noise when the engine is cold..
I'm crossing my fingers hope that this will be fixed when I bring my car in at the end of this month for the oil consumption repair.
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