Crackling while under acceleration
Created by: kaelanfrost
Found 34 Messages
Total posts: 19
Last post: May 28, 2020 Member since:Jan 25, 2019
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Quote:
Originally Posted by h_lankford
did you ever change to colder plugs?
You had mentioned that this would lower the combustion chamber temperature.
Much more likely, it would lower the spark plug temperature and if a hot plug was the cause of preignition then that might help.
You had mentioned that this would lower the combustion chamber temperature.
Much more likely, it would lower the spark plug temperature and if a hot plug was the cause of preignition then that might help.
Total posts: 19
Last post: May 28, 2020 Member since:Jan 25, 2019
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Quote:
Originally Posted by kenatminimania
Quote:
Originally Posted by kaelanfrost
Quote:
Originally Posted by kenatminimania
Detonation in an engine to me 'sounds like' loose marbles in the engine. Does this sound like what you are hearing?
Just want to try to be sure before you spend more $$...
Just want to try to be sure before you spend more $$...
The only thing that really has me beat is why is it happening to this mini in particular?
Purchased with low miles, good condition, well maintained, and now it comes to me (I do not like to unnecessarily push the car at every stop sign and red light) and has this bizarre issue. Maybe it always had this issue, but would you all agree that pretty much everyone who does a 15% pulley, ignition, and CAI doesn't see a similar issue? So it must be a mechanical part at fault or maybe a tuning issue? (has stock tune as far as I can tell)
However, I'm also quite positive that when I did the CAI and ignition prior to the pulley swap, it had the same issue.
I really am getting stumped and any suggestions will be greatly appreciated.
Detonation (or engine knock) means the combustion is happening before the piston reaches top dead center. Typical causes are lean air/fuel mix, timing too far advanced, compression too high, combustion temps too high.
'Normally', the computer would detect detonation from the knock sensor and pull back the timing and richen the air/fuel mix. This should stop the detonation.
Some high performance engines require high octane fuel to keep it from detonation. Perhaps you might try adding an octane boost additive to see if the noise changes?
We've mentioned carbon deposits on the pistons because the buildup takes up volume which in turn increases the compression ratio.
Air/fuel can run lean with a leak in the intake system, where more air is added to the metered fuel thus creating a lean condition.
Clogged fuel injectors may have trouble delivering enough fuel to keep the mixture correct.
Perhaps all this has been already discussed, but maybe someone else can add to the discussion.
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did you ever change to colder plugs?
You had mentioned that this would lower the combustion chamber temperature.
Much more likely, it would lower the spark plug temperature and if a hot plug was the cause of preignition then that might help.
You had mentioned that this would lower the combustion chamber temperature.
Much more likely, it would lower the spark plug temperature and if a hot plug was the cause of preignition then that might help.
Total posts: 9543
Last post: Apr 20, 2024 Member since:Aug 14, 2002
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Kaelan, some "maybes":
Maybe the car was doing it before you got it (as you suspect).
Maybe the previous owner didn't drive it hard enough to keep the engine cleaned out.
Maybe the carbon buildup is to the point of increasing the compression ratio.
Maybe the previous owner was advised the engine needed the head removed and the combustion chambers cleaned and decided not to spent that much.
or Maybe not!
Maybe the car was doing it before you got it (as you suspect).
Maybe the previous owner didn't drive it hard enough to keep the engine cleaned out.
Maybe the carbon buildup is to the point of increasing the compression ratio.
Maybe the previous owner was advised the engine needed the head removed and the combustion chambers cleaned and decided not to spent that much.
or Maybe not!
.
"Hang on a minute lads....I've got a great idea."
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Last post: May 23, 2023 Member since:Dec 29, 2004
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Quote:
Originally Posted by kaelanfrost
Quote:
Originally Posted by kenatminimania
Detonation in an engine to me 'sounds like' loose marbles in the engine. Does this sound like what you are hearing?
Just want to try to be sure before you spend more $$...
Just want to try to be sure before you spend more $$...
The only thing that really has me beat is why is it happening to this mini in particular?
Purchased with low miles, good condition, well maintained, and now it comes to me (I do not like to unnecessarily push the car at every stop sign and red light) and has this bizarre issue. Maybe it always had this issue, but would you all agree that pretty much everyone who does a 15% pulley, ignition, and CAI doesn't see a similar issue? So it must be a mechanical part at fault or maybe a tuning issue? (has stock tune as far as I can tell)
However, I'm also quite positive that when I did the CAI and ignition prior to the pulley swap, it had the same issue.
I really am getting stumped and any suggestions will be greatly appreciated.
Detonation (or engine knock) means the combustion is happening before the piston reaches top dead center. Typical causes are lean air/fuel mix, timing too far advanced, compression too high, combustion temps too high.
'Normally', the computer would detect detonation from the knock sensor and pull back the timing and richen the air/fuel mix. This should stop the detonation.
Some high performance engines require high octane fuel to keep it from detonation. Perhaps you might try adding an octane boost additive to see if the noise changes?
We've mentioned carbon deposits on the pistons because the buildup takes up volume which in turn increases the compression ratio.
Air/fuel can run lean with a leak in the intake system, where more air is added to the metered fuel thus creating a lean condition.
Clogged fuel injectors may have trouble delivering enough fuel to keep the mixture correct.
Perhaps all this has been already discussed, but maybe someone else can add to the discussion.
Total posts: 19
Last post: May 28, 2020 Member since:Jan 25, 2019
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Cars in Garage: 0
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Quote:
Originally Posted by Dan Moffet
Quote:
Originally Posted by kaelanfrost
Quote:
Originally Posted by Dan Moffet
If you have been experiencing irregular fueling due to the faulty knock sensor, your cylinders may have a carbon buildup. Carbon can heat up and cause pre-ignition. Try (if you can or haven't already) using a de-carbon treatment.
Thanks for the feedback.
Perhaps those familiar with new MINIs can make suggestions of a safe, appropriate product and how to use it.
I am surprised you could remove carbon from the intake valves on the manifold side - all you'd see would be the stem and back of the valve head, and I'd be surprised to see any significant carbon there because each valve would be closed tight at combustion. I suppose though, if you did/do have pre-ignition, there might have been blow-back through the valve, or the valves aren't sealing well.
The carbon in a cylinder that would cause pre-ignition would be a hard, ceramic like build-up, not a soft, wipe-able soot. Typically the treatment is used on a hot engine when the deposit is good and hot. When the chemical hits it, the deposit suddenly cools and cracks of and goes out the exhaust system. In the really old days, water would be dribbled into the carb carefully so as to NOT chill the valves and damage them. I have also seen transmission fluid used in the same way - supposedly much easier on the valves. (It makes a huge cloud of white smoke!) But I wouldn't use either on a modern engine.
Total posts: 19
Last post: May 28, 2020 Member since:Jan 25, 2019
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Cars in Garage: 0
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Quote:
Originally Posted by kenatminimania
Detonation in an engine to me 'sounds like' loose marbles in the engine. Does this sound like what you are hearing?
Just want to try to be sure before you spend more $$...
Just want to try to be sure before you spend more $$...
The only thing that really has me beat is why is it happening to this mini in particular?
Purchased with low miles, good condition, well maintained, and now it comes to me (I do not like to unnecessarily push the car at every stop sign and red light) and has this bizarre issue. Maybe it always had this issue, but would you all agree that pretty much everyone who does a 15% pulley, ignition, and CAI doesn't see a similar issue? So it must be a mechanical part at fault or maybe a tuning issue? (has stock tune as far as I can tell)
However, I'm also quite positive that when I did the CAI and ignition prior to the pulley swap, it had the same issue.
I really am getting stumped and any suggestions will be greatly appreciated.
Total posts: 9543
Last post: Apr 20, 2024 Member since:Aug 14, 2002
|
Cars in Garage: 0
Photos: 0 WorkBench Posts: 0 |
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Quote:
Originally Posted by kaelanfrost
Quote:
Originally Posted by Dan Moffet
If you have been experiencing irregular fueling due to the faulty knock sensor, your cylinders may have a carbon buildup. Carbon can heat up and cause pre-ignition. Try (if you can or haven't already) using a de-carbon treatment.
Thanks for the feedback.
Perhaps those familiar with new MINIs can make suggestions of a safe, appropriate product and how to use it.
I am surprised you could remove carbon from the intake valves on the manifold side - all you'd see would be the stem and back of the valve head, and I'd be surprised to see any significant carbon there because each valve would be closed tight at combustion. I suppose though, if you did/do have pre-ignition, there might have been blow-back through the valve, or the valves aren't sealing well.
The carbon in a cylinder that would cause pre-ignition would be a hard, ceramic like build-up, not a soft, wipe-able soot. Typically the treatment is used on a hot engine when the deposit is good and hot. When the chemical hits it, the deposit suddenly cools and cracks of and goes out the exhaust system. In the really old days, water would be dribbled into the carb carefully so as to NOT chill the valves and damage them. I have also seen transmission fluid used in the same way - supposedly much easier on the valves. (It makes a huge cloud of white smoke!) But I wouldn't use either on a modern engine.
.
"Hang on a minute lads....I've got a great idea."
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Quote:
Originally Posted by kaelanfrost
Quote:
Originally Posted by onetim
API service SN plus and Dexos Gen2 motor oils are designed to prevent a new type of low speed pre-ignition found in DI turbo engines. Go figure.
Total posts: 2271
Last post: May 23, 2023 Member since:Dec 29, 2004
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Detonation in an engine to me 'sounds like' loose marbles in the engine. Does this sound like what you are hearing?
Just want to try to be sure before you spend more $$...
Just want to try to be sure before you spend more $$...
Total posts: 19
Last post: May 28, 2020 Member since:Jan 25, 2019
|
Cars in Garage: 0
Photos: 0 WorkBench Posts: 0 |
Quote:
Originally Posted by kenatminimania
can you get a hold of a borescope to inspect the inside of the cylinders for carbon buildup?
Total posts: 19
Last post: May 28, 2020 Member since:Jan 25, 2019
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Quote:
Originally Posted by onetim
API service SN plus and Dexos Gen2 motor oils are designed to prevent a new type of low speed pre-ignition found in DI turbo engines. Go figure.
Total posts: 19
Last post: May 28, 2020 Member since:Jan 25, 2019
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Cars in Garage: 0
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Quote:
Originally Posted by Dan Moffet
If you have been experiencing irregular fueling due to the faulty knock sensor, your cylinders may have a carbon buildup. Carbon can heat up and cause pre-ignition. Try (if you can or haven't already) using a de-carbon treatment.
Thanks for the feedback.
Total posts: 2271
Last post: May 23, 2023 Member since:Dec 29, 2004
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Cars in Garage: 1
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can you get a hold of a borescope to inspect the tops of the pistons inside the cylinders for carbon buildup?
Total posts: 1007
Last post: Jul 19, 2022 Member since:Jul 24, 2014
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API service SN plus and Dexos Gen2 motor oils are designed to prevent a new type of low speed pre-ignition found in DI turbo engines. Go figure.
Total posts: 9543
Last post: Apr 20, 2024 Member since:Aug 14, 2002
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Cars in Garage: 0
Photos: 0 WorkBench Posts: 0 |
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If you have been experiencing irregular fueling due to the faulty knock sensor, your cylinders may have a carbon buildup. Carbon can heat up and cause pre-ignition. Try (if you can or haven't already) using a de-carbon treatment.
.
"Hang on a minute lads....I've got a great idea."
Total posts: 19
Last post: May 28, 2020 Member since:Jan 25, 2019
|
Cars in Garage: 0
Photos: 0 WorkBench Posts: 0 |
Hello once again, I had a great evaluation written out but chrome decided to stop working so here we are again.
Bottom line, "crackling" sound upon heavy acceleration wouldn't go away with changes in my ignition system, or an octane booster, so it was ruled down to a faulty knock sensor.
I replaced the sensor and it worked! But "worked" is a relative term. The crackling subsided to a significant extent, but there is still a crackle audible while under hard acceleration every now and then while doing a pull.
I really am not satisfied with the fix yet because it still doesn't seem "fixed" to me. I read a forum on spark plugs, and I might try a copper or silver plug. I read that the Iridium ones I have don't lend a hand towards much of a performance gain and that they're for longevity. Being that my Mini is experiencing detonation, it means the combustion temperatures are too great, so a colder plug is needed to transfer more heat from the combustion process to the cylinder head itself, lowering the combustion temperature and reducing the chance for detonation. The only issue is that I already have a one-step colder set of plugs in my Mini right now, and I have almost since I originally purchased the car. I don't want to put two-step colder plugs in because I know I am not making the kind of power needed for a plug of that rating with the mods I have done (15% Sc pulley, CAI, MSD ignition)
So it looks like I'm running out of options. I'm going to throw the old ignition and plugs in to see if it makes a difference with the new knock sensor, but other than that I really don't know what to do.
BTW- if you're thinking of changing your knock sensor, you can test the old one while it's still in the car with a multimeter, so you don't waste your time pulling everything apart to get to it. I read that a reading of 500-600 kiloOhms is a healthy sensor (on most vehicles). I'm not 100% on how applicable this info is to our Minis but I couldn't find much info on the surface. I didn't actually do this test yet, so I can get some numbers for a fallowup.
Thanks for the help
Bottom line, "crackling" sound upon heavy acceleration wouldn't go away with changes in my ignition system, or an octane booster, so it was ruled down to a faulty knock sensor.
I replaced the sensor and it worked! But "worked" is a relative term. The crackling subsided to a significant extent, but there is still a crackle audible while under hard acceleration every now and then while doing a pull.
I really am not satisfied with the fix yet because it still doesn't seem "fixed" to me. I read a forum on spark plugs, and I might try a copper or silver plug. I read that the Iridium ones I have don't lend a hand towards much of a performance gain and that they're for longevity. Being that my Mini is experiencing detonation, it means the combustion temperatures are too great, so a colder plug is needed to transfer more heat from the combustion process to the cylinder head itself, lowering the combustion temperature and reducing the chance for detonation. The only issue is that I already have a one-step colder set of plugs in my Mini right now, and I have almost since I originally purchased the car. I don't want to put two-step colder plugs in because I know I am not making the kind of power needed for a plug of that rating with the mods I have done (15% Sc pulley, CAI, MSD ignition)
So it looks like I'm running out of options. I'm going to throw the old ignition and plugs in to see if it makes a difference with the new knock sensor, but other than that I really don't know what to do.
BTW- if you're thinking of changing your knock sensor, you can test the old one while it's still in the car with a multimeter, so you don't waste your time pulling everything apart to get to it. I read that a reading of 500-600 kiloOhms is a healthy sensor (on most vehicles). I'm not 100% on how applicable this info is to our Minis but I couldn't find much info on the surface. I didn't actually do this test yet, so I can get some numbers for a fallowup.
Thanks for the help
Total posts: 2271
Last post: May 23, 2023 Member since:Dec 29, 2004
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Let us know what you find out!
Total posts: 19
Last post: May 28, 2020 Member since:Jan 25, 2019
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Quote:
Originally Posted by kenatminimania
Maybe a new knock sensor?
Total posts: 2271
Last post: May 23, 2023 Member since:Dec 29, 2004
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Maybe a new knock sensor?
Found 34 Messages