Timing
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Timing
I tried a search for timing but didn't get any useful results, but if this is a repeat I'm sorry.
Does anyone know what would cause the computer to pull timing?
I know if the knock sensor triggers it will pull timing, but are there other things? Will things such as reduced air flow to the mass air flow sensor also trigger a drop in the timing?
If i do use regular fuel or have something else that reduces the timing how long until the computer readjust the timing back?
Does anyone know what would cause the computer to pull timing?
I know if the knock sensor triggers it will pull timing, but are there other things? Will things such as reduced air flow to the mass air flow sensor also trigger a drop in the timing?
If i do use regular fuel or have something else that reduces the timing how long until the computer readjust the timing back?
Melting Slicks
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C6's are very dynamic, they will always try to run the timing they are programmed for and will pull it the instant knock is read. The recovery from pulled timing is quick.
For knock to occur, the usual culprit is fuel is below 93 octane. Additional culprits such as high operating temp can also lead to knock (search C7 Z06 heat soak problems how badly that was affected). For reference, if you run 91 octane, it should really only pull some timing on a full WOT pull to 6500RPM with knock occurring a bit after 4k rpm. Any less octane will see timing pulled even under very light driving.
An improper air mixture such as un-metered air could also contribute to detonation as well due to lean conditions, more rare ones are O2 sensors giving incorrect feedback causing lean condition as well or MAF sensor being way off can do it.
For knock to occur, the usual culprit is fuel is below 93 octane. Additional culprits such as high operating temp can also lead to knock (search C7 Z06 heat soak problems how badly that was affected). For reference, if you run 91 octane, it should really only pull some timing on a full WOT pull to 6500RPM with knock occurring a bit after 4k rpm. Any less octane will see timing pulled even under very light driving.
An improper air mixture such as un-metered air could also contribute to detonation as well due to lean conditions, more rare ones are O2 sensors giving incorrect feedback causing lean condition as well or MAF sensor being way off can do it.
Last edited by SladeX; Aug 13, 2019 at 10:40 AM.
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This is the reason I was asking. I noticed a large decrease in preformance due to the above filter. I got most of i the performance back upon replacing the filter, but I am still getting a little hesitation on the throttle. I thought it could be due to timing.
Based on what you said the filter could have caused a drop in timing, but sound like it should come back quickly. I'll try to get at least 100 miles after the filter change and see if it comes back fully.
If not I guess I might be looking at spark plugs next.
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I'll check my plugs. Getting to 60k miles soon, so worth a look.
Last edited by flyingbunnys; Aug 13, 2019 at 12:09 PM.
Melting Slicks
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Air intakes usually get that dirty when there is a direct cold air feed like having a cut out to the area.
Since it is aftermarket, I would pull the MAF and clean it. The older style wire MAFs can get covered up by oil and dust and give false air meter readings triggering lean conditions due to unmetered air flowing by. It would be exaggerated by the now replaced clean filter in this case if it was dirty.
As previously stated, timing is quick to recover (like seconds). There is no need to do 100 miles. It's either pulling timing or its not.
Since it is aftermarket, I would pull the MAF and clean it. The older style wire MAFs can get covered up by oil and dust and give false air meter readings triggering lean conditions due to unmetered air flowing by. It would be exaggerated by the now replaced clean filter in this case if it was dirty.
As previously stated, timing is quick to recover (like seconds). There is no need to do 100 miles. It's either pulling timing or its not.
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Air intakes usually get that dirty when there is a direct cold air feed like having a cut out to the area.
Since it is aftermarket, I would pull the MAF and clean it. The older style wire MAFs can get covered up by oil and dust and give false air meter readings triggering lean conditions due to unmetered air flowing by. It would be exaggerated by the now replaced clean filter in this case if it was dirty.
As previously stated, timing is quick to recover (like seconds). There is no need to do 100 miles. It's either pulling timing or its not.
Since it is aftermarket, I would pull the MAF and clean it. The older style wire MAFs can get covered up by oil and dust and give false air meter readings triggering lean conditions due to unmetered air flowing by. It would be exaggerated by the now replaced clean filter in this case if it was dirty.
As previously stated, timing is quick to recover (like seconds). There is no need to do 100 miles. It's either pulling timing or its not.
Last edited by flyingbunnys; Aug 13, 2019 at 01:39 PM.
Melting Slicks
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Not sure how sensitive your hearing is, but with windows down and radio low, I can hear pinging. It's like the sound of rapid metallic popcorn going off. It's a very contrasting sound to the normal LS sewing machine sound or lifter ticks.
Even pinging that audible is handled well by the computer and just means you aren't going to win any mile long races.
Even pinging that audible is handled well by the computer and just means you aren't going to win any mile long races.
Last edited by SladeX; Aug 13, 2019 at 01:48 PM.
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There is no pinging, I am familiar with that sound though from the few times I ran 87 fuel if I'm heavy on the gas it'll ping a bit. But usually the computer works that out by the second stop light. I've never had any pinging though as long as I use 89 and up. I prefer 93 though and use that almost exclusivity, but never lower than 89 now a days.
Just the slightest hesitation on the throttle, so little in fact I'm wondering if it was always there and just in my head.
I'll provide an update if I find anything looking at the Maf or plugs. I am almost at 60k miles/12 years on the original plugs unless the previous owner changed them before I got it at just under 30k miles and I'm sure the Maf has never been cleaned, at least by me in the last 30k miles I've owned it.
So it's probably time for both, and a cabin air filter too and what ever else needs to be done at 60k.
Just the slightest hesitation on the throttle, so little in fact I'm wondering if it was always there and just in my head.
I'll provide an update if I find anything looking at the Maf or plugs. I am almost at 60k miles/12 years on the original plugs unless the previous owner changed them before I got it at just under 30k miles and I'm sure the Maf has never been cleaned, at least by me in the last 30k miles I've owned it.
So it's probably time for both, and a cabin air filter too and what ever else needs to be done at 60k.
Melting Slicks
Joined: Aug 2014
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Hesitation a bit at throttle has been a complaint of some C6 owners, basically a lazy feeling or along the "slow" throttle response route. This is what vitesse throttle controllers and the cow booster alleviate for those owners.
If you've been running 91 or lower octane for awhile, there's a chance the pinging has eventually gotten to the plugs and damaged them somewhat potentially causing some detonation on quick throttle changes. Basically, you blip throttle to accelerate and that initial rush of air doesn't combust as well, or even detonates just a bit below the audible threshold, but enough to feel as a hesitation. Once timing is adjusted, the ping is gone and it accelerates with just a -1 or -2 timing then it puts it back all before you climb an extra 1k more rpm.
Had this happen on my camaro when I had my coolant level sensor pop out and I lost coolant and basically almost overheated. It damaged the plugs and started hesitating on any quick throttle changes.
If you've been running 91 or lower octane for awhile, there's a chance the pinging has eventually gotten to the plugs and damaged them somewhat potentially causing some detonation on quick throttle changes. Basically, you blip throttle to accelerate and that initial rush of air doesn't combust as well, or even detonates just a bit below the audible threshold, but enough to feel as a hesitation. Once timing is adjusted, the ping is gone and it accelerates with just a -1 or -2 timing then it puts it back all before you climb an extra 1k more rpm.
Had this happen on my camaro when I had my coolant level sensor pop out and I lost coolant and basically almost overheated. It damaged the plugs and started hesitating on any quick throttle changes.
Instructor
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If your air filter is that dirty your MAF is very likely also dirty.
Please don’t clean your MAF, buy a new OEM one. Think about how critical that sensor is, think about how precise it has to be, just buy a new one.
If the MAF is dirty your car will think it has less air than it does, so it will run lean, AND add too much spark because it doesn’t know how much air it has. The knock sensor will retard spark very quickly, you will never hear “pinging” but that doesn’t mean that the knock sensors don’t.
There are are many other reasons why it retards spark: high intake temps, high coolant temps, knocking, rattling exhaust ( interpreted as knock by ty the ECM), intake air leak, cat light off, torque intervention( spinning wheels) low octane fuel ( causes knock) ... I’m sure I’m forgetting some ...
Please don’t clean your MAF, buy a new OEM one. Think about how critical that sensor is, think about how precise it has to be, just buy a new one.
If the MAF is dirty your car will think it has less air than it does, so it will run lean, AND add too much spark because it doesn’t know how much air it has. The knock sensor will retard spark very quickly, you will never hear “pinging” but that doesn’t mean that the knock sensors don’t.
There are are many other reasons why it retards spark: high intake temps, high coolant temps, knocking, rattling exhaust ( interpreted as knock by ty the ECM), intake air leak, cat light off, torque intervention( spinning wheels) low octane fuel ( causes knock) ... I’m sure I’m forgetting some ...
Race Director
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Maf sensors are too easy to clean with Maf cleaner, so no reason to replace it to start with; unless its going bad.
You don't give a year or vet, but on the early models, its the round piece in line that needs to get pulled, and just need to focus on the back side of the U's and the small wires that run behind the U's.
On the newer vets, Maf is a small box type device that is held into the hosing via the two small screws, and on his type, just need to spray cleaner into the side slide to clean the fouling out of it when you have it in hand..
If you are using a air filter that is the oil type, don't over oil the filter. The excess oil just ends up in the Maf, and means that you have to clean the Maf more often instead.
Also, if you are not running Top tier fuel, the every few tanks, make sure to add techron at fill up to keep te fuel system and injectors clean.
One last thing, and some of the after market air cleaner system can cause problems with the Maf not reading correctly. The don't produce a clean flow of air through the MAF, and some cases, have to have the car tune to adjust the Maf tables so they are reading correctly for the amount of air that the maf is reading instead..
You don't give a year or vet, but on the early models, its the round piece in line that needs to get pulled, and just need to focus on the back side of the U's and the small wires that run behind the U's.
On the newer vets, Maf is a small box type device that is held into the hosing via the two small screws, and on his type, just need to spray cleaner into the side slide to clean the fouling out of it when you have it in hand..
If you are using a air filter that is the oil type, don't over oil the filter. The excess oil just ends up in the Maf, and means that you have to clean the Maf more often instead.
Also, if you are not running Top tier fuel, the every few tanks, make sure to add techron at fill up to keep te fuel system and injectors clean.
One last thing, and some of the after market air cleaner system can cause problems with the Maf not reading correctly. The don't produce a clean flow of air through the MAF, and some cases, have to have the car tune to adjust the Maf tables so they are reading correctly for the amount of air that the maf is reading instead..
Last edited by Dano523; Aug 14, 2019 at 12:07 AM.
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As dirty as that air filter was, and appearing to be an oiled gauze air filter, the MAF is very likely dirty. In addition to cleaning it, you should also clean the throttle body. It can cause throttle tip-in stumbling/hesitation if it is dirty, and as dirty as the filter was I am betting it's dirty as well.
Last edited by BadAV; Aug 14, 2019 at 07:22 AM.