Detonation Issues
Detonation Issues Okay so here's my situation. I have a 2000 M6 Z28. My only mods are
Magnaflow cat-back, SLP Lid, & K&N filter. Since the weather here
has gotten over 90 degrees I have been having some problems with
detonation. I am not having problems in the upper RPM. Mainly just
when I am cruising in 5th or 6th & I get into the throttle.
Pretty much if I am driving with the cruise set at 65 & I press the throttle
while going up a hill to maintain speed, I will hear a slight metallic rattling noise.
My plan for now is to baby it until Saturday & then replace the:
Fuel Filter, Air Filter, Spark Plugs & Wires, & clean my MAF sensor.
I bought a used K&N air filter that had been re-oiled (Didn't know better
at the time) so I think that replacing it & cleaning my MAF might fix
the problem.
I figured I would try the cheapest things first & hope that works.
Does anyone have any other suggestions as to what I should do?
Any feedback is greatly appreciated. I'm half affraid to drive it now.
I don't want to screw my engine up.
Magnaflow cat-back, SLP Lid, & K&N filter. Since the weather here
has gotten over 90 degrees I have been having some problems with
detonation. I am not having problems in the upper RPM. Mainly just
when I am cruising in 5th or 6th & I get into the throttle.
Pretty much if I am driving with the cruise set at 65 & I press the throttle
while going up a hill to maintain speed, I will hear a slight metallic rattling noise.
My plan for now is to baby it until Saturday & then replace the:
Fuel Filter, Air Filter, Spark Plugs & Wires, & clean my MAF sensor.
I bought a used K&N air filter that had been re-oiled (Didn't know better
at the time) so I think that replacing it & cleaning my MAF might fix
the problem.
I figured I would try the cheapest things first & hope that works.
Does anyone have any other suggestions as to what I should do?
Any feedback is greatly appreciated. I'm half affraid to drive it now.
I don't want to screw my engine up.
Are you getting a SES code for the detonation? Is it doing it at the same throttle position to what the rpm would be in 3rd and 4th(cruising, not accelerating). That would produce a similar load on the motor. Also does it do it with only the cruise control on? It sounds like it could possibly be the tranny but I would say check the plugs to see what they look like, are you 100% sure it is coming from under the hood? The K&N should be fine as long as it was cleaned before it was reoiled(and not over oiled)??? Cleaning the MAF is always a good idea also, it can't hurt
Are you getting a SES code for the detonation? Is it doing it at the same throttle position to what the rpm would be in 3rd and 4th(cruising, not accelerating). That would produce a similar load on the motor. Also does it do it with only the cruise control on? It sounds like it could possibly be the tranny but I would say check the plugs to see what they look like, are you 100% sure it is coming from under the hood? The K&N should be fine as long as it was cleaned before it was reoiled(and not over oiled)??? Cleaning the MAF is always a good idea also, it can't hurt
I think it will do it in 4th, if the RPM is low enough & I floor it.
I don't think it will do it in 3rd. I'm not really sure though.
I never have detonation while cruising, regardless of speed.
Only on acceleration. It doesn't matter if I have the cruise set or not.
I've had detonation issues on different cars before. I'm 99% sure that
it is coming from the engine. I don't really think that it has anything to
do with the transmission.
The K&N filter may have been over oiled. I bought it used & I could tell
that the past owner had oiled it. I didn't know that would be an issue at
the time.
I should probably add that the car has 77K miles & I don't know if the
fuel filter or spark plugs have ever been changed. I kept meening to get
around to it but I never have. (I've owned it since 63K miles).
BTW, Thanks for the help.
I would definitely check the plugs for sure and change the fuel filter (so you know it's done) for sure. Check to see what plugs are in there too. I ran Bosch's when I first got my 99TA and after awhile it didn't like them at all. Try putting a set of NGK TR55 in there anyway, that could very well be the problem. Everytime my car has detonated it has thrown a SES light, so that is why I posted that. No problem fella, trying to help ya out if i can
NGK TR55 plugs, MSD wires, AC Delco fuel filter, & a new K&N filter are already
ordered from WS6store. I'm keeping my fingers crossed that the parts
come in by Saturday. I don't know about the SES light. The noise isn't
that loud, so maybe the detonation isn't bad enough to set it off.
I'm wondering if maybe my fuel filter is clogged & my engine isn't getting
enough fuel when I give it gas. I hope it's not the fuel pump.
If the cat converters are clogged, that gives me a good excuse to get
the LT headers & catted Y-pipe I've been wanting.
ordered from WS6store. I'm keeping my fingers crossed that the parts
come in by Saturday. I don't know about the SES light. The noise isn't
that loud, so maybe the detonation isn't bad enough to set it off.
I'm wondering if maybe my fuel filter is clogged & my engine isn't getting
enough fuel when I give it gas. I hope it's not the fuel pump.
If the cat converters are clogged, that gives me a good excuse to get
the LT headers & catted Y-pipe I've been wanting.
Fuel pump isn't that bad and the Racetonixs pump isn't that expensive if it is that. But i bet putting plugs and wires will help dramaticly.
But... i think your cats are clogged for sure time for that full exhaustlol
But... i think your cats are clogged for sure
time for that full exhaustlol Trending Topics
Today on my way to work, I put the car into 5th at 45mph & accelerated
to 65mph in 5th gear. I could hear the detonation up until I reach about
2000 RPM, then it goes away. Or it becomes inaudible.
I've driven it the same way for the last 14K miles & I've never had
problems with it before. I don't know. Hopefully I can figure it out.
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TECH Enthusiast
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From: NW burbs of Chicago
You know I've wondered about this.
Today on my way to work, I put the car into 5th at 45mph & accelerated
to 65mph in 5th gear. I could hear the detonation up until I reach about
2000 RPM, then it goes away. Or it becomes inaudible.
I've driven it the same way for the last 14K miles & I've never had
problems with it before. I don't know. Hopefully I can figure it out.
Today on my way to work, I put the car into 5th at 45mph & accelerated
to 65mph in 5th gear. I could hear the detonation up until I reach about
2000 RPM, then it goes away. Or it becomes inaudible.
I've driven it the same way for the last 14K miles & I've never had
problems with it before. I don't know. Hopefully I can figure it out.
I get lugging under high load at below 1400rpm.
12 Second Club
Joined: Mar 2009
Posts: 196
Likes: 0
From: deer park (houston area)
What is detonation? this may be a complete noob question, but I’ve only herd this word used in the nitrous section.. i guess when there is like a nitrous backfire? Does detonation mean he's having backfires?
Detonation is metalic a pinging sound. It is caused by the fuel in the
combustion chamber igniting before it is intended. If you fill your
tank with 87 octane you will hear it.
Don't do that though. Detonation can be hard on your engine.
You can damage pistons & piston rings.
combustion chamber igniting before it is intended. If you fill your
tank with 87 octane you will hear it.
Don't do that though. Detonation can be hard on your engine.
You can damage pistons & piston rings.
Teching In
Joined: Jun 2009
Posts: 6
Likes: 0
Detonation is metalic a pinging sound. It is caused by the fuel in the
combustion chamber igniting before it is intended. If you fill your
tank with 87 octane you will hear it.
Don't do that though. Detonation can be hard on your engine.
You can damage pistons & piston rings.
combustion chamber igniting before it is intended. If you fill your
tank with 87 octane you will hear it.
Don't do that though. Detonation can be hard on your engine.
You can damage pistons & piston rings.
detonation is a general term and simply means the air/fuel mixture was ignited by something other than the spark plug. When detonation occurs, there are typically multiple reactions and flame fronts that collide together to give you the metallic noise that you hear. When you hear it detonate, you can actually shut the engine down and pull one of the plugs and you will see black specs on the porcelain of the plug. This is the carbon from the top of your piston that was exploded, for lack of a better term and stuck to the plug.
pre-ignition can be caused by hot spots on the piston and an ignition advance that is too high. These hotspots can ignite the fresh fuel from the injectors as the piston is still traveling towards TDC. As you can probably imagine, the cylinder pressure forced down onto the piston that is still traveling upwards can be quite traumatic to the rest of the rotating assembly. Mostly the rod bearings and piston ring lands.
What gas octane do you use? How many threads on the spark plug show a color change from the heat? What is your distributor base timing?
detonation is a general term and simply means the air/fuel mixture was ignited by something other than the spark plug. When detonation occurs, there are typically multiple reactions and flame fronts that collide together to give you the metallic noise that you hear. When you hear it detonate, you can actually shut the engine down and pull one of the plugs and you will see black specs on the porcelain of the plug. This is the carbon from the top of your piston that was exploded, for lack of a better term and stuck to the plug.
pre-ignition can be caused by hot spots on the piston and an ignition advance that is too high. These hotspots can ignite the fresh fuel from the injectors as the piston is still traveling towards TDC. As you can probably imagine, the cylinder pressure forced down onto the piston that is still traveling upwards can be quite traumatic to the rest of the rotating assembly. Mostly the rod bearings and piston ring lands.
What gas octane do you use? How many threads on the spark plug show a color change from the heat? What is your distributor base timing?
pre-ignition can be caused by hot spots on the piston and an ignition advance that is too high. These hotspots can ignite the fresh fuel from the injectors as the piston is still traveling towards TDC. As you can probably imagine, the cylinder pressure forced down onto the piston that is still traveling upwards can be quite traumatic to the rest of the rotating assembly. Mostly the rod bearings and piston ring lands.
What gas octane do you use? How many threads on the spark plug show a color change from the heat? What is your distributor base timing?
The spark plugs didn't look too bad. The first 2 or 3 threads had some
black gunk on them. The tips had white on them. They were AC Delco
plugs, so I'm assuming they were the original plugs.
I haven't touched my distributor & I don't plan to unless it breaks.
So the timing is stock.
I haven't finished the passenger side plugs & wires yet. The car seems
to be running really well now though. The passenger side plugs almost
make me miss my old integra. I could change the plugs & wires in 5 minutes!
TECH Enthusiast
Joined: Aug 2006
Posts: 502
Likes: 1
All joking aside....
Ruling out bad gas or low fuel pressure or a partially clogged injector, it is possible to have a bad sensor and not get a MIL for it. Any problem with the ignition system on a distributorless engine (such as the LSx engines) would most likely result in misfire, not detonation, so we can pretty much rule that out also.
Both the coolant temp sensor and the intake air temp sensor pull timing when temps get higher. The coolant temp sensor does the majority of the work, although the IAT sensor is referenced under very high loads (such as lugging it in high gear).
Seeing this is a problem that is occuring during periods of high temp, I would lean toward one of these two sensors providing false data and not pulling timing as it should.
A live scan would reveal this.
Check around the forum to see if there is anyone with HPTuners or EFILive that could scan your car for you.
Ruling out bad gas or low fuel pressure or a partially clogged injector, it is possible to have a bad sensor and not get a MIL for it. Any problem with the ignition system on a distributorless engine (such as the LSx engines) would most likely result in misfire, not detonation, so we can pretty much rule that out also.
Both the coolant temp sensor and the intake air temp sensor pull timing when temps get higher. The coolant temp sensor does the majority of the work, although the IAT sensor is referenced under very high loads (such as lugging it in high gear).
Seeing this is a problem that is occuring during periods of high temp, I would lean toward one of these two sensors providing false data and not pulling timing as it should.
A live scan would reveal this.
Check around the forum to see if there is anyone with HPTuners or EFILive that could scan your car for you.
Last edited by Dan Stewart; Jun 21, 2009 at 10:10 AM. Reason: grammar.....before the grammar nazis get me
distributor at the back of the engine like the old small block chevy
engines did. I just assumed that there was some sort of ignition
control module somewhere under the hood.
Is the engines ignition just controlled by the ECM?
BTW, thanks for the help. If I get the tune-up done & I still have
issues I'll check into the sensors.
TECH Enthusiast
Joined: Aug 2006
Posts: 502
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Yeah, the pcm does the ignition control now. Not even a seperate ignition module to fool with anymore. To be honest, I believe the IM died with the Series II 3800. As far as I know, all the GM's now are directly controlled via the pcm.
BTW, not trying to give you a hard time. I didn't know squat about GenIII/IV engines at one time either.
BTW, not trying to give you a hard time. I didn't know squat about GenIII/IV engines at one time either.
Teching In
Joined: Jun 2009
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