One other data point in my case. I noticed this morning on the way to work that it doesn't rattle until the engine is good and hot. Even with the coolant at normal operating temp, I get no rattle until 15-20 miles of driving.
How To Stop Pre-Detination Rattle?
- Thread starter LFD2037
- Start date
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I had the same thing with my 97 when I first got it. Then I took a trip up to Big Bear where I drove it HARD (3000 rpm + ) all the way up the mountain. Hasn't ping'd since. I think the P.O. just babied it too much cruising around town. Now, once per tank, I get on the freeway and do a manually shifted full throttle 0-70 run. It seems to keep things cleaned out.
I get a minimal wrist pin knock (pre detonation) with the AC on and cheap gas when coming off a stop. Knowing cars in general, inside and out, its a common sign of needing to do a timing chain/guides and get it all tightened up in there. It doesn't do it with primo gas, which means its very minimal. A timing chain is in my future, as PO never did PM on this thing unless it was out of commission. My luck of buying my 80 from a dentist is showing its true colors.
Need to step back here and find some more info on proper terminology, causes and effects. There are links to info on mud and elsewhere about what you are hearing, its causes, and what it does to your engine
My knock is wrist pin knock, which many people call pre detonation, which it is. My engine has higher mileage, but nothing crazy, and when you can go between 87 octane and 91octane and it goes away, that's what it is. In ~most~ cases
LFD2037
TEXAS LEXUS!
- Thread starter
- #167
If you are referring to me:
I've stepped back for over a year. Hasn't changed.
Proper terminology- Ive been pretty damn sure it's pre-detonation/pinging but have done EVERYTHING there is to cure that, to no avail, so now it has me 2nd guessing it may be valves. I've been around cars for 30+ years & am very familiar w/them.
Causes- knew quite a few then learned the rest. Reversed/repaired them all.
Effects- aware of those as well.
Thanks.
They are two different things
Valves or wrist pins are NOT one of them
http://www.nicoclub.com/archives/detonation-preignition-tuning.html
Valves or wrist pins are NOT one of them
http://www.nicoclub.com/archives/detonation-preignition-tuning.html
Ok I haven't read the entire thread
Have you:
1: Replaced front O2 sensor
2: Checked logged AFR when it happens
3: Was the head and block decked? If so how much?
4: Find/Rent a borescope and pull the spark plugs and check the top of the pistons for build up or any damage.
Have you:
1: Replaced front O2 sensor
2: Checked logged AFR when it happens
3: Was the head and block decked? If so how much?
4: Find/Rent a borescope and pull the spark plugs and check the top of the pistons for build up or any damage.
Sorry, OCD kicking in: "Detonation" and "Pre-Ignition" are actual SAE recognized terms, two different things which may give the same perceived symptoms (similar noise). Neither are a strictly mechanical noise, rather a fault or failure in the process of controlled combustion, and oddly enough, both may lead to mechanical noises and excessive wear on mechanical components like flattened rod bearings, piston crown fractures, holes in piston tops.... well, you get the idea.
Wrist pin rattle, piston slap, rod knock... all these can also be attributed to a failed ignition process, which can be either detonation or pre-ignition.
So, that being said, and rather long-windedly I might add, detonation is an instantaneous explosion of the air-fuel mixture, and pre-ignition is a premature beginning of the ignition process, said process being a controlled, timed combustion of the air-fuel mixture.
Here's a good explanation of detonation:
http://progl.com/General/detonation.htm
There are also some very good discussions on the same subject on various aircraft forums. Imagine adjusting your own mixture and ignition timing while you're flying and the consequences of holing a piston or two in flight.
Think: Detonation= Too fast
Pre-ignition=Too soon
"Pre-detonation" is not a recognized term to the best of my knowledge.
I feel better now, thank you very much.
Wrist pin rattle, piston slap, rod knock... all these can also be attributed to a failed ignition process, which can be either detonation or pre-ignition.
So, that being said, and rather long-windedly I might add, detonation is an instantaneous explosion of the air-fuel mixture, and pre-ignition is a premature beginning of the ignition process, said process being a controlled, timed combustion of the air-fuel mixture.
Here's a good explanation of detonation:
http://progl.com/General/detonation.htm
There are also some very good discussions on the same subject on various aircraft forums. Imagine adjusting your own mixture and ignition timing while you're flying and the consequences of holing a piston or two in flight.
Think: Detonation= Too fast
Pre-ignition=Too soon
"Pre-detonation" is not a recognized term to the best of my knowledge.
I feel better now, thank you very much.
LFD2037
TEXAS LEXUS!
- Thread starter
- #172
Jeez, we are getting off topic here. Detonation is the action of causing a bomb or explosive device (in this case a spark plug igniting a combustion chamber full of fuel) to explode. That 'explosion' happening too soon is pre, meaning before. When the engine explodes, not ignites but explodes, too soon that is pre-detonation. This can happen due to many reasons but usually it's due to all the required elements being available, other than ignition, & they meet at the right time in the right balance to cause detonation. This is done w/out 'ignition' so therefore pre-detonation. Since the prefix 'pre' is throwing y'all off, we'll stick to just the word detonation.
Or call it pre-ignition. Call it cat s*** for all I care. The signs/symptoms have been represented & that's what we shall focus on. I've read many threads on here where people have the same signs/symptoms but there's never a viable fix.
Hope I don't offend anyone w/the above but I'm just trying to stay on track here. I used basic physics & common nomenclature.
Sincerely, Thank you for any assistance.
Or call it pre-ignition. Call it cat s*** for all I care. The signs/symptoms have been represented & that's what we shall focus on. I've read many threads on here where people have the same signs/symptoms but there's never a viable fix.
Hope I don't offend anyone w/the above but I'm just trying to stay on track here. I used basic physics & common nomenclature.
Sincerely, Thank you for any assistance.
I just re-read the title of the thread, seems like I'm still on-topic. People are looking for a fix for a particular noise, and I did say I was maybe a little bit OCD.
It's hard to discuss something when using terms that technically don't exist as there's no common ground. My dad worked on the MBT70 project way back when, and he said the biggest issue they had with working with all the German engineers was agreeing on terminology before any engineering could happen. And then there was the Metric/Fractional debate.....
I'm not offended, discussion is good, but take a look at the link I posted. Detonation can begin at the exact correct time, but as you do say, it's an instantaneous explosion, not a controlled burn. Pre-ignition is when the ignition and combustion process start too soon, which may or may not cause detonation. Neither are good.
They are two distinct but often inter-related conditions, and recognizing that is essential in discussing and diagnosing them both.
Sorry, I'll go back to work now.
By the by, I see you're in Waxahachie. You ever run across Frisbee?
It's hard to discuss something when using terms that technically don't exist as there's no common ground. My dad worked on the MBT70 project way back when, and he said the biggest issue they had with working with all the German engineers was agreeing on terminology before any engineering could happen. And then there was the Metric/Fractional debate.....
I'm not offended, discussion is good, but take a look at the link I posted. Detonation can begin at the exact correct time, but as you do say, it's an instantaneous explosion, not a controlled burn. Pre-ignition is when the ignition and combustion process start too soon, which may or may not cause detonation. Neither are good.
They are two distinct but often inter-related conditions, and recognizing that is essential in discussing and diagnosing them both.
Sorry, I'll go back to work now.
By the by, I see you're in Waxahachie. You ever run across Frisbee?
LFD2037
TEXAS LEXUS!
- Thread starter
- #174
I've seen his rig once, which is a really cool rig btw, but haven't met him. I've talked w/him on here, though. I'm actually contemplating taking my rig to him to see if him & I together can diagnose this situation & choose the best course of action.
The way i see it is I could say I think I have a blown turbo. Then describe the signs/symptoms of the situation. Thru that you'll learn I don't even have a turbo much less is it blown.
I run on people all the time who have given the diagnosis of their situation as, say, a heart attack. They explain their signs/symptoms & thru that I discover it's not a heart attack, it's a panic attack. Weird analogy, I know, but I'm not very good @ trying to get my point across even though it's very clear in my mind.
Sorry for any inconvenience as I'm not too well @ communicating via computers/emails/texts/etc.
Gotcha, Ed Zachary. Your comm skillz are just fine.
If you get a chance, drop in on Mike, good guy and knows where all the skeletons are buried. Plus he's got some good stuff going on in the shop, as a rule.
Your comm skillz are just fine.If you get a chance, drop in on Mike, good guy and knows where all the skeletons are buried. Plus he's got some good stuff going on in the shop, as a rule.
Hey, been following this thread since you started it. I remember that on page 3 you snapped a pic of your #3 plug... being very lean. Have you checked for a small leak somewhere on your exhaust manifold all the way down to bank one o2 sensors? Air being sucked in could cause the ecm to lean it out
Exhaust is pressurised . Be hard to leak air in. Just back off the timing a couple degrees.
LFD2037
TEXAS LEXUS!
- Thread starter
- #179
Timing is at 3*. Are you saying it needs to be LESS than factory specs? I put 92 or 93 octane in it about 50 miles ago. After a good 30 minutes drive in 100* weather with a good heat soak the rattle is barely noticeable. To reiterate:
92/93 octane makes it 90% go away in just 50 miles of higher octane use
And
Lower ambient/intake/engine temps it's non-existent. Thanks.
A thought: Any chance the valve clearance may be a little tight? Exhaust valves more so than intake transfer heat back to the head when they're closed, and a tight valve or two will run a tad warm when at operating temp, sometimes even causing detonation.
