Screeching noise during acceleration
Racer
Joined: Apr 2018
Posts: 349
Likes: 55
Since I'm not having other symptoms (no knocks, no detonations, etc.), I'm not sure if it's a faulty knock sensor. The code 43 may be a symptom, not necessarily the cause. That being stated, I do run 91 octane. I do this because I had some pinging (quiet, but there) a while ago when taking off from a stop (no codes).
I've read that C4s shouldn't need 91; could this be a contributing factor? Or could the 91 octane be covering up other symptoms? I've also read that a old/clogged fuel filter can cause ping due to lean mixture, resulting in a code 43.
I've read that C4s shouldn't need 91; could this be a contributing factor? Or could the 91 octane be covering up other symptoms? I've also read that a old/clogged fuel filter can cause ping due to lean mixture, resulting in a code 43.
Racer
Joined: Apr 2018
Posts: 349
Likes: 55
Ok Captain Armchair Mechanic, I'll defer to your indefinite knowledge as to help OP fix their problem, assuming you are done whining about other's advice? Or is being constructive too much work?
Clearly neither of our cars burst into flames, and we actually got useful information out of the test.
You can call it BS, what you beleive doesn't matter.
I'm done replying to your non-helpful input, have a good one.
Clearly neither of our cars burst into flames, and we actually got useful information out of the test.
You can call it BS, what you beleive doesn't matter.
I'm done replying to your non-helpful input, have a good one.
Race Director
Joined: Apr 2003
Posts: 17,697
Likes: 1,666
From: moraga ca
Doing a full throttle pull at any time can crack a head, or a piston, or spin a bearing, or drop a valve. One pull isn't going to increase the chances of a failure to unsafe levels. Guy I know drove a C3 50 miles with no water pump belt (belt was thrown), it was fine. There's Jeeps that drive around their impeller fins all broken off and face no issues. OP has already done it with the belt off, same as I did, and go figure, no cracked heads. His squeal persisted, I found my was due to the belt.
Le Mans Master
Joined: Jul 2004
Posts: 6,215
Likes: 694
From: Clifton Park, NY ............Clearwater, FL ... 85 Original Owner
Ok Captain Armchair Mechanic, I'll defer to your indefinite knowledge as to help OP fix their problem, assuming you are done whining about other's advice? Or is being constructive too much work?
Clearly neither of our cars burst into flames, and we actually got useful information out of the test.
You can call it BS, what you beleive doesn't matter.
I'm done replying to your non-helpful input, have a good one.
Clearly neither of our cars burst into flames, and we actually got useful information out of the test.
You can call it BS, what you beleive doesn't matter.
I'm done replying to your non-helpful input, have a good one.
Last edited by Cruisinfanatic; May 31, 2018 at 08:37 AM.
Le Mans Master
Joined: Jul 2004
Posts: 6,215
Likes: 694
From: Clifton Park, NY ............Clearwater, FL ... 85 Original Owner
Doing a full throttle pull at any time can crack a head, or a piston, or spin a bearing, or drop a valve. One pull isn't going to increase the chances of a failure to unsafe levels. Guy I know drove a C3 50 miles with no water pump belt (belt was thrown), it was fine. There's Jeeps that drive around their impeller fins all broken off and face no issues. OP has already done it with the belt off, same as I did, and go figure, no cracked heads. His squeal persisted, I found my was due to the belt.
Racer
Joined: Apr 2018
Posts: 349
Likes: 55
Since I'm not having other symptoms (no knocks, no detonations, etc.), I'm not sure if it's a faulty knock sensor. The code 43 may be a symptom, not necessarily the cause. That being stated, I do run 91 octane. I do this because I had some pinging (quiet, but there) a while ago when taking off from a stop (no codes).
I've read that C4s shouldn't need 91; could this be a contributing factor? Or could the 91 octane be covering up other symptoms? I've also read that a old/clogged fuel filter can cause ping due to lean mixture, resulting in a code 43.
I've read that C4s shouldn't need 91; could this be a contributing factor? Or could the 91 octane be covering up other symptoms? I've also read that a old/clogged fuel filter can cause ping due to lean mixture, resulting in a code 43.
Also, what brand belt did you get? I had a cheap-o one that would sqeal if I got on the gas pedal. Is your belt tight? The parts store sold me one that was 2 inches longer than stock at first. Also, too short a belt can squeal if it's too tight. Does the tensioner move smoothly without binding?
Last edited by TheBlaster9001; May 31, 2018 at 09:50 AM.
Thread Starter
Intermediate
Joined: Oct 2017
Posts: 27
Likes: 0
The belt is tight, and the tensioner moves without binding. I haven't checked the rear diff, but the sound is most definitely coming from the front. Besides, my speed doesn't necessarily play a role. I can be cruising at 70 and gun it and the noise will appear, so long as coolant temp is above 200.
Racer
Joined: Apr 2018
Posts: 349
Likes: 55
The belt is tight, and the tensioner moves without binding. I haven't checked the rear diff, but the sound is most definitely coming from the front. Besides, my speed doesn't necessarily play a role. I can be cruising at 70 and gun it and the noise will appear, so long as coolant temp is above 200.
My other though is that since the sound is t-stat related, since it has to be hot to happen.
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Thread Starter
Intermediate
Joined: Oct 2017
Posts: 27
Likes: 0
Well, I think I may have figure it out. This car was a barn find, rats and all. Well, those said rats had eaten the wire to the knock sensor. I've been driving without a knock sensor... 😨 Some how, I've had no other symptoms or engine damage I can find. The car will be down until I can get it rewired. I might as well replace the knock sensor for good measure.
Racer
Joined: Apr 2018
Posts: 349
Likes: 55
Well, I think I may have figure it out. This car was a barn find, rats and all. Well, those said rats had eaten the wire to the knock sensor. I've been driving without a knock sensor... 😨 Some how, I've had no other symptoms or engine damage I can find. The car will be down until I can get it rewired. I might as well replace the knock sensor for good measure.
Thread Starter
Intermediate
Joined: Oct 2017
Posts: 27
Likes: 0
Such a small thing to cause such a big problem. As is life, I suppose. Oh well, at least I caught it before any (known) damage. Thank you all for your help! I'll update after the repair and let you all know if that fixed the noise.
Race Director
Joined: Apr 2003
Posts: 17,697
Likes: 1,666
From: moraga ca
Dude, if you don't know what you're talking about, it's better to keep quiet. You may be able to fool someone occasionally, but to others, you sound foolish.
Last edited by 383vett; Jun 2, 2018 at 02:39 PM.
Racer
Joined: Apr 2018
Posts: 349
Likes: 55
Code 43 pulls timing. I'm trying to help OP think through why a code 43 may cause a screech. Belts can do that, right? If the engine pulls timing fast, the drop in power lets the belt slip, and the loss of static friction between the pulleys and belts means the belt contiunes to slip until it can grab when the engine slows. Right?
I'm all for you offering your explanation of why no knock sensor input would cause a screech. I'm throwing an idea out there, there are respectful ways to disagree with them, or correct me.
Race Director
Joined: Apr 2003
Posts: 17,697
Likes: 1,666
From: moraga ca
Code 43 pulls timing. Belts can do that, right? If the engine pulls timing fast, the drop in power lets the belt slip, and the loss of static friction between the pulleys and belts means the belt contiunes to slip until it can grab when the engine slows. Right?
. I'm throwing an idea out there, there are respectful ways to disagree .
Racer
Joined: Apr 2018
Posts: 349
Likes: 55
So you are saying that when the timing is pulled, the engine slows quickly like it has a brake causing the belts to slip? This folly doesn’t deserve a respectful correction. Your ignorance is more and more apparent with every post. Yes, it is the air conditioner compressor throwing oil. My own car experienced the same manifestation.
You got a better explanation of OPs problem? Any ideas at all? Please, share them - constructive input is usually appreciated by others. Or do you just come here to gripe? I can't tell at this point. If only all of us could be as smart as almighty you, I guess. I'll bow down and kiss the blessed ground you tread, O' All Knowing One.
Race Director
Joined: Apr 2003
Posts: 17,697
Likes: 1,666
From: moraga ca
Compressor oil is the same color as engine oil. Did you think it was green? Might want to either keep quiet or learn something about cars before you spew your trap any further. No advice is better than the wrong advice. Oh, try driving 5 miles without a belt and report back with your engine temperature.
Last edited by 383vett; Jun 2, 2018 at 06:44 PM.
Racer
Joined: Apr 2018
Posts: 349
Likes: 55
Compressor oil is the same color as engine oil. Did you think it was green? Might want to either keep quiet or learn something about cars before you spew your trap any further. No advice is better than the wrong advice. Oh, try driving 5 miles without a belt and report back with your engine temperature.
AC comprssors in C4s call for mineral oil, one source I read specifies ND-6 was the oil that came in the stock compressors. Nearly every mineral oil out there is clear, ND6 is as well. Other posts I read indicate the oil should be clear. The OP of that post said the oil he found was clear. "You might want to keep quiet or learn something about cars before you spew your trap any further." Lmao. Way to double down.
I've driven up and down the street with no belt, about a mile. Head temp sensor got to 150. Not that I expect someone as blindly arrogant as you to take my word for it. What is it with you and lacking any human decency? You can disagree with someone without berating their intelligence. Unless you're insecure and projecting, I guess.
Racer
Joined: Apr 2018
Posts: 349
Likes: 55
I think its the serpentine belt slipping. When coolant reaches 200-ish the fan turns on, putting load on the alternator. I don't have an explanation for the loss of power when it screeches. The fan turns off when road speed reaches 45MPH. So make it screech, keep accelerating until speed exceeds say 50MPH and if the screeching stops, it is the fan load on the alternator causing the belt slip.
In OPs case, the no belt could be risky. I didn't read close enough to see he couldn't get the squeal until over 200. Mine would do it cold, so it didn't hurt to run up the road. Just needed the one pull to make sure it was the belt, then easy going back to the garage.
The fan spinning the pump is what I figure saved my friends C3. That and it was freezing out, I'm sure helped.
Racer
Joined: Apr 2018
Posts: 349
Likes: 55
Except that the 43 did not occur at the outset of the screeching. Read the first few posts again. The 43 wasn't present until later.
When 43 sets, the ECM commands timing advance based on RPM and TPS, it does not disable timing advance altogether. 43 means there is no feedback available for knock retard. So the ECM commands timing to "safe" levels where detonation won't occur.
I do not see how the screeching, and 43 are related.
When 43 sets, the ECM commands timing advance based on RPM and TPS, it does not disable timing advance altogether. 43 means there is no feedback available for knock retard. So the ECM commands timing to "safe" levels where detonation won't occur.
I do not see how the screeching, and 43 are related.
I'd have to think the lack of knock input would account for low power, when my connector cracked it would pull under 3/4 throttle, but any more just bogged down. Although I imagine your assertion that the code and squeal are not related may be correct.
Racer
Joined: Apr 2018
Posts: 349
Likes: 55
Wow. Five suppositions in a single post. You can't do this on forums. (I've been on forums since before you were born. Literally). You have to READ and Go By what the OP posts. Don't guess, because you'll probably get off on the wrong track. :Like you have in this post. The OP has a belt problem. Period.
And the winner is:
The OP's power loss occurs at 50% throttle, not 3/4. So not the same conditions, eh?
Dude, you're GUESSING. Just STFU and follow along for awhile. You're making a fool of yourself.
And the winner is:
The OP's power loss occurs at 50% throttle, not 3/4. So not the same conditions, eh?
Dude, you're GUESSING. Just STFU and follow along for awhile. You're making a fool of yourself.