1G Eclipse 1G Naturally Aspirated Pinging/Detonation

[IvanovBG]

Hi guys,

I drive a 1993 Eclipse GS. It has a stock non turbo 7 bolt engine.

A few months ago, I noticed a weird noise coming from the engine bay, which I believe to be pinging/detonation, after reading this older thread: https://www.dsmtuners.com/threads/grinding-rattiling-noise-when-accelerating.435464/#post-152970553
I can hear it during normal driving conditions, but it gets worse when the engine is under load on steeper hills.

The noise is present only at lower RPM's, and it goes away after I go past 2000-2300RPM. It starts only when the car reaches operating temps, if the engine is cold I don't hear anything, even when lugging it in a higher gear.
The check engine light isn't on, but I don't have a tool like ECMLink to check any logs.

First thing I did was to buy a timing light and make sure the timing is correct by following these steps from VFAQ: http://www.vfaq.com/mods/wayback/BradBauer/engine/timing.html
Even with the correct factory timing, it still made the noise, so what I tried next is retarding it. The noise went away only when the CAS is almost completely turned clockwise to retard the timing as much as possible.

The car is drivable, but accelerates quite a bit slower, so I tried swapping some parts that I read could have helped.
New parts:
- Spark plugs (NGK BPR6ES)
- NGK Spark wires
- Coils
- 82°C Thermostat

The radiator is also new from a couple of years ago, as the neck for the upper coolant hose on the OEM one broke. I swapped the MAF as well, because I have a backup replacement, but it didn't make a difference.
The car is driven only with 95+ or 100 octane fuels, which are the highest grades possible in my country. I used Liqui Moly Injection Cleaner a couple of times to help with possible carbon buildup as well.

Any ideas what I could do to remedy this? If the knock sensor is bad, could swapping it help?

PS: I'm new here, so if you'd like to check out the car, this is my introduction thread: https://www.dsmtuners.com/threads/new-member-1993-eclipse-gs-fwd-naturally-aspirated.547297/

 

[TerminalTalon]

You can post a video for the noise reference.
95-100 octane on a stock NA car without tuning seems crazy to me. Have you checked the timing belt/timing?

 

[danl]

Does your car consume oil? What oil are you using? Do you have a bore scope to inspect the piston tops and intake/exhaust valves?

 

[BLACK'98DSM]

You can post a video for the noise reference.
95-100 octane on a stock NA car without tuning seems crazy to me. Have you checked the timing belt/timing?

That's standard fuel for the Russia continent and surrounding areas. O.P. is from Bulgaria, so nothing abnormal.

 

[steve]

I'm assuming that's RON Octane.

 

[IvanovBG]

You can post a video for the noise reference.
95-100 octane on a stock NA car without tuning seems crazy to me. Have you checked the timing belt/timing?

Hi,

I've attached a video that I made a while back, on which the noise is audible. Sorry for the odd angle, but it was hard to film with my phone while driving.

I have a cousin that's a mechanic and he helps me out with maintenance. We've already changed the timing and accessory belts, as well as the pulleys, water pump and timing tensioner. The timing marks lined up as they should.

The noise was present before and after we did this.

As for the fuel, this is standard here in Bulgaria. The lowest is regular 95 octane, and then most gas station brands have their own premium 95 and 100 octane fuels, that include additives. All of them are E10.

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Does your car consume oil? What oil are you using? Do you have a bore scope to inspect the piston tops and intake/exhaust valves?

Hi,

The engine does burn oil, about 1 liter per 1500km/932miles, which is a lot. I'm planning a rebuild where the valve stem seals, lifters, piston rings and bearings are replaced, which should be in the next few months. I've read that excessive oil burning could cause detonation, but it was burning oil long before I started to hear that noise.

The oil I use is Motul 6100 Synergie+ 10W40, and make sure to regularly check the level.

I don't have a bore scope, but when I changed the spark plugs the top of the pistons that I could see, did seem to have some buildup. I've used injection & valve cleaners a few times to help with possible buildup, but the noise didn't go away. Throttle response also felt the same.

I'm assuming that's RON Octane.

I believe that most if not all European countries use the RON figure, yes.

 

[danl]

Are you sure it’s not a rattle? Are any of your motor mounts torn?

 

[IvanovBG]

Are you sure it’s not a rattle? Are any of your motor mounts torn?

Initially I thought it might be rattle as well, but why would it go away completely when I retard the timing? Right now the CAS is almost all the way in the retarded position, and I don't hear the noise at all, even on steep hills. But if I move it even a little in the clockwise position to advance it, the noise comes back when I drive the car.

The engine mounts were bought new like 4-5 years ago from a local parts store. They look fine when I check them, I don't see any tears.

 

[danl]

The only thing I can think of is to try engine oil that is specifically made for direct injected engines. They are prone to low speed pre ignition if they consume oil. A stock na 4g63 should not be pinging at low rpm. Older engine oils are known to reduce octane. In the USA we call it “SN+” oil rating.

What You Need to Know About Low-Speed Pre-Ignition LSPI - Valvoline™ Global

As engines are transforming, so are the issues associated with them.

team.valvolineglobal.com

Carbon buildup from burning oil may also cause it. Do you have a catalytic converter? Could it be clogged, causing the pinging?

 

[IvanovBG]

The only thing I can think of is to try engine oil that is specifically made for direct injected engines. They are prone to low speed pre ignition if they consume oil. A stock na 4g63 should not be pinging at low rpm. Older engine oils are known to reduce octane. In the USA we call it “SN+” oil rating.

What You Need to Know About Low-Speed Pre-Ignition LSPI - Valvoline™ Global

As engines are transforming, so are the issues associated with them.

team.valvolineglobal.com

Carbon buildup from burning oil may also cause it. Do you have a catalytic converter? Could it be clogged, causing the pinging?

Thanks for the suggestion! I wasn't really familiar with this API.
When I checked some of the online stores here, they do seem to have some SN+ oils, but the majority of them are 5W40. Would this viscosity be okay for summer driving? I might just give it a try on the next oil change.

The catalytic converter was either removed from the previous owner or stolen, as there is some kind of Mitsubishi branded resonator in its place.

 

[1990TSIAWDTALON]

Heavy carbon build up on the piston can cause preignition, making it "ping" when hot and the carbon is glowing, setting off the fuel charge prematurely. This is an OLD trick to clean carbon off the piston tops. Place a vacuum hose into a container with water. Unhook a vacuum source on the intake and start introducing the water into the induction side, all while keeping the car running(it WILL want to die but do not let it die, that could make it hydrolock). Keep feeding it water and Rev the heck out of it repeatedly. That will "steam clean" the piston tops of excessive carbon build up. You should start seeing a good amount of smoke out of the tail pipe during this. After using about a Liter or so, Rev the car too clear it out and put the vacuum line back on the motor. I did this treatment to my mother-in-laws old Ford Fairmont and it left a BIG BLACK SOOT stain in the grass and the car idled and ran so much better afterwards. We did this way back in the 70s and 80s at a shop I worked at.
Just an old tip for carbon removal from an old mechanic.

 

[IvanovBG]

Heavy carbon build up on the piston can cause preignition, making it "ping" when hot and the carbon is glowing, setting off the fuel charge prematurely. This is an OLD trick to clean carbon off the piston tops. Place a vacuum hose into a container with water. Unhook a vacuum source on the intake and start introducing the water into the induction side, all while keeping the car running(it WILL want to die but do not let it die, that could make it hydrolock). Keep feeding it water and Rev the heck out of it repeatedly. That will "steam clean" the piston tops of excessive carbon build up. You should start seeing a good amount of smoke out of the tail pipe during this. After using about a Liter or so, Rev the car too clear it out and put the vacuum line back on the motor. I did this treatment to my mother-in-laws old Ford Fairmont and it left a BIG BLACK SOOT stain in the grass and the car idled and ran so much better afterwards. We did this way back in the 70s and 80s at a shop I worked at.
Just an old tip for carbon removal from an old mechanic.

Hi Marty,

This is a good suggestion, but I've never attempted something like this and would be worried not to mess something up and cause damage. So maybe it would be best to clean the pistons during a rebuild, which I hope to get done by the end of this year. Hopefully that will help, as the retarted timing really kills acceleration and it also bothers me that there's an underlying issue.

I was also thinking, is it possible that the knock sensor isn't properly pulling timing at low RPM?
A couple of weeks ago I reached under the manifold to touch it, and the black goo was sticking to my fingers.
This is a picture of it I was able to take:

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From what I've read on this forum, when the black goo is falling off and you can see that bolt, it should be replaced.

 

[1990TSIAWDTALON]

Yes sir, your knock sensor has leaked all if it's "goo". It is no longer functioning. You will need to replace that. I will see if I can find one still available. The 1g knock sensors are discontinued but some aftermarket companies still make it.
I understand your feeling on the steam cleaning. If you are going to rebuild the motor, then of course, the pistons will be spotless clean. That procedure is for a car that has carbon build up and it works very well if you don't plan on taking the motor apart. It will NOT clean the tops of the valves. That would require them getting soaked in a combustion chamber cleaning fluid and sitting for a good day or so, then start it up and clear out the loosened carbon and cleaning fluid. Some products like that include Berrymans Chemtool, and you would be introducing it the same way as water only letting the motor die so the fluid soaks into the carbon on the valves.
Just old time remedies.
Here is the knock sensor you need. There may be other suppliers also. You need a Mitsubishi #MD141510.
Marty

 

[steve]

Yes, another dead/dieing 1G Knock Sensor. I haven't yet had a change/need to use my AliExpress knock sensor but they are cheap.

https://www.aliexpress.us/item/2255800796193691.html

 

[IvanovBG]

Yes sir, your knock sensor has leaked all if it's "goo". It is no longer functioning. You will need to replace that. I will see if I can find one still available. The 1g knock sensors are discontinued but some aftermarket companies still make it.
I understand your feeling on the steam cleaning. If you are going to rebuild the motor, then of course, the pistons will be spotless clean. That procedure is for a car that has carbon build up and it works very well if you don't plan on taking the motor apart. It will NOT clean the tops of the valves. That would require them getting soaked in a combustion chamber cleaning fluid and sitting for a good day or so, then start it up and clear out the loosened carbon and cleaning fluid. Some products like that include Berrymans Chemtool, and you would be introducing it the same way as water only letting the motor die so the fluid soaks into the carbon on the valves.
Just old time remedies.
Here is the knock sensor you need. There may be other suppliers also. You need a Mitsubishi #MD141510.
Marty

I'll make sure to update the thread after a potential rebuild in the next few months, to let you guys know what the end results would be. Hopefully there will be good news!

As for the knock sensor, I actually read a lot of the older and more recent threads about it. It seems like the consensus is that the best option is to get a Miata sensor and swap the plug. You've included a link to the GPD sensor in one of the threads, but Partsgeek doesn't ship internationally, and the ones from Ebay have both a markup and high delivery cost.

On Amazon, only the Beck/Arnley 158-1039 can be ordered, and that's what I was thinking of getting. All the other US websites I found it on have a lot higher delivery cost than Amazon.

 

[IvanovBG]

Yes, another dead/dieing 1G Knock Sensor. I haven't yet had a change/need to use my AliExpress knock sensor but they are cheap.

https://www.aliexpress.us/item/2255800796193691.html

Hi Steve,

I might get one of these as a backup as well, just the connector itself could end up being useful. But I don't really trust it as a long term replacement.
When reading about it on older threads, it seems like no one has tested if it actually works yet.

 

[dwb]

Wait, the N/A 4g63 has a knock sensor?

 

[97egl]

Wait, the N/A 4g63 has a knock sensor?

I noticed that too, but its european so as usually they probably just got better/different stuff than american cars did.

 

[1990TSIAWDTALON]

Trust it. I have 5 of them and I build 4g63 motors. These 2 are from Steve's link and will be used in one of the next builds. Nobody can answer if the Miata sensor picks up the same knock so I would really suggest getting the correct sensor. The AliExpress sensors are VERY reasonable.

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[IvanovBG]

Trust it. I have 5 of them and I build 4g63 motors. These 2 are from Steve's link and will be used in one of the next builds. Nobody can answer if the Miata sensor picks up the same knock so I would really suggest getting the correct sensor. The AliExpress sensors are VERY reasonable.

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Thanks for the assurance Marty!
I'll order one and report back after I install it and advance the timing to see if it will help with the pinging issue.

 

[1990TSIAWDTALON]

I have a real good feeling that the car will perform better after replacement. It is hard to get the correct tightness of that sensor, so just get it tight enough to not come loose and you definitely don't want it to wiggle.
I guess I am saying it should not be as tight as you can get it. I think the book calls for 15 ft/lbs or some low number like that.

 

[IvanovBG]

I have a real good feeling that the car will perform better after replacement. It is hard to get the correct tightness of that sensor, so just get it tight enough to not come loose and you definitely don't want it to wiggle.
I guess I am saying it should not be as tight as you can get it. I think the book calls for 15 ft/lbs or some low number like that.

Hi Marty, I've decided to give you an early update on this thread and share my progress.

I got my AliExpress knock sensor today, so I decided to go ahead and remove the old one and swap them out, but to my unpleasant surprise, the plug wasn't exactly the same and didn't fit. These are some comparison photos with the OEM one:

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Those two little plastic bits should be on the top part that connects to the manifold bracket, but instead they've put them on the bottom, and there's no way to connect the two plugs. I'll have to use a snap blade to cut off the extra plastic, and hopefully it will fit okay.

The old one has definitely seen better days, and it was a good idea to get it replaced. In general, the quality of the Chinese one seems decent, but you can really tell the difference in materials when you have them side by side. I really hope this new one will do the job.

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I'll try to put the new sensor in place by the end of this week and drive the car around to see if there's any noticable difference.

PS: The old knock sensor was REALLY on there tight and I nearly tore my hand off trying to get it loose. Even with some penetrating oil, it's hard to get a good enough grip on the wrench an pull hard enough. I removed the battery, EGR valve & starter in order to make room for a 24mm wrench, otherwise, it would have been impossible (I tried) to remove the sensor. For anyone attempting this, this old thread was very useful to me: https://www.dsmtuners.com/threads/d...knock-sensor-removal-and-installation.106675/

 

[IvanovBG]

Hi guys, today I tried to install the new sensor and unfortunately I have some bad news!

The fit and finish of this Chinese part just isn't there at all. When I tried to install it on the block, it just couldn't be done! I spent a good 15 minutes trying at different angles and positions, but you just can't get it to engage the block threads properly. There was a single bite point I could find, but it didn't start to spin and I was afraid to use too much force. There is no way I'm going to ruin my block to make it fit! The OEM one didn't have this issue when I tried to put it back in.

It's hard to tell from these photos I've taken, but you can see that the one on the right is a lot less precise and rough looking.
In person the OEM one is just so much more precisely machined.

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It doesn't end there! The black ground wire is less than 1cm long and it's barely even attached to the main wire. I tried to test fit it after shaving off some of the plastic from the plug that wasn't matching the OEM one, and just by doing that without any force, it broke off!

Here is a photo of that as well:

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Sorry, but I can't recommend that anyone tries this on their car. I can't imagine it will work well, even if someone manages to install it without tapping the threads.

From an older knock sensor discussion I saw that Jan from Poland tried a different one that's used in Mazda models: https://www.dsmtuners.com/threads/best-source-for-replacement-knock-sensor.525046/page-2#posts

There are multiple manufacturers that make the part with OEM number E1T50371, so I'm thinking of going the same route, as they are available locally.
This is what it looks like:

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[dwb]

Same thread pitch? You could try running a die over it. With the condition of the harness you'd have to repair that too. Maybe just snip the old plug leaving a pigtail, and wire it in place with the new sensor?

It gets harder and harder to keep these cars on the road and this is one reason why. I'm sure anywhere not in the US is nearly impossible, and I applaud you for doing just that.

 

[IvanovBG]

Same thread pitch? You could try running a die over it. With the condition of the harness you'd have to repair that too. Maybe just snip the old plug leaving a pigtail, and wire it in place with the new sensor?

It gets harder and harder to keep these cars on the road and this is one reason why. I'm sure anywhere not in the US is nearly impossible, and I applaud you for doing just that.

Thanks!

It's getting harder each year. When I got it, there were at least a lot of them being sold for parts and it was relatively easy to find something used in decent shape. Now, they very rarely come up and you have to pray that discontinued interior or exterior parts don't get damaged.

It doesn't help that aftermarket support is basically zero here. There are no specialized tuning shops for Japanese cars that I know of. People here are crazy for run down German diesel cars, which makes me mad. There are only a few mechanics for Japanese cars that people from the Bulgarian Mitsubishi forum seem to trust.

In regards to the knock sensor, I don't trust the Chinese one at all anymore. I'd rather get a E1T50371 and swap the plug. I'll probably order one soon.