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/

 

[1990TSIAWDTALON]

Here is what I did with the Chino Store knock sensors. It took 2 or 3 minutes...other than the plug itself, the component looks like a good replacement. This mod keeps the plug and polarity correct for those that are unsure and have the same sensor.
If I weren't filming with the phone between my legs and working with both hands, it takes about 10 seconds.
Marty

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[1990TSIAWDTALON]

And a follow up to make sure it really plugs in and is polarity correct.
Maybe I should make a post just about this sensor, IDK.
AFTER THIS, I also tested all 3 of my sensors in 1 of my own blocks, and they thread in just fine, so that isn't a concern about them having bad threads, they go all the way in. Also, what we refer to as the ground is only a shield wire, like ham radio antenna line, it's there to keep out stray interference.
Thanks for watching anyway!
Marty

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[IvanovBG]

And a follow up to make sure it really plugs in and is polarity correct.
Maybe I should make a post just about this sensor, IDK.
AFTER THIS, I also tested all 3 of my sensors in 1 of my own blocks, and they thread in just fine, so that isn't a concern about them having bad threads, they go all the way in. Also, what we refer to as the ground is only a shield wire, like ham radio antenna line, it's there to keep out stray interference.
Thanks for watching anyway!
Marty

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Hi Marty, thanks for the update!

Maybe I just had to use a bit more force to install mine on the block, but it really felt like I'm going to ruin the threads, so I'm not willing to try it again.

Modifying the plug is easy, but the build quality isn't there in my opinion. You shouldn't need to shave the plug, secure the black wire so it doesn't come off and potentially use a thread die. I'll keep it as a backup, but have decided to use the Mazda sensor instead.

I went ahead and got a bit more expensive one from an Italian distributor called ERA for like $28, which isn't bad at all. The build quality and machine work is so much better than the Chenho sensor.

Here are some photos:

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The opening on the sensor is also smaller, like on the OEM one. I don't know what they used for the black part on the Chenho sensor, but it feels like a very hard ceramic and doesn't have any give. This isn't right, is it? The ERA feels like it's actually some kind of silicone, like the original.

Manufacturer number: ERA 550340A
OEM number is E1T50371 and it seems like it was made by Mitsubishi originally, so I doubt it isn't going to work. Soon I'll have the plug swapped and install it, then update you with the results.

 

[1990TSIAWDTALON]

The original black goo actually contains some metal (mercury, silver?), I can't remember, but a local company that used to manufacture thems' Engineer (Standard Motors) told me about it. He was in the department that made those before they ceased production. Although the plugs on mine needed trimmed, my shield wire was fine on mine.
I am glad you have a part you trust now. I was only doing it as instructional information for the "masses".
Marty

 

[IvanovBG]

The original black goo actually contains some metal (mercury, silver?), I can't remember, but a local company that used to manufacture thems' Engineer (Standard Motors) told me about it. He was in the department that made those before they ceased production. Although the plugs on mine needed trimmed, my shield wire was fine on mine.
I am glad you have a part you trust now. I was only doing it as instructional information for the "masses".
Marty

Hi Marty,

Today is finally got around to installing the new Mazda knock sensor with the swapped plug. It threaded in very easily, so for sure something wasn't right with the threads on my Chinese sensor. Anyway, I made sure to tighten the sensor just enough so it doesn't move, and it's position ended up being the same as the old one before I removed it. I made sure to compare the photos I took. It needed to be finger tight an then around 1/4 of a turn with the wrench.

After putting everything back together, I used my timing light to set the timing to 5° BTDC as per this VFAQ article:

Base Timing Adjustment

Sadly, the pinging issue wasn't resolved! The car performed exactly the same as before, there was no perceivable difference to when it had the OEM sensor.
I ended up retarding the timing quite a lot again, until it stopped pinging, in order to prevent potential damage. It seems like my issue isn't caused by a bad knock sensor, but something else, which is really disheartening.

I would still like to do a rebuild in the near future, but I'm worried that it might not help either at this point.

 

[dwb]

Is it possible your harmonic balancer (crank pulley) separated or has an incorrectly located timing mark? That can cause your readings for BTDC to be off and may explain why you have to retard the timing.

 

[IvanovBG]

Is it possible your harmonic balancer (crank pulley) separated or has an incorrectly located timing mark? That can cause your readings for BTDC to be off and may explain why you have to retard the timing.

Around a year back I did a timing job with my cousin and I remember that we had a good look at the pulley after cleaning it. We came to the conclusion that it looked very good and didn't have signs of going bad, there were no cracks or tears.

This is the position the CAS needs to be in, in order to stop the pinging:

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It's past the marks on the timing cover, but it's retarded by at least 10-15°, isn't it?. I don't really know how much you can retard it this way, but it's almost as far as the CAS will go counterclockwise. The car is drivable this way, but more sluggish than I would like. I also don't feel the best driving it, knowing that there's an underlying issue.

 

[dwb]

A way to check your harmonic balancer - if you set #1 cylinder to TDC, the timing mark on the balancer should align with TDC on the cover.

Also it just occurred to me that maybe you have the CAS 180 degrees off. Timing would still be fine, but injectors don't fire at the correct time.

 

[IvanovBG]

Also it just occurred to me that maybe you have the CAS 180 degrees off. Timing would still be fine, but injectors don't fire at the correct time.

I haven't removed the CAS on my end, so I can't say for sure how it's installed. However, I remember that before the pinging started, it was in an advanced position, similar to where it is visually at around 5° BTDC. There was no pinging for many years with it being installed like that, so I doubt it's not properly mounted.

There was a period of time where I didn't really mess with anything on the car, the pinging started out of nowhere. I don't really like listening to loud music while driving, so I notice weird noises almost right away. When the noise caught my attention, I couldn't get it out of my head until I found out what it was.

I'm not excluding that it might be an overheating issue, because it does start to ping only when the engine reaches operating temps. But the radiator & water pump, thermostat (82°) are all new. Before removing the old radiator, I also did multiple flushes until the water was clear, to make sure the system is clean. The teamp gauge on the dash also doesn't move from where it should normally be. Dealing with this issue has been really frustrating.

 

[danl]

Just to be clear, this issue started nearly instantly? Not over the course of days or months?

 

[IvanovBG]

Just to be clear, this issue started nearly instantly? Not over the course of days or months?

It could have been a few days before I heard it, but not months for sure. I noticed it one night while driving. At first I thought something could be loose as it sounded like a rattle and I didn't know what pinging sounded like.

After reading some threads on this forum, I took it on a steep hill and that's when it became very clear that something isn't right with the engine.
Anything that I tried to remedy this, has made absolutely no difference.
- Multiple fuel system cleaners
- Higher octane fuel
- Coils
- NGK spark plugs & wires
- Different MAF sensor

The recent knock sensor change, also didn't do anything.

 

[IvanovBG]

I'll actually give you a list of things that I've changed in the last 2-3 years, that I can remember.
This will be before & after I noticed the pinging.

Before:
- Radiator (NISSENS 62865), because the upper neck for the hose cracked really badly. This brand is what I could find locally and it seems to be of good quality, it wasn't cheap either. I used green coolant for it.
- Thermostat, this one was 88° because I didn't know the OEM was 82°. Reason for the change was that the old one was bad and the engine wasn't getting up to operating temps.

The radiator was changed in August 2022, thermostat was changed in January 2023.
I can't remember when the pinging started exactly, but it was in late 2023 from what I can recall. I've rarely driven it since then, and it's with the retarded timing, because I'm scared of causing damage. Shortly after it started, I did a timing job with my cousin.

After:
All of these were changed around the same time, shortly after I noticed the pinging.
- Thermostat, this time an 82° one, as I was worried the 88° could be causing overheating issues.
- Timing job, which includes all the belts and timing belt pulleys. The harmonic balancer looked fine, so we didn't change it.
- Water pump, this one was made by AISIN, so it's of good quality.
- The gasket on the oil filter housing was changed, as it was leaking oil.
- Coils, spark plugs & wires, as mentioned previously.
- MAF sensor was changed with a different OEM one.

Of course, the engine oil, fuel, air & oil filters have all been changed as well.

Around 8 years ago, my dad rebuilt the engine and he for sure changed all the bearings and piston rings, but he didn't change the hydraulic lifters of the new head. I suspect he might not have changed the valve stem seals as well, and that's why it probably burns oil, but I can't say for sure. I can't ask him because we're not on speaking terms currently.

 

[danl]

So you increased the fuel octane and that didn't help? However decreasing timing does? Can you explain more about how you increased fuel octane? Do you have access to 100+ octane fuel? Can you pull all the plugs and take good pictures of them?

 

[IvanovBG]

Yes, the only thing that stops it is retarding the timing a lot, as shown on the picture I posted. From that point, if you start turning the CAS clockwise to advance it even a little, it will start to ping, the more you advance it, the worse it gets.

Regarding the fuel, the highest you can get here is E10 98-100 octane. We use the RON figure, so the AKI figure in the US should be around 93 octane. I haven''t used any octane booster additives, only Liqui Moly valve clean & injection cleaner, which don't mention anything about raising the octane.

I won't be able to take off the spark plugs today, but when I removed the old ones, they all seemed fine to me. There wasn't any abnormal fouling or damage to them.

 

[RamenPride]

I honestly wouldn't worry too much about knock under 2000rpms on an NA. The ECU isn't going to instantaneously retard ignition timing enough to completely eliminate knock at the first sign of it which could be why it goes away once you get over 2000rpm. Could be a fuel issue, like clogged/dirty injectors causing it to run lean at lower rpm's. Might want to try getting them cleaned (like off the car, not a bottle you pour into the tank). Fuel pressure regulator might be worn as well, causing a lean condition due to low fuel pressure. Fuel filter could be clogged.

 

[1990TSIAWDTALON]

When you checked timing, did you ground the tining tab and set it at 5*.

 

[IvanovBG]

I honestly wouldn't worry too much about knock under 2000rpms on an NA. The ECU isn't going to instantaneously retard ignition timing enough to completely eliminate knock at the first sign of it which could be why it goes away once you get over 2000rpm. Could be a fuel issue, like clogged/dirty injectors causing it to run lean at lower rpm's. Might want to try getting them cleaned (like off the car, not a bottle you pour into the tank). Fuel pressure regulator might be worn as well, causing a lean condition due to low fuel pressure. Fuel filter could be clogged.

Driving it on steeper roads with advanced timing at low RPM, actually sounds pretty scary, like the engine is going to granade itself any second.

I'll make sure to check if the injectors are clogged. I did have a look at them when changing the coils, and their rubber o-rings need to be changed. I actually have a set of OEM rubber o-rings and lower insulators, but haven't gotten around to changing them yet. Maybe the bad o-rings could be causing loss of pressure? There aren't any fuel leaks though.
Fuel economy is normal, at least from what I've read. It's around 9.5-10L/100km combined and 11-14L/100km city driving, depending on the driving style. MPG equivalents should be something like 24-25MPG combined and 17-21MPG city.

The O2 sensor was changed maybe 4-5 years ago, I can't remember exactly, but it's a DENSO sensor.

When you checked timing, did you ground the tining tab and set it at 5*.

Yes, I do it exactly the way it's stated in the VFAQ article.
When the terminal for ignition timing is grounded, I set it to 5° BTDC. If the terminal isn't grounded, the timing is around 8° BTDC, like mentioned in the article.

 

[IvanovBG]

Hi guys, I have some good news and wanted to update the thread!

I focused on RamenPride's comment on the possible clogged fuel injectors, and decided to clean basically the entire air intake system.

The following things have been done:
- The fuel injectors were removed and sent to a shop for ultrasonic cleaning. They also installed new filters for them.
- New o-rings & insulators for the injectors.
- The intake manifold was removed and wet blasted.
- The throttle body was also wet blasted, but wasn’t taken apart for a rebuild, only the BISS screw has a new o-ring.
- I have one of those black OEM ISC motors, so I’ve changed the internal orange silicone o-ring, as well as the black one that goes on the FIAV.
- The PCV valve was cleaned.
- The throttle cable & idle switch have been adjusted properly.
- After everything was installed, I followed the VFAQ articles for adjusting the timing & idle speed.

In the end, at the factory 5° BTDC, it still had some pinging, which is a bummer. However, without the jumper wire connected to the terminal, I adjusted the timing to where it jumps around 1-3° BTDC, then went for a test drive and couldn’t hear any pinging! Even when lugging the engine on a very steep hill, I didn’t hear anything. It seems like all of this cleaning has had a positive effect, as before I couldn’t even see the pulley timing mark anywhere near the marks on the cover, as the timing had to be very retarded.

Currently, the car feels a lot more eager to accelerate and I'm quite pleased with the way it performs.

I've included some pics of the results below.

Injector tests:

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Throttle body & intake manifold:

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[IvanovBG]

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

I use MOTUL 6100 SYNERGIE+ 10W40. The car burns around 1 litre per 1500km. I can't be very exact, because I don't let it drop much below the middle between the minimum & max marks on the dipstick.

Today I asked a friend to lend me his borescope and had a look at the pistons. Unfortunately, it doesn't have a feature where I could connect it to my phone, so I couldn't take pictures, but I can give you an idea of how they looked.

I'm not an expert in this, but to me it didn't seem like they had a thick layer or carbon buildup at all, more like a thin layer of oil. These black portions were mainly on the outer parts of the crown, where it has those valve reliefs. The center portion of the piston looked very clean, and I could clearly see the casting numbers (63DMK). When the intake manifold was removed, I had a look at the valves, and they also didn't have any thick clumps of carbon buildup, but rather a very thin, even black layer.

These are some pictures of the spark plugs, which have around 5000km on them, or 3100 miles:

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The threads look a bit oily, but the electrodes look normal to me. Again, I'm not a mechanic and haven't changed a ton of spark plugs. The injector cleaning did help a lot with allowing me to advance the timing to around 1-3° BTDC without the connector being grounded. Maybe irregular combustion due to oil burning is causing the pinging after that point?

 

[dwb]

You're burning oil. Since some of those plugs look more oily than others, I'd venture to guess you have an issue with valve stem seals or rings. Have you performed a compression test recently?

 

[IvanovBG]

You're burning oil. Since some of those plugs look more oily than others, I'd venture to guess you have an issue with valve stem seals or rings. Have you performed a compression test recently?

I performed a compression test earlier today, here are the results:

Cylinder 1: 13.8 bar / 200 psi
Cylinder 2: 13.5 bar / 195 psi
Cylinder 3: 13.5 bar / 195 psi
Cylinder 4: 13.5 bar / 195 psi

I read that the non turbo engine should be around 192 psi stock, so it seems like the compression is right where it should be.

 

[danl]

The deposits on some of those plugs could be caused by burning oil. If you want to get rid of the pinging, just run a high octane oil.

 

[FIBA M - EC17PSE]

1-4 look worse off, 3 looks bad also.

you got some other issues going on here. you will need to dig deeper. Are you burning any oil and have you checked your exhaust to see if its wet in the manifold ports. your spark plugs being coated in oil is the misfire no doubt. now to find out where its coming from,

 

[IvanovBG]

1-4 look worse off, 3 looks bad also.

you got some other issues going on here. you will need to dig deeper. Are you burning any oil and have you checked your exhaust to see if its wet in the manifold ports. your spark plugs being coated in oil is the misfire no doubt. now to find out where its coming from,

Yes, the exhaust manifold is wet. The leak looks to be from the cylinder 1 port, and it goes all the way down to the oil pan. It has left a few very small oil spots on the ground, where I park for longer periods of time.

The next thing I plan on doing is changing the valve stem seals, as they haven't been changed since I've owned the car, so who knows how old they are. Hopefully that will reduce the oil burning and pinging.

 

[FIBA M - EC17PSE]

Yes, the exhaust manifold is wet. The leak looks to be from the cylinder 1 port, and it goes all the way down to the oil pan. It has left a few very small oil spots on the ground, where I park for longer periods of time.

The next thing I plan on doing is changing the valve stem seals, as they haven't been changed since I've owned the car, so who knows how old they are. Hopefully that will reduce the oil burning and pinging.

If your not getting smoke from the exhaust its not likely they are the issue. Generally speaking once they go you will get puffs of smoke as this is exactly what happened to me and was not fun .

But i guess its not harmful to do it as maintenance anyway and use the viton ones as they better and will last longer. Thats one thing off the check list at least