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detonation pinging pinking at minimal load - not at high load

HONDALEO

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This one has me baffled.

Any suggestions welcome.

The car will start to pink on a slight incline, at 15% throttle, 1800 RPM, IAT 35°C for example.

I acn't be too sure about the ingition advance as I have no reliabale way to measure it.

This car is one of those with a 5 pin OBD connector so it's difficult to get it to communicate withany decent scan tool.

I did get it to connect to an Autel but the be honest the data logging feature doesn't have very good resolution so it's a bit difficult to post process the logged data.

I have:

fitted official NGK lambda sensor.
done a fuel pressure test. - perfect
did an injector balance test - all identical
ran a can of Moly injector cleaner through the system
checked the function of the air bypas system
done a bore scope cylinder inspection
fitted new plugs / leads just as routine service
fitted new exhaust
measured TPS voltages 0.4 -> 4.59 (I guess 0.4V is okay ? but my next task is to recalibrate this to begin at 0.5V)
checked MAP sensor voltage output with reference pressure - spot on
checked IAT termistor output with reference temperature - spot on
checked vacuum hoses for leaks with Mityvac - spot on
checked valve clearances
replaced knock sensor
measured crank position sensor out and tdc sensor output - look fine
taken a feed directly from the coil primary and logged it in my Picoscope, checking phase shift with respect to tdc sensor

I did wonder if the car has had its head skimmed before I bought it. (It has had this problem from day one about 8 years ago !!!)

However, I would guess giving it more gas would make the problem worse if it was a too high compression issue.

I've probably done a few more tests but can't remember right now.

I've used both standard and ultimate fuels but with no improvement.

I think it is worse on hotter days. (Somedays the IAT sensor is about 60°C !!!!)

I even replaced the IAt with a potentiometer so I can dial in any IAT I like, but I still can't dial out the pinking.

Likewise I created a resistor arrangemt to let me mimic the MAP sensor, so to fool the ECU to read any value I want.

All I have on my list left to try is to put a thermcouple into the plenum to measure the actual air temperatue independently.

Also to measure the compression ratio, but I think I am clutching at straws.

I even tried putting the cam beather pipe into a catch tank instead of back into the plenum.

I hope I have been an idiot and missed something really simple?

Any ideas ???

Here is another thread I found, but which didn't help me, as no conclusion was arrived at.

It could almost have been written by me, it is so similar.

https://www.ericthecarguy.com/kunena/8-Service-and-Repair-Questions-Answered-Here/47961-d16y7-pinging-under-load?start=20

Thanks

PS I should have said, the lambda voltage are fluctuating as normal, and the STFT is between fluctuating between about 0% and -7%

The LTFT is fixed at 0% and has never ever changed from 0% no matter what I do. Maybe it should be called a VERRRYLTFT :)
 

skhell

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I also have this problem. I have it for a couple of years, did almost everything you did, and got no success.

I have mine running on LPG, but this only happens when running on Petrol. Although LPG have a higher octane value, which helps with detonation/pinging, I suspect this can be related with the petrol feed system. One thing that occurred to me is that it could be related to the fuel pressure regulator. If the fuel pressure is too high I think it can make this happen. I never had the chance to test this or try another fuel pressure regulator.

Mine also has the 5 pin OBD connector. I have found the hondash (https://www.hondash.net/) which apparently work in our cars. I have never tried it, but have exchanged some emails with the guy and it really seems to work. The only problem is that you need to use their own application, but I guess that is ok.
 

HONDALEO

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Thanks. I tested my fuel regulator and it was spot on to the Honda spec at both vacuum levels. I do have the Hondash already, thanks to you I think. (I think it was you who recommended it to me). It's money well spent. It would be nice if it would allow the data to be exported but that isn't available yet, although you can save the info you need then recall it. I synchronised the clock of my Hondash android tablet, with my Picoscope laptop, to within a second, so between the two I can correlate some information. It's all a bit clumsy but better than nothing. I just find the spark advance and knock retard numbers a bit weird in the Hondash. I did contact the bloke who designed it and he said it was a bit confusing to him too.

I just have the throttle body almost removed. I have hit it quite a thump with aluminium drift, but it is pretty tight. Doesn't want to come off easily. Gonna have an early lunch and ponder it a while longer.
 

skhell

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Glad to know Hondash is working for you!
Didn't noticed you had already tested the fuel pressure. There is also the fuel pressure damper. Don't know if it has any influence and have no idea how to test it.

I see that you have used a bore scope to inspect the cylinders. Were you able to check if there is a significant amount of carbon deposits on the pistons? I have already done the same, but I couldn't get to a conclusion. The image quality was not good enough....

I have tested the cylinder compression, and they were all good. It was almost too good. All 4 cylinders presented compression values as if the engine was new. This could mean two things: 1) the engine is in really good condition; or 2) there are carbon deposits in the piston will increase the compression values.

If the problem is really carbon deposits, that would mean take of the engine head and give it a clean. Something that I will not do...

I bought BG44K (https://www.bgprod.com/catalog/gasoline-fuel-system/bg-44k-fuel-system-cleaner/) to clean the carbon, but I messed up when I was pouring the stuff into the petrol deposit and most of it went straight to the floor... Dind't tried it again, but I have read good things about it. Maybe worth a try if you can easily find it...
 

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SKHELL, you should try one of these ebay scopes if you have an old android phone or tablet available.

They're so cheap and the picture quality is pretty good.

I've used a Snap On borescope that a friend has and it is useless compared to this Chinese cheapo.

https://www.ebay.co.uk/itm/For-Android-Micro-USB-C-Endoscope-Borescope-Waterproof-Inspection-Camera-6-LED/292665058957?var=&hash=item442432668

Compression test is next on my list, but I don't expect it will help me. I'm just doing it to gather more info.

The carbon build up was negligible, although I did run a can of cleaner through my tank anyway.

I wonder is this a mapping issue, and no amount of changes elsewhere will ever cure the problem.


One point that might be relevant is that I once wanted to make up a break out cable to let me T into the O2 sensor wires.

I went to the breakers to get the plug from the wiring loom which connects to the O2 sensor.

While I was at breakers I just decided to buy the O2 sensor as well just to have as a reference.

I think I got it from a CR-V, but I didn't care as I was only interested in the connector and it was identical to mine.

However, I did try this old O2 sensor in the car, and it immediately performed like a racing car!!!

It was quite a surprise.

However, it was very short lived, and after just a few minutes running, the IML would come on and the car start to run erratically.

This does suggest that if the fuelling was different, the problem might go and stay away.

I did try tampering with the O2 output, using a voltage divider, but it seemed that once I tried to fool the ECU, it just changed the STFT to undo my changes.

I began to read up on bias voltages and got completed confused and ended up giving up on that test.
 

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So here's the latest.

I filed out the distributor which gave me the option to retard the timing by about 10°(crankshaft).

When I set the distributor to this new position (with the SCS shorted), I strobed the tiiming pulley and it showed to be firing about 2° BTDC.

I removed the SCS paperclip and took the car for a drive and it did feel better, and the pinking seemed less pronounced.

I couldn't remove any more material from the distributor slot so the next step was to find a way to give even more retard.

The easiest option I could think of was to make a new drive coupling, which connects the cam to the distributor.

I made the one shown below with the drive pin hole displaced by 7° (camshaft).

This would allow me to further retard the timing by another 14° (crankshaft) if needed.

I repeated the paper clip procedure, but I didn't apply full retard just yet. I went halfway.

The car drove much better, so I then introduced to total retard possible and it got better still.

Pinking now appears about 2500rpm, but only if I give her lots of throttle.

The engine is much more responsive, even in top gear at about 3000rpm.

I suppose now I really need to make another one of these drive couplings.

This seems a bit weird. It's almost like the engine, map is wrong.

In case somebody thinks what I thought, that could the timing pulley index marks be out sync with the piston position, the answer is no, they're not.

I put a TDC gauge into the sparkplug hole and checked.

TDC on the timing pulley is spot on with regards to the piston at TDC.

I am going to try to accurately record when the spark event occurs with respect to the camshaft sensor pulse, and maybe that way get an accurate idea of when the spark actually occurs with respect to TDC.

 

skhell

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Wow, that is a really nice hack :)
I have a cheap ebay bore scope but the quality is not that great. It already has a couple of years, maybe the new ones are better.

About your new findings, as you say, it really seems like it's a mapping problem. But that doesn't makes any sense, unless there is an issue on ECU...

When I tried to solve the problem, I tried to understand what controls the advance of the ignition and what sensors can influence the advance, but was unable to reach a conclusion. It seems that the ignition advance is not being correctly calculated.

There is a chip/module inside the distributor, but I am not sure if it related with ignition advance.

Also, when we put the clip in the SCS, it seems that whatever controls the ignition advance is ignored, which makes sense to understand if the base ignition advance is ok.

Considering the amount of sensors replaced and tested, could it be a bad ECU? I am not sure... That is a pain to test. I think it would have to be paired with the immobilizer...

Also, since I replaced my distributor a couple of years ago, that chip inside the distributor was also replaced, but the problem remained the same... I guess this would be another item to exclude.

I also tested the ignition advanced with the clip in the SCS and a strobe light and it was spot on.
 

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Unfortunately the better performance was short lived.

The car began to become very lumpy at idle, then went I went into the motor shop, when I came back out it didn't start immediately.

I had to crank it about 5 seconds which is completely not normal.

Regarding that module in the distributor, I already did a swap on that one too.

I think it is purely the igniter though, so all it does is control the dwell time and limits the current once the coil is charged.

In my case the igniter change made no difference at all.

I think I'm getting ready to give up.

I've ran out of ideas.

I wouldn't simply do an ECU swap.

It would be too much hassle and I don't have enough confidence to believe it would make a difference.

I did some tests where I logged the crank TDC sensor output, at the same time as the firing kV at the coil primary winding.

I paused the Picoscope when the pinking began, and the spark advance was 8° BTDC !!!!

This is very strange. I don't believe it.

I don't know what triggers the TDC sensor, but it is internal. I guess it is a machined notch in the crankshaft?

If it was actually a trigger bar / disc which bolts to the crankshaft internally, then my question is, could it come loose, and possibly be experiencing some angular displacement?

That's the only way I can explain that pinking occurs at 8° BTDC spark advance.

In other words, although I am recording that the spark kV takes place 8° BTDC, if the trigger bar / disc can float around, then dear knows where it is really firing with respect to true TDC

I would love to solve this before sending it to the crusher :)
 

skhell

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The crack position sensor and the top dead position sensor are located near the crankshaft.
I (myself) have replaced the timing belt twice, and I think the sensors are triggered by the pulleys.

Take a look at the following picture. You can see the sensor on the left which points to the smaller pulley, and the sensor on the right which points towards the back of the other pulley.
I don't believe that what triggers the sensor can suffer any displacement.

BTW: it's time for me to fix that oil leak :)


 

skhell

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After a closer look on the image, I think the left sensor is triggered by that metal plate behind that pulley that have a notch. I think that plate is attached to pulley.
 

HONDALEO

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Thanks for the photo. It makes a bit more sense now. But does that imply that the sensor on the left actually detects the pulley right through the rubber belt? I am going to have to connect my scope again to help clarify this. From what I remember there were 12 crank sensor pulses for 2 TDC pulses, however the pulley in your photo has 20 teeth, so now I'm guessing I must have counted something incorrectly. I will upload a few photos once I capture them.

P.S. on your image in the previous post, the sensor to the left seems very far away from the pulley teeth. These type sensor normally have a gap of 1mm or less. I find it hard to understand how it could work so far from the teeth.

P.P.S

I just came across this civic photo below, so now it makes sense again if the Accord is the same. The plate on top of the pulley has 12 lobes and is close to the sensor.

 

skhell

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That steel plate with the two "ears", one in front of the left sensor and the other hidden under the right sensor makes part of that pulley. I suspect those "ears" are what triggers that sensor. If you look closer, those "ears" seem to be right in front of the sensor. Something like hits:



 

skhell

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According to the repair manual, the left (front) sensor is the TDC sensor, the right one is the crank shaft position sensor:

 

skhell

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The other pulley, which i guess is what triggrers the CKP sensor, has 12 notches. That makes the 12 CKP pulses for 2 TDC pulses. You can see it mounted in the engine and in the ground where you can see the rear side:



 

HONDALEO

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Excellent. It's all clear now. When I observed the TDC pulse on the scope I noticed the sinewave shape was non symmetrical, and had a slight blip at the start of it. I can now see why. The two lobes on the pulley have a slight ramp before their peak, so that correlates exactly with my scope trace. I should get some time tomorrow to capture some traces. I have a funny feeling mine are out of sync somehow. Did you notice in the manual that it says if you remove the distributor you must attach it when cylinder 1 is at TDC ? That part has me mystified, since it is impossible to fit it any way other than the one way. I cna't see how you can put it on wrong?
 

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Here are the four images I captured.
Hopefully they're self explanatory.
I just have to try to capture these details when the trouble starts and see if I can make any sense of it.
These were capture while stationary.
The car won't even idle now. I possibly incinerated my O2 sensor with that overly late timing. The car hasn't run properly since.
I've even put everything totally back to normal, although I can't undo adding the fuel injector cleaning additive.


(The first image is just pointing out the asymmetrical pulse I mention previously - you can see the pulse begins to appear round about the red arrow)











 

skhell

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HONDALEO said:
Excellent. It's all clear now. When I observed the TDC pulse on the scope I noticed the sinewave shape was non symmetrical, and had a slight blip at the start of it. I can now see why. The two lobes on the pulley have a slight ramp before their peak, so that correlates exactly with my scope trace. I should get some time tomorrow to capture some traces. I have a funny feeling mine are out of sync somehow. Did you notice in the manual that it says if you remove the distributor you must attach it when cylinder 1 is at TDC ? That part has me mystified, since it is impossible to fit it any way other than the one way. I cna't see how you can put it on wrong?
I think that you can't install the distributor in other way. They do say to put the engine at TDC in cylinder 1, but they also say the lobe is offset to prevent mounting the distributor 180º out of time...
 

skhell

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Those readings are awesome? Try do get them when the pinking is happening to see if we can reach to a conclusion.
BTW, what did you used to get those readings? And where did you got the signals? Straight from the ECU wires?
 

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I got 3 signals at the ECU beside the passengers feet, but you need a rubber neck to get in at them.

GREEN TRACE = PIN 20 (green wire TDC sensor) 31 pin connector
BLUE TRACE = PIN 11 (brown wire INJ 1 pulse) 25 pin connector
BROWN TRACE = PIN 29 (yellow wire CAM sensor in distributor) 31 pin connector

The red trace is directly from an inductive pickup on the spark plug wire at cylinder 1.
The ECU does NOT send out a dedicated pulse to each cylinder.
It just sends a pulse to the distributor and the distributor sends it to the relevant cylinder.
 

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So, it is finally fixed :))))

I will explain the fix for the detonation, but I will first explain how I stumbled upon the fix.
I actually found the detonation fix, as a result of trying to get the car to even idle again, after messing it all up a few days ago

Since a few days ago after seriously retarding the timing, the car hasn't ran properly.
Like I said I put everything back to standard and it was still a dog.
I had to drive with my heel on the throttle and my toe on the brake to keep it running.

I searched around to see if had forgotten to connect some hose or something but couldn't find anything.
I then remember testing that my EGR passages were clear a few weeks ago by simply energising the EGR solenoid with two jumper wires a few weeks ago, with the engine on idle.
As expected the engine stuttered and stalled, proving my passages were clear.

I then realised that the car was now acting a bit in a similar way so I removed the EGR valve and there were some carbon boulders stuck in the valve keeping it open.

These particles have probably become dislodged as a result of the fuel additive I recently added in case there were some hot spots of carbon in the combustion chamber.

When I was cleaning these carbon lumps out, I detected that the EGR return spring wasn't really very powerful, and in fact if I pulled the poppet valve out, then released it slowly, I could release it and it would just sit about 0.5mm off the poppet being seated. If I released it suddenly it would spring back home and whack against the seat okay, but doing the slow release test proved my point, i.e. that maybe this valve was not sitting properly on its seat, at the times when the detonation was happening.

I then tried to disassemble the EGR valve from the solenoid but couldn't see how it could be done.
I had intended to try to make the poppet spring do a better job at keeping the valve hard on its seat.
The next best option I could think of was to add an extra gasket at the split plane where the actuator meets the valve.
I then thought this would be too awkward to make and install so I thought about just adding a few copper washers instead.

I did this and immediately both issues where solved.
The car was idling perfectly and the detonation was gone !!!!

There was a slight glitch in that the car stalled again, and I immediately knew I had a few more boulders stuck in my valve.
I took it off again and true enough there they were.
I bought a tin of throttle body cleaner and gave it the best going over that I could, and so far so good.
I think I have got it sorted.
I know now that if it does misbehave again that it is an easy fix, and I am sure it won't be very long until the carbon deposits just begin to stick again, since the additive has just about finished going through my system.

Here are a few photos.
The copper washers are 0.9mm thick.








 

skhell

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Wow, great finding!
I did checked and cleaned my EGR a couple of years ago, but never looked in the detail to see if it closes completely. I also didn't check if the spring was working properly.
When I have the time, I will take it apart and give it a look.
 

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So, just to close this off, here is the valuable lesson that I learned with this.

This was a classic case of the OBD data showing the opposite of what was actually true, in a way.

When I started the car with these lumps of carbon stuck in the EGR valve seat, my Hondash app showed the STFT taking a big nose dive, from 0 down to -25

This was leading me to believe the car was receiving too much fuel from the injectors, i.e. it was correcting for an over rich mixture.

When the actual truth was that the engine needed more oxygen, NOT less fuel.

That's when I then realised that this situation could be the cause of the detonation, i.e. a lean mixture yet the STFT showed no problem, since the revs were much higher than at idle, and the valve was just slightly open by about 0.25mm due to low spring pre-load.

It definitely was a teaser and I did learn quite a lot from it. Before I tackled this I had no idea what the multitude of vacuum hoses etc were all for, but now I know every single one of them!
 

skhell

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I definitely have to buy the Hondash to properly diagnose my Accord!
 
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