Please help diagnose pinging/detonation
 

Hello all,

I've mentioned my issue in a few threads in the past, but I hope you will forgive me for starting a separate thread to deal with this issue specifically.

Basic info:
111k miles
Re-man engine installed just before 100k (compression below spec on 1 rotor)
11k miles on coils and wires
1.5k miles on spark plugs

Problem Description:
Has been pinging ever since the reman went in, but never having experienced that before, didn't recognize it for several thousand miles :pat: Has all classic symptoms of pinging - happens on acceleration between 3k - 7k rpm, more severe on hot/heat-soaked engine, most of the time sounds like lightly shaking a jar full of screws. Happens in 2-6th gears, but most blatant case is climbing hill in 5th or 6th gear at highway speed. Here's a video I took - hard to discern but you can hear it at 00:09 if you listen carefully.


Other symptoms:
The idle is a little funny. With no load it is almost normal, but sometimes fluctuates +/-50 rpm. Tends to idle a little lean, with a bit lambda around 1.02-1.05. With the AC on, it fluctuates up to 1000 rpm, with ECU periodically giving it a little throttle when it starts getting rough. Normally idle LTFT is +8.5 to +10%, and cruise LTFT is about the same. STFTs are near zero. However, when engine bay is heat soaked idle LTFT can climb to +15% in short order. Eventually it returns to "normal" after driving at night.

Idle MAF reading is only about 3.3 g/s. All the above led me to believe I had a vacuum leak but a recent smoke test did not turn up anything. For the smoke test, they disconnected the accordion tube at the throttle body. Now I'm thinking maybe my MAF is bad?

Vacuum at idle is in the 16-18 in Hg range at 2,500 ft ASL.

What has been done to try and fix this:
Cleaned MAF
Cleaned ESS and reset profile
Cleaned fuel injectors (1 was found dripping, another had crappy spray pattern)
Replaced fuel filter (was pretty nasty)
A couple of tanks of 100 octane gas (did not hear pinging while running 100 octane, but it came back after filling with 91 again)
De-carb

Kind of running out of ideas here. I'm want to try and see if replacing the MAF will help, and put some Gumout in the tank as a hail mary. I wanted to eliminate any causes external to the engine core before I take it back to the dealer, because they are going to try and charge me an arm and a leg.

1. Any ideas on what might be causing my issues?
2. The Mazda MAF P/N L321-13-215 seems to be a Denso unit, which also has Denso P/N 197400-2010 (on Mazmart) or 197400-2160 (on Amazon). However on Denso website it only lists P/N 197-6020. I would buy 197-6020 because it is cheaper but because it is less than half the cost I am suspicious. Anyone know if it is an identical unit?

Should be unrelated, but maybe worth mentioning:
Before giving the car back, dealer reported that it threw a code for stuck open SSV. This is when they tried to sell me an intake manifold for $3k. The SSV actuator moves smoothly and freely, and I have not seen any codes or evidence of SSV problems. Which is why I am reluctant to go back to them, but at this point may have little choice.

Thanks for your help!

Please help diagnose pinging/detonation
 

So you added 100 octane, and that stopped the pinging?
Have you had your ecu tuned at all?

EDIT: Car is completely stock with stock tune. Putting in 10.5 gallons of 100 octane stopped the pinging. If only 1/3 of the tank is 100 octane, I think it helps, but it still does it. Needless to say, 100 octane is an expensive solution, and I do not wish to keep using it.

Unplug the MAF and see if it still happens? With it unpluged it goes into open loop and it won't idle for shit, but it should drive ok. What is your fuel trims? There are 2 size denso MAF sensors. one has a larger hole and it depends on the year of your car wich one you need. I think they went to a smaller one in 2006. Don't quote me on that.

As RX8soldier asked have you had it tuned at all. It could be wrong. But the MAF definately sounds like a porblem.

From the last driving cycle:
Cruise LTFT: +9.4%
Idle LTFT: +8.6%

STFTs tend to be around 0. The weird thing is I am pretty sure I've heard the detonation even when in open loop acceleration, where the lambda was < 0.9 per the WB O2 sensor. I will try to post up some cruise and idle logs as soon as I get a chance to pull them off my phone.

Ordered a MAF from Mazmart to be on the safe side. P/N matches dealer part, and what is on my car now.

Those are kind of far off, but if STFT is 0 they aren't that bad. if Lambda's

I can't hear anything in the video. When you say your STFT are at 0, is that at idle with the engine warm?

Compression test. Here's why...

This is all to familiar to what i was experiencing recently - low maf reading even after cleaning the maf and cleaning and resetting the Ess profile (mine was 4.5 - 4.8 grams/sec ), elevated long term fuel trims (+10%) that got higher when heat soaked (+12%), no vacuum leaks found during multiple smoke tests, and occasional idle speed fluctuations (750-850 rpms ) when I was brave enough to take the car out of the garage. However, in contrast to your report, at idle my lambda was at 1.0 and I never experienced pings (For what it's worth I used 93 octane rather than 91, and the report from the dealer indicated that the ecu detected only 1 misfire in the last 10 drive cycles, well below what is required to trigger a flashing cel (or at least that's what they told me). After running down everything I could think of I was about to buy a new maf but decided to get a compression test first, at the very least it would put my mind to rest. Rather Unsurprisingly, the compression test showed that all 3 faces of both the front and rear rotors were below spec (and with a starter speed of 310 rpms it's no surprise that starting a hot engine never showed any indications of a compression problem).

Wish you all the best on getting this resolved and I hope I'm wrong and that it isn't a compression issue.


P.s. I apologize if This post is hard to read, this autocorrect thing thinks it's smarter than me and changes what I typed.

Idle log
 

Guys here's an idle log. Fully warmed up after a long drive. Note that idle oscillates about 100 rpm and AFR is a little bit lean. My new MAF should have arrived today, so I'll see if it improves things.

https://cimg8.ibsrv.net/gimg/www.rx8...a2ee3a2381.jpg

Poacher, sorry to hear about your engine. I agree mine is displaying a lot of the same symptoms, but it has been doing it from 1st day since the reman was put in. Will be taking it for a compression test soon.

Just took a video where it is very obvious. Uphill climb at highway speed, 5th gear. Felt like a terrible person afterwards... Normally, I try to avoid this.

Hard to tell the colors on my tablet but are your LTFT at idle almost at +9%? If that top purple line is LTFT then you have an issue as STFT and LTFT should be within 3% from zero at idle.

I'm guessing it is very lean under WOT which has been cased by something screwy happening with the install of your intake . The ECU is trying to correct but can't correct well enough to stop it leaning out .

Acceleration Log
 

I agree that the idle data seems to indicate a vacuum leak that might cause lean operation at WOT, but none was found during a smoke test, and moreover, O2 sensor data does not support this. (See below)

Today I swapped in a brand new MAF sensor. I noticed the O-ring on the old one was pinched, however, I don't think this was the cause. The new sensor didn't help a whole lot. Idle smoothed out a little bit, but idle AFR is still in the 15.0-15.4 range, and idle mass flow is around 3.3 g/s now. Idle LTFT shot up to +15%, not sure why. Seems to happen on hot days like today though, even with the old MAF. (I did check the screws were tight). Took her out for a spin. The detonation problem is still as bad as ever, if anything seemed slightly worse.

Captured a log of the detonation while accelerating. Started in 6th gear, then downshifted to 5th and then 4th. Detonation audible throughout, however the O2 sensor does not show it running lean. At about the 17 seconds it switches to open loop and the AFR drops to about 11.3, and still it was detonating. It would be interesting to check the logged ignition advance against the stock tune, to see if it's retarding timing (do the knock sensors even do anything??) EDIT: Looked at what I assume is the stock timing map here: https://www.rx8club.com/series-ii-en...188268/page40/
It appears my ECU is somehow a few degrees more aggressive around 5000 rpm...:Wconfused

STFT was all over the place. Not sure what's up with that. Maybe I should have re-set the trims....

https://cimg4.ibsrv.net/gimg/www.rx8...079152682f.jpg

Here's a link to the raw data (google docs) for anyone who's interested.
https://docs.google.com/spreadsheets...26&single=true

Not sure which tree to bark up at this point. This is definitely temperature related, because driving at night (ECT @ 180 F) there's no detonation or it is barely audible. Much worse on a warm day with ECT > 200 F. But then, of course, detonation is a temperature dependent phenomenon... Could this be down to carbon buildup and the low air flow at idle be unrelated? Also noticed that STFT drops 5-6% when the EVAP purge duty cycle goes to 0. Is that normal?

Will take it to the dealer Saturday, unless anyone has any other ideas.

it shouldn't detonate at those afrs/loads .

Can only think ...............

Spark plugs fouled or combustion chambers full of carbon ,

2,000 miles on the spark plugs currently, they were replaced along with a de-carb, which didn't solve the problem. What it did do is seemingly move the onset of detonation to higher load levels, but when it does start it is more sudden/severe.

On the carbon side, when I got my injectors cleaned, two were found to have crappy spray patterns. Reports are below. The engine had 5,000 miles on it at the time.


https://cimg4.ibsrv.net/gimg/www.rx8...77e9c40416.jpg


https://cimg5.ibsrv.net/gimg/www.rx8...d1c31fc355.jpg

Could this have caused enough carbon buildup to give me the current detonation issues? Although this engine had a detonation problem from the first day... :scratchhe
If it is due to carbon, is there anything that can really be done about it short of a re-build? I have tried de-carb, running 100 octane and a PEA fuel additive already. According to some members here, all those are useless :tear:

I wonder if it's a vacuum leak/install error on the lim that allows one rotor to run lean ......

Have you pulled the plugs to see how the colouration compares ?

I can't imagine a vac leak causing that. Not in my head at least, but that made me think maybe injector wiring on p2 or secondary. If 2 injectors are on the same rotor. Maybe?

idle maf is very low, ltft is high , afrs at wot don't look too bad (although higher than I would like to see when in CL), yet it detonates ..... Seems like a high probability one rotor is not the same as the other.

Please help diagnose pinging/detonation
 

I agree it makes sense one rotor is having a prob. And it all looks like a vac leak across the board, i was just saying I didn't see exactly how a vac leak in the lim would affect things.

To also note on a all stock tune at wot the wideband should be on its lower limit


Ahh I just reread what I wrote. Sorry, I don't word things well, and writing on my phone doesn't help.

I think I can rule out wrong injector wiring or switched injectors, because the local rotary shop took them out and re-installed them for cleaning and specifically mentioned that the wiring was not switched. And the detonation problem was there before & after, albeit diminished in severity after injector cleaning.

I have not pulled the plugs that were installed after de-carb. I'll do that next time I'm under the car. I agree that the theory of vacuum leak to 1 rotor seems to fit my symptoms. Maybe a messed up LIM gasket? So one rotor would be running lean, the ECU is throwing in fuel trim because of the vacuum leak, causing the other rotor to run rich. I guess it may even be detonating on both rotors, one because of lean mixture, the other because of carbon... :Freak_ani I have noticed that my exhaust tips have gotten more sooty lately.

Brettus' theory also fits with my dealership conspiracy theory that goes something like this:
1. Dealership messes up engine install, realizes they have a problem.
2. Tells me a tall tale about a stuck SSV, caused by carbon buildup in the intake manifold. BTW..I have not had a single CEL since getting the car back, and SSV actuator moves freely within specified vacuum.
3. Try to convince me to replace the intake manifold, so that they could charge me $$$$ while fixing their mistake. Naturally I refused.

Then again, it could have been a fluke CEL, and just a hopeful upsell pitch on their part.

Guys, thank you for your input. Next trip for the car is to the dealer next week to stay within warranted mileage. I foresee an unpleasant process.

Sorry for late response, Agree with virtually everything Brett and 9K says.

I had a quick read (sorry if I missed details) but after 100K, what is the condition of your IGNITION, like Spark Plugs and more importantly Ignition Coils and the HT Leads, also the condition and age of your cars Battery and Alternator?
Have you had a Battery, Alt and Starter conductance test, one of the simple and low cost tests to determine the 'juice' condition of the critical items which store, generate, and use your 12volts which is so commonly overlooked by owners.
ANY Ignition system (coils) including BHR's set up does and can wear out or perform below acceptable guide lines.

When you experience this so called 'detonation' or similar breakdown in more cases than not it is IGNITION SYSTEM condition, usually in a poor one.

A bit like a good home sound system, ALWAYS start and improve your equipment at the source or start of it's journey...
In a Car it is..
1. 12V Battery.
2. Alternator.
3. Starter.
4. Coils and Leads.
5. Spark Plugs.
6. Fuel and it's delivery method (Injectors, Fuel pumps).

Jastreb, a few more check offs.

Get your Mazda Dealer to plug in the Mazda (factory) IDS into DRL port, and run the Module Re-Programming/Update feature, IDS should do this automatically and download any system updates usually for PCM/ECU and or IMMO or Air Bag control module.

Why I can not confirm the exact firmware update(s) I do know certain Series II's did require these code updates.
Mazda are never forthcoming to their Dealers on why or what the IDS 'system' updates are for.
Unless it is a TSB (code) fix for a specific error or issue which is ECU/Module controlled.

SSV in Series II have been much better from a reliability and use standpoint and there have been way fewer problems since the LIM updates used on all S2's.
Renewing your LIM is a bit drastic and expensive, the part in US is about $1800 USD.

Since you have a reman engine, definitely check to see that correct INJECTORS were installed in correct wiring order as I know the Tech information that MNAO put out to their Dealers was wrong and has not been rectified after about 5 years. (wiring Plug and loom/ wire colour traces).

And yes a Vacuum leak is always possibly, and again I would also demand a proper Compression Test just to make sure the remain is OK.

Good luck.

What did they do with the design ? Anything that we can do with an S1 valve ?

Brettus, not sure if you knew or not but the SI SSV was changed at some point.

(Updated part on the left)

https://cimg9.ibsrv.net/gimg/www.rx8...8da67f02d6.jpg

https://cimg6.ibsrv.net/gimg/www.rx8...22e68d7bf0.jpg


I'm not sure if the SII SSV uses the same updated one but the actuator on the R3 I have at my house is black and looks very similar to the updated part.

interesting ............ looks like they fitted a bigger actuator and made a disconnect between the actuator and the valve ....