Hi,
I'm having issues with the engine knocking(pinging, detonating) the car is a 2005 auto transmission completely stock with no modification whatsoever and it shows no trouble codes on the scan tool. Already replaced coils, plugs, cleaned fuel lines and injectors, de-carbed engine using water and wd-40 premix(compression is at first rotor at 77,78,79 psi and at the second rotor is 83,85,88 psi) checked fuel pressure at 48psi. any help with somebody having same issue with an auto RX-8 will be greatly appreciated.
thank you in advance.

 

Can you explain why you think it's pinging/detonating?

It's almost always not audible on our engines. Even a deadly detonation isn't really heard. I'm guessing you hear something you think is pinging, but is actually something else.

 

WD-40 premix and water ? oh boy.

 

it is audible I have to let off on the throttle because I'm afraid it will damage the engine and yes I'm positive it is pinging.
thanks!

 

What fuel are you using? Reg or Prem?

I did this and it helps but when the engine is HOT only Prem Gas will help....

https://www.rx8club.com/rx-8-discuss...iac%2A-121249/

 

I may be wrong, but I'm pretty sure that by the time the pinging is audible on a rotary the seals are already long shattered, and you would have heard the engine chewing up the seals, followed by severe lack of power and a general inability to start the engine.

So to me, it just sounds like you are chasing the wrong problem and only think you are hearing knock.

Example on what knock sounds like when it doesn't immediately destroy the engine: https://www.rx8club.com/series-i-tec...cluded-243347/



I'll bow out though, and see where this goes, if you are so sure.

 

I'm using prem gas and even a 4 point octane booster from Liqui-Moly and it won't help, the engine exhibits a noticeable lack of power just before the pinging sound comes to show, I'll try the throttle body coolant passage blocking maybe this will solve the problem on my car I really hope so since I've tried everything to solve this issue with no success. I should say the weather here is really hot like 98 degree sometimes.

 

I really appreciate you trying to help me don't get me wrong but I have some experience with knocking on rotary engines and based on the video you post it sounds just like it on the video at 1:28........

 

Did the coolant bypass on the TB and detonation is almost gone if I have to give a % I would say is 90% gone it is almost inaudible so this simple bypass really help but the lack of power is still felt mostly at 5000rpms and up on 2nd and 3rd gears so I'm thinking I have a fuel feed related problem but I don't know what else to do since I've already clean injectors, fuel lines, checked fuel pressure at 48psi....I really appreciate your help Old Rotor since the pinging issue is only felt sometimes and only when the transmission is about to shift from 2nd to 3rd gear and as I said before is almost inaudible....at first I thought the loss of power was felt because the engine was starting to ping but since now the pinging is almost gone I'm guessing it is cause by a fuel issue and was really audible before because of the intake air temperature magnifying a problem that is still there.

 

When ambient air temps increase, as in your case, the engine is more susceptible to detonation. Also a restricted catalytic convertor will cause a build up of extra heat in the engine due to exhaust gas restriction.
Have you ever changed the ignition coils? Have you checked the Cat visually? Is the engine temperature gauge moving? If it moves the engine coolant temp is above 230+ degrees. This will also cause an increase in the chance of having detonation.
What brand of fuel do you use? Not all brands are good.

Detonation is caused by excessive heat in the combustion chamber. Causing the fuel to ignite under compression from being too hot. One must look for the cause of the excessive heat build up in the combustion chamber. Cat clogged, bad fuel octane rating, to lean a mixture A/F. Overheating coolant/engine. Does it run better when the car is cool?

 

If I used 87 octane in either of my last two engines they would pings, and it is VERY audible. If my 8 wasn't in the shop awaiting its third engine I'd throw some 87 in and record the sound for you. LOL Oh, before you ask, Mazda's fix for my engines issue is don't use 87 octane.

 

Considering premium is required, I have to agree with Mazda on this. 3rd engine you say? And still using 87?



There have been enough noises over the years attributed to knocking/pinging that actually aren't (like intake valve rattle, rotor tips hitting the housing, loose bolts, belts, alternator bearings, etc...) plus engines that shatter seals on a detonation that was otherwise completely silent ahead of time...

...I just struggle to believe you could hear non-deadly knock on these engines, and what people this is knock is usually something else that is being ignored because they are incorrectly labeling it as knock and troubleshooting it as such.

 

cat removed for testing, premium fuel with the adition of a Liqui-Moly brand 4 point octane booster, a lean mixture I won't know since I don't have anything on hand to measure it, it was overheating but it was cause by a faulty thermostat but I've already replaced it and the problem persists, but after all of this is said please remember in my previous post that I said that the knocking noise is almost gone completely after the TB coolant bypass and no trouble codes on the scan tool yet so the pinging issue is not much of a concern for me any more but the loss of power after 5000rpms in second and 3rd gears is still felt even though the pinging noise is almost inaudible now.
thanks!

 

Back in 04 91 was recommended but not required,and no I don't use 87 anymore. Long story short, Mazda replaced 1st engine because of pinging and was fine with 87. Then changed their mind about 87 after 2nd engine pinged too. My engine is shot now, so I would use 87 in it for science, though.

 

I'm alone now I see

 

Your always alone on the internet. Until someone types.


Anyway. So you feel you have removed some of the "occurrence", by doing a throttle body bypass.

 

absolutely! the pinging noise is almost gone maybe the lower intake temperature is helping remember the ambient temperature is 98 degrees but as I said before it could be that the bypass is putting a mask on a problem that is still there because the power loss is still felt at high rpms..

 

where are you?

 

Honduras, central america

 

crap fuel pump, runs lean, boom