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I took the car today for a quick drive and I gave the car a full throttle on second gear and I heard pop / backfire noise and after that the car feels gutless.
The car was pretty much limping to get home.
The car is bone stock standard car with no modification whatsoever ( stock exhaust, ecu, twin turbo, etc )
I left the car cooled down for the 3 hours and I manage to started it ( took slightly longer than before ) but the car is struggling to idle and sounded like running on 1 rotor
The engine when I bought the car it had 100-120psi compression and I've only done like 1000km since I bought the car.
Please tell me its gonna be something simple and my engine isnt f***ed !
I hope those compression reading photos were taken AFTER the incident where it lost power, as they are good numbers, and would rule out a compression issue.
To easily rule out a major loss of compression as the problem, do the following:
1. Disconnect the Circuit Opening Relay and the Ignitor connector - this prevents fuel & spark while cranking. Refer to the FSM for info on where to find these components to disconnect.
2. Remove the trailing (top) spark plug from the front rotor.
3. Make sure you have a fresh/fully charged battery, and crank the engine over for at least 5~10 seconds with the throttle floored and listen closely to the sound coming from the removed spark plug hole. If there were no major compression failures, you should hear a regular POP-POP-POP.... type of sound pattern, i.e., a nice loud POP for each of the 3 rotor faces, which indicates that you at least have compression on all 3 rotor faces. But if you hear something like POP...hiss...hiss...POP, or nothing but a hisses with no distinct POPS, that rotor had a major malfunction
4. Re-install the trailing plug in the front rotor & remove the rear rotor training spark plug.
5. Repeat step #3 to test the rear rotor.
Rather than a check engine light, when the ecu registers a default, it will put the car in "limp" mode, and you have to, in fact, limp home. The ecu may reset if you disconnect the battery. It will then throw you into limp mode again when it cycles through its internal diagnostic.
The owners manual says "take the car to the dealer'. This means that the dealer would run a specialized diagnostic tool on the car to read the codes. Thing is, no one has that tool anymore. (You might get lucky in NZ).
But you can easily run codes with a led light (with resistor) and a jumper wire.
There is a guy on here that is a automotive teacher in NZ. he could likely help you.
Was it a "pop" or a distinct "bang". Pop is more likely a vacuum hose popping off literally. Distinct bang is "detonation", which can blow out a seal.
Check the big hose that puts vacuum to your power brake servo. That will cause a big vacuum leak. if it popped , or split This very thing happened locally recently. However, you would also have lost your power brake assist. That vacuum hose has a check valve in it so you can't just replace it with any length of hose.
MAP sensor has a filter that often gets put back facing the wrong way. The narrower end of the filter should face toward the sensor.
Does your car have its original ecu or has it been replaced with and aftermarket one?
A third thing to do is to have a shop do a "smoke test". They hook up a device to your intakes and pump smoke through the system. It is cheap and surprisingly effective.
Many of the vacuum hoses you can not see easily, so smoke coming up from locations unknown can be helpful.
( I discovered this week, I have likely been running around with one broken vacuum hose for several years. Lucky I was running premix as it was the vacuum line to my OMP injectors.)
From 1996 onward (Version 4~6 cars) mazda switched the order of the coils around. They only made a small note of this in an FSM update. People that did not catch that have a risk of hooking up the coils wrongly. Did anyone change your plugs recently?
The good news, perhaps, is that Mazda also replaced the "rats nest" with a solenoid box. This greatly reduced the complexity of the vacuum system. However, before anyone pulls off the UIM to poke around in your vacuum system, you best run the tests above.
As for running the car hard to burn out the carbon, etc. You should only do such when you have confidence everything in your car is otherwise sound. If there is a weaknesses, something could blow out under increased pressures.
A third thing to do is to have a shop do a "smoke test". They hook up a device to your intakes and pump smoke through the system. It is cheap and surprisingly effective.
Many of the vacuum hoses you can not see easily, so smoke coming up from locations unknown can be helpful.
( I discovered this week, I have likely been running around with one broken vacuum hose for several years. Lucky I was running premix as it was the vacuum line to my OMP injectors.)
Hello !
Wow thank you so much for the write ups !
Regarding the sound to be honest now i cant even remember if it was a pop or a bang but the car is 100% stock standard ( stock turbos and ecu also ) I have no boost controller whatsoever
Can the car really get detonation from over boosting even when the car is bog standard ?
I have disconnected the battery for half an hour but its still doing it
This is the link of the cold start this morning when I had to move the car to the side. The car barely able to go up the hill and I had to ride the clutch hard to get it move
From 1996 onward (Version 4~6 cars) mazda switched the order of the coils around. They only made a small note of this in an FSM update. People that did not catch that have a risk of hooking up the coils wrongly. Did anyone change your plugs recently?
The good news, perhaps, is that Mazda also replaced the "rats nest" with a solenoid box. This greatly reduced the complexity of the vacuum system. However, before anyone pulls off the UIM to poke around in your vacuum system, you best run the tests above.
As for running the car hard to burn out the carbon, etc. You should only do such when you have confidence everything in your car is otherwise sound. If there is a weaknesses, something could blow out under increased pressures.
Yes I got my mechanic friend to changed the plugs recently. He removed and re-installed one plug at a time so he didnt mix it up.
The car previously had the BR8HS plugs ( the type of plugs that you need to get your socket machined very thin to able to use it ) but now its got the proper rotarty NGK 7's and 9's
I would have a check of the leads hook up in any event. I drove around for six months with mine hooked up wrong. The detonation only occurred when a friend did some pulls to 6000 rpm (I rarely go over 4500 - cuz old man.)
( I also had a fuel pump problem that may have only come up at the higher rpm. A bent o-ring)
If you have had a detonation, best not to run the car.
The path from the rotor housing to the exhaust impellers on the turbos is pretty direct and unrestricted.
Detonation can happen in a situation where the car unexpectedly runs to lean. The thinner mixture can cause an out of phase ignition. Failure of the fuel pump could be a cause.
(Get an wide band afr gauge.)
Not to cause you possible undo concern.
You will get used to it.
Try to find out how to do the code reads. (Hence ZacMan).
The best advice might come from your ecu.
Compression test will tell you pretty quick if you have a blown seal.
Good you have the prior test results handy.
Smoke test devices are portable.
Maybe someone will come to you. For a few extra bucks.
The diagram in the trouble shooting manual is a bit miss-leading (no pun intended). The leading plugs actual fire twice for each face presentation. The second firing of the leading plug (lower plug) occurs into the exhaust plume of the combustion event in right side diagram. If the leading plug lead is hooked up to the trailing (top plug) a spark will be sent into the incoming gas mixture, causing an out of phase ignition. Perhaps surprising to learn, the leading plugs fire at the same time, all the time.
Here is the changed coil positioning for Version 4~6 cars. Is the harness hooked up in the right order, or is it flipped?. Best to check the wiring manual for the correct version car. (Your car is Version 5 with a VIN 500 ___, right?) To be sure check the wires correspond to the right coil. wire colours. The plugs seem to be colour coded but i have not found what the colours correspond to.
I would say first step would be to pull a plug on each rotor one at a time and listen to the compression at minimum. Would be a quick peace of mind or heart break listening for even pulses. Probably your simplest check at the moment given the circumstances. No use tracking down an electrical gremlin if it's low compression.
I would say if the car was driving just fine before this event i wouldnt be too worried about the ignition lead position until you confirm compression. I'm pretty sure that isn't the issue of running poorly if this only started after the pop and nobody messed with the wires during that time
Haha, I may be getting well ahead of the curve. Good luck with the simple compression test. Post us up a youtube of it.
Another set of vacuum hoses to easily check is the set of four that come of the double solenoid (green one) that sits at the front of the uim behind the little triangle shaped vacuum chamber.. These are critical solenoids, and the nipples to which the vacuum lines are attached break easily at this age. Also check the vacuum hoses going to and away from the little vacuum box, that box also is in line for feeding vacuum for critical functions.
10-21-23, 04:25 AM
