Hi,
at first sorry for bad english.
I searched all over internet i found many similar threads but nothing helped.

My RX8:
133 000 KM, new/second hand engine around 30 000 KM (compression test ok).
It is 2004 192 hp, manual 5 gear 4 injector model.
New coils, plugs, wires, o2 sensors, battery, engine, and PCM .
Cleaned MAF, ESS, Reset both memories(20 times pushed brake=oil gauge movement and disconnected battery for 30 mins or more..).

What it is doing:
I am getting sometimes misfire pid, sometimes rich/lean mixture pid. Stalling.
Car is sometimes poping from exhaust, shaking when it idless but only when warm.
Sometimes idle rpm is jumping from 750 to 1100. Fuel pump running always on fast circuit.
Strange thing i found is the one of secondary injectors is running even when car is idling. If disconnected car begins to stall but wont stall at all only shaking much when i checked secondary o2 sensor voltage at this time it was shoving nearly 0 volt.
If the car stays off for at least 12 hours fuel falls back to tank and it takes long to start up engine because fuel pipes are empty. Bad fuel pump?


1. First and the main problem, hard to describe, is that the car will stall if i quickly release gas/accelerator pedal and the RPM drops from for example 5000 RPM. If i am gently releasing pedal leaving it just before idling RPM then the car wont stall.

This problem disappears when i disconnect maf sensor. Bad MAF or it is doing due to battery disconnection (lost memory)???

2. Second problem is that my rx8 lost nearly all power under 4k RPM.
So i thought about injectors. They are ok, i cleaned them in gasoline/petrol/benzin bath and used then little contact cleaner spray.
Then fuel pump it was as well clean as new but cleaned it as well.
Then i thought o2 sensors are bad so i disconnected them both (front and rear)
but no change everything same no CEL massage. Is this normal behavior?

I am using Forscan live data stream to check MAF voltage it has 1,3v when idling and a maximum 3,2v around 7k RPM. Strange is that i can see only rear o2 sensor voltage when idling i am getting aroung 0,8v sometimes 0,9v. If i push accelerator pedal it drops sometimes under 0,1v but then quickly back to 0,8.
Is this normal behavior?

One thing i thought about is low fuel pressure in pipes but i dont know how to check it...

So what the hell is with my car??? I am realy desperate..

If all what i writed here is un-understable/opaquel (or you are lazy to read )just tell me i record it on video and post it here.

Thanx for help...

 

Why did you change the PCM? Did the replacement get programmed properly?

 

Oh yes i forgot to mention. First i thought running secondary injector under 4k and other problems are caused by failing PCM. So i bought second hand one with keys, imobilizer and keyless opener.
Only thing it is doing with new PCM is i get CEL code of mismached PCM/ABS,TCS.
Difference between running car on old pcm and new pcm is usage of oposite secondary injector under 4k.
Other way car is running same crap.
It havent been programed because PCMs are completly same (and it could cost me lots off money:D).

Should i switch back old pcm?

 

firstly - put original ecu back in .
Is there a chance the injector plugs were reversed when the new engine was installed ? - happens a lot !

 

I thought about it as well. Wiring harness is short. It wont allow you to switch between injectors. Only thing i was able to switch were wires between primary injectors but my 8 havent started up so i put them back to original position.

But at all i dont know how they should be connected.
If you can give me picture/photo of wire connections it could help a lot.
I found pictures of wire connections for 6 injector rx8 only..

 

No - don't have anything .
Does your scanner log AFR ?

 

If you mean Air/Fuel Ratio...
I am getting only rich/lean fuel ration code. I cant log directly AFR.
Can you give me a scanner name which can do this?
Only thing i was able to check is rear o2 sensor voltage as i wrote here :

 

1.3 v is a little high . Have you taken apart your maf tube lately ? Might be worth a look

 

Do you mean with "maf tube" air intake?
If yes. I dismantled whole intake tube from air filter to engine and cleaned everything (air filter, maf, throttle, and pipes between).

 

Today i put back my old PCM/ECU,reset DTC codes and start up engine.
Again as soon as it was warm when i touched accelerator pedal and left it engine stalled.
Again unstable idle...

After a 20 mins running i got these Dtc codes as pending : fuel trim too rich bank 1, misfire cylinder 2, low voltage on front o2 sensor.

These DTC codes came up when engine was stalling and running around 500 rpm so the voltage in whole car was low (dimming lights).

 

so .... how do you know the sec injectors are running when they shouldn't ?
Are the P1s running at the same time ?
You really need to see what the AFR is when you get this bogging .

Here is an option : epifanSoftware | mazdaEdit | Versions & prices

Lite version is $180 i think, plus you need the Tactrix as well.

 

While engine was running i disconnected one of Secondary Injectors nothing happened.
Disconnected second one and car began to braise (rpm 500 and much shaking) as i wrote here :
I dont think injectors are the problem checked them many times.
I am thinking about primary o2 sensor.

 

Well - the secondary injectors don't fire at idle .... full stop . I don't know if that test you did confirms if it is or isn't running .

If the 02 sensor was faulty the ecu would report the same afr under all conditions IE pegged at 14.7 AFR

 

On previous PCM/ECU when i disconnected o2 sensor i didnt got any report about that in ecu. I didnt tested it on this one.
Tomorow i check on it...

 

Today i checked few things again.
O2 sensor are now reported in PCM when disconnected = they are OK.
Tested car with new MAF sensor = no changes. So i put back old MAF sensor.
Still 2 primary and one secondary injector running while idling .

When i disconnected secondary injectors, while idling, i got lean mixture according to secondary O2 sensor .
If primary O2 sensor is disconnected the RPM while idling, will stay on 750 = no oscillation between 1000 and 500 RPM
If primary O2 sensor was disconnected and i disconnected secondary injectors, while idling, the car stalled after moment.

So i guess there is low preasure in fuel system.

 

So i am back again.
I tested the engine with classic compression meter and it looks like engine is bad
at 187 rpm i was getting from 1st rotor 6,9bar and from 2nd one 6,1bar compression (highest value).
I speaked with previous owner and he still had the old engine.
So i took it from him cleaned it and put it to my rx8.

The old engine has 130 000 km. This engine runs better has more power at all. This one was tested with same compression meter and i got these numbers:
187 -185 rpm
1st rotor 7,3 bar
2nd rotor 7,0 bar

But at all i know only the highest compression i dont know if it has broken apex seal on 1 side.

This engine (one with 130 000km) is as well lazy to spin up (but less lazy then the new one with 30 000 km) when running low rpm (under 4k rpm).

Maybe i am just feeling it that way or the engine is realy broken.
So i recorded that lazy spin up and stalling on video:


On video it isnt easeiy visible but any time when running low rpm i push full gas it has long response time much shaking and after that it starts to spin up.

 

I was about to tell u ur engine is bad. Well guess u already figured it out

 

If my engine is dying i would like some suggestions about what to do with it.

I have apsolute no warranty so i was thinking about rebuilding the old engine or switching the engine with some cylinder engine.

I want some cheap and durable repair.
So any suggestions?

Thanks...

 

So i resealed (new apex side seals water seals springs) my engine lapped irons and put it back together.
It ended up with unstable idle, shaking and misfire + exhaust popping under throttle.
Now i am realy desperate about what to do i am out of ideas.

 

Check the injector wiring. .. often they get mixed up on reinstall and it makes it run like Crap

 

Wiring Ok.
But it looks like the coils were bad after replacement misfire disappeared and another problem appeared from 4 spark plugs only 1 was working. :D

Do i have to buy expensive NGK RE8C-L and RE9B-T ?
I cant find any relevant info on net about what other spark plug type fits in.

Can you suggest something ?

 

You csn buy stock ones for $75 Or so. .... they work the best for an NA engine

 

Finally my rx8 is running!!! Just a little unstable idle when warm.

Looks like the secondary injector was running because it was mixed with primary injector. After messing with wiring i fixed it finally.