Building an RX-8 out of two broken ones
03-05-2017 | 09:26 AM
#51
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Misfire is at over 5,000RPM. The CEL starts flashing but I feel no power loss or anything wrong. The only indication was lots of smoke and the MOT failure. Did an ECU reset, no more smoke but the MOT is still a failure due to un-burnt fuel so it's still misfiring.
Checked the CAT and both O2 sensors (Lambda sensor) and they are fine.
Checked the leads going to which spark plug from each coil and they are fine. The coils are new, the spark plugs and the leads are also new. New battery also.
Checked the CAT and both O2 sensors (Lambda sensor) and they are fine.
Checked the leads going to which spark plug from each coil and they are fine. The coils are new, the spark plugs and the leads are also new. New battery also.
03-05-2017 | 12:18 PM
#52
Ok, found the issue. Missfire on Rotor1 (and not the O2 sensors). The problem is, the leads and the spark plugs are in the correct order. Which means that somehow, the connectors from the car that connect from the electrical system into the coils, have been reversed.
How can I find out the correct order for reconnecting the coils to their respective connector / socket? Or is the order irrelevant?
All I can find is the order for connecting the leads from the coils to the spark plugs but nothing on which order is correct to connect the coils to the car itself.
How can I find out the correct order for reconnecting the coils to their respective connector / socket? Or is the order irrelevant?
All I can find is the order for connecting the leads from the coils to the spark plugs but nothing on which order is correct to connect the coils to the car itself.
The trigger wire colors on each coIL are different...so you need to find a wiring diagram and then compare colors to which coil they go too. The way the harness is built it is difficult to get them too mixed up....
03-05-2017 | 11:02 PM
#53
I would pull and examine the spark plugs. See if any are not firing. If the coil order was off, it would cause problems throughout the rpm range. However if one coil is dead, you would certainly get unburned fuel. Normally, high rpm misfires are caused by a plugged cat. How did you check it?
03-06-2017 | 05:39 AM
#54
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I used an OBD2 tester for the checks. About all I have. Said that the CAT is operating normally and at temperature of 800 something degrees Celsius
But I'm in over my head with the title for the damn thing and the mechanical part so I'm taking it to the dealer this week. They can't measure the gasses but they will be able to tell me what is wrong with the spark plugs, coils, leads, etc.
I'll just keep it under 5,000RPM until I get there. Didn't want to do this as it's a 380Km round trip but it needs to be done.
Thank you all for your support and replies, it really helped along the way to finishing this build!
P.S. : would the 10W40 semi-synthetic oil cause it to fail emissions testing? I have the Mazda 5W30 on stand-by if needed.
But I'm in over my head with the title for the damn thing and the mechanical part so I'm taking it to the dealer this week. They can't measure the gasses but they will be able to tell me what is wrong with the spark plugs, coils, leads, etc.
I'll just keep it under 5,000RPM until I get there. Didn't want to do this as it's a 380Km round trip but it needs to be done.
Thank you all for your support and replies, it really helped along the way to finishing this build!
P.S. : would the 10W40 semi-synthetic oil cause it to fail emissions testing? I have the Mazda 5W30 on stand-by if needed.
03-09-2017 | 01:47 AM
#55
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Actually, yes. Wiring was done ok. ECU was misfiring because it thought it was still using the old engine (now dead) with the old coils and the old mileage. Did a reset and goes all the way to 9,500RPM with a fuel cut-off at about 9,600 I think (won't let me get higher). Pulls like never before. I'm afraid of wheel-spin so I didn't really hammer it but I'll get there eventually 
2nd gear ends at about 120KM/h which is hella nice!
Emissions test still fails (mixture is too rich) so I'm switching back to the Mazda Dexelia 5W30 oil just for the test and I'll be filling her up with 100 grade octane petrol.
Ordered new O2 sensors from Denso DOX-1449 and DOX-0330 and a new Type R103 CAT, model number MA6025T which is a direct fit. Gutted or not, the old CAT has 128,000KM so I'm guessing (by the old blown engine) that it's long gone.
The engine running rich should also be fixed by replacing the O2 sensors since the pre-cat O2 sensor dictates the mixture. Want to pass emissions and I also want to keep the new CAT since emissions tests are mandatory (with a pass) every 2 years here.
I'll keep you guys updated. Thanks again for all the info posted here. Man...owners when the car was new must've had it rough! I've read schematics, oil viscosity charts, operating temperatures, mods etc. You have to be a Mazda tech to drive an RX-8 and keep it running.
But when the engine revs like a bat out of hell...oh, it is worth it!
2nd gear ends at about 120KM/h which is hella nice!
Emissions test still fails (mixture is too rich) so I'm switching back to the Mazda Dexelia 5W30 oil just for the test and I'll be filling her up with 100 grade octane petrol.
Ordered new O2 sensors from Denso DOX-1449 and DOX-0330 and a new Type R103 CAT, model number MA6025T which is a direct fit. Gutted or not, the old CAT has 128,000KM so I'm guessing (by the old blown engine) that it's long gone.
The engine running rich should also be fixed by replacing the O2 sensors since the pre-cat O2 sensor dictates the mixture. Want to pass emissions and I also want to keep the new CAT since emissions tests are mandatory (with a pass) every 2 years here.
I'll keep you guys updated. Thanks again for all the info posted here. Man...owners when the car was new must've had it rough! I've read schematics, oil viscosity charts, operating temperatures, mods etc. You have to be a Mazda tech to drive an RX-8 and keep it running.
But when the engine revs like a bat out of hell...oh, it is worth it!
03-17-2017 | 08:21 AM
#56
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Ok, got the car back from the dealer. Issues as follows :
-Engine compression is low. Both rotors are at around 620kPa
-Misfires occur due to the low engine compression. The coils, leads and spark plugs are fine
-Engine mounts are shot (again)
-Gearbox is shot. 3rd and 4th gear pinion ring is almost dead
-Pressure plate and clutch are almost gone (explains the jerkiness when shifting too fast)
-O2 sensors were filled with silicone on the inside (what the hell?). Explains the engine running too lean then too rich and constantly switching between the two
-CAT is completely blown
-Radiator and thermostat are fine. Overheating is due to the expansion tank. Mentioned R008 / 09A which I saw was a recall for faulty expansion tanks
The CAT and the O2 sensors arrived and will be fitted tomorrow, same as with the expansion tank from the parts car.
Also, here's two videos I made recently :
Gonna try and change the ignition barrel from the other car also, as I only have 1 key for mine and the other car has 2 keys + remotes.
-Engine compression is low. Both rotors are at around 620kPa
-Misfires occur due to the low engine compression. The coils, leads and spark plugs are fine
-Engine mounts are shot (again)
-Gearbox is shot. 3rd and 4th gear pinion ring is almost dead
-Pressure plate and clutch are almost gone (explains the jerkiness when shifting too fast)
-O2 sensors were filled with silicone on the inside (what the hell?). Explains the engine running too lean then too rich and constantly switching between the two
-CAT is completely blown
-Radiator and thermostat are fine. Overheating is due to the expansion tank. Mentioned R008 / 09A which I saw was a recall for faulty expansion tanks
The CAT and the O2 sensors arrived and will be fitted tomorrow, same as with the expansion tank from the parts car.
Also, here's two videos I made recently :
Gonna try and change the ignition barrel from the other car also, as I only have 1 key for mine and the other car has 2 keys + remotes.
