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1. Engine replaced 8,000km / 5,000 miles ago
2. New Denso DOX-1449 si DOX-0330 pre and post CAT sensors
3. New CAT
4. EN3H1-A starter
5. Rotary Revolutions D585 coil kit
6. 2 x NGK RE8C-L + 2 x NGK RE9B-T - new spark plugs
7. Magnecore Competition leads
8. Bosch 70Ah S04 26 battery
9. Mishimoto 76C / 168F thermostat
10. MAF replaced with new part
11. Stage0 ECU mod by Wankelshop.de which includes:
1. Elimination high revving the engine during cold start cranking.
2. Lowering the high idle speed rpm when the engine is cold.
3. Setting idle to 1,100RPM
4. Cold start limiter set to your wish rpm.
5. Increasing the oil injection amount.
6. Lowering the switch on temps cooling fan 1 & 2.
7. Elimination of dangerous lean running engine at part load all gears - The well known cat killer.
8. Adjustment of installed performance coils included.
The car has sat for a few months with no battery in it. After starting it, I have noticed that it will no longer hold idle, not to mention that it will not hot start. I have tried with both the stock ECU and the modified ECU, it behaves the same.
Here's a video of it trying to hold idle when hot, with the A/C on in order to calibrate idle. I have driven the car also and it behaves the same. While not mentioned in the video, air-to-fuel ratio is 15.0 commanded and 14.8 measured, throughout a 15min interval before the engine just dies. I did not touch the gas pedal since the car was started after performing KAM reset.
I have performed the KAM reset bot via the brake pedal and also with the odometer button. The engine does not show CEL no matter the revs. Here is video of it going to redline and then dying:
I enabled all of the sensors that were available to me from Torque. Here's the video, from cold start to stalling. It took way longer than expected because the local temperature here is 22C / 71F. I've also attached the Torque logs
I'm a little concerned that all your fuel trims are 0. 0 is good but perfect 0.00 is a bit... unexpected? It's like it hasn't learned anything and / or it's running open loop, rather than closed loop.
Also, your MAF g/sec seems too high. at 725 rpm it's showing 7g/sec. A normal warm idle around 800rpm is 5ish g/sec. So potentially, the MAF scale is off (this is a map in the ECU map).
Have you tried reverting to the stock tune to eliminate the possibility the "stage0" tune is the source of the problem?
For some reason O2 1x2 (which I interpret as the post-cat O2 sensor) goes from 0.7 to 0 volts as the car warms up. It should never show 0 volts, that's weird.
Your intake temp steadily climbs to 70+C, so potentially as the intake temp climbs you start getting into knock. How old is the gas in this car? Is it high octane?
AFRs and the rest looks fine. Any check engine codes?
The gas in the car was pretty old but I got it down to 2% fuel level before putting in 20L of high octane.
I'll swap to the stock ECU(I have 2 units, one tuned and one stock) and do the tests again. The MAF was coveree in gunk so I replaced it before the tests. Also pulled out the air filter while I was doing that, in hopes of getting cleaner air to the engine(I have no idea what I'm doing but I try).
I added every green sensor I could find in Torque but going through the settings, there might be more which I didn't add. I'll do that tonight, after work.
The car seems to not like my new O2 sensor(pre-cat, as you have correctly mentioned). Here's a pic of the old one. The check engine light was on from the start of the tests but I ignored it since the engine was already warm and I couldn't shut it down or clear the code since I knew it was from the O2 sensor.
The old sensor had a longer cable which the new one didn't have. I spliced the new sensor into the old cable. As faras I knowz it should be a direct fit since all the cables had the same colors so I spliced each cable with the colornit had(white to white, blue to blue etc.) . Maybe I did something wrong?
The post cat is 14 years old so I think it may be broken. I'm runnin deCAT for now so maybe that is an issue also?
The gunk on the old MAF is oil and gas from the old, low compression engine which was spewing oil and gas into the air intake and thus, into the filter. But not before covering the MAF in it.
I replaced the MAF with another one, from another RX8. Was very clean and I didn't have any brake cleaner so I just swapped them. I'll take a photo of it tonight(7:50AM right now for me).
I've cleaned the MAF with MAF sensor cleaner and re-ran the tests with the stock ECU. The MAF with 2 white stripes is the one which was used in the tests from yesterday/the previous video.
The tests from today were run with the MAF that was cleaned (original). Here are the results:
The car detects the sensor (look at 4:00 in the video as I scroll through the list of sensors) but it gets no data from it. Either my measuring equipment is wrong or the sensor itself is fried?
I'm using an original ELM237 bluetooth OBD2 adapter. Do I need to get a newer one? It's from 2015.
STFT and LTFT aren't sensors, they're variables in the ECU. It's basically how many % more fuel the ECU has learned to give at a given rpm/load point to get the desired AFR. And you AFR is holding steady throughout the experiment. So either it hasn't learned anything yet, or your AFR is fine (which it appears to be from the reported AFR). I'm gonna go with 'it hasn't learned yet'.
Can you tell if the car is operating in open loop or closed loop? There should be an entry in the list of variables for that. Open loop = front O2 sensor data is not used. Close loop = front O2 sensor data is used to tune the AFR.
How exactly did you splice the O2 sensor wiring together? Is it crimped or soldered? If the ECU doesn't trust the O2 sensor for some reason, then it wouldn't learn fuel trims and you would have a code for that. It has a plug, usually cutting wires creates more problems than it solves.
O2 sensor was crimped. Each wire was isolated from the others and color-matched. I'll try and re-wire it and maybe get a signal from the ECU but it will take about a week.
I have no idea if it is running in open or closed loop. How can I check? All I can say is that there is a strong fuel smell coming from the exhaut. No smoke of any kind, though. The smell is hard to describe but I think it smells of un-burnt fuel.
The smell is weird because the AFR is normal. Does the car have a cat? It will smell if it doesn't, or if the cat isn't working. Or if the O2 sensor is lying. How much do you trust the new sensor?
Closed or Open Loop status should be a reading available in the list of sensors in torque. Perhaps under another name...
The thing with crimping or soldering sensor wires is you need to be sure there are no dissimilar metals, that will mess with your readings.
I'm not sure I replaced them correctly or if it is even possible for me to have switched them. The 1449 came with a very short cable which I cut and spliced into the old one that was on the car.
Could I have accidentally switched the sensors? Put the one on the CAT in the exhaust manifold and vice-versa?
I've been doing some reading on short and long fuel trim and I noticed something in my videos: in the first one, the O2 sensor voltage is 0.
In the second video, it is 0.8 for the fist 5 seconds immediately after starting the car and then drops down to 0 as the car warms up. Based on what I've read and what you all have said, this is because:
1. The wiring was not done correctly
2. The sensor is broken
3. Huge vacuum leak (although for it to be zero, the sensor would have to sit outside the exhaust manifold
This would explain why the car is not calculating fuel trim.
Which O2 sensor? Rear O2 shouldn't really really matter since it's just checking catalyst efficiency. Front O2 sensor, definitely but I can't imagine it not throwing a code.
Your front O2, is definitely working, because you can see AFR. What's 0V is your rear, post-cat sensor. That's a problem but wouldn't stop your car from running.
Have you swapped to the stock yet? That would seem to me the obvious first suspect.
Wait a minute. I just looked up the oxygen sensor you linked. Is whichever one you put in the front actually for an RX8? You can't use just any ole sensor in that position. The cable being too short raises alarms, since the description for both states they're plug and play for an RX8. If it's not a wideband, that would explain most of this.
The second video is on stock ECU, yes. The sensors are exact OEM spec for the RX8. Denso made them for the RX8 and their replacements are 1449 for upstream / front / pre-CAT and 0330 for downstream / rear / CAT, according to my research. It can also be seen in the first picture of the sensor that it says Denso N3H3 on it.
I am scared because I don't know if I mixed them and may have accidentally put the downstream sensor in upstream and the upstream one in the downstream but as far as I know, 1449 (which is what I have) is in upstream and 0330 in downstream
Hmmmmmmmmm. It's obviously reading an AFR, rather than flopping around like a narrow-band sensor, so if you had swapped them it, we'd have a different set of problems... I guess... worth a check. It bugs me that you had to cut and splice the wires, the sensor specifically says it plugs right into the stock harness.
08-20-2018, 10:26 AM
