HELP! Car wont idle and running extremely rich
07-18-23, 07:18 PM
#1
Full Member
Thread Starter
HELP! Car wont idle and running extremely rich
I'm sorry if I am posting this in the incorrect place, I am fairly new to posting on here.
92 FD3S
Engine mods -
Rebuilt motor 1500km since rebuild
Aftermarket exhaust (stock cat)
Apexi intake
Power FC
I have tried to exhaust my resources by searching for a solution to my problem but have not been progressing.
I was driving the other day and everything was running fine, something traffic came up and I knew I was going to be sitting for a while so I turned my car off. 25-30min later I turned the car on and it was having a hard time idling, it is running very rich to the point it is stalling itself out. I can rev it into boost and it doesn't seem like the issue is present then.
I got my car home and looked at my MAP sensor, vacuum lines, and any obvious damage, but nothing looked off. I thought maybe I fouled some spark plugs, so I swapped all of them with new ones and new spark plug wires, which didn't work. I noticed my air temp sensor was showing in the negatives sometimes and other times reading normal so I bought a new sensor but that did not fix anything. I had a friend look at my engine and he said my air pump was running abnormally but I don't know where to start when troubleshooting any of the emissions relays and sensors.
Any help would be appreciated.
92 FD3S
Engine mods -
Rebuilt motor 1500km since rebuild
Aftermarket exhaust (stock cat)
Apexi intake
Power FC
I have tried to exhaust my resources by searching for a solution to my problem but have not been progressing.
I was driving the other day and everything was running fine, something traffic came up and I knew I was going to be sitting for a while so I turned my car off. 25-30min later I turned the car on and it was having a hard time idling, it is running very rich to the point it is stalling itself out. I can rev it into boost and it doesn't seem like the issue is present then.
I got my car home and looked at my MAP sensor, vacuum lines, and any obvious damage, but nothing looked off. I thought maybe I fouled some spark plugs, so I swapped all of them with new ones and new spark plug wires, which didn't work. I noticed my air temp sensor was showing in the negatives sometimes and other times reading normal so I bought a new sensor but that did not fix anything. I had a friend look at my engine and he said my air pump was running abnormally but I don't know where to start when troubleshooting any of the emissions relays and sensors.
Any help would be appreciated.
07-18-23, 07:33 PM
#2
pull the spark plugs and disable spark. crank it and check to see if there are consistent and stable hissing sounds. if you have access to an actual compression tester that would be ideal. start there and see what happens. based on what you're describing, I'm thinking the worst right away because it was just so sudden. start at the worst thing and go backwards in this case. i am going to make the assumption you know its running very rich because thats what your wideband is telling you and you're not just saying that to say it.
the air temp sensor randomly reading negative numbers is it dropping offline. that will absolutely cause the car to run extremely rich, stall and not start at all since it thinks it -40c outside. saying that fixing it made no change leads me to think the worst. its also possible an injector may have randomly just stuck open which will be evident when you crank it with the spark plugs out and *SPARK DISABLED*. If your problem is a corner or side seal then you wont really hear it when cranking it over. a broken corner seal or stuck side seal will give "blown engine" symptoms.
the air temp sensor randomly reading negative numbers is it dropping offline. that will absolutely cause the car to run extremely rich, stall and not start at all since it thinks it -40c outside. saying that fixing it made no change leads me to think the worst. its also possible an injector may have randomly just stuck open which will be evident when you crank it with the spark plugs out and *SPARK DISABLED*. If your problem is a corner or side seal then you wont really hear it when cranking it over. a broken corner seal or stuck side seal will give "blown engine" symptoms.
07-18-23, 08:02 PM
#3
Full Member
Thread Starter
pull the spark plugs and disable spark. crank it and check to see if there are consistent and stable hissing sounds. if you have access to an actual compression tester that would be ideal. start there and see what happens. based on what you're describing, I'm thinking the worst right away because it was just so sudden. start at the worst thing and go backwards in this case. i am going to make the assumption you know its running very rich because thats what your wideband is telling you and you're not just saying that to say it.
the air temp sensor randomly reading negative numbers is it dropping offline. that will absolutely cause the car to run extremely rich, stall and not start at all since it thinks it -40c outside. saying that fixing it made no change leads me to think the worst. its also possible an injector may have randomly just stuck open which will be evident when you crank it with the spark plugs out and *SPARK DISABLED*. If your problem is a corner or side seal then you wont really hear it when cranking it over. a broken corner seal or stuck side seal will give "blown engine" symptoms.
the air temp sensor randomly reading negative numbers is it dropping offline. that will absolutely cause the car to run extremely rich, stall and not start at all since it thinks it -40c outside. saying that fixing it made no change leads me to think the worst. its also possible an injector may have randomly just stuck open which will be evident when you crank it with the spark plugs out and *SPARK DISABLED*. If your problem is a corner or side seal then you wont really hear it when cranking it over. a broken corner seal or stuck side seal will give "blown engine" symptoms.
I assumed it was running rich because when I was driving it to try and get to a place to change my spark plugs it flooded and the exhaust has distinct black color. On my PFC commander it shows injector duty at 12% at 600rpm as well. I just pulled the spark plugs and cranked it over with the EGI fuse pulled and it sounded like it had good compression, see attached video.
Last edited by philiprivers; 07-18-23 at 08:19 PM.
07-18-23, 09:42 PM
#4
thats a lot of gas... keep cranking it until the mist stops. once you get to that point, put the egi relay back in and prime the fuel pump a few times. pull the egi relay and crank it over again. if you have a strong mist then you likely have a stuck injector and its just dumping fuel. if you dont have mist then prime the fuel pump a few more times and run the test again. if there's absolutely no mist then you can rule out the injectors. 12% duty at idle is really high but it also shouldn't be idling at 600rpm.
07-18-23, 10:23 PM
#5
Full Member
Thread Starter
thats a lot of gas... keep cranking it until the mist stops. once you get to that point, put the egi relay back in and prime the fuel pump a few times. pull the egi relay and crank it over again. if you have a strong mist then you likely have a stuck injector and its just dumping fuel. if you dont have mist then prime the fuel pump a few more times and run the test again. if there's absolutely no mist then you can rule out the injectors. 12% duty at idle is really high but it also shouldn't be idling at 600rpm.
07-18-23, 10:42 PM
#6
Full Member
Thread Starter
Here is a video from inside my car of the engine running, 1000+rpm’s are me on the throttle and when it dips down is it running without any input
https://youtube.com/shorts/BCabtlD-UZY?feature=share
https://youtube.com/shorts/BCabtlD-UZY?feature=share
07-18-23, 11:33 PM
#7
Eats, Sleeps, Dreams Rotary
Here is a video from inside my car of the engine running, 1000+rpm’s are me on the throttle and when it dips down is it running without any input
https://youtube.com/shorts/BCabtlD-UZY?feature=share
https://youtube.com/shorts/BCabtlD-UZY?feature=share
Are you saying the car dies if you take your foot off the throttle, or that it just idles too low?
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07-18-23, 11:40 PM
#8
Full Member
Thread Starter
07-18-23, 11:50 PM
#9
Eats, Sleeps, Dreams Rotary
The car drives awful. Anytime I have to come to a stop and go into neutral I am fearful the engine is going to stall and become flooded. It doesn’t rev smoothly and feels like it is misfiring. When the car is on the engine is bouncing back and forth from the unstable idle. I have been trying to run it as little as possible in fear I am going to break something else given I don’t know why it is running this way.
What part of Japan are you in?
Make sure that your MAP harness connector or wire isn't damaged. It might have an intermittent connection.
Check your plugs again. See if any or all of them are wet. Make sure you installed the wires correctly. Make sure they are all firing, and in the right order. Check your grounds.
Check for vacuum leaks. Might need to check the injectors for leaks.
You might want to take it to a professional (or even a rotary specialist) if you don't have the tools or aptitude. Get it trucked if you have to.
I assume your PFC's idle setting is ~1000 RPMs?
07-19-23, 02:42 AM
#10
Full Member
Thread Starter
What part of Japan are you in?
Make sure that your MAP harness connector or wire isn't damaged. It might have an intermittent connection.
Check your plugs again. See if any or all of them are wet. Make sure you installed the wires correctly. Make sure they are all firing, and in the right order. Check your grounds.
Check for vacuum leaks. Might need to check the injectors for leaks.
You might want to take it to a professional (or even a rotary specialist) if you don't have the tools or aptitude. Get it trucked if you have to.
I assume your PFC's idle setting is ~1000 RPMs?
Make sure that your MAP harness connector or wire isn't damaged. It might have an intermittent connection.
Check your plugs again. See if any or all of them are wet. Make sure you installed the wires correctly. Make sure they are all firing, and in the right order. Check your grounds.
Check for vacuum leaks. Might need to check the injectors for leaks.
You might want to take it to a professional (or even a rotary specialist) if you don't have the tools or aptitude. Get it trucked if you have to.
I assume your PFC's idle setting is ~1000 RPMs?
Last edited by philiprivers; 07-19-23 at 03:10 AM.
07-19-23, 09:14 AM
#11
That would be an incredible vacuum leak if it was. Sounds more like your map sensor may have taken a dump. Put a longer section of vacuum line on it and blow/suck into it. See if it responds on the commander.
Where exactly do you have the vacuum line for the map sensor connected?
Where exactly do you have the vacuum line for the map sensor connected?
07-19-23, 09:21 AM
#12
RX-7 Bad Ass
iTrader: (55)
My money is on the vacuum line to the MAP sensor came off.....
Dale
Dale
07-19-23, 09:32 AM
#13
That's exactly what it sounds like but he said he checked it. Also, when the line comes off it's typically a start and then shut down situation. It will fire up and then shut itself off a second or 2 later. His car idles..... opens the possibility of the map sensor itself being the problem. Although every bad stock map I've ever seen fails and defaults to reading peak boost where his is reading atmospheric.
I'm willing to bet his map sensor is uncalibrated and reads a vacuum with key on like 99% of power fc cars out there. So the evidence points to a few possibilities. Could also be grossly overthrowing.
I'm willing to bet his map sensor is uncalibrated and reads a vacuum with key on like 99% of power fc cars out there. So the evidence points to a few possibilities. Could also be grossly overthrowing.
07-19-23, 10:01 AM
#14
Full Member
Thread Starter
That's exactly what it sounds like but he said he checked it. Also, when the line comes off it's typically a start and then shut down situation. It will fire up and then shut itself off a second or 2 later. His car idles..... opens the possibility of the map sensor itself being the problem. Although every bad stock map I've ever seen fails and defaults to reading peak boost where his is reading atmospheric.
I'm willing to bet his map sensor is uncalibrated and reads a vacuum with key on like 99% of power fc cars out there. So the evidence points to a few possibilities. Could also be grossly overthrowing.
I'm willing to bet his map sensor is uncalibrated and reads a vacuum with key on like 99% of power fc cars out there. So the evidence points to a few possibilities. Could also be grossly overthrowing.
also my map sensor is plugged into the the nipple on the side of the uim closest to the throttle body.
07-19-23, 11:58 AM
#17
Full Member
Thread Starter
Last edited by philiprivers; 07-19-23 at 12:00 PM.
07-19-23, 12:59 PM
#19
Full Member
Thread Starter
Will applying a artificial 400mmHg vacuum to MAP sensor while the car is running give me an idea if the sensor is working or not? Or will that potentially damage the engine if there is a massive vacuum leak somewhere.
07-19-23, 01:20 PM
#20
Tricking the map into seeing what idle vacuum would be while running the engine will be fine and is an excellent idea. You don't necessarily have to have it running to do the test though. Key on, apply the vacuum and see if it will even reach -400. I think what banzai might be on to is it may be possible the filter is to blame. Maybe something small is stuck in there and causing an issue. Remove the filter and run the vacuum line straight to verify.
Your idea to run it while applying the vacuum will work and the motor wont hurt itself at idle while doing it. You will want to start it and gradually apply the vacuum while it's running. In theory, it will run better as the applied vacuum increases.
Just so you know, even with a paper LIM gasket that has failed, you won't see atmospheric on the map sensor and that is a pretty big leak in itself. Evidence is really pointing to a failed map sensor. If default key on (before your current issue) you're seeing 0.00 then whoever tuned your car calibrated the map sensor and that's pretty cool and rare honestly lol.
With the map reading not responding to idle vacuum then it indicates the line is not seeing the intake manifold (POST throttle body) at all, the line itself is somehow compromised completely and is not seeing intake manifold vacuum, or the map sensor has failed. Even with a cut or hole in the vacuum line, it will still see something at idle and you're saying it's seeing nothing.
To eliminate the wiring of the map sensor as an option, you can look at the sensor check screen on the commander. If you look at pim voltage, it should be a value and not just a black highlighted area. You can test it by unplugging the map sensor and seeing if the pim voltage goes black
Your idea to run it while applying the vacuum will work and the motor wont hurt itself at idle while doing it. You will want to start it and gradually apply the vacuum while it's running. In theory, it will run better as the applied vacuum increases.
Just so you know, even with a paper LIM gasket that has failed, you won't see atmospheric on the map sensor and that is a pretty big leak in itself. Evidence is really pointing to a failed map sensor. If default key on (before your current issue) you're seeing 0.00 then whoever tuned your car calibrated the map sensor and that's pretty cool and rare honestly lol.
With the map reading not responding to idle vacuum then it indicates the line is not seeing the intake manifold (POST throttle body) at all, the line itself is somehow compromised completely and is not seeing intake manifold vacuum, or the map sensor has failed. Even with a cut or hole in the vacuum line, it will still see something at idle and you're saying it's seeing nothing.
To eliminate the wiring of the map sensor as an option, you can look at the sensor check screen on the commander. If you look at pim voltage, it should be a value and not just a black highlighted area. You can test it by unplugging the map sensor and seeing if the pim voltage goes black
07-19-23, 01:50 PM
#21
Full Member
Thread Starter
Tricking the map into seeing what idle vacuum would be while running the engine will be fine and is an excellent idea. You don't necessarily have to have it running to do the test though. Key on, apply the vacuum and see if it will even reach -400. I think what banzai might be on to is it may be possible the filter is to blame. Maybe something small is stuck in there and causing an issue. Remove the filter and run the vacuum line straight to verify.
Your idea to run it while applying the vacuum will work and the motor wont hurt itself at idle while doing it. You will want to start it and gradually apply the vacuum while it's running. In theory, it will run better as the applied vacuum increases.
Just so you know, even with a paper LIM gasket that has failed, you won't see atmospheric on the map sensor and that is a pretty big leak in itself. Evidence is really pointing to a failed map sensor. If default key on (before your current issue) you're seeing 0.00 then whoever tuned your car calibrated the map sensor and that's pretty cool and rare honestly lol.
With the map reading not responding to idle vacuum then it indicates the line is not seeing the intake manifold (POST throttle body) at all, the line itself is somehow compromised completely and is not seeing intake manifold vacuum, or the map sensor has failed. Even with a cut or hole in the vacuum line, it will still see something at idle and you're saying it's seeing nothing.
To eliminate the wiring of the map sensor as an option, you can look at the sensor check screen on the commander. If you look at pim voltage, it should be a value and not just a black highlighted area. You can test it by unplugging the map sensor and seeing if the pim voltage goes black
Your idea to run it while applying the vacuum will work and the motor wont hurt itself at idle while doing it. You will want to start it and gradually apply the vacuum while it's running. In theory, it will run better as the applied vacuum increases.
Just so you know, even with a paper LIM gasket that has failed, you won't see atmospheric on the map sensor and that is a pretty big leak in itself. Evidence is really pointing to a failed map sensor. If default key on (before your current issue) you're seeing 0.00 then whoever tuned your car calibrated the map sensor and that's pretty cool and rare honestly lol.
With the map reading not responding to idle vacuum then it indicates the line is not seeing the intake manifold (POST throttle body) at all, the line itself is somehow compromised completely and is not seeing intake manifold vacuum, or the map sensor has failed. Even with a cut or hole in the vacuum line, it will still see something at idle and you're saying it's seeing nothing.
To eliminate the wiring of the map sensor as an option, you can look at the sensor check screen on the commander. If you look at pim voltage, it should be a value and not just a black highlighted area. You can test it by unplugging the map sensor and seeing if the pim voltage goes black
I will try and get my hands on a known good MAP sensor to plug and run in my car. I also was thinking maybe my MAP sensor wasn’t calibrated. It could be so far off baseline that when I’m blowing and sucking into the vacuum line I’m going way more than 400mmHg but that’s just what it is reading
I am also going to try and get my hands on a pressure gauge to plug into the back of my UIM where a boost sensor would go. To see if that is reading normally or is showing 0 at idle as well.
Thank you for the help and suggestions. I am from Tampa so if I ever end up there again I know where I will go for rotary work!
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FDAUTO (07-19-23)
07-19-23, 06:38 PM
#23
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Thread Starter
okay I have done some tests and I can unfortunately confirm my MAP sensor is functioning correctly.
video of my car running with boost visible on my PFC
https://youtube.com/shorts/GomHmxPWWGI?feature=share
I borrowed a known good map sensor and did the same suck and blow calibration test as I did with my original and the numbers matched up pretty similarly.
First I removed the filter and started the car with the new MAP and it was running the same.
Secondly I moved the MAP connection to the end of the UIM where the boost gauge nipple goes and started the car, again same symptoms.
Then for the third and final test I plugged both holes on the UIM and gave it the good ol calibrated 450mmHg suck and started the car. againnn the car was running bad and then it stalled out.
I think this confirms the massive unusual vacuum leak somewhere in my engine…
edit, I just did the voltage check and when I unplug the MAP sensor the voltage spikes from 2.62 to 4.84.
Last edited by philiprivers; 07-19-23 at 06:43 PM.
07-19-23, 07:11 PM
#24
Eats, Sleeps, Dreams Rotary
okay I have done some tests and I can unfortunately confirm my MAP sensor is functioning correctly.
video of my car running with boost visible on my PFC
https://youtube.com/shorts/GomHmxPWWGI?feature=share
I borrowed a known good map sensor and did the same suck and blow calibration test as I did with my original and the numbers matched up pretty similarly.
First I removed the filter and started the car with the new MAP and it was running the same.
Secondly I moved the MAP connection to the end of the UIM where the boost gauge nipple goes and started the car, again same symptoms.
Then for the third and final test I plugged both holes on the UIM and gave it the good ol calibrated 450mmHg suck and started the car. againnn the car was running bad and then it stalled out.
I think this confirms the massive unusual vacuum leak somewhere in my engine…
edit, I just did the voltage check and when I unplug the MAP sensor the voltage spikes from 2.62 to 4.84.
video of my car running with boost visible on my PFC
https://youtube.com/shorts/GomHmxPWWGI?feature=share
I borrowed a known good map sensor and did the same suck and blow calibration test as I did with my original and the numbers matched up pretty similarly.
First I removed the filter and started the car with the new MAP and it was running the same.
Secondly I moved the MAP connection to the end of the UIM where the boost gauge nipple goes and started the car, again same symptoms.
Then for the third and final test I plugged both holes on the UIM and gave it the good ol calibrated 450mmHg suck and started the car. againnn the car was running bad and then it stalled out.
I think this confirms the massive unusual vacuum leak somewhere in my engine…
edit, I just did the voltage check and when I unplug the MAP sensor the voltage spikes from 2.62 to 4.84.
FWIW, map sensors only read exactly zero at sea level when the air is dry. It's normal for it to be slightly off when the engine isn't running. Not by much, though...
07-19-23, 07:34 PM
#25
Full Member
Thread Starter
If you have access to a source of compressed air, do a boost leak test. More effective than trying to ferret out vacuum leaks. It's very easy if you have an aftermarket intake.
FWIW, map sensors only read exactly zero at sea level when the air is dry. It's normal for it to be slightly off when the engine isn't running. Not by much, though...
FWIW, map sensors only read exactly zero at sea level when the air is dry. It's normal for it to be slightly off when the engine isn't running. Not by much, though...