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limp mode?

Old 09-04-16, 04:06 AM
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limp mode?

I have a 1988 Na Rx7 and i was wondering if this model has limp mode cus a problem im having seems like my car is in limp mode,if so what triggers it in this cus theres lots of info around and im reading that s4 omp is mechanical and won't put the car into limp mode.
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Old 09-04-16, 08:23 AM
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Have you tried checking for codes?
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Old 09-04-16, 09:52 AM
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Explain exactly what is happening to your car. S5's have a true limp mode. S4's do not, but they have default modes in case something is wrong w/the sensors or coils which could cause the car to behave in an abnormal manner.
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Old 09-04-16, 01:49 PM
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When in neutral the car will rev up to redline but in gear driving in the bottom end (pre 4k rpm) i can floor it but after 4k i cant give the car more than a little throttle or it like hitting a wall.
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Old 09-04-16, 01:59 PM
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Originally Posted by satch View Post
Explain exactly what is happening to your car. S5's have a true limp mode. S4's do not, but they have default modes in case something is wrong w/the sensors or coils which could cause the car to behave in an abnormal manner.
I also have New Ngk Plugs+wires,Walbro oem fuel pump,new fuel filter,new maf sensor and coolant temperature sensor if you needed more info
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Old 09-04-16, 02:00 PM
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Originally Posted by Rikk View Post
Have you tried checking for codes?
no i haven't had the chance cus the car isnt legal im trying to find a local place with a code reader i can bring the car down on trailer to get them read
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Old 09-04-16, 02:14 PM
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Code reader won't work on your car (too old and thus code readers work for the FD and not the FC). Secondary injectors work at 3800 rpm and engine under load. Reving does not create load thus why you can rev and pass through the barrier you are not able to while driving. You need to check the output wire of the pressure sensor. That wire (Brown/Red) should read 3.5 to 4 volts w/key to on. The AFM you replaced could be faulty for it helps create load along w/the TPS and pressure sensor.

You could also have a ground issue which is prevalent on your car and that issue will prevent the secondary injectors from kicking in when they are supposed to. Your pressure sensor has 4 wires. you already know about the Brown/Red wire. the other 3 wires should read as follows. Black/White 12 volts w/key to on. Brown/White 5 volts w/key to on. The 4th wire is the ground and thus should have 0 volts w/key to on. If this ground wire is tapped into and the new wire run to the engine housing then that will help overcome a grounding issue.

Also, if the TPS were unplugged and the pressure sensor's vacuum hose removed that will cause load on the engine thus when reving in neutral you can create load on the car while it is sitting still.


How to check S4 error codes:

http://fc3spro.com/TECH/HOWTO/ERRORC...KI/zerror.html

And the oem pump you speak of is designed for the NA and not turbo? Turbo pump is overkill for an NA.

Last edited by satch; 09-04-16 at 02:26 PM.
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Old 09-04-16, 10:14 PM
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Originally Posted by satch View Post
Code reader won't work on your car (too old and thus code readers work for the FD and not the FC). Secondary injectors work at 3800 rpm and engine under load. Reving does not create load thus why you can rev and pass through the barrier you are not able to while driving. You need to check the output wire of the pressure sensor. That wire (Brown/Red) should read 3.5 to 4 volts w/key to on. The AFM you replaced could be faulty for it helps create load along w/the TPS and pressure sensor.

You could also have a ground issue which is prevalent on your car and that issue will prevent the secondary injectors from kicking in when they are supposed to. Your pressure sensor has 4 wires. you already know about the Brown/Red wire. the other 3 wires should read as follows. Black/White 12 volts w/key to on. Brown/White 5 volts w/key to on. The 4th wire is the ground and thus should have 0 volts w/key to on. If this ground wire is tapped into and the new wire run to the engine housing then that will help overcome a grounding issue.

Also, if the TPS were unplugged and the pressure sensor's vacuum hose removed that will cause load on the engine thus when reving in neutral you can create load on the car while it is sitting still.


How to check S4 error codes:

FC3S Pro v2.0:&nbsp How-To - Zenki FC3S Error Codes

And the oem pump you speak of is designed for the NA and not turbo? Turbo pump is overkill for an NA.

The car had this problem before and after the afm swap and the new one is guarenteed by cardone,yes the fuel pump is the Na oem pump and not the turbo one. I can check the other stuff tommorow, can you remind me where my presssure sensor is? im thinking its the little box near the air filter box
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Old 09-04-16, 10:46 PM
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Reman AFM's are mostly garbage. Never heard of a member on this site using one and having good results. You would be better off getting one from the classifieds section on this site. And why did you replace the AFM originally? Lastly, you were given the wire colors for the pressure sensor so that will tell you if you have the right sensor or not.
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Old 09-05-16, 11:48 AM
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Restrictor Pill in the Altitude Pressure Sensor Vacuum Line? Someone replaced the line & forgot this little doo-dad inside? Seems like an easy thing to forget & the ECU thinks your underwater or otherwise freaks out from excess pressure pulses to the sensor.

of course I say this all the time & don't have a clue... You could pull the line & stick a piece of wire or something in the hose to see if the restrictor is in there or not...
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Old 09-05-16, 12:19 PM
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Originally Posted by satch View Post
Code reader won't work on your car (too old and thus code readers work for the FD and not the FC). Secondary injectors work at 3800 rpm and engine under load. Reving does not create load thus why you can rev and pass through the barrier you are not able to while driving. You need to check the output wire of the pressure sensor. That wire (Brown/Red) should read 3.5 to 4 volts w/key to on. The AFM you replaced could be faulty for it helps create load along w/the TPS and pressure sensor.

You could also have a ground issue which is prevalent on your car and that issue will prevent the secondary injectors from kicking in when they are supposed to. Your pressure sensor has 4 wires. you already know about the Brown/Red wire. the other 3 wires should read as follows. Black/White 12 volts w/key to on. Brown/White 5 volts w/key to on. The 4th wire is the ground and thus should have 0 volts w/key to on. If this ground wire is tapped into and the new wire run to the engine housing then that will help overcome a grounding issue.

Also, if the TPS were unplugged and the pressure sensor's vacuum hose removed that will cause load on the engine thus when reving in neutral you can create load on the car while it is sitting still.


How to check S4 error codes:

FC3S Pro v2.0:&nbsp How-To - Zenki FC3S Error Codes

And the oem pump you speak of is designed for the NA and not turbo? Turbo pump is overkill for an NA.
i only have 10.5v to the wire that should be 12v, is this due to a weak battery? Others are same volts as what you told me and i unhooked the line from the pressure sensor without disconnecting the tps and it made it so i can experience the issue while the car is sitting still, when it hits that point at 3800 rpm the car also starts smoking like crazy.

Last edited by rx7fan5645; 09-05-16 at 01:09 PM.
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Old 09-05-16, 12:58 PM
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Originally Posted by rx7fan5645 View Post
i only have 10.5v to the wire that should be 12v, is this due to a weak battery?
You obviously have a voltmeter, check the battery and see.
At rest (car off) you'd like @12.4v across the terminals and with it running you'd expect 14.4v or so.
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Old 09-05-16, 01:00 PM
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Could be that, could be resistance in the wire, etc.
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Old 09-05-16, 02:54 PM
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What is this next to the boost sensor on the mounting bracket for the air filter box. it looks like the thing sticking out the top is broke off
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Old 09-05-16, 04:23 PM
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It's the variable resistor which is used to fine tune the fuel mixture.
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Old 09-05-16, 04:53 PM
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Originally Posted by satch View Post
It's the variable resistor which is used to fine tune the fuel mixture.
should i replace that or turn it any my car is running really rich
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Old 09-05-16, 05:03 PM
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Did a few things and now with the pressure tube and tps unhooked its not getting caught at 4k anymore its going right through so it may be fixed but i cant go for a ride cus its memorial day and cops are out(car isnt road legal). ill take it out tommorow and let you guys know.The car is smoking really bad right now also.
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Old 09-05-16, 06:05 PM
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W/the TPS unplugged and the vacuum hose to the pressure sensor not connected you are taking two sensors out of the equation thus one of them might be your problem. You'll find out sooner or later.
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Old 09-05-16, 10:41 PM
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Originally Posted by satch View Post
W/the TPS unplugged and the vacuum hose to the pressure sensor not connected you are taking two sensors out of the equation thus one of them might be your problem. You'll find out sooner or later.
ive tested my tps before and its good so you think i should replace my pressure senser?
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Old 09-05-16, 11:50 PM
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You don't replace until you know first off. Secondly, you were given the expected voltage readings for the sensor. thirdly, there are more than one way to test the TPS and that would be the sweep test.

Last edited by satch; 09-06-16 at 12:10 AM.
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Old 09-06-16, 02:49 PM
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Originally Posted by satch View Post
You don't replace until you know first off. Secondly, you were given the expected voltage readings for the sensor. thirdly, there are more than one way to test the TPS and that would be the sweep test.
voltages on senser were good and i spliced in a ground like you told me and didnt make a difference. should i try to get a video to show you what its doing?
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Old 09-06-16, 02:54 PM
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How did you test the TPS? The TPS voltage on the Green/Red wire should gradually increase from close to 1 volt to about 4.5 volts as the piston on the TPS becomes fully extended (test is done w/an analog meter). What was the reading on the Brown/Red wire of the pressure sensor w/key to on?

Last edited by satch; 09-06-16 at 03:00 PM.
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Old 09-06-16, 03:24 PM
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Originally Posted by satch View Post
How did you test the TPS? The TPS voltage on the Green/Red wire should gradually increase from close to 1 volt to about 4.5 volts as the piston on the TPS becomes fully extended (test is done w/an analog meter). What was the reading on the Brown/Red wire of the pressure sensor w/key to on?
i did that it started at 1 ohn then went up graudually to 4.5 ohms at like 1/3 throttle then stayed 4.5 through the rest of the throttle
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Old 09-06-16, 03:36 PM
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And what about the Brown/Red wire of the pressure sensor?

Has your car always had this problem or not?
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Old 09-06-16, 05:16 PM
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Originally Posted by satch View Post
And what about the Brown/Red wire of the pressure sensor?

Has your car always had this problem or not?
yes since ive owned it this problem has occured, i also checked the codes per your guide and my leds came on for 3 sec light they should but didnt throw any codes after.
Pressure senser readings were 3.46,11.88 and 4.95v
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