fc problem with powerloss and and bad mileage
05-31-09, 05:02 PM
#1
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fc problem with powerloss and and bad mileage
i own a 1991 naturally aspirated . i have replaced 02 sensor fuel filter air filter and mass air flow sensor please help
05-31-09, 05:19 PM
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05-31-09, 06:37 PM
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05-31-09, 06:41 PM
#7
well if thats the case then it could be that your secondary injectors are not firing or your 5th/6th ports are not actuating. Im not familiar enough with S5' to be able to give a better diagnosis. But a compression test woul let you know how the seals are doing.
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05-31-09, 06:44 PM
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what is s5 and injectors were my guess haha do you know who rebuilds them ???
05-31-09, 06:47 PM
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how do you do a compression test what numbers am i looking for i know how to do it just is there a conversion formula for correct compression ??/
05-31-09, 07:24 PM
#11
S5 refers to the 89-91 rx7's, as they have a different intake design and other tweaks than the S4's (86-88). To do a compression test you can use a piston compression tester (20bucks at most auto parts stores and walmart) and remove one spark plug, doesnt really matter). screw the tester into that plug hole an crank the car over with the EFI fuses removed so the car cant start, but can still turn over. hold in the valve on the tester (the reset valve as it can be called) so you can watch the needle bounce. you want to see between 90 and 120 psi for each bounce, with each bounce representing a face of the rotor. anything below 90psi is signs of a weakening engine but still drivable. If you get no bounce at all then there is a chance that seal is stuck or gone altogether, signifiying you need a rebuild.
And by rebuild, do you mean engine rebuild or injectors? there are several known and reputable rotary rebuilders around the country, varying from mild to wild rebuild/modding capabilities.
And by rebuild, do you mean engine rebuild or injectors? there are several known and reputable rotary rebuilders around the country, varying from mild to wild rebuild/modding capabilities.
05-31-09, 07:36 PM
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S5 refers to the 89-91 rx7's, as they have a different intake design and other tweaks than the S4's (86-88). To do a compression test you can use a piston compression tester (20bucks at most auto parts stores and walmart) and remove one spark plug, doesnt really matter). screw the tester into that plug hole an crank the car over with the EFI fuses removed so the car cant start, but can still turn over. hold in the valve on the tester (the reset valve as it can be called) so you can watch the needle bounce. you want to see between 90 and 120 psi for each bounce, with each bounce representing a face of the rotor. anything below 90psi is signs of a weakening engine but still drivable. If you get no bounce at all then there is a chance that seal is stuck or gone altogether, signifiying you need a rebuild.
And by rebuild, do you mean engine rebuild or injectors? there are several known and reputable rotary rebuilders around the country, varying from mild to wild rebuild/modding capabilities.
And by rebuild, do you mean engine rebuild or injectors? there are several known and reputable rotary rebuilders around the country, varying from mild to wild rebuild/modding capabilities.
06-01-09, 06:25 PM
#17
6pi (6 port induction, aka 5th and 6th ports or auxiliary ports) is a system on n/a RX7s that opens an extra set of ports at 3800-ish RPM for more power, while keeping them closed at lower RPM for more torque.
Here's a good method for testing them: http://aaroncake.net/RX-7/6porttest.htm
VDI is an additional system on series 5s only, it operates in a similar way so you may be able to test that using the same method.
It sounds plausible to me, having everything closed up down low will net you great torque, but once youy hit the point where all the aux induction systems are supposed to activate, the car would hit a wall. Something worth checking out before you go removing your injectors and stuff.
Here's a good method for testing them: http://aaroncake.net/RX-7/6porttest.htm
VDI is an additional system on series 5s only, it operates in a similar way so you may be able to test that using the same method.
It sounds plausible to me, having everything closed up down low will net you great torque, but once youy hit the point where all the aux induction systems are supposed to activate, the car would hit a wall. Something worth checking out before you go removing your injectors and stuff.
06-03-09, 01:48 AM
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6pi (6 port induction, aka 5th and 6th ports or auxiliary ports) is a system on n/a RX7s that opens an extra set of ports at 3800-ish RPM for more power, while keeping them closed at lower RPM for more torque.
Here's a good method for testing them: http://aaroncake.net/RX-7/6porttest.htm
VDI is an additional system on series 5s only, it operates in a similar way so you may be able to test that using the same method.
It sounds plausible to me, having everything closed up down low will net you great torque, but once youy hit the point where all the aux induction systems are supposed to activate, the car would hit a wall. Something worth checking out before you go removing your injectors and stuff.
Here's a good method for testing them: http://aaroncake.net/RX-7/6porttest.htm
VDI is an additional system on series 5s only, it operates in a similar way so you may be able to test that using the same method.
It sounds plausible to me, having everything closed up down low will net you great torque, but once youy hit the point where all the aux induction systems are supposed to activate, the car would hit a wall. Something worth checking out before you go removing your injectors and stuff.
06-03-09, 01:36 PM
#19
The car can run fine without 6pi or vdi; you'd have less power but nothing noticeable. A lot of people drive this way none-the-wiser until they finally test them. Just like all the other cars on the road that don't even have 6pi or vdi, or just like the 1st-gen rx-7's.
The secondary injectors are needed at 3800rpm+ or you'll get hardly any power, especially as you get higher. I would guess that yours aren't firing or they're clogged or some such. Start looking there.
But that doesn't explain the rotten gas mileage when you're driving below 3800 rpm. That sounds like another problem. Might as well start with a compression test. Or maybe the motor is fubared and it gets worse at higher rpms. Does the problem come gradually (engine or something else) or almost all of the sudden (secondary injectors)?
The secondary injectors are needed at 3800rpm+ or you'll get hardly any power, especially as you get higher. I would guess that yours aren't firing or they're clogged or some such. Start looking there.
But that doesn't explain the rotten gas mileage when you're driving below 3800 rpm. That sounds like another problem. Might as well start with a compression test. Or maybe the motor is fubared and it gets worse at higher rpms. Does the problem come gradually (engine or something else) or almost all of the sudden (secondary injectors)?
06-03-09, 10:52 PM
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The car can run fine without 6pi or vdi; you'd have less power but nothing noticeable. A lot of people drive this way none-the-wiser until they finally test them. Just like all the other cars on the road that don't even have 6pi or vdi, or just like the 1st-gen rx-7's.
The secondary injectors are needed at 3800rpm+ or you'll get hardly any power, especially as you get higher. I would guess that yours aren't firing or they're clogged or some such. Start looking there.
But that doesn't explain the rotten gas mileage when you're driving below 3800 rpm. That sounds like another problem. Might as well start with a compression test. Or maybe the motor is fubared and it gets worse at higher rpms. Does the problem come gradually (engine or something else) or almost all of the sudden (secondary injectors)?
The secondary injectors are needed at 3800rpm+ or you'll get hardly any power, especially as you get higher. I would guess that yours aren't firing or they're clogged or some such. Start looking there.
But that doesn't explain the rotten gas mileage when you're driving below 3800 rpm. That sounds like another problem. Might as well start with a compression test. Or maybe the motor is fubared and it gets worse at higher rpms. Does the problem come gradually (engine or something else) or almost all of the sudden (secondary injectors)?
06-03-09, 11:52 PM
#21
Maybe the primary injectors are partly clogged and the secondaries are completely clogged? 
You could always throw away $10 on some Techron concentrate and see if that helps. But even if it helped a little (and it might not even if the injectors are the problem), the solution would then be to get the injectors professionally cleaned.
You could always throw away $10 on some Techron concentrate and see if that helps. But even if it helped a little (and it might not even if the injectors are the problem), the solution would then be to get the injectors professionally cleaned.
06-04-09, 05:07 PM
#25
New injectors can cost upwards of 250.00 a piece. Witch-hunter performance cleans the injectors for 18.00 a piece. You make that call, lol. How have the tests gone to see if the aux. ports are working? How did the compression test go? Letting us know answers to these questions can help us find the cause of your problem.