FC3S problem/need help....PLEASE!!

[Kenjithelonely1]

I have a 87 N/A FC and everytime I give it more than 1/4 throttle it causes the engine to loose power and cut out around 3800RPM, then when you let off it makes a loud backfire. This problem seriously impairs the car and almost prohibits it from being daily driven. We have replaced the air filter, mass airflow sensor, spark plugs, wires, and the leading and trailing coils. If any rotary experts out there have any suggestions, anything would help, thanx.

[SpeedMachine]

So at 3800 it will cut out, or if you give it throttle over 1/4 before 3800 it will cut out? Secondaries are stagging at around 3800, so there could be something wrong there.

[eyecandy]

Originally Posted by SpeedMachine

So at 3800 it will cut out, or if you give it throttle over 1/4 before 3800 it will cut out? Secondaries are stagging at around 3800, so there could be something wrong there.

I thought 4K is when the secondaries come online, whether or not thats the case, the fact that its at a quarter throottle means it probably something else. I would have to say its your TPS, and then a possible dashpot with engine decleration. Last thing I can think of is a bad ECU.

I asume this is stock?

[Drift Alliance]

sounds like secondary stumble, check your grounds sucka!

[SpeedMachine]

Originally Posted by eyecandy

I thought 4K is when the secondaries come online, whether or not thats the case, the fact that its at a quarter throottle means it probably something else. I would have to say its your TPS, and then a possible dashpot with engine decleration. Last thing I can think of is a bad ECU.

I asume this is stock?

No, they stage at 3800 rpm. I highly doubt anything with the dashpot, since I have never seen one go bad. Maybe out of adjustment, but the odds of that and the TPS at the same time are slim to non unless someone has dicked with the settings.

S4 TPS's are only 1/4 throttle units anyway, so over 1/4 throttle, the engine is getting no further signal changes from the TPS until it goes lower than 1/4. That is why I asked him if it was at 3800 it will cut out, or if you give it throttle over 1/4 before 3800 it will cut out.

Either way, I doubt he cares since I asked that 3 days ago and he never replied.

Grounds could be a role as well. Good re-grounding, cleaning the injectors and throwing the stock ECU in the trash will usually cure stuff like this