Why does my rx7 fd3s behave different everytime i drive it?
 

Hello everyone, a few months ago i picked up a 1993 rx7 fd3s. The car was automatic and had a busted engine. I changed the engine and also changed it to manual. The car is really amazing but everytime i drive it it behaves different power wise. For example, sometimes the car would behave very sluggish and would not go on boost or sometimes when cruising at about 3000 rpms the car would jerk violently for a little and at other times it would get fuel cut at about 5000 rpms. The car is fully stock. Any suggestions?

When you changed engines and transmissions, did you change to a manual ECU?

yes i did

No codes or CHeck Engine Light? Did you make any modifications at all to the engine? Air pump and all emissions intact?

[QUOTE=Sgtblue;12178142]No codes or CHeck Engine Light? Did you make any modifications at all to the engine? Air pump and all emissions intact?[/QUOTE
no engine check light or codes. Only modification to engine is the performance air filter. Didnt check the emissions or air pump but im sure theyre in tact. I can check though

Is your car Left hand drive or Right hand drive? IIRC, if it's Right hand drive you may have to pull the codes as some don't have a check engine light...
---> Check Engine Light Codes

Check your tps voltages for narrow and full range. Sounds like you got something wonky going on with a sensor or something. To what extent did to change the motor? Did you swap EVERYTHING or just the block and swap over all your external parts? When you did the MT swap did you do the applicable wiring modifications? If you have your other throttle body, assuming it was a complete swap, swap it with the one currently on the car and see if it makes a difference.

Knocked off the MAP sensor line?

As others have suggested.... You need to verify your TPS voltages are in spec. Another drivability culprit is the MAP sensor (Located on the firewall).

With the age of these cars, the heat they generate under hood, and how many of them have been modified and/or screwed with... wiring is becoming more & more of an issue.

I've seen quite a few wiring issues that caused intermittent issues (not just on FDs), anything from loose grounds to terminals pulling in and out of the connector housing.

With that being said, a great upgrade is the PowerFC with the commander. It really helps diagnosis issues as all you have the data readout right on the commander. I know this has saved me a ton of aggravation from being able to quick reference my sensors.