My dad has a 88 mazda rx-7 SE,a while ago he blew his apex seals. So he rebuild the engine and took off the non nessary stuff like ac and ect. After it was finished and he put it back it , it started and ran fine and when he went to take it for a spin it has no power it takes off fine and when he is around 4000 rpm it boggs and doesnt have power. My dad has no time to actully check it out anymore and he used to think it was the computer chip so he got a new one and still no difference. I want to help him so it can be fixed and when can ride around and i can have the car later on. This is my first post and it would be great for any help. Thanks , nick.

Check the O2 sensor? I had a T2 that would do that. It ran great under 4krpms, but as soon as the secondary injectors turned on, it would hesitate and stumble like crazy. Found the O2 sensor wire was burned all the way through, so there was absolutely no signal to the ECU and it was just dumping fuel.

My guess is you have an issue with your secondaries, they come on at 3800 rpm, does it fall flat on it's face, then come alive, or does it fall flat on it's face and never come back?



I would suggest having the injectors professionally cleaned or replaced.

It just about falls flat. and has no power

I'd check the O2 senseor then look into the injectors.

It may be that you're in default or "limp home" mode.



The "check engine" light should come on as a test when you first turn on the key.



If it comes on after that, you need to pull the error code.



Check out the link to the manuals in my sig.

You can download & print what you need from the "fuel & emmissions" section.

sounds like the famouse 3500 to 4000 power loss might what to check gorunding wires, all of them.

That's usually a stumble with a free up after around 4,000 though is it not? My grounding issue was the ECU and it stumbled... then came alive, not fell on it's face and never came back.



None the less I just through a topic about grounding in the FAQ's

how would you describe a stumble?



arent the aux ports supposed to "kick in" at 3800 rpm?



because that how it feels in my car.