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-   -   91 s5 na idle/running issue (https://www.rx7club.com/new-member-rx-7-technical-256/91-s5-na-idle-running-issue-1122250/)

Osiel Carizales 01-07-18 09:31 AM

91 s5 na idle/running issue
 
I have a 91 Mazda RX7 I rebuilt the motor about 5000 miles ago. Currently has 135,xxx miles I mostly use it to burn tires and cruise on Sundays.
Last Friday I was revving it pretty high and let off the gas for a big back fire. Going about 80mph when I went to give it gas it lost power. I pulled over and it cranked back on. But its very slow at revving up now. I hear the afm making a thumping noise. Almost like the air pressure is coming back out of the intake. Making the air flow sensor close and open really fast. Going to try another afm and see if it helps.

I drove it home in that condition and it sounds horrible backfiring randomly and almost no power band using 1st 2nd and 3rd with my foot to the floor. When I let off the gas pedal the engine sounds healthy. Like its receiving the proper fuel/air ratio...
I will post back when I figure out something.

insightful 01-07-18 11:02 AM

probably spit some apex seals out the exhaust. do a compression test and i bet you have 0psi on one of the rotors.

Osiel Carizales 01-07-18 12:21 PM

I ran the compression test I got 75 PSI from the front rotor and 35 PSI from the rear rotor I think you are correct

insightful 01-07-18 03:26 PM

you didn't reuse the original apex seals i hope. it's the main reason why an n/a engine would fail so prematurely.

Osiel Carizales 01-07-18 03:35 PM

No I didn't reuse seals
I bought some from aktins rotary and used those I'll post pictures of the damage. Whenever I take it apart so I can get a better understanding of what happened.


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