Ok nobdy bitch about searching because I have specific details. I have a '89 GXL converted to a 5 speed. Now this car has been getting shitty mileage and didn't seem to run right for a while now. Now when the car was an auto I ran it on the track bone stock and it pulled (remember altitude) 20.6@73mph. That was way shitty I know. However after the swap (TII drivetrain w/auto rear end) The car pulled a 1.92 60ft and ran 18.0@73mph. WTF? it trapped at the same speed as the automatic? Since then I've installed straight 2.5" exhaust and have noticed some flames at high rpm. Which is usual of course. But flames randomly coming out of the exhaust at idle? And barely pulling 150 miles on a tank meanwhile my GTU pulled 500 miles? Motor doesn't burn oil whatsoever but exhaust fumes are thick.
So one would assume its running to rich and the timing is off. The engine pushed a consistant 105 p.s.i on both housings. How would I go about getting my mileage and high end power back? The car isn't gutless by no means. But should be running faster.

 

Hmmmm....new O2 sensor, tune up and an s-afc? I dunno...could be anything...

 

you might need new apexi (i dont think i spelt apexi right but its late at night so i dont care ) seals. so its probably time for a rebuild

but i'm no expert so dont take my word on it

 

Read out your 5v sensors from the ECU, while driving if you wish. These sensors' inputs determine your fuel scheduling, so that's the logical place to start...

https://www.rx7club.com/2nd-generation-specific-1986-1992-17/troubleshooting-your-car-ecu-340578/

 

Well out of curiosity I went out and checked on my car. Now 1 year ago I replaced my busted auto with a rebuilt one (then later a 5 speed) and I kinda half assed it back together. My engine light came on after that. Anyways I noticed a plug (two prong) on the drivers side of my manifold was disconnected. Odd. So I connected it and to my surprise my light went off. Also my car felt like a new car. No fire and back fire was at a minimum. Also had a different tone to the exhaust. And my idle was steady! Except it was at 1400rpm. Thats a quick fix. But any idea what that plug was? It has two prongs and is bolted to the lower part on the back side of the intake manifold(drivers side).

FYI- If a motor is pushing a constant 105 p.s.i and doesn't smoke the apex seals are far from needing a rebuild.

 

Intake air temp sensor? Hard to guess, lol...How big was the plug, what color, and how big was the sensor that it connected to?

 

Yep thats the one. I just looked it up. Would that possibly affect my performance and gas mileage? Damn dude right on the nose.

 

Yeah, that's one of the sensors that's used for fuel scheduling, so it's kind of important

 

The others are AFM, TPS, variable resistor, atmospheric pressure sensor, water thermo sensor, and boost sensor...

 

Hmm. So all this time I've been getting half the gas mileage, less HP, and yet iwas a simple plug? I am going to miss the flames. Jeeze no wonder this car ran 18 seconds. Thanks!

 

makes me scared to take mine to the track and i only get 200 miles to a tank is that bad

 

Probably not for exclusive track use, lol...