I have two friends that have 88 SE 5sp NA cars. BOTH of them have the same problem. At full throttle they hesitate bad, at light throttle they will go to redline but when floored they do it. I have check the ignitions, injectors,all the sensors, mas, throttle sensor, fuel pressure, everything checks out. The Factory mazda dia. tool shows no codes. The three grounds in the engine bay( bolt on driver side harness, The 6 prong plug under the trailing coils, and the tranny harness to the firewall. They both have new motors in them and compression is 90 or better all the way around on both motors. We are at 3000 ft. so the compression is within specs. I have checked everything even replaced the ecu with a spare and nothing. IS there a common problem with 88 SE's Or something. Any Ideas will help. Thanks

 

Common Guys need Ideas

 

put a bigger battery in it? check the entire cars wiring (audio system, horns, lights etc etc...). fuel filter? fuel lines? fuel pump? throttle cable?

 

also make sure the air filter is getting good air supply.

is your voltage staying slighty above 12v? check the alternator at your local autozone.

make sure the alternator belt is nice and tight...

 

there's 4 major grounds, u spoke of 3 except that ecu ground under the intake mani

if its an ecu problem causing that hesitation / stutter ... that's the ground you're looking for ... this weblink saved my car from amazing electrical happenings

http://www.aaroncake.net/rx-7/grounding.htm

 

That ground has been checked. More Ideas please.

 

Clip your ohmmeter on the signal pins of the TPS & AFM.
See if the values make a smooth sweep as you work the plunger or flap.
Any drops or bumps in the sweep of either sensor will freak the ECU.

An unlikely, but possible cause could be a stuck FPR running you lean.
That happened on my turbo, and before I could replace it, the problem went away.

 

fuel filter... fuel filter... fuel filter.

 

i have the exact same problem, and replacing the fuel filter was the first thing i did, and i have also done everything on here. idk what the deal either