So If I'm on the highway and I sit between 3 and 4 grand for too long the car will... umm... studder. It's a fresh rebuild so I'm at a loss of what it could be...

ask questions and I'll answer the best I can... so I can narrow down what it could be.

thanks guys

 

maybe a clogged fuel filter.

 

Yea, check the fuel filter, the sock filter on the pump, the condition of the pump itself (age, voltage, etc...)

And 2nd, make sure your TPS is set properly

And 3rd, make sure your grounds are good.

 

what do you mean by stutter?

Like, cruising between 3-4k rpm with light throttle to stay at same rpm? and it stumbles/stutter?

 

Yeah I buddy just told me it might be my tps... what about my injectors though? could that be it?

 

most probably a filter rather than injectors. by "stutter" does it sound like its starving for fuel?

 

Yes... in a way. It can't be the fuel filter though... it's new... lol

 

You can wire up an LED light to your ECU to tell you whether the problem is occuring when the secondary injectors are turning on or not.

 

I'm taking the injectors out and having them cleaned for $15 a piece. Hopefully that'll solve the problem.

 

in that range the injectors are staging and if driven long enough the ECU will attempt to put the system into closed loop and adjust based off the O2 sensor readings, with the age of these cars the stock O2 sensor is usually dead or near dead.

the rest of it is left up to the fuel system. the ECU takes the TPS reading to know if you are off throttle or not to adjust fuel accordingly and the AFM signal to know how much fuel to inject via air volume.

the fuel system needs to be in decent shape for the injectors to stage properly also, so new fuel filter, good fuel pump voltage at the pump, clean fuel sock, cleaned and balanced injectors, good EGI voltage to the main engine harness and finally a good ground system to the ring loop off the rear rotor housing which feeds ground to the ECU which is triggered to open and close the injectors.


several of those things are usually neglected on these aged cars. check the fuel pump voltage at the pump while driving while the issue is ocurring. cleaning the injectors is also a good idea, set and adjust the TPS properly as well as ignition timing and lastly test the O2 sensor voltage to the ECU to see if it is switching properly meaning it is "alive". cleaning the ground terminal to the ring terminal on the block is also a good idea and possibly adding a ground extension from there to the battery as well.

 

The 02 sensor isn't hooked up now that I think of it... would that solve the problem?

 

it's a good place to start, though the ECU requires a set criteria before it attempts to go into closed loop but if it isn't getting a good signal it may still be trying to force the AFRs up based on preset values.