1992 5.7 TBI sputters between 2500-3500 RPM / Acceleration

[rugger55]

Could really use someone's help!!    I've read a ton of threads and bought lots of new parts on suggestions...  My local mechanic shop is 4 weeks out, so I've tried fixing myself.

 

5.7  TBI  stutters badly and backfires when accelerating between 2500 and 4000 RPMs, then cleans up past that.   Even when I accelerate slowly... same effect.

 

Motor :   Have a 1992 5.7 TBI in a Jeep CJ with a 700R4 transmission.   It has been driven infrequently over years, but when I drove it recently it would suddenly die intermittently when I took foot off gas or even underway...  so I bought a new ignition module under the distributor and that fixed it.  No more dying.   But it hesitates/sputters when accelerating hard. (Usually I see the tach start to bounce and hear the sputter at about 2500 RPMs.)   Pretty sure it did this before changing module too.

 

Fuel:   I've checked the fuel psi... which read about 10 psi.  Filter is new.  Injectors "look" even - but I'm no pro.   Fuel is not old.

 

Ignition:    Dist. cap, wires and plugs are new.  So is ignition module (napa version not GM) under the cap.  Timing is at 0 with bypass unplugged. 

 

Ended up getting almost all new sensors cause I said screw it.  Changed Air idle control, throttle position sensor,  MAP sensor and temp sensor.  And the sensor that sits between vacuum between EGR (forget what that is).   Actually tried a new EGR while I was busy wasting money, but new one would not even run... died easily.... and read that I probably had wrong EGR.  Plugged EGR tube to take out of equation, and was back to baseline running (sputter on acceleration), so I put stock EGR back on and we are still at original problem.

 

Would ECM or computer chip be an issue?  What about the ignition module on firewall?  Seems like these would all fail vs have weird issue but I'm at wits end.  There's a pickup coil under distributor too right?

 

Any help would be gold.  

 

 

 

 

 

[Gambithewigbandit]

I also have the same problem with most of the same new/swapped parts except my 1992 Chevy 1500 5.7 is all original and in the all original truck. I have not purchased a new EGR or MAP yet but I swapped most all other sensors, rebuilt TBI, new cap, rotor, wires, plugs, new fuel tank, fuel pump, filter and reset TCU and ECM. So, the only other acronym I can think of is the WTF sensor.