94 Prizm 4FAE hesitation

[skipper20_3]

94 Prizm 4FAE, 1.6L, AT, AC, 114K --bought it used (clean car). Rough at idle and spark knock -- not running real smooth. Replaced: Ign wires, plugs, cap, rotor, air and fuel filters.... timing belt (kinda big job but I've done it before on other vehicles). Still runs the same. Checked timing-- and it was @25deg -- way off. Re-set timing to 10 deg per the specs --now idles very smooth -- but stutters very bad during acceleration -- not streetable.With timing light connected -- light goes dark during throttle movement(engine stutters) -- then signal resumes when throttle stationary at any position. Same condition at all 4 wires. Not getting any OBD1 codes. I can usually fix about anything, but this has me baffled. Appreciate any thoughts......

[blb]

Check the Throttle Position Sensor

[94_Rolla_Guy]

did you put it in diagnostic mode when you set the timming you have to have it up to temp and TE1 and E1 jumpered in the diagnostic connector before you set the timming

Reason i ask is because 25 deg is about right for if its not jumpered

[Bitter]

so its loosing spark when you open the throttle.
put the light on the other wires as well and see which ones are going dead, check for any spark leaks.

[skipper20_3]

Yes, I jumpered between te1/e1 when I set the timing. The timing originally was 25deg -- also when jumpered. I also visually looked at night -- was not able to see any spark leaks. The spark goes dark across a 4 cylinders when accelerating. I've swapped back to the old plugs/wires/cap and rotor -- no difference. Tonight I will check the TPS -- can anyone explain how TPS problem may affect acceleration?... My Haynes manual says the TPS controls fuel delivery... not spark control. Haynes manual says the spark knock sensor retards timing during knock -- anyone have experience with SK sensor failure?....Thanks to all.....

[skipper20_3]

Checked the tps -- didn't find a problem. Even went to a salvage yard and picked up another --just in case. Swapped it out -- no difference. It idles great -- but sputters so bad during acceleration it can't be driven......

[tashirosgt]

If the sparks go dark when you accelerate, doesn't that indicate a problem with the distributor? Besides the distributor itself, what else could it be? The other possibilities seem too strange: some problem that caused the camshaft not to rotate, some strange condition in the cylinder itself that prevented the spark or some interruption to the input voltage on the distributor. ( If you have a volt meter with a quick enough response, you could check the input voltage to the distributor as you rev the engine. ) Can the air/fuel mixture be so bad that it prevents a spark? I don't know.

[skipper20_3]

I finally got around to replacing the distributor with a reman unit -- now it runs AOK. More than likely the coil? was the root cause of the problem. Now I have a great running Prizm with lots of life left in it. Thank You to all that gave assistance.