supersc30

Alright I have a 93 sc300. I just did the spark plugs and cap and rotor and a new ecu for the car. But it sometimes dies and comes back on when I'm slowly accelerating but if I just push the peddal half way it's fine. And doesn't doesn't die. Best example I can give is like when your stuck in traffic and go to accelerate a Lil bit bamm dies and turns it self back on without me doing anything....it's ****ing weird just to say. Its not throwing any codes either But anything can help. Thank you

mmarshall

Sorry I can't be any more specific, but that could be any one of a number of glitches......a bad Throttle-Position-Sensor (TPS), an overly-lean mixture coming off idle from a bad oxygen sensor, a bad ECU for the transmission that momentarily gets mixed-up as to which gear it should start off in (assuming it's an automatic....some SC manuals were built), a weak fuel pump that is not delivering enough fuel for initial acceleration, and several other things. You may need to have it analyzed in a shop....and your car has the older, pre-1996 OBD I computer system that is simpler and less-sophisticated than the post-1996 OBD II system.

Oh, and BTW.....I didn't know the '93 SC had a cap and rotor. Many engines, by then, had gone to individual ignition and coils on each spark plug.

CleanSC

Problems like these are usually not solved over keyboards as testing and observations need to be done to properly and quickly get to the root of driveability concerns.

That being said,

Unplug the throttle position sensor and drive it. Report back.

supersc30

Nothing changed with unplugging the throttle position sensor. Could it possible be the other one? Just can't figure out when I barely feather the throttle it dies then comes back on but if you give it half throttle it Flys and doesn't miss a beat and sometimes almost dies when I let off the gas after barely hitting it

CleanSC

To confirm, you tried the TPS and not the idle control valve, correct?

If so, try the maf sensor.

If no chance then you're going to need someone with the right equipment to take a look at it.

supersc30

Yes did the tps and I have all the right tools and it's at a shop I'm doing the work with my mechanic cuz he is stumped and did the maff

CleanSC

Does your mech know how to read secondary ignition waveforms? If so scope the secondary ignition while it's stumbling/misfiring to see what they look like. This will reveal what exactly is happening inside the cylinder when this happens.

It would also verify if your ignition coil is bad.

Have to tested the MAF and the TPS? Not just unplug, but test?

This "new" ecu, is it really new, or a used unit? OEM?

On the fuel side, have you verified proper fuel pressure? If you scope the fuel injectors, you can verify they are working electrically and opening mechanically. Scope the fuel pump to verify it's not failing or had bad commutators.

You haven't modified the EVAP system on the car, correct?

How old is the gas in the car?