So I flushed my cooling system the other day and replaced the thermostat, thermostat housing, sensor, radiator cap, etc. Flushed the heater core. And now.....she takes about 5-7 full seconds to start up and sputters a bit before evening out. Before this she started immediately and smoothly no problem. Does anyone know what might be causing this? I'm thinking I MAY have gotten something wet but I was pretty careful.

So far I've replaced the distributor cap, rotor, wires, and plugs, CPS, and the problem persists. Fuel pump is confirmed working, ("poor man's prime" does not solve the issue). All injectors are firing and none are leaking. I'm at a loss and need help! I'm tempted to just keep replacing parts until it fixes itself. Next up would be the TPS and MAP sensor but I've spent enough already that I'd like to truly diagnosis before buying more parts.

 

What year and model?

 

1994 4.0

 

Unplug the thermostat sensor and try to start. It massively controls fuel mix based on temp. If it is reading too warm it leans out fuel and too cold it richens the mix. Since you just changed it , it could be bad.

 

The sensor would the only thing I can think of to have any influence on the starting issue. Unless anything got soaked during the coolant works, there is not much else that should have been affected by just doing a coolant flush.

 

The wires to that temp sensor are known to break too.

 

Check the connector to the cam sensor. The cam sensor tell the PCM the firing order to sync injectors to their respective cylinders. The PCM will figure it out but may take a few extra cranks. Could have gotten wet while flushing.

 

I'm taking notes!!! Thanks guys I'll ponder these and check the sensors thoroughly

 

A broken wire to the sensor sets a check engine light...as does disconnecting it, but it sends it into pre- program mode that usually works well

 

UPDATE: i put the old sensor back in, and woulda y know it, the ****er started right up. now i'm not sure if i should get a NEW new sensor or just roll with the old one until i know it's toast. Big thanks for suggesting to look there, i would not have suspected it

 

Good job. Just role with it the old working one and see if its indeed that.

New parts being faulty out of the box is the worst for troubleshooting. Next to intermittent electrical problems 🤣

Safe travels