vwfreak

car is an 89 90Q- recent engine replacement.
car starts fine when cold, but is hard to start or wont start at all when hot- turns over but wont catch. hit it with ether and it starts right up. any ideas?

dtompsett

Vacuum leaks? Cold start valve not working? Bad temp sensor giving false temp signal?

AudiSport4000

Sounds like a vac leak to me

vwfreak

I did the injector seals and injector cup seals, I have verified the intake boot is properly clamped, replaced the upper intake gasket and throttle body gasket, I sprayed ether around the intake and the engine didnt change pitch, so it may be a vacuum leak but if so I dont know where to check for it.

I can attempt to verify the cold start valve fires but shouldnt it not work on hot start up anyway? My CIS knowledge (based mostly on K-Basic and K-Jetronic) that the thermotime switch on the older cars prevents the cold start valve from activating when hot.

now, temp sensor could be a real possibility, as the oil pressure switch on the car seems to be bad too as it shows zero oil pressure when running even though the engine is fine. so the temp switch could be bad as well.

I replaced an NG with an NF but left the sensors intact so they might need to be switched back to the NG sensors? I did swap the throttle switches and the knock sensor.