My old zx2 started to act up lately by hesitating early in the morning when the engine is still cold.Yesterday night when leaving work has been doing the same thing but this time the engine died on me when trying to accelerate.The idle was OK but I felt a strong smell of sulphur coming up.After I left the engine warm up a bit everything came back to normal and I was able to make it home safely.Any idea what could cause that ???

 

Just a few ideas. When the engine is cold, the computer isn't using sensor data to update engine operations - it runs on defined values. After the engine warms up (closed loop) sensor data is used to make adjustments to help the engine run efficiently.

If you don't have a SES light on, I would check for a vacuum leak when cold (spray water all around the intake manifold & brake booster and listen for an RPM drop). Put a fuel pressure gauge on it and see what fuel pressure is VS spec (you can do this with KOEO). I don't have that fuel pressure spec handy - maybe you can google it.

A vacuum leak when cold can be masked when warm by the PCM adjusting fuel trims to counteract the lean condition caused by the vac - eventually, it should turn on the SES lamp.

 

Thank you for the answer I will try it this weekend since the problem seems to get worse.I'll keep you posted with the results.

 

viewing fuel trim will a scan tool is the easiest and best way to find a vacuum leak. when the system goes into closed loop operation (which won't take long with heated 02 sensors) view the fuel trim data. if its adding fuel at idle MT 10% but the drops back to normal (LT 10%) at 2500 rlpm there is a vacuum leak. If its lean at both idle and 2500rpm its not a vacuum leak causing the lean running condition.


you might also want to do a throttle body clean. a dirty tb will cause a longer crank time and the car will fall on its face when transitioning off idle...especially when cold.

 

Just finished cleaning the TB,also replaced couple bad vacuum lines behind the TB,the bad news is...nothing changed,still stumbling.

 

stumbling and hesitation are 2 different things.

post the fuel trim at idle and 2500rpm
post dtc if any
are you describing a lean misfire condition?

 

This morning the car did not start.Engine was cranking but not firing.The "service engine soon" light was blinking fast,the fan went off and there was a clicking noise on the driver's side of the radiator.I noticed the clicking after I disconnected the fan.Any idea what the problem could be???

 

the starting point for any diagnostic is to check for dtc.
post them

 

If the dtc mean the faulty codes there's none.I plugged the OBDII several times but there's no codes.

 

If you have not already done so, it is always a good move to check the ground connections and while doing that also confirm good connections from the battery to the fuse panels. The computer and sensors operate with very low voltages and the slightest poor connection can cause all sorts of problems. If you can, let us know what the part is or looks like that is providing the clicking sounds.