I'm having major dramas starting my car when it's cold. When I turn the key on I can clearly hear the pump prime and stop when it gets pressure. Since it started happening I've replaced the injectors for cleaned and tested ones, replaced the iacv hoses for brand new ones, the car has a brand new engine wiring harness and I've checked the other pipes and hoses for cracks. To get the car started in have to remove the clutch booster hose from the balance pipe and spray fuel into there with a small hand sprayer. It starts instantly this way and starts pretty easily when it's warmed up but still needs a few pumps on the pedal. Any ideas what's going on here?
Nissan Factory Service Manual. Fuel & Emissions Section Trouble Diagnosis Trouble Diagnostic Procedure 4 - Hard To Start Or Impossible To Start When The Engine Is Cold.
My money's on the Air Regulator...... Its job is to raise the idle while the engine is warming up, gradually reducing to normal idle as operating temp increases.
Just consulted the manual and it may be the air regulator. This sux because I just replaced the reg and iacv a little while back trying to fix this problem. Maybe the ones I bought were no good.
Maybe they are..... .....however it is preferable to test components & verify they are defective before replacing them, as it's possible the fault could be related to the wiring to the component, rather than the part itself. It may be worthwhile conducting a fuel pressure test while you are sorting out this issue. The test procedure outlined in the FSM terminates at the ECU, therefore it's possible though uncommon, the ECU could turn out to be the issue.
Check the temperature sender for the e.c.u . It is the 2 wire one. If it is playing up the e.c.u thinks the motor is a different temperature to what it actually is and it will effect the starting and running. Cheers Dave
So I swapped over the air regulator for a different one and it still doesn't start, I've ordered a new temp sensor hopefully that'll make a difference.
None of the air bypass system components will have any effect on cold starting. Only how fast the thing idles when cold. Pumping the throttle does nothing other than make you feel good! Dave is on to the money with a dodgey coolant temp sensor (CTS) or its wiring but you say the car has a new engine loom..? If the cts is faulty, the ecu will consider the engine at *blah* degrees temp. i cant remember the figure but its usually enough to get it going in most cases and stop it from flooding out when hotter. E
The default setting is 25* -this is what it will drop to if the CTS is disconnected. As resistance decreases the ecu registers hotter temps. Get the car up to temp (verify with I/R thermometer) and check resistance across the two pins.
Incorrect........ When the engine temperature sensor (also the fuel temperature sensor) have output voltage outside predetermined parameters, the temperature is fixed at 20Cdeg while starting and 80Cdeg once the engine is running. So, if the temp sensor is faulty, the motor should still start but will probably have trouble idling.
20/25 is much of a muchness... I'm not sure about 80 when running I went through this recently with ECU talk connected troubleshooting a TWD. You're probably right and I saw 20* with sensor disconnected key in "on" as opposed to engine running. In any case point stands if the sender is suspect checking the restistance against the spec in the manual will give a pretty clear diagnosis
It was the CTS. Put a new one in this morning and it started up instantly. Thanks for your help guys the sensor is something I would never have thought to check.
