Questions and Answers

Nissan Stanza Hard Start Hot And Cold Q. 1990 Nissan Stanza 2.4 liter 4 cylinder engine and automatic transmission. It is hard to start cold or hot, but mostly after the car is warm. When the engine is at idle it shakes, but as soon as I drive it the shake goes away and drives like a champ with no noticeable loss of power. I have replaced the plugs, cap and rotor, wires, fuel injectors and fuel filter have been replaced with new parts along with the fuel pump.

The old plugs had some corrosion on them which is best described as a tan powder. Although I have replaced the plugs this made no difference at all in the shaking. I do notice the Check Engine Light comes on once and a while. Funny thing is when the Check Engine Light comes on, I have no issues starting the vehicle. This makes me believe it is a sensor going bad. I have been told it is a "Cold Start Sensor" but I cannot locate it. Any ideas?

Thank you for your time in advance!
James

A. What you need to do first is check all the vacuum lines and make sure they are in good shape. A vacuum leak is the most probable cause for this problem. Once you have done that, and the problem still exists, you will need to pull codes from the computer. Look in my Trouble Shooting and it will tell you how to pull the Diagnostic Trouble Codes and what they are.

Giving the throttle body and IACV a good cleaning will also be a help to starting. My article Cleaning Throttle Bodies will take you through it step by step.

Another possibility is the Coolant Temperature Sensor (CTS). A CTS that's reading incorrectly will cause a hard start condition.

Check to be sure the EGR valve is not sticking. You can check it by putting your fingers under the EGR valve and lifting up the diaphragm. It should lift up freely and snap shut. If the engine is running it will make the engine stall when you open it fully.

But I think the important thing is to find out what that DTC is and once we know it we will be able to get the problem fixed.