Occasional starting issue - any suggestions?

[Setanta]

I have a problem with starting with my SiR. It seems to be more of an issue when the temperatures are high 28-40 degrees Celsius although quite often it isn't an issue.

Occasionally the car will either crank but not fire or briefly fire up and then shut down. On cranking there is spark through the leads but spraying aerostart down the throttle body won't kick the engine over. Repeated attempts have the same result. After leaving the engine for 15minutes to an hour it can usually be started. Engine bay temps at the time of cranking range from high to cool (black car, it can build up a lot of heat under there even if the engine hasnt been used in hours). Interior temps on the other hand can be quite hot.

It really is an occasional issue but it's got me beat (and stranded) when it happens. It seems to be a day thing not a night.

Engine is a B16A from factory as are all the electricals. Battery is new, starter motor works fine, alternator has been rebuilt and the car is regularly services. The spark plugs have about 10,000kms on them.

I've never experienced the issue before but am thinking its the main relay if the solder has dried up. Does that sound about right?

Any suggestions would be appreciated.

Cheers
Pete

[GTA]

could be main relay. thats the usual sound of one going out but mine wasnt when it did that. mine wouldnt start sometime usually after sitting for a little while. it ended up being my ignition switch going kuput, i totally lost the ON position, i has ACC and Start but no on.

[88_SC_CRX_Si]

Are you hearing a click, a second or two after turning the key to the on postion...?

I would start looking at the coil and igniter, if the Main Relay checks out OK. Sense it tends to sound like failing ignition component due to heat soaking.

Another thing... which I doubt, is the ECT sensor. When it's failing it will tell the ECU that engine is cold. Even tho it's at operating temp or higher due to heat soaking, and needs more gas to start. Which in turn will just flood the engine instead...

Sad to Say.... These types of problems are pretty hard to guess. Since it takes a voltmeter and ocelliscope, to properly figure out whats wrong with what part. You may have to wait until it finally does die, in order to save $$$$ on re-placing parts that did not need it....

BTDT waayyy to many times...