Ford Repair: Lincoln Town car wont start, lincoln town car, upper intake manifold

Question
I have a 1999 Town car that lately has had  intermittent strt problems. It cranks fine, but doesn't even try to start. Like it has no spark. I wait a few, jiggle key back/forth, shift in/out of neut, nothing. After a few minutes and several attempts to crank up to 5 secs each, it will just start up like nothing was wrong! Then runs fine and may not do it for several days. Sometimes though, it will do it every time I shut it off for a couple days.

Last time it was consistently failing, I took it to my mech. He tried it, it started right up, then tried to make it faisl a bunch of times and it won't do it. Worked fine for a couple weeks, then last night just failed to start again. Did it 7 times since!

I'm stumped. Lincoln mech said to watch for check engine light while starting (something about pickup sensor). Check eng light does not come on during crank.

Seems like injectors must be ok since when it starts it runs like a raped ape. NO stalling, no rough idle, nothing. Also, it does not seem to be related to any one condition. Has done it when damp, when dry, full tank, almost empty etc.

Just has a mind of it's own. Impossible to fix since every time I have it in, it works! Need some things to check to isolate, since it only likes doing it to ME!

Thanks in advance.

Answer
My guess is the Idle Air Control Valve (IAC).  When starting the engine and at idle, the throttle plate is closed and the only air entering the engine is through the IAC. This is all controlled by the Powertrain Contol Module. It uses the IAC to allow a small amount of air to enter the engine for starting and to adjust idle speed. The IAC is mounted to the upper intake manifold with two small bolts, and has a small electrical connector on it. It is about two by four inches. It may be sticking closed, you can remove it (be careful, it may have a paper gasket) and clean it out with an Air Intake Cleaner. If this doesn't help, it may have failed and need replacing.  I have also seen a bad Mass Air Flow Sensor cause an intermittent hard starting problem.

I hope this helps,
Dave

I hope this helps,
Dave