Starting issues

[SC457A]

Working is one thing. Proper output is different.

Diagnosing over keyboards is tough as I'm sure you know. You have replaced the secondary ignition system, "cleaned IAT", checked map, coolant, o2's (technically, they dont mean much in start up mode).

Follow the three rules. Right amount of fuel, right amount of compression, spark at right time. I call them the three R's One is missing. I'd bet fuel if I had anything to bet.

[jyro]

when it won't start

do the plugs have fire?

if no, ignition switch

[motoman]

After checking, double checking, and triple checking, the mechanic working on my truck believes my intermittent (sp?) starting issue is being caused by something going bad in the ECU.

Here's the thing, if I buy a new one, hook it up, and it's still having issues, I'm out the entire cost. Is there a way to hookup an ECU to tell is something is bad or has gone out on one?

[motoman]

I ended up picking up a new ECU online and it's going in the truck on Friday. If that doesn't fix the issue then this will probably be the most expensive not needed part that I've ever bought.

[homealone]

might check TFI

I have experienced the exact symptoms do to a faulty TFI. Autozone can check them.

I have also experienced the exact symptoms with a faulty TPS. Those you can test yourself with a volt meter.

[motoman]

I have experienced the exact symptoms do to a faulty TFI. Autozone can check them.

I have also experienced the exact symptoms with a faulty TPS. Those you can test yourself with a volt meter.

Both of those were replaced with the issue still persisting.

[lowthreeohz]

IAT should only effect the fuel trim, i can't see how it would cause a no-start condition. same with coolant temp sensor.