run the engine properly? IE what is the min volts that the ECM can handle to operate properly? Most TTL chips run at 5 volts, but I am not sure what is in this 15 year old computers.

What I am getting at is this. During engine crank we all know the bat sags a bit, maybe like 2-3 volts. I have seen about 8.0volts, even less with my scan tool during engine crank. If the volts is too low, maybe the ECM isn't working properly, as in pulsing the injectors?

I am troubleshooting long crank times when car is hot or warm. At ambient temp car fires up in a sec or less.

 

Low voltages are just all around bad.
Especially for the ignition system. Poor spark during crank and nothing happens combustion wise.

In theory there are voltage corrections that take the injectors way down in voltage and responce, but from what I've seen under 9v and you'll just be lucky it starts. It seems to be the cal is for cold and low voltage. Things get real rich real fast. Rather then gas wash the cylinder walls, I'd suggest getting the motor to spin at like 200+ RPM, and have 10v during crank.

It sounds more like the temp correction for the crank PW needs work. There is also a warm position for the IAC that can be fun.

 

Not so sure about the older stuff we're dealing with, but the newer stuff will start sutting down (Limp In) at 10.5 V and below. If you have stock-ish compression and the voltage is dropping that low, I'd be load testing the battery to make sure it's ok, and maybe even get a larger one, along with checking the amps the starter is pulling when warm. If the battery, starter, and charging system all check out, start looking into that Warm position for the IAC, and the other stuff.

Remember, always chek the basics, you can make a problem much more difficult than it really is! (I wish I could get this drilled into my own head when I'm working!)

 

Yea I forgot about the bat correction PW table. It does get real rich as the volts goes down, like 1801uS at 9.6v and 2899uS at 8.0v. I'm sure the low voltage is not good for everything.

I have been playing with the crank fuel tables, just when I thought I was making progress, it still cranks long. I did prove that adding fuel is not the answer, since one time I had it so rich that it flooded out, and wouldnt start at all, until I did the clear flood.

I didn't want to mention this in my original post, but I do think it is the battery. I checked my records, and it is over 8 years old, so it is out of warranty. I don't run it in cold weather, and it is kept on a battery maintener inside my house during winter.

My mechanic checked it out with his fancy $350 capacitive load tester, and it failed. Should be 630 CCA, and it read 455. I guess heat is just as bad to a battery as the cold weather is.

I just wanted to get some opinions on what is the lowest volts for the ECM to be safe.

 

Many people don't realize how heat is bad for a battery. There is an ideal temp (I think it's around 80 F) and much above that the battery effieciency goes way down -- Fast!. On the cold side of things, it's more about the amount of charge it holds. That's why they say not to charge or store a battery on concrete. The cold pulls the charge out of it. Takes longer to charge a battery on concrete for that reason.