DanTheIROCMan

In searching this board for some possible answers to my starting problems, I stumbled across 2 interesting theories as follows:

1) Ignition module bad

Based on what I read, there are 2 modes the ignition module runs in: "Cranking" and "Run". My understanding is that if the module is bad, it might not be telling the ECU that I'm cranking the car, thus not firing the fuel injectors. My only problem with this theory is that this will be my second ignition module, although they are cheapy AutoZone models, but come on, they should work, shouldn't they??

2) Clear flood mode

I undertand that if the car computer things the engine is flooded, I guess by the position of the TPS, the ECU will go into "clear flood mode", which prevents the fuel injectors from firing. This sounds interesting and may be the answer. What happens is that, I can turn the car on for litterlly 30 seconds first thing in the morning, shut it down, then it won't start back up for another minute or so. No starting system or battery issues as it will just crank and crank. I have fuel pressure and spark. So I'm thinking this clear flood mode may be preventing the fuel injectors from firing. So my question is, what circumstances would cause the ECU to go into clear flood mode?

IROCThe5.7L

Did you ever monitor your fuel pressure after shutdown?

DanTheIROCMan

Yep. Here are the tests I did:

1) While car was running, tested fuel pressure. Solid 40 psi

2) Turned car off, test fuel pressure. Solid 40 psi

3) Turned key to on, without starting, fuel pressure went back up to 40 psi.

4) Tried starting car, wouldn't start, but kept at 40 psi.

Now that I'm thinking about it, the only test I didn't do was to relieve the fuel pressure after the initial cranking to see if the fuel pressure would come back up. I know for sure this is a fuel issue and know for sure the fuel pump, relay etc are all in order. But I'm really thinking for some reason or another, the ECU is cutting out either the fuel pump or fuel injectors at some point causing a non start condition. I will pick up a noid light tonight to see if the fuel injectors are not firing at some point.

aklim

I thought the fuel pressure is 44-45 but 40 might be ok. If it is the ignition module going bad, it is unlilkely that you ahve 2 all at once going bad. You can crank it but have a friend stand by and look at the DVOM which would be hooked up to read the injectors. Use a couple of pins to stick into the wires and clip the DVOM onto the pins.

If you want to check the Clear Flood and idea, get a scanner and read the TPS voltage when the key is on and engine off. See what it says when your foot is off till the foot is all the way down. Voltage should stadily increas and not drop off.

TheGreatJ

A WOT reading from the TPS while cranking is the only way the ECM will initiate "clear flood mode." If the TPS doesn't read close to 5v, clear flood isn't an issue.



If you're getting GP Sorensen modules that's probably your problem. I bought one once and it was bad right out of the box. Got it warrantied....the next one cranked once, ran 5 minutes, and died. I checked everything else I could think to check and it was all fine...had the module warrantied again and it lasted a week before it died. Took it back, demanded a refund, got an Accel module and haven't had a problem from it since.

DanTheIROCMan

Okay guys, I don't think my problem is clear flood mode. I purchased a noid light and hooked it up to the injectors. Turned the key and the car started right up. The light did seem a little dim but since I have no reference, I have no idea if it really was dim. Just for kicks, I stepped on the loud pedal. The light got much brighter. Let off and the light dimmed back down. Turned the car off, tried to start it back up but wouldn't start, just kept cranking. The noid light did light up dimmly during the cranking. So that pretty much tells me it is not in clear flood mode while cranking, thus not my problem. As I was cranking it, I thought I would just floor the gas pedal to see what happened. The light then when out completely, thus indicating it was now in clear flood mode. Lifted off the gas, the light came back up, but the car just cranks and cranks, doesn't start.

So I guess that theory is blown out of the water. Do you guys know if the light should be fairly bright just at idle? Or is it correct that it's pretty dim?

So I just don't know what the heck is going on here. I have fuel pressure, the injectors are firing, I have spark and of course I have air. So what is missing here?? Something is preventing it from starting after it was ran without letting it cool down a bit. And again, it doesn't even have to get warm to not want to start. It is very consistent and I can repeat it every single time. Turn the car on for 30 seconds, turn it off, turn it back on, won't start, wait 30 seconds, it starts and the whole cycle repeats.

I have a new coil, distributor, ignition module and spark plugs. I'm desperate guys! Help!!!

aklim

Maybe you need to borrow a scanner to see what is up. Are you getting any codes at all? Also we would need to see what the TPS voltage is without your pushing on the pedal and also what temp the ECM sees.

DanTheIROCMan

TPS voltage with car off, but ignition turned to on without the gas pedal pushed is .54 volts.

Regarding the temp, how can I get that info?

No codes coming from test port.

aklim

TPS sounds good. When you hit the throttle slowly, is it constantly going up and to what voltage. There must be no drop in voltage till you have mashed the pedal to the floor. If there is, you have a bad TPS sensor among other things.

Best way to get the temp is to have a scanner then you can see what the IAT and CTS sensor see. When you start the car, they should be equal because it is cold and at room temp.

DanTheIROCMan

What is IAT and CTS? Regarding the scanner, is that the same scanner that I can borrow from AutoZone? Or is that something else? If I have to buy it, forget it. Not worth it as I'm sure it would be upwards of $100.

Why are you interested in the temp? Would that cause a non start issue?

aklim

Intake Air Temp sensor and Coolant Temp sensor.

Well, if the Air Temp is thought to be higher than it really is, the ECM could lean out the mixture same with the CTS.

You might be albe to borrow it from Autozone but why not buy it and then return it within 30 days? Just something I read in a book or something.

DanTheIROCMan

When my car runs, it actually seems to run really rich, just going off of the pretty foul smell coming out of the exhaust. I mean, if you stand by the car while it's running, your eyes litteraly start to burn and water up. It's that bad. Do you think the MAF could be causing it to run pig rich? Also, there does seem to be a slight miss when I give it some gas. For example, I can hold it steady at 2,000 rpm and there seems to be a slight miss in there. Is a miss a fuel problem or a spark problem??

Damon

"clear flood" mode is only engaged if you hold the throttle wide open while cranking over the motor. It's an electronic interpretation of what carbs had built into their linkages years ago to pop the choke open manfually if you opened the throttle all the way. Has no bearing on your situation if you are craning it over with the throtle at idle.

TheGreatJ

The CTS can make a car run real rich if it's bad, but I've never seen one cause a no-start problem, much less an intermittent one. A bad IAT will do the same thing but to less effect.

Your 'noid light test sounds like it came back pretty good. The light should appear brighter as you rev the engine because it's actually flashing faster and staying on longer during each flash.

Do you have a fuel pressure gauge? I'd be interested to see exactly what the fuel pressure does when the car will and will not start.

rottonj

Did you have your module tested.I had a similar situation happen to me with a faulty module. Sometimes it would start sometimes it wouldn't.I put in a accel module and it fixed it. I was also not getting any codes. Have yours tested before you buy a new one.