|Quote, originally posted by shryocdj »|
|i wont say a word, especially since it probably wasn't the problem |
You know, I hate it when you are right......especially when it was me that helped you with that switch issue! (And it isn't the switch either!)
And I still honestly don't know what it is.
Here is what I found.
I went out and started the car...3/4 in pipe in and ICV hooked to its harness and out. Car was cold. Started it and basically did the same thing that I did yesterday....no response at the ICV. So I took the ICV out and gave it 12v....it snapped open. I put it back in the harness and pinched the hose until I could hear the engine really start to fade. No change...ICV stayed shut. So I check the harness....it is pumping out 12v. I check to see which is hot and which is ground and it is the WHITE wire that is hot, and the black wire with the (white?) stripe that is ground. I check and white wire has 12v to ground. I check the black wire and I got some different readings on continuity I think due to bad connections, but eventually it clearly gave me 0 when I went between that pin on the harness and ground.
So, we have 12v coming in and continuity to ground going back. Seems like ECU wants ICV open, but it ain't opening when I connect it.
So, I go and look at the closed throttle switch. I open it and can hear it click. What the hey...I disconnect it. Engine starts to run really rough...disconnecting it would tell the ecu that the throttle is open when it really is shut.
Then all hell breaks loose and the car starts to run really rough and backfire and sputter and start, and then it dies. I get in and try to start it.....won't. Now I am going what the heck. Was there some weak component that just caved (and I am secretly hoping so so that it will finally reveal itself....) Anyway, turns out it was just out of gas.
I reconnect the harness for the closed throttle switch, and the car runs better. In fact it gets pretty smooth and I am thinking it is running better.
So I go back to the harness and do more tests. 12 v in. I check the negative wire for continuity to ground, and I don't get 0 anymore....I get -12.1. WTF? How can you have negative ohms? Then I realize that I forgot to change my multimeter to ohms and I was still on volts. But, WTF(2)? Why am I getting NEGATIVE volts when I am going between the negative ground wire and the NEGATIVE terminal on the battery. I mean, if I just switch my leads around, I will have 12v between a ground and a ground.
Methinks that should not be.
What are you all thinking the problem is. Are you thinking what I am thinking. Is there some sort of short in the ECU that is causing it to have + current going through a negative wire. Bad Ecu! BAD ECU!
I have a spare ECU that I use to test as I know the car has run fine with it. So I pull that out and plug it in. I plug in the ICV in its harness and wait for it to begin ticking properly. Engine is idling nicely with the 3/4 pipe. ICV stays closed. I rev the engine. Still closed. Absolutely no different than with the other ECU. So I REALLY pinch off the hose, to the point where I kill the engine, and....JUST before the engine dies, that ICV yawns wide open. It appears to be working.
I plug the original ECU back in and repeat the same test and get the same result...JUST before the engine dies, she opens wide.
What have I learned? I learned a good test for the ICV. I learned that once again, Rob was right in his suggestion that the ICV was not the problem (more on that later). I learned that Shryocdj is also right in that if all the ICV does is open just before the car dies to give it more air, it really isn't THAT important in the running of the vehicle, and we blame it too much for other issues.
I also learned something that I think is critical. The ICV is normally closed. This is very important to me because remember that my car runs either with the pipe in place (which would be an OPEN ICV) or with the temp sensor disconnected (which would signify a COLD car).
When the ICV opens, does it increase air or fuel?
Oh, and the reason it doesn't open when there appears to be current there, and why I get voltage on the negative side....I believe that might have to do with "duty cycles".