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Car dies after reconnect battery

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Nayr747

15+ Year Contributor
248
1
Feb 10, 2004
somwhere, Nevada
Okay, I have been dealing with this problem forever and finally wanted to see if I could get some help with it. Short story: Whenever I disconnect my battery to work on my car I will have to let it "re-learn" its maps or idle or whatever for 10-15 minutes.

If I take off one of the battery post clamps for ANY length of time (two seconds, 5 hours--doesn't matter), the next time I start it up it will normally die, or sometimes idle fine initially. If it idles initially it will always die or try to die after I drive any distance and then push in the clutch. It always follows the same pattern. When the clutch is pressed the RPMs just continue to drop to zero like it doesn't understand it should be stopping at 700-1000. If it doesn't plumet all the way to zero, it will get to almost zero then bounce back up to <1500, then down, then up, and eventually if it can keep itself off zero it will slowly get to the normal idle. Sometimes during this up down RPM thing it will be at 100 or so RPM, barely able to keep the engine running. But even though it seems like it learned the idle now, if I again drive for any distance then push in the clutch it will do the same routine, most of the time dieing. When I didn't have time to let it re-learn I've even had to come to stop lights pushing in the clutch with my left foot while braking with my toes and holding the RPMs up with my heel.

I've figured out that I have to follow a specific pattern to get it to idle normally and not die. After driving and pushing in the clutch and it settling at normal idle (usually takes a couple restarts) I have to let it sit for at least two minutes idling. I then have to repeat this at least two more times, each time getting a little better, until finally after 10 minutes or so of this routine it idles fine. If instead I only let it sit for say 30 seconds each time it will NEVER learn. Before I figured this out I drove around all day with it dieing every time I came to a stop. Normally stop lights aren't long enough for it to learn. And for some reason it doesn't seem to be able to learn while coasting down a hill after pressing in the clutch.

It is NOT the battery or the alternator. I've replaced both several times. I actually just put in a 90 amp Galant alt with a big 3 rewire, and a Diehard battery within the last two days, and the problem is still there. And I've adjusted the TPS multiple times exactly to spec. So I can't think of what it could possibly be. Any help would really be great!
 
Okay, I finally got home and was able to do the IAC/ISC tests (thanks for the recommendation btw). I got almost exactly 40 ohms on all pins. I thought it was kind of weird that it was so consistent right at 40, but oh well. So that's above the 28-33 that it should be, but should that really cause a problem? The 6 volt battery test I'll have to redo tomorrow since I had to ghetto rig it and I don't really trust it. I do think I heard a click, like a really muted relay, but no vibration at all. I may have to take the throttle body off and take the IAC off that to really feel for any movement (and also clean the TB).

I haven't done a boost leak test in a while so that might be a good idea too. The air tank I used to use for this is old and I'm kind of scared it will blow. So I'll probably either try a bike pump or go to the gas station and see how quickly I can get my intake pipe off before someone notices I'm not filling up my tires. :D
 
A little update: I found out that I probably have the newer IAC that Mitsu started putting in their cars starting in 2000. This one actually should be 40 ohms, not 28-33 like the manual says. So that checked out on mine. But I pulled the IAC off the TB and did the 6v battery test and there was absolutely no movement or noise, so it seems shot. So I ended up ordering a new OEM one off DSMISC Automotive (New ISC Supplier). They had by far the best prices I could find on an OEM IAC, and they have lots of info on their page. It ended up being $136 total with a new o-ring.

I'll post another update when I install it. Hopefully it will fix the idle problem. Oh and I also did a boost leak test (at midnight with the gas station's free air :D), and there were no leaks other than the BCS hose which I just vice gripped shut
 
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