I'm baffled, problem running right off the bat but it runs great afterward... help!

Thor06 · #1 07-31-2007, 11:13 PM

Well guys, I have a problem with my beast. Normally when something is going wrong I have a pretty good idea what it is or could be and once I get to looking I can get it. Well, I have no friggin idea on this one.

So it starts right up every time and it does the normal idle at like 1200-1500 (cant remember what it is, but its not stumbling around my any means) for the first minute or so and it slowly works its way down to a nice, solid idle at like 750-800 rpms. Well, I usually let it sit for a couple minutes and I just twidle my thumbs. Then I go and after driving for like 3 minutes it just falls on its ass. I then have to pull over and give 'er gas to keep the rpms from falling too far down and dieing. Then I try to run it again after like 2 minutes and it runs just fine. Oh, and it only does this when cold. What could be the problem, does anyone have a clue? I cant even think of what it could be, its so confusing to me. Any insight would kick ass, I think if I cant figure it out by next summer I am just going to bite the sack and take it to a "professional" but I would really like to get it hammered out myself. Anyway, thanks in advance.

kjewer1 · #2 08-01-2007, 03:25 AM

First thing that comes to mind is the ISC. They can fail only when warmed up. Check the resistance between the pins (30 ohms?) when it's dead cold, then again when it's actin a fool.

I can't really think of anything else that would reduce idle speed when warm. It's almost always the opposite. Throttle cable setting, bad FIAV, etc, all end up causing a high idle speed.

Do you get any CELs? Specifically closed loop idle speed control faults? Shit, I guess another thing you can try if you haven't is to reset the ECU (make sure the ISC is plugged back in if you do any testing), it will force the ISC to resync with the ECU. It's possible that it's our of sync and fast idling well by chance.

Wait a minute. It shits the bed while your driving, not just when you come back to idle? That's a bitch. I'd start with checking the ECU and ignition components.

Blackcrow64 · #3 08-01-2007, 04:37 AM

Wait a minute, my brothers 1g did the same thing last winter!... I'll have to ask him what it was then that was causing it to happen... I remember he messed with it for like 2 weeks and couldn't figure out what it was, but then right before he sold it he fixed it...

Blackcrow64 · #4 08-01-2007, 05:23 AM

Ok, I just talked to my brother about it and he said after he replaced like everything, it ended up just being a dead O2 sensor... So I would check that out man and see if thats the problem with yours too...

eclipse98gst · #5 08-01-2007, 04:52 PM

That makes sense, if the o2 sensor goes bad it will only show after the car is warmed up. After the ECU reads a bad o2 signal it defaults to a crappy fuel setting that would cause the symptoms your describing.

TalonEclipseMixGsx · #6 08-01-2007, 07:34 PM

I had the o2 sensor unplugged on my gsx and all i got was a check engine light and very rich conditions according to my wideband. I was able to compensate with the safc, but i never had stalling problems, or any idle problems. It ran just like normal except for the shitty gas mileage. Of course thats a 2g and not a 1g.

Thor06 · #7 08-01-2007, 11:55 PM

Wow, so many replies! Thanks all!

Ok, here we go...

I did some cruising today and payed attention to it plus I have been thinking about it all day at work. I think I got a bit wordy in my first post, I guess what I was getting at is that it starts and runs completely fine until just after I start driving then it just falls on its face. It only is on its face for probably 10-30 seconds and then it runs completely fine again.

Yes, I am throwing a CEL but I figured it was because of the lack of EGR. That is was I figured was wrong after thinking about it all day, maybe it tries to "turn on" the EGR and is anticipating that much more air flowing through there. Well, since there is no EGR (I have a block off plate) none of that extra air gets in there and it goes uber rich thus the sputtering a loss of power. After it realizes there is something wrong, it stops trying to compensate for the EGR's airflow and thus it runs good again. Does this make sense to anyone else or has it happened like that for anyone?

I dont think that it was the o2 sensor, but I will check it for sure. That first night we got it going again it was running a little shitty and my buddy and I were under the hood checking fluid levels. He points to the turbo area and says, "What that cord for?" Well, turns out we had forgotten to plug in the o2 sensor. Plugged it in and it ran much better. I should also say that it did this problem with and withouth the o2 sensor plugged in so I sorta have this ruled out in my mind.

One of these days I will get my buddy's multimeter and check all the sensors and shit. Oh, and I will reset the ECU in the morning and see if that helps. To do that I just unplug a battery terminal for 10-15 seconds right?

eclipse98gst · #8 08-02-2007, 12:55 AM

Yeah, I didnt know you had gotten rid of your EGR system. I think you are right, the EGR plays a pretty vital role when using a stock ECU, there are probably some sensors going out of wack because of it.

kjewer1 · #9 08-02-2007, 06:45 AM

The only thing lack of EGR will do is give you a EGR is fucked code. If you have DSMlink just disable the EGR DTC.

If the o2 sensor is dead and the ECU ignores it that is the same thing as not having it plugged in. Since it ran shitty with it not plugged in, I'm not sure how you've ruled that one out in your mind.

I don't think we can speculate much more until we know what the CEL is for.

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