LS1 JAY

This morning it was about 45* evrything was normal but about 1 mile from home I stopped at a red light, the car started to idle funny, it normaly idles at 500 rpm's but it went down to 400 then up to 700 then back to 400 and so on like it was surging. I took off and it drove fine no codes or anything stopped again 1 mile further and it did it again but this time on the last surge it went up to maybe 1000 rpm's and then everything settled back down to 500 as normal since then everything has been fine but what could have caused this? my car has 38,000 miles on it and it is a A4 '99. <img src="images/icons/confused.gif" border="0">

LS1powerN20

do you have an aftermarket cam or torque converter?

LS1 JAY

Nope, it's bone stock except for a lid and a K&N filter! I took it out earlier and it seemed fine,no idle problems, even when it happened this morning it ran fine when I accelerted it only did it twice at an idle, strange????? <img src="images/icons/confused.gif" border="0">

Supertrapped

I've noticed, over the past couple of years, that these engines do that sometimes...."out of the blue" so to speak. A lot of the time its due to aftermarket converter though. But still, a lot of peoples engines do this for no known reason. Kinda weird, eh?

DóòD

As for 'out of the blue'..
I can attest that that bigtime!!

The WEIREDEST thing I've ever seen a car do was
2 years ago...
I pulled my car out..it was about 25*'s out.
The car surged at idle to over 2000rpms!! I'm NOT KIDDING!
Because there was snow on the ground I had to jam the brakes HARD just to keep the tires from spinning! I was FREAKED! I restared the car 3 times, and everytime i put it in gear It would surge! I called my father over to my house to guide the car back into the garage cuz it was THAT BAD. A few restarts later, it went away..
It hasnt happened since..
Very...VERY..bizzare!

LS1 JAY

Thanks for the replys guys! keep em' coming if you have any other ideas or experiences with this sort of thing.
JAY <img src="gr_eek2.gif" border="0">

LS1 JAY

TTT!

WILWAXU

iTrader: (6)

Hey Jay... Just a thought... next time look down at the voltmeter. I bet your running a low on "juice".. the alternator is working over time pulling the engine down, not mention what the other electronics are do at the lower voltage.

m1key99WS6

iTrader: (1)

You didn't just Re-oil your K&N did ya. hehe <img src="gr_grin.gif" border="0">

01Z0H6

iTrader: (63)

Something in the air i guess.. Mine did that today too. <img src="images/icons/confused.gif" border="0"> Have had the car since new & have never experienced that. Other than that, runs like new!! <img src="graemlins/burnout.gif" border="0" alt="[Burnout]" /> Oh yeah, mine has 34K!!

bobholio

My car did the same thing recently. It turned out to be caused by a weak battery in my case. Apparently the pcm can lose its idle and does wierd things like this if it forgets and tries to relearn. I started the car up and made it to the corner and the tach jumped up to over 2000 rmpms at a stop like something was in the throttle body or the accelerator was stuck. It scared the crap out of me. I drove it back to the house and it cycled between 400 and 1000 rpm for a few more minutes.

LS1 JAY

Thanks for all the replys guys! the car runs great but this kinda freaked me out today! I'll check the volts out later but I have not recently re-oiled the K&N it has been a couple of months since I did that, it really did seem like it was trying to re-learn the idle, then all of a sudden it's like it did and all was ok. WEIRD! <img src="gr_eek2.gif" border="0">

[ December 26, 2001: Message edited by: JAY ]</p>

Kurt D

iTrader: (2)

You say you have the airlid? My car did this and turned out the airtemp sensor was bad. This also happened when I accidently left my MAF and Airtemp sensor unpluged after I did the free ramair thing. That triped an SES light. The bad airtemp sensor didn't trip a light. Might want to check the connections there. The little airtemp module from SLP caused this to my car too.

Oh well, just an idea. Sometimes these computers just go wacky because of the moon/plants/sun thing. <img src="gr_grin.gif" border="0">

LS1powerN20

Mine does that everytime I start the car and the engine is cold...it's because of the cam <img src="gr_tounge.gif" border="0">

1dirtyZ

iTrader: (1)

check for vaccum leaks (egr o-ring) , and don't you think 500 rpm is a tad too low??

LS1 JAY

[quote]Originally posted by 1dirtyZ:
<strong>check for vaccum leaks (egr o-ring) , and don't you think 500 rpm is a tad too low??</strong><hr></blockquote>

My other car idled at 700 but this one sits at 500 maybe it's the gauge??? it usually runs smooth!

DROPTAWP

I had an '88 Crustang Auto that did the exact same thing. We'd pull up to a stop sign or a traffic light with the brake on and the car just wanted to keep on going. Just as if the throttle was stuck or something... Not too bad on dry roads but with a bit of snow or ice, forget it man.... big time freak out! We had numerous mechies look at the POS with no luck. Nobody could locate the prob. Since it was the wife's daily driver at the time and she was scared silly to drive this possesed beast, I told her we are going to trash it and get a new car. We ended up getting a Chev Cavalier, new in '95. Almost 7 years old and still going strong! <img src="gr_grin.gif" border="0">

The SS hasn't had this prob (YET).... <img src="gr_images/icons/wink.gif" border="0">

Fran D

iTrader: (5)

JAY, how was the car under load? I had this problem start about a month ago and eventually it had a hard time pulling through the gears. Wound up that the #8 plug wire (stock) had shorted to the block. It took a long time for the car to throw a code. Wire was replaced under warranty.

Pro Stock John

iTrader: (34)

That's a very good point about how it could be a low battery.

LS1 JAY

Car was fine at WOT, today it was fine as well no problems whatsoever, it pulls hard and smooth, one question though, where should I be @ idle? mine idles @ 500-550 maybe it's just the gauge? my old T/A idled @ 600-700???? where does yours idle at? also my battery seems fine but 3 days before this fluke the battery almost died and I had only driven maybe 20 miles since that happened when the idle was jumping around.