Engine Start Up

GMAN

GMAN

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Once you start your car after it's been sitting, what is the reading of your tach? My tach on my car goes up to 1500 Rpm's and then idles around 500 rpms. My son's Mark idles right away at 500 rpms. Is this normal?
 
Mine usually idles high for about 10 seconds probally less and then settles down to around 500 to 700
 
It sounds like yout son's car might have a problem with the IAC valve.

I had a problem like that before (low idle speed when the engine was cold) but luckily, it went away. I think it reset when I had to disconnect my battery.

I'm not looking forward to changing it so, I'll wait until it acts up again.:D
 
billcu said:
It sounds like yout son's car might have a problem with the IAC valve.

I had a problem like that before (low idle speed when the engine was cold) but luckily, it went away. I think it reset when I had to disconnect my battery.

I'm not looking forward to changing it so, I'll wait until it acts up again.:D
Click to expand...

yes,every modern fuel injected vehicle i have seen starts high and drops after 8-12 seconds if everything is working correctly,
 
Mine (96) starts up at around 1200 and drops to 600 within about 10 seconds-I did have a problem with the IAC, got off a freeway and it idled in drive at 1200, in park/neutral at 2200-nursed it home, tried to do the sea foam thing, finally disconnected the battery and clamped the pos and neg terminals together for about 10 minutes, hooked it back up, no problems since. You do not want to remove the IAC unless you have no choice, it is in a joke of a location to remove.
 
So immediately idling at 500 RPM's with no surge at first is not good? The battery has been disconnected many times during the painting process and the transmission installation. I don't know if it did this before. This is just the first thing i noticed. Would some seafom possibly clear this up? Also, where is the IAC valve located?
 
the IAC is back by the firewall on the passenger side, near the throttle body-it has an electrical connection to it, and I do know some people who have removed it, but it is a bear becasue of where it is-you have to remove all kinds of stuff to get out of the way to get to the two bolts that hold it in place. When I was asking about this a while back (really not that long ago) someone sent me a photo of it with the engine out, I'll go back and see if I can send it to you, but after seeing where it was and what it would take to get it off, I'm glad I didn't have to-try the SeaFoam thing, and maybe do the battery thing, when you reconnect it, just let it idle, don't drive it right away so that the Ecm has to 'relearn' how to control the IAC-also, clean terminals and posts are a must on these things, as I'm sure you and everyone else knows-good luck
 
So when the car idles immediately at 500rpm's is this a sign that the IAC is malfunctioning? I wonder if this is it, because I don't have any CEL lights. I just thought it was strange for it to not idle high at first. Perhaps this engine has great lubricatation and compression.
 
It's supposed to idle high like that on cold startup, then gradually work it's way down to around 750 or so. I would check for stored codes (just because there's no CEL doesn't mean there isn't something stored) and go from there. Pray it's not the IAC, because it's a royal pain in the balls.
 
It idles high like that to get the oil flowing through the engine, perfectly normal.
 
I tried to remove that dam IAC valve awhile back, was able to break the bolt next to the firewall but the other one I could not break, instead broke a bone in my hand trying with an ignition wrench. I was just at the local Lincoln dealer looking for a "burst panel" for the intake manifold and asked if there was a special tool or procedure to remove it and he just said that the mechanics used to just remove the intake because it was such a pain in the ass to get at. Just hope that is not your problem and that it fixes itself.
 
OK, what does this mean? I just got in the car to move it. It started as usual at 500rpm's and stays at 500. I rev it a few times and the headlights got brighter as I revved. Is this the alternator going bad? I started to back out of the driveway and it died. I restarted and revved it some more. What do you think?
 
In the PCM there is a scalar that allows the "start up idle" to be increased or decreased by a particular amount of seconds..

and an additional scalar that determines "how much" idle to add during this start up time.

it's normal for the idle to surge on start up.

In the sct software I have my "idle speed adder" zero'd out and the "time scalar" also zero'd out.. and it idles like you describe.. start the car and no idle surge.

Just FYI.

If you car has no custom tuning to eliminate the idle surge, then everyone that posted IAC problem is probably correct.
 
Good luck changing it, it's right by the throttle bodies in the back near the firewall.
 
IAC valve

Yeah, that bugger is on the passenger side of the intake in the back by the firewall. When I tried to change mine I removed the pass. side windshield wiper cowling, and the TB for a little more room but still couldn't get the dam thing off. Good luck with that.
 
Sorry, the're here

P4060030.jpg


P4060031.jpg
 
from what I've read and been told, you really have to take the intake off to get to them-I know Ponytail John has tried to do it without, and I am pretty sure he gave up (after getting injured). It is the kind of thing that you'd ony try if you have no choice. Just a thought, is the connector hooked up? Does it make a difference how it runs connected or disconnected? I ask because when I had a problem with mine (high idle) I disconnected it and it ran alright, just very low idle. I probably could have driven it like that for awhile until I removed the IAC, but I ended up doing the SeaFoam thing and disconnected the battery Pos and Neg terminals and clamped them together for about 10 minutem so that the ECM had to 'relearn' to control the IAC, and it has been good now for about a month and a half, all normal. If you didn't try that, Greg, I'd give it a shot-good luck.
 
Jeff /SVO/ Great Gazoo in bastrop does IAC valves with apparently no problem he's changed his twice in the last two years.
He's a small framed little gnome,which comes in handy when trying to work in such cramped positions.

Gman, I'm sure he could hook you up with an IAC install.. and he's only 2 hours north of houston.
 
I plan on doing the Seafoam this weekend. What I can get a grasp on is the battery terminal thing. How is putting the positive and negative terminals together going to do anything? There's no power going anywhere without the battery. Please explain in detail. Who figured this out?
 
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