I adjusted the tps to where its supposed to be. between .98 to 1 volt. The problem with that is i doubt the meter is that accurate. That is a pretty tight window. I've heard people talking about the computer needs to re-adjust itself and it takes time. If so how much time? The idle is about 1200 but the hanging rpms is what really sucks. any suggestions?
I unhooked the battery for ten minutes. It still idles at 1200. When I rev it up the rpms drop great until about 1800 rpms, then it hangs up for a second and sluggishly goes down to 1200.
Unhooking the battery does not effect the tune, it only erases the KAM (Keep Alive Memory) which is basically a set of baseline values for sensors emissions controls etc.
Assuming nothing is sticking, double check this real good, it could be anything.
The TPS does not have to be adjusted although it's happy at .98v so leave it there.
If you read the thread I posted, my car never settled down so I returned the unit.
You may need a tune to fix it or it may fix itself after a week or so of driving.
TPS voltage didnt matter to me, mine was hanging really bad when i se the idle to 800 rpm with the IAC dissconnected. I read a post from Randy Stinchcomb stating that with the iac disconnected the car should just die or barely run ( ~550 rpm for me)
I ignored TPS voltage and set the trottle body lower and lower till the car just stumbled and died. since then the car is idleing perfect again.
Essentially, with a higher un assisted idle ( from the IAC valve) the car acts like it has a vaccum leak.
TPS voltage didnt matter to me, mine was hanging really bad when i se the idle to 800 rpm with the IAC dissconnected. I read a post from Randy Stinchcomb stating that with the iac disconnected the car should just die or barely run ( ~550 rpm for me)
I ignored TPS voltage and set the trottle body lower and lower till the car just stumbled and died. since then the car is idleing perfect again.
Essentially, with a higher un assisted idle ( from the IAC valve) the car acts like it has a vaccum leak.
Since idle is a 'learned' function, that answer is partially correct - you need to clear the KAM -a nd messing with the stop screw throws the TPS off - normally the TPS value is reset in the PCM at key-on, but if it is off by too much, you need to readjust it to 0.9-0.99. Here is the procedure we give out to customers who get chips from us...
You probably will need a helper for this procedure.
1)With the motor running unplug the idle air control valve (IAC).
2)The motor may stall or flare at this point.
3)If it stalls, start it again still with the IAC unplugged – have a helper keep the revs up – if it flares go to the next step.
4)Using the throttle stop screw, adjust the idle to where it was commanded – if you do not know, then just pick 800-850 – most tunes are 850. It should idle OK like that.
5)Shut the motor off and disconnect the negative battery cable and step on the brake 3-4 times. Turn the headlight switch on – this drains any excess voltage. Wait 5 minutes or so.
6)Reconnect the battery, plug in the IAC again and start the motor. Should idle better.
7)Shut it off and re-check the TPS voltage. Try to get it back to under 1.0. If it’s too far out of whack, you may have adjusted the throttle stop screw too much. Or if you did not, you have a throttle body that’s a mess. In that case try to come to a happy medium of throttle body stop screw to TPS setting.
8)Sometimes with a BIG cam drilling a small hole in the throttle blade will help get things right, but you do this at your own risk as you can REALLY mess things up if this wasn’t the problem or you made too big a hole.
Be SURE there are no vacuum leaks if it will not hold idle – do a smoke test if necessary.
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