Sounds pretty high. When I had the 2.8, cold idle was about 1,200 - 1,400 and warm was 900. A good idle is in the 900 - 1,000 range. Not sure what could be causing you to get the high RPM if all vacuum is good. I'm sure there will be somebody here that can chime in to help.
I reset the IAC adjustment by jumping the pins on my obd1 connector with the engine cold waiting about 30 seconds and disconnecting it from the wiring. pulling the jumper and then starting the engine.
With the IAC reset and disconnected the cold idle was at 650 in gear, and warm idle in gear was about 800.
(I used the throttle plate adjustment screw on the throttle body to fine tune it)
When warmed up and driving around. It feels like the throttle sticks at a stop because the idle doesn't come down to 800 it usually stays above that, and hovers around 1k.
[This message has been edited by AL87 (edited 11-17-2013).]
Are you reading that from the tach, or a scan tool? The stock Fiero tach is notoriously innacurate and many (most) read too high. Mine read more like double what is was supposed to be. There is a fix posted on here somehwere.
I think it was because I disconnected the battery***
anyways, its cold idle is about 1.5K now. and warmed up idle is at 1.1K in gear and stopped. it wont drop any lower than 1k, and it rarely gets there, its always about 1.1-1.2K in gear idle.
If I set the IAC like I need to (cold, jumped A/B, and then disconnect the IAC after 30 seconds, and then unjump a/b) the throttle set screw idles the engine right at 650 when at operating temp. (which is what sinister says to do, when calibrating idle with a new IAC)
I am curious as to whether you found a fix for this yet.
I have the identical situation on my 1986 SE V6. I took it in to a Mechanic about 2 years ago and he was able to apply some sort of temporary fix, but it only lasted about a year. I think he replaced the TPS, vacuum tube and an O2 sensor. Regardless, he is now out of business and I cannot figure out what he did for the life of me.
It's like the choke is sticking or something. If I warm the car up for about 10 minutes the idle drops to normal while it is sitting in the driveway. But then when I drive it a mile or so the RPMS go up and it runs at about 1800 at every stoplight. And you can actually feel it pushing the car along while in first gear. Traffic jams are a real P in the A! On rare occasion, at very long lights, I can rev the engine with a quick burst and get it to drip to about 1200. But that is only when the car is warm and it goes right back up after ai drive it a few blocks.
High Idle is most often caused by a vacuum leak. Finding the leak is sometimes difficult. If you have the original EGR tube it is probably cracked. The other small tubes may be leaking also.
Another reason may be a sticking IAC and a third cause could be a bad throttle cable. If you are familiar with the search options, there are many helpful threads on how to pursue these problems.
an older engine fouls the 02 sensor & they must be replaced more often never use a bosch 02 sensor in a fiero 2,8 V6 they are suppose to work slower . I read this some where years ago !! yes I know there will be many who have a bosch 02 & it works great!! check all those hoses on any old car when you check the hoses if the rubber hose does not have a tight fit at the connection, cut a small piece off the end ,as long as you have enough to work with.. the EGR system on the V6 is to complicated,every thing has to be proper of course the egr itself must be pulled & checked, follow the instructions in haynes manual,, the EGR tube that runs from the egr to the upper plenum/manifold is a major leak problem area check spark plug wires if they are old at night to see if there is arching or glow along wires if you locate a tube leak, a temp inexpensive fix is to use alum foil ,or aluminum pastry/pie plate to cover the leak. secure the foil with a hose clamp or whatever works a new EGR tube is $75 to $100 so with a small leak,find out how good your soldering skills are most fiero,s have an old timing chain you check tis with a timing lite to make sure the timing does not jump around or use the crank bolt ,,& move back & forth to check for slack using timing mark & distributor a bad timming chain will also have a hesitation when you accelerate
My 85 gt v6 had a high idle that would run at 17 to 2000 rpm when id start it cold an when it warmed up it droped to 12-1000 but as soon as I drove it an cooled it down it jump back up. The prob was the EGR tube. It had a crack an it would open more when cool an close up more when hot. I put a new one on an my motor purr's at 900 rpm. If I where you id get a small clear hose that you can put to your ear an the other end to the EGR tube and move it from one end to the other if it's cracked you will hear it. You also can move the hose all around your motor to find any vac leak's. I found mine this way it work's great. Good luck
I completely deleted my egr, is this going to cause a higher idle than normal? I'm having the same idling issue. high idle like all the time. 1,200-1,500 rpm. I don't know why its fluctuating. there are a few issues i'll have to resolve in order to make sure though.
I read that heat shrink tube is a fiero-owner's friend when it comes to repairing the vacuum lines or to re-enforce what's currently there.
my iac is set properly, and the throttle body screw is set correctly as well.
Sinister performance says 550 in drive with an auto trans in gear, and 650 with a manual trans in neutral.
remember, you are setting the throttle set screw for the butterfly and the IAC controls idle from the base setting above.
here is an exerpt:
1) With the IAC valve connected, ground the diagnostic (ALDL) terminal (same as you would do to flash trouble codes thru the check engine light).
2) Turn ON the ignition, but do NOT start the engine. Wait at least 30 seconds.
3) With the ignition still on, disconnect the IAC electrical connector.
4) Remove grounding of the diagnostic (ALDL) connector and start the engine. Allow the engine to fully warm up and go into closed loop.
5) Adjust the idle stop screw so the engine idle speed obtains 550rpm in drive (auto trans) or 650rpm in neutral (manual trans).
6) Turn the ignition off. Disconnect power from the ECM for at least 10 seconds to clear codes (in case any are present) and reconnect the IAC electrical connector.
Sinister performance says 550 in drive with an auto trans in gear, and 650 with a manual trans in neutral.
remember, you are setting the throttle set screw for the butterfly and the IAC controls idle from the base setting above.
here is an exerpt:
1) With the IAC valve connected, ground the diagnostic (ALDL) terminal (same as you would do to flash trouble codes thru the check engine light).
2) Turn ON the ignition, but do NOT start the engine. Wait at least 30 seconds.
3) With the ignition still on, disconnect the IAC electrical connector.
4) Remove grounding of the diagnostic (ALDL) connector and start the engine. Allow the engine to fully warm up and go into closed loop.
5) Adjust the idle stop screw so the engine idle speed obtains 550rpm in drive (auto trans) or 650rpm in neutral (manual trans).
6) Turn the ignition off. Disconnect power from the ECM for at least 10 seconds to clear codes (in case any are present) and reconnect the IAC electrical connector.
Yup, and then after that, if the TPS is adjustable, key on engine off adjust TPS so closed throttle voltage is .5v to .9 volts.
If it is not adjustable check TPS voltage and verify it is .5v to .9v. If not replace TPS with one that will have this voltage at closed throttle.
I did learn a few things at the GM training center for Service Technicians in the late 80`s
Okay, is it normal for the IAC to buzz and click while in ALDL mode? Normally it does, but not this time, until I went to unplug it, and it buzzed sporadically, indicating a loose connector plug.
Also, normally it has a loud vacuum at idle, and I could stall the engine by putting my finger over the IAC port in the neck of the throttle body. Now that I've set the idle, there isn't much vacuum at all in the port, and it's idling at 900-1,000 like it should. But I don't know if the IAC is working properly, or if it's just idling through the TB.
[This message has been edited by PatrickTRoof (edited 01-06-2014).]
my engine is modified, and thus requires more adjustment than the OE setting.
Umm, the norm is to leave the screw TF alone. It is set for maximum performance from the factory and unless you are Smokey Yanuk or a GM engineer with a 5 gas analyzer you can't see or know what your doing turning that screw that is supposed to be left alone. But...It's your car.
I think people worry too much about that screw. If it's never been opened, then leave it alone, but if it has, then I really don't think it's that critical to get it "just right". The ECM will target a 900rpm idle when hot. It will open the IAC however much is required to achieve that. The more the throttle is closed, the lower the starting TPS value and the more steps the IAC will open to maintain idle. This gives the ECM more resolution to work with on both values. But you want the throttle open enough so it doesn't stick.
My attitude is to open it enough so it doesn't stick, but no further. This way the ECM has control of the idle, and not the screw. I don't know of any reason the adjustment should be any more complicated than that. If you find you need an excess throttle opening to get it to idle smoothly, then you may have a bad IAC or dirty IAC ports.
I've tried using the official adjustment procedure for the screw, but in repeated attempts I could never get it to work. When it gets to the point where the IAC is supposed to close, mine never did. I couldn't hear it moving, and when I restarted, it was very open (idled much faster than normal). So I gave up and just did what I said above. From memory, WinALDL reports my closed throttle TPS voltage in the 0.6x range.
