probably an easy question but how do i adjust the idle on the fiero with a manual 4spd transmission? what should it be idling at as well?
right now its at 1500 to 2 grand it changes every time i drive the car...really annoying when the radio doesn't work...


Thanks

The idle for the 2.8 V6 is controlled by the ECM as most MPFI engines are when they are operating in closed loop mode and no user adjustable idle screws are provided. Sounds like you have a vaccuum leak or the idle air control valve (IAC) is stuck full open. I had an similar high idle problem with my 85 2M6 SE and it turned out to be that the intake manifold to head gasket had been sucked into the air passage on one cylinder and caused the idle to be quite high and erratic. The normal idle should be around 700 - 900 RPM in neutral. An automatic transmission car with a 2.8 V6 should be around that RPM in drive.

[This message has been edited by Sidecar 2M6 SE (edited 12-25-2009).]

If it's 2.8 then I would suspect a cracked EGR tube or other vacuum leak. Possibly a defective Idle Air Control (IAC). If it's a 2.5 then vacuum leak or again the IAC

edit: correct idle on both is 900-950 in neutral.

[This message has been edited by 2farnorth (edited 12-25-2009).]

hmm vacuum leak huh? where is most common vacuum leaks at? I'll check for that 1st before i tear apart the intake manifold. although i would like to replace all the gaskets on the car. .Thanks guys

now that you mention the egr tube the car is loud as hell...that might be the issue. I'm bringing it to an exhaust shop to get that looked at.

[This message has been edited by WTFRACING88 (edited 12-25-2009).]

Check the idle adjustment screw, you know, make sure that the previous owner didn't mess with it in an attempt to "fix" an issue. On the upper side of the throttle body there is a factory installed cap covering the screw, if it's still there you're good, if not just check to make sure the the butterfly throttle plate is in the fully closed position at idle so the ECM can control the idle.

I would start by making absolutely sure that the electrical system is good. Pull all positive (+) connections and cables, clean and replace. The grounds are equealy important. Same thing, clean all grounds and replace as necessary. Many wierd idle issues have been solved by this process.

A good tune up is in order, timing set properly, filter, new O2 sensor too.

This could be a vacuum leak. There is an emissions diagram on the deck lid for reference, start at the EGR tube, brake booster hose and work from there. A can of throttle body cleaner sprayed at various hoses will detect a vacuum leak, have a fire extinguisher at the ready, you know, safety first.

Check the sensors, IAC, MAP, MAT, and throttle position sensor.

As you are going through all of these processes, clear the codes and go for a drive so the ECM can re-learn the idle characteristics. You might pull an occasional engine trouble code that will help you diagnose the difficulties.

Good luck and keep posting your results as progress.

------------------
jetman
Silver 86 SE 2M6 4-speed, with "check wallet light"
Now fortified with 8 essential slices of bacon goodness

my initial plan was just to replace all the sensors on the car and do a full tune up. what kind of plugs/wires and cap and rotor do you guys recommend?

so i'll check the idle screw and see if that was touched. if it was i should just return the flap to the fully closed position and drive the car?

Do the usual tune up stuff, good ole AC Delco plugs, cap, rotor and etc. works the best. Please don't waste your money replacing every sensor, the folks here on the forum can help you narrow down the difficulties before you ring up the cash register.

Skybax posted a good article on the throttle body re-set procedure.... (the word of caution is not to mess with it unless absolutely necessary).
https://www.fiero.nl/forum/A...06-2-060970.html#p12

I would love to see if the ECM has stored an engine trouble code or two that might point us in the direction of the elevated idle....
https://www.fiero.nl/cgi-bin/main.cgi?ECMCodes

this is really the 1st car i'm getting my hands into more than just basic maintenance. I found a scanner tool for OBD I. its by innova..

any input on it? good bad indifferent? and would it be wise to purchase this for future use?

[This message has been edited by WTFRACING88 (edited 12-25-2009).]

Personnally I would not waste my money on a scanner tool for the Fiero. It might be nice to have and if you have the money to spend it might be o.k. The fiero engine codes when set by the ECM can be retrieved by a paper clip or small wire and observing the check engine light on the dash. It is very simple and the code printouts are readily available on the internet or in the service manual from Haynes or GM.

its also and OBD II scanner. All my friends have OBD II cars. I might do it when i get some extra cash laying around. I was just curious

thanks for every ones input. Sadly i'm to busy with family today and can't touch my fiero...

Stock Fiero ECM is ALDL, not OBD.

Norm

[This message has been edited by gt88norm (edited 12-25-2009).]

okay then, scanner is pointless got it. time to check it the old fashion way. This car is turning out to be quite the project vehicle.

here is a decent site i found with info on ALDL (which is OBD-1 btw...)
you can buy a premade cable there
http://www.aldlcable.com/

i found this site:
http://cable.invisibill.net/

it has a schematic for making an interface cable to work with a serial connection on a PC

WinALDL should talk to the fiero and give you a good readout of its goings ons

I will be making one of these cables myself soon and will post on here how well it works, etc

let me know, i'm a deff interested. I'll even pay you for one.

http://www.aldlcable.com/ has a cable they sell already, it works with the WinALDL software, you just have to get the right cable, i think the stock fiero ECU is the 12 pin connector, someone confirm for me?

I put a ADS super chip in mine, and its idled around 1000 - 1500 ever since.. Never bothered me..

my car idles at 2500 and 1500...jump when ever i start the car. it was at 2500 when i started it earlier and then 1500 about 20 minutes ago when i moved my car for the night

quote Originally posted by yashmack: here is a decent site i found with info on ALDL (which is OBD-1 btw...) you can buy a premade cable there http://www.aldlcable.com/ i found this site: http://cable.invisibill.net/ it has a schematic for making an interface cable to work with a serial connection on a PC WinALDL should talk to the fiero and give you a good readout of its goings ons I will be making one of these cables myself soon and will post on here how well it works, etc

Contact "dodgerunner" here on the forum. He makes ALDL cables for the PC connection - both serial and USB. I believe you can buy this cable form DR for about the same as it would cost you to build your own. Less frustration of building it yourself and DR's cables work!

WinALDL works good and is share ware and can be found here on the forum too. Go to search and type in "winaldl" and "dodgerunner". You will get numerous threads with links to what you are looking for.

If you are just checking the codes, a paper clip is the cheapest easiest way to go.

Here's a few links to get you started:

https://www.fiero.nl/forum/Forum4/HTML/041052.html

https://www.fiero.nl/forum/Forum1/HTML/073532.html

http://winaldl.joby.se/

https://www.fiero.nl/cgi-bin/main.cgi?ECMCodes

Enjoy and good luck!

Pat

[This message has been edited by katatak (edited 12-26-2009).]

thanks for the info
making my own will get me the cable the fastest
I will post up to let everyone know how it works out when i get it completed

<-- runs off to the computer graveyard called his closet for parts and wire...

well i went to go see if the screw was messed with only to find out my throttle body isn't stock...its made by Holley..also the EGR tube is a stainless steel one from the Fiero store. But the EGR valve appears to be stock...and most of the hoses also appear new. I'll have to see if i can contact Holley and see if they can help me out on this throttle body...unless some one knows this one inside and out...

Ah so grasshoppers ,""remember simple diagnostic checks"" ,first check vacuum !! pull one hose, does idle speed increase ??,does it drop ?? plug off hose with finger and feel suction from connector..I love good suction..
this is a one of the FIRST simple test to check for vacuum leaks .. One of the first checks, for a poor running engine ..Free, no cost..
any time an I A C valve is suspect ,,pull air cleaner large snorkle hose and check TBI (intake) for carbon and soot at entrance of TBI,,often just spraying carb/injector cleaner into IAC hole which is at entrance of TBI will cause better running..
The IAC is a major source of high idle
only remove IAC with open end wrench ,ajustable ,or channel locks if it moves "easily"..A six point deep 1/14 thin wall socket is best to prevent damage,, the best cheap socket is ampro T334520 a tight fit but it will not damage IAC..look for one with a machined thiner spot,,got mine at advance auto..
the interior of the IAC TBI hole should be cleaned with carb/injector cleaner ,spray it good and while damp clean it out with Q tips or a SOFT rag, gentle ,untill Q tip comes out with no crapola ..
gently clean the cone tip,check for pitting..make sure the pintle will move & does not extend more than 11/8 inch,, follow instruction in Manual to alter position..
You can spray the pintle with WD 40 to aid movement,sometimes it will bind
Now GURUS,and super GURU,s like jetman, listen up,advise needed !! On most OB2 system you can turn on key and observe IAC pintle for movement (2nd person needed for this ..is this true for FIERO IAC.??.I just never checked it.. this would be prime check for bad I A C

[This message has been edited by uhlanstan (edited 12-27-2009).]

quote Originally posted by WTFRACING88: well i went to go see if the screw was messed with only to find out my throttle body isn't stock...its made by Holley...

The 2.8 comes from the factory with a Holley TB.

really? on my buddies its just a black TB...no logos or anything...maybe i'm going crazy...

quote Originally posted by WTFRACING88: really?

Really.

well i just picked up a full tune up kit. Plugs (ac delco), wires, 02 sensor, air filter, sea foam, throttle body cleaner...since it needed a brake job anyways i picked up some cross drilled and slotted rotors that my buddies dad's shop made for the car.

let the fun begin

[This message has been edited by WTFRACING88 (edited 12-27-2009).]

Pull the engine codes, use a simple paperclip for now. Let's get those codes before the tune up, so we'll know if something has changed after the tune up.

well i found a but load of vacuum leaks. I replaced every vacuum line in the car. took apart the whole intake manifold and i ordered the gaskets. Also found out I'm missing 4 exhaust manifold bolts....the car gave no codes...

[This message has been edited by WTFRACING88 (edited 12-29-2009).]

Good luck on the exhaust manifold bolts. If you are lucky they are missing. If you're not they will be broken off in the head like mine were. The front (firewall) side is bad for that and a major operation to repair.
Don't put your intake back on until you determine what you need to do about the missing/broken bolts. Some people end up pulling the head to get the exhaust manifold bolts drilled out.

they don't seem to be broken off...just completely missing....the cyl heads are aluminum on the car correct? i intend on replacing the manifold gaskets as well.

The stock heads are steel.. the major cause of hi idle is a vacuum leak ,,the lead suspects are the IAC and the EGR tube,,that runs from the EGR to the under side of the plenum..
check rubber hoses for loose or harden ends then for splits or breaks

just cleaning the IAC and chamber it installs in will drop the idle down a few hundred RPM at start up 50% of the time,, this is not difficult to do

The first check is just to see if you have strong vacuum.
if the leak is at the EGR metal flex tube,,you can make a solid seal/block gasket from a piece of aluminum pie pan or soda can and block it off ,,untill you can purchase new tube,(($100.oo at Fiero Store)) .. you can run this blocked off for many years ,,If you do this place rag under lower plenum bolts ,,so they do not disapear ,,you can cut slots in the blocking gasket loosen bolts and slide it in ,,easier said than done ha ,ha..

quote Originally posted by WTFRACING88: they don't seem to be broken off...just completely missing....the cyl heads are aluminum on the car correct? i intend on replacing the manifold gaskets as well.

As stated above the stock 2.8 has cast iron heads. Does the top part of the engine look like this one in a pic I borrowed from JScott's thread? If it looks a lot different then some one may have swapped in the lower power aluminum headed (Celebrity etc) engine
https://images.fiero.nl/i...20091227_163829s.jpg

Stick a probe of some sort in each of the exhaust manifold missing bolt holes to see how far in it goes. That will confirm whether or not they are broken or missing. I hope they are just missing.

got the car almost put together. found out what lines i was looking at. so the fiero is almost road read in my eyes. the bolts are just missing i just checked with a probe so this is going to be an easy fix i'm hoping.

[This message has been edited by WTFRACING88 (edited 12-29-2009).]

quote Originally posted by WTFRACING88: the bolts are just missing i just checked with a probe so this is going to be an easy fix i'm hoping.

Wow. You must live life just right. I'm stunned to say the least. For one who has done battle with manifold bolts, I'm happy for you. You just don't know how lucky you truley are.

As jetman said you must have walked with the gods at some point,,Remember to clean out manifold bolt holes..remove as much rust as possible,use q tip if you can not think of any thing else ,, use heat resistant grease or better,, and dap a little on each thread,, the thread are only 12mm deep so make sure you get as deep as you can with out bottoming
the bolts are 8x1.25x30mm,,Make sure bolts do not bottom ,if so space with washer or lock washer ..
the factory bolt seems to be a bit short of 30mm,,the specialfactory bolts are best but difficult to find.. I use 8,8 bolts from ace hardware
run the manifold shield on starter side to protect hot pipes from water ,, they will crack

[This message has been edited by uhlanstan (edited 12-29-2009).]

the car still idles high....2500RPM...keep in mind i haven't driven it since i did the vacuum replace or changing any sensors. i have literally changed every sensor on the car except for the MAP sensor. The reason behind this is because they all had cracked housings. I felt safer replacing them. But even after that my idle sits at 2500 and a very smooth 2500 may i add..before the car was missing and wasn't running very well...

i haven't checked the vacuum line from the brake booster yet though..would that cause the car to idle that high?

[This message has been edited by WTFRACING88 (edited 12-30-2009).]

do you hear any hissing sounds when its running??
maybe you have a cracked cly head?
did you replace every vac line?
you replace the head, intake, and exhaust gaskets? did you replace the throttle body gasket?

just had the car down to 2K. Now its up at 4K for some reason...waiting for the book to arrive in the mail. also my check engine light has just popped out..how hard it to replace a stupid bulb like that? I replaced the upper intake plenum gasket, the throttle body gasket..i have not replaced the head, exhaust or gasket that connects the lower intake to the engine.

okay what would the coolant temp senor do if it was shot?

And i was not the owner who "rebuilt" the engine

[This message has been edited by WTFRACING88 (edited 12-30-2009).]

It is like 7 screws total to remove the back of the instrument console. From memory, 5 in rear and 1 on each side to access the bulbs.
You really have a huge vacuum leak, at this point I would be tempted to remove all vacuum hoses from the engine and cap them off, block off the EGR tube at the plehnum and work your way back out from there.

quote Originally posted by jetman: It is like 7 screws total to remove the back of the instrument console. From memory, 5 in rear and 1 on each side to access the bulbs.

Three torxs on top, two down in the groove between the inst panel and the dash, and two 7 mm under each end of the inst panel. Carefully lift the rear cover away from the back of the inst panel. There will probably be some deteriorating foam that falls off. Then look in through the windshield and you will see several gray knobs. Find the one that is directly behind the bad bulb, twist it, and pull it out. There will be a bulb inserted in the knob. Pull the bulb straight out of the knob and get a replacement for it. Reassemble in reverse order.

[This message has been edited by 2farnorth (edited 12-31-2009).]

thanx for the info. I'll be having some fun tomorrow morning. I literally just took apart the entire lower intake and fuel rail just to find out the O rings are shot the gasket was shot and every time i try to touch a gasket they just break into little pieces...this is fun...