my 87 base model with the 2.5 4cyl dies when stopping at stop signs.
its been doing this ever since i got it. its starting to get quite annoying.
it has msd ignition, new fuel pump and filter new fuel injector new map sensor and coolant temp sensor.
any help would be great.

Sounds like a vacume leak a can of wd40 or starter fluid spraying around listening for a rev sometimes helps to identify leak g/l Ray

thanks. brakes use vacuum right?

That sounds very typical of a bad IAC.

I would start there first.

Auto or manual?

manual. sorry i forgot to mention that.

Make sure plugs are gaped at .060 and spark plug wires do not run close and parrallel for a long distance,check vacuum lines do not forget line that runs close to fuel filter up to tank behind battery vacuum line connetion at pipe should not be harden

the egr could be in early stage of clogging make sure it is tight at base mount point,normally if you disconnet and plug vacuum line and problems go away !!!! Clean and thorough check of egr IS NEEDED do not replace unless you must/CLEANING AN egr IS OFTEN EFFECTIVE ..Idle stalling and & hesitate at accelleration is often E G R.. a very common cause of hesitation on many cars,sometimes fiero
a back fire indicates a bads module in V6( just threw this in)
vacuum EGR can be cleaned in carb or injector cleaner , electric EGR should not be submerged but can be cleaned

A duke is easy to check for bad cylinder or plug or injector,, pull plug wires one at a time , the dual coil duke will actualy run on 2 cylinders(hard to start) check for weak cylinder this way( always have a grounded spark plug in a running fiero)ALWAYS.. If you determen a bad cylinder ,,check spark of plugs from same coil then against the different coil...TH THre is a single fuel injector ,if it is at fault it just needs cleaning or some injector cleaner run thru it
sniff around after key is turned on the connection from the fuel line to the inlet nut that screws into the TBI
clean & Tighten ground wire at head stud more to prevent future no start and clean and tighten the ground small wire where it connects to inner fender

were there any codes??
The TPS sensor can "bind" and cause this normally this causes more severe problem ,,tho as a last resort a very small amount of W D 40 can be sprayed into crevis you have to remove to do this to do so ,this may kill unit!! info on volt oms check are in manual check first if bad be my guest and spray well..

cleaning IAC unit often clears up a hesitation often it can be sprayed!! this works better on the V 6,but worth a shot to spray clean with out removal..On the duke better to remove ..Place rag at bottom of TBI and spray as if an army of mutant cockroches are comming out the bore after you ,check bottom retaining bolts and also the 2 screws that hold the top of the TBI to the lower half
Check manifold to engine bolts
If the check engine light comes on under light load or going down hills then goes off SHORTLY and does not leave code this is a lazy 02 THIS HAPPENS before hesitation starts check connections before you replace 02 on fiero should be replaced at 30,000
is this an auto or a manual
check vacuun line to auto trans.look for fluid inside when yo check make sure all lines and wires are connected..check ajustment of T V cable
An hesitation is as difficult to detect as any problem ,,that is why I listed so many causes the actual checking will not take very long
When many electrical components are replaced,, there is often a connector that needs to be tighten, a connector that slips the male inside the female (i need a smoke now ) needs to be squeezed or corrosion removed

Hes not having problems at idle, hes having problem getting to idle when RPM returns.

That is where the IAC comes into play, and is usually the problem with his symptoms.

I would clean it as best you can, and see what happens. Whenever I've had this problem, I never cleaned them - just replaced them, so I dont know how well that will work out for you

[This message has been edited by AutoTech (edited 03-23-2008).]

could i clean the iac with carb/choke cleaner or is there something better for this?

Sure. I would use brake cleaner, but that should be fine.

okay i have brake cleaner too.
ill try that and see how it works.

Stick to carb or injector spray clean I some times use quick start(ether )but carb cleaner is better soak it a little in a small cap, be gentle just clean area and part with spray,, this will probably cure problem photo was blured ..it does not take much to hurt idle , do not take a chance with harsh sprays ruining your part. if cone has holes, craters ,replace .. you can clean and see how this works

Let us know, I have a working one here if you want it, just give me a few bucks for shipping. Hope you wont need it though

thanks alot for the help.
ill check back in a bit with my results.

After it died and you restarted it, did it idle at 1100 from then on? I mean, will it then stay at 1100 in idle until you drive it again?

You could also try resetting the IAC now that you have cleaned it. It's simple and free and quick. You jumper ALDL pins A&B, then turn key to RUN and wait 30 seconds. You will hear the IAC being driven closed. After 30 seconds then pull the power connector to the IAC, now turn the key to OFF, then reconnect the IAC and remove the jumper from the ALDL connector. Next drive the car over 35mph for the ECM to relearn idle.

yes it did stay at around 1100 in idle
i will try resetting the iac like you described in a few minutes.

Not long at all really. It should idle good immediately but get better after driving it awhile. It should never, ever stall though.

thanks i will have to drive it tomorrow as it is quite dark outside right now.
but thanks for your input. :]

Had the same problem with mine after rebuilding my engine
Some are gonna say never touch the screw on the throttle body but i did
Car was stalling at every corner ,What i did is turn the screw clockwise one 8 of a turn and go try it until it doesn't stall , never had any problem with it since then .
Guy at an auto électric fixed it once before like that , saying that when you come to a stop the pallet close too much for a fraction of a second , thus not allowing any air in .
Then sometime it recuperate going down to 500 RPM .
But when it goes less than that it stall . The oil ight is coming on and BANG dead engine .

which screw do you mean?

The one on top of the throttle boby under a sealed little tin cap . As you can see the seal is gone on mine . Hey there is a guy playing for the Montreal Canadiens hockey club with the same name , except he's got an 's" at the end of George .Number 26 Josh Georges .

[This message has been edited by Robert 2 (edited 03-24-2008).]

The 2.5L Dukes also have the throttle plate set screw. Some have mistakenly called it the idle screw. Since the ECM sets idle through the IAC motor, if you try to set idle with this screw it really messes up the ECM. The purpose of the screw is to set the minimum opening of the throttle plate so it does not get stuck in the bore by closing too far. The tell-all is the IAC counts. 25-30 counts at idle is perfect. Anything less means the plate is too far open (or a vacuum leak), and more means the plate is too far closed. If you have the software and cable to hook up to the ALDL connector you could look at the IAC counts. Otherwise you're just guessing.

dont because i have a dis i cant use winaldl or is it possible to still use it?

pick up a product called "sea-foam" and pour a little down the TBI and the IAC vent hole as you run the engine. If it stalls, restart. You could just some some carbon build up or a bad vac. connection/line. Your EGR could be stuck open a little. I believe you replaced it. Did you get the correct one?

I had a similar problem with an 88 coupe (same ign system as 87) and the sea-foam fixed the problem.

J.

i have not replaced the egr as it seems to be okay.

I would replace the IAC with a new one. Guess I didnt pay attention enough to see that you have the 2.5l, so I dont think the one I have will work, its for a V6.

SeaFoam is always a good idea, especially on older engines.

Let the engine fully warm up first. Pour the solvent into a clear glass cup, or similair, so you can see the fluid. Connect a vacuum hose to the intake, as close to the TB as possible, and you will use this hose to suck in the fluid.

Start the car and let it idle, slowly dipping the hose into the solvent. The car will die if you try to add too much, so do it slowly. You may want to raise the idle a few hundred to help this, just try not to let the engine die.

After all the solvent is gone, turn off the car immediately, and let it sit for at least 30 minutes. After that, take it out for a spin until all of the smoke is gone. It is better to "get on it" while driving, as this helps to break up the carbon deposits even further.

You will get alot of funny looks too, your car will look like its on fire, and thats exactly what people will think especially with a Fiero

[This message has been edited by AutoTech (edited 03-24-2008).]

where would i connect the vacuum hose on the intake?

Couldnt really give ya an exact location. I've never had a 4cyl, and have never really paid any attention to them either

You could use the PCV line if you have the plastic one. The metal PCV line does not like to move, lol. Others have used the brake booster hose. Basically, use any hose off the back of the throttle body that you can get to. I used a spray bottle and just misted the seafoam straight down the throttle body while holding the rpm's up a bit to keep it from stalling.

Sent joshgeorge a PM. Wondering what the status is?? I have the same problem.