SEE HAIR PULLED OUT: Still having trouble getting it to idle!! Drove the car 15 miles today idle ar 1400 when I started out and at 2200 when I got back. Set code 35 when I pulled into driveway. I will list what I have done so far.
1) Replaced EGR tube becahuse insulation was trash and it just looked bad.
2) Replace MAP sensor to correct code for it.
3) Checked TCC and it is all working.
4) Tested all EGR components and they all check good.
5) Checked P/P switch and it is working good.
6) Set timing at 10 degrees with A&B shorted.
7) New IAC and checked all components for it and they seem good.
8) Replaced vacuum lines with Rodney's Stainless Steel ones (there are vacuum leaks from hem )
9) Sprayed starting fluid around all vacuum connections to verify no leaks.
10) Checked temperature with my old scanner and temp seemd to agree with gauge.
11) With IAC electrics disconnested car will not idle at all, stalls.
12) With IAC electric connected it iudles high.
13) Pulled out a few more hairs.
This problem started suddenly, I replace the egr tube and took the car for a drive, it stalled when I pulled intio the drive and would not idle in gear (stalled). As yopu can see I have made a difference as it now wants ti idle high. Tis car is to become daily driver and I just love the Fiero so I need to figure this out soon or I will be walking. ANY AND ALL EPLIES WILL BE TAKEN SERIOUSLY AND I WILL FOLLOW UP ON THEM. Thanks guys perhaps someone can put a finger on it for me. I just feel it is something simple that I am overlooking.
MIKE

Code 35 means the ECM is unable to control the idle to the proper speed. First clean the code. Then try idling the engine warm for a longer time (somewhat long red light) and see if the light comes on consistently.

If code 35 is coming on consistently then you know that the problem is not an ECM input but instead a problem with air getting into the intake.

There are only a few ways that much air can get into the intake. (assumes return of Code 35)

Throttle valve

IAC

Leaking IAC tube gaskets

Leaking intake manifold gaskets

An open brake booster vacuum hose.
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All the other vacuum hoses are way too small to make the idle increase that much.
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quote (11) With IAC electrics disconnested car will not idle at all, stalls.

This doesn't make sense at all. With the IAC unplugged, the position of the IAC pintle will 'freeze'. So whatever the engine was idling at, it should stay at. The only thing I can think of is that you unplugged the IAC connector with the IAC pintle fully extended. That could happen if you unplugged it after jumpering A-B and then turning the key on. Jumpering A-B with the key on, but with the engine not running will fully extend the IAC pintle for diagnostic purposes.

[This message has been edited by phonedawgz (edited 08-01-2012).]

Have you looked into the ICM, pickup coil, ignition coil?

Any of those going bad could cause an off idle.

An angle of thinking that maybe the code isn't the only issue.

[This message has been edited by sirtimeless (edited 08-01-2012).]

Probably correct on unplugging the iac while A&B shorted and key on, but should it have readjusted with jumoer removed and engine running? Sprayed started fluid around intake, throttle body and all vacuum connctions and saw no rpm change. I do notice that when I apply brakes while running changes rpm about 100rpm, that is setting still in gear and idle going at about 1200rp. ANy thig else you vcan think of I will check. Thanks for the reply.
MIKE

Yes applying/pumping the brakes will result in an increase of idle RPM. That is normal.

Is the only problem the high idle?

[This message has been edited by phonedawgz (edited 08-01-2012).]

High idle s the problem. Thanks for your reply.
MIKE

Here is the applicable troubleshooting page from the '86 service manual regarding an incorrect idle speed:



And here are the pages for code 35. These next two pages refer to the use of the Scan Tool, though there is still very useful information even if you may not have access to one:

It surely sounds like your problem is that at times the ECM can not move the IAC's pintle. So the question is why.

Any chance the IAC passage has carbon in it, or something else that may block the movement?

The IAC wiring looks good?

If it is still idling high remove the IAC, retract the sprin and unscrew the pintle just a bit. Perhaps the pintle is jammed at a fully retracted position.

Here is an IAC pintle movement test - Take out the IAC. Fully retract the pintle by retracting the spring and screwing it in. Then unplug the IAC from the harness. Then jumper A-B and turn the key on. Now plug in the IAC and wiggle things around while watching to see that the IAC pintle is continuously moving. Watch out - if the pintle fully extends - the pintle and spring can launch themselves into the deep dark corners of your garage - AND when installing your IAC, make sure the pintle is retracted. If it is too extended when you install the IAC, the pintle will jam into the end of the bore and it will wreck your IAC.

Wiring looks good. I will remove the IAC and do the unscrew that you suggested (iac is new) I found out about it shooting across the garage with the old one, just got curious and hooked her up with A&B junpered. Did not mind as had new one in hand. Bore is clean I took q tips and Throttle Body cleaner and swabed it out good. Dad Gum It I just know it will be something simple when I find it. I am going to set base timing again 10 degrees with A&B shorted. Then I am going to spray the atreter fluid around again to triple check for vacuum leaks. The I am going to get that bottle od Jack Daniel that I have been saving for a special occasion and have a good pull on it, fixed or not. I need some relief. Thanks again for the replies.
MIKE

The vacuum going to the brake booster needs to go through a tube to the front of the car, could it have corroded or been punctured?

Where the heck does this tube hook to? Mine is not connected anywhere and I can not seem to discover it's connections in the service manual. Shown as IAC air tube.
Mike

[This message has been edited by oldbikeracer (edited 08-02-2012).]

It goes to the underside of the throttle body, right below where the upper intake plenum and throttle body mat together. There is a hole that it simply inserts into. Look at the throttle body and you'll see it.

IAC feed tube. It connects to a hole in the bottom of the intake face of the throttle body. There is an internal O-ring that seals the tube to the throttle body.

If the engine will not run with the IAC valve fully closed, it can not be this seal that is leaking. You can double check this by taking out the IAC VALVE, starting the engine and sealing the output of the IAC VALVE passage by sticking your finger down in there and sealing it off. If the idle is 500 rpm or slower then you don't have an vacuum leak.



btw - If your engine is hot, it will be hot inside the IAC hole.

[This message has been edited by phonedawgz (edited 08-02-2012).]

quote Originally posted by phonedawgz: IAC feed tube. It connects to a hole in the bottom of the intake face of the throttle body. There is an internal O-ring that seals the tube to the throttle body. If the engine will not run with the IAC valve fully closed, it can not be this seal that is leaking. You can double check this by taking out the IAC VALVE, starting the engine and sealing the output of the IAC VALVE passage by sticking your finger down in there and sealing it off. If the idle is 500 rpm or slower then you don't have an vacuum leak. btw - If your engine is hot, it will be hot inside the IAC hole.

I appreciate the cheese head feel in this picture

[This message has been edited by sirtimeless (edited 08-02-2012).]

Let me get this straight in my mind. With this tube not connected it should not create a vacuum leak and IAC would get ait supply fro outside air instead of through this tube and still work correctly. Does that seem correct? I will pull the throttle body andd reconnect it. Thanks for the reply.
MIKE

If that tube is open to the air, then your IAC cant control your idle and you have a wicked vaccuum leak. Is that what you are saying?

No - that tube extends the vacuum of the intake manifold to the throttle body's IAC valve. "Feed" refers to the intake manifold getting fed from the IAC valve.

So that tube is under intake vacuum. If the O-ring leaked, the engine would idle fast. But the IAC valve could not affect that idle. So if your engine idled fast with the IAC valve fully closed, I would suspect the O-ring. But from what I understand your engine won't even idle with the IAC valve closed.

* - The IAC valve's actual 'feed' input is a hole in the floor of the bore of the throttle body - outside the throttle plate - on the bottom of the bore. Take off the rubber snorkle and you can see it if you look into the throttle body.

[This message has been edited by phonedawgz (edited 08-02-2012).]

ZKWENNUNGS,

Yes that is what I am saying. I am at work now and will hook that bugger back up when I get home. Hope my problem is somethning stupid like this. I am learning more about the Fiero than I wanted to know. Perhaps this will make me an expert like you guys and I can help someone in the future.Thanks for the reply.
MIKE

[This message has been edited by oldbikeracer (edited 08-02-2012).]

quote Originally posted by oldbikeracer: ZKWENNUNGS, Yes that is what I am saying. I am at work now and will hook that bugger back up when I get home. Hope my problem is somethning stupid like this. I am learning more about the Fiero than I wanted to know. Perhaps this will make me an expert like you guys and I can help someone in the future.Thanks for the reply. MIKE

Welcome to Fiero's! I purchased my first last November, and already know more about this car, than any other car I have owned.

I took off work and am now hooking up that darn tube, keep your fingers crossed with me. I just never noticed it when i removerd the plenum to raplace vacuum lines with SS ones. I am goinf to RTV all around it in case I damaged the O ring. I have had experience like this before. I purchases a C4corvette several years ago, that is why I have an OBDI scanner now. Corvettes have only 2 things in common with the Fiero , wnen you drop a tools it usually goes through to the floor and plasric bodies can create grounding problems. If you ever buy a C4 corvette make your first thing to do go to l ground points and clean them up. I thank everyone again for the replies and help. You guys have held my hand through this process and I am very grateful for the help.
MIKE

[This message has been edited by oldbikeracer (edited 08-02-2012).]

I am embarashed to tell what the problem was. Car now idles and runs great. All this time it was that I had pulled the IAC air tube out of the throttle body and kust plain did not notice a black tube going nowhere until today when I was looking through other threads for a hint. Beleve me that insignificant looking black tube IS IMPORTANT. On the bright sidfe Ilearned a LOT about the fiero and did some upgrades that it needed, such as replacing vacuum hoses with Rodney's stainless steel ones. MAP sensor was intermittant so I replaceit. Replaced EGR tube and a couple of other things. Put new wire harness plastic covers on all underhood wire harnesses. Cleaned the engine. I want to thank everyone that replied and helped, it was somewhat hand holding but invaluable. THANK YOU!!! I knew that it would be somethig small or stupid on my part and I was correct. I do have a little excuse, I am 71 so brain fade is the usual thing and blind in my left eye. Now I am going for a little drive in my great looking, great running 1987 Medium Red Matalic GT I also installed Mr Mikes seat upholestery during this process while waiting for parts, they are light gray cloth with bolsters dark gray vinyl. Thaks again I can not say that enough.
MIIKE

Okay guys, I'm really confused here. With that tube not connected to the throttle body, I would think there'd be a massive air leak into the intake plenum. Air leaks lead to high idle. So why would this engine stall and not idle at all? What am I missing here?

Nobody else finds this strange?

quote Originally posted by Patrick: Okay guys, I'm really confused here. With that tube not connected to the throttle body, I would think there'd be a massive air leak into the intake plenum. Air leaks lead to high idle. So why would this engine stall and not idle at all? What am I missing here?

I think he fixed the stalling problem only to lead to a high idle condition.

Perhaps I can unravel it for you. First it would stall at idle, getting codes 32, 33, 42. Whil looking at the egr stuff I noticed vacuum lines were brittle and breakingo I replaced them with Rodney's Staibless steel ones. When I got the plenumn back on it ran like crap. Found that vacuum line to fuel pressure refularor was not connected at the regulator, I knocked it off whil putting the plenum on. Corrected that and put her back together, this time I missed the IAC air line top the throttle body and idle went sky high.. Fixed that and now whe runs like it should. In the process I replaced MAP sensor, IAC Valve, Vacuum linesand egr tbue. Does that help explain it.?

EDIT: Forgot to tell what the original problem was, stalling at idle. EGR solonoid was somehow allowing vacuum to egr valve keepinf it open at idle thus stalling the engine. This explains my first trip after ionstalling the EGR tube car ran great until I turned into the dribe and car stalled. During that trip i drove at anout 60 for about 15 minutes which would have opened the egr valve, solonoid stuck on return trip causing the stall at idle. Does someone make an egr delete kit with chip, block off plates and instructions? It wopuld be nice if a complete kit were available ro get rid of this extinct monster. Again THanks for a great forum and all the replies.
MIKE

[This message has been edited by oldbikeracer (edited 08-04-2012).]

http://www.tlg-auto.com/V6_...ff_p/fieroeng009.htm

http://www.reddevilriver.com/Related_Products.html

Thank you for the linke. I will probably purchase both and get rid on one headache and lowers engine compartment heat. I can do both for half the price of an EGR solonoid. Thanks again.
MIKE

Make sure it has gas! The gas gauge is famous for reporting incorrect fuel level.

BTW, the IAC tube pictured above is mine from the original engine. I don't think the oil was ever changed by the PO as it's baked and caked 1/2 inch deep in places.

Since you replaced the ICM, I'd suspect the pick-up coil in the bottom of the distributor next (you have to pull the dizzy to replace it). Since you have to pull the dizzy, your ignition coil may also be the culprit, and it's way easier to replace the ignition coil, you might want to try it first? Are you ready for that Rogain yet?

[This message has been edited by carnut122 (edited 08-05-2012).]

Found the problem. Previous owner replaced the 4 wire connector to the distributor and did a crap job splicing wires. Two of them were worn bare and touching. No Rogain!! No hair cuts down on shampoo overhead so I can fix this darn Fiero. Thanks Guys.
MIKE

FIXED !!! Month old MSD coil went bad, checked good with meter as per service manual. When I did the paper clip t ground test it would have spark once in a while, but weak. When I first did this test spark seemed good with new spark plug gounded to blosk. Test it again and all of a sudden it would not spark, tr4ied iy 6 times before I got any spark but it was weak. Put a new coil on her and she fired right up. I now know more about the ignition system tha I wanted to know. Learned more that I wanted with the EGR system also. DARN CAR, it owes me many trouble free miles now as I have petted it for a couple of weeks now. Again Thanks for all the replies.I just neede to know that someone oput there cares and give moral support. Hopefully I will not come back here with any more problems.
MIKE

quote Originally posted by oldbikeracer: Hopefully I will not come back here with any more problems.

You're driving a 25 year old car. You'll be back.

GEE thanks for the kind words, LOL. Yes I know it is an old B^&% but so am I. Just turned 71 and lucky I have obtained some patience through the years, otherwise it would be reported stolen and at the bottom of a river. I have learned a lot and if same problems require attention in the future I am much better equiped to handle them because of the knowledgI have acquired here. THANKS
MIKE

quote Originally posted by Patrick: You're driving a 25 year old car. You'll be back.

I treat mine like Timex watches.
Treat yourself the same~!!!!

quote Originally posted by oldbikeracer: FIXED !!! Month old MSD coil went bad. MIKE

Was it an MSD HEI coil -- Part # 8226?

I've got one, but it's not installed. I was advised to not use it because they are supposed to be prone to failure. If yours was the above unit, then I will try to get a refund.

Thanks

[This message has been edited by I FAR I (edited 08-07-2012).]

quote Originally posted by I FAR I: Was it an MSD HEI coil -- Part # 8226? I've got one, but it's not installed. I was advised to not use it because they are supposed to be prone to failure. If yours was the above unit, then I will try to get a refund. Thanks

That stinks I have a blaster in my fiero right now lol.

Good thing i keep a spare in the trunk :P

hm, i just took my msd coil out and put my stock one back in because i was tired of going thru cap and rotors. i just installed a new dist. too, went for a ride but drove it home. i went thru the stock air box [v-6] made a new gasket for the bottom and then i moved over too the vapor canister, too it out and cleaned out the crap under neath it and inspected the filter. i have done alot of reading and replaceing/cleaning. this car keeps you on your toes. glad you worked everything out.