3800superfast.... or anybody else, Did you find what the issue was? Mine just started doing this. After chasiing down some other issues and finally getting it to where it started and idled absolutly great, a week later I had a manifold gasket leak then this started up. I changed the gasket, but still ticks when cold. But the idle is driving me nuts.

I know Superfast did not find a solution.

It might or might not be related to your gasket issue. It seem to happen this time of year in the spring and fall when the air temps start to hit the 50-80* range. Hotter and colder and it does not happen. It's been a common occurence during this time of year.

[This message has been edited by Dodgerunner (edited 09-13-2007).]

well see no matter what temp mine does it, if your start it up in the morning it idles at 1300 rpm, (which i normal cold i think) and then like 2 minits later when the idle drops to normal it starts to hunt, or ANY time the eng is warmed up it will hunt regardless of air temp., btw i put a brand new ecm in and it didnt change a thing.

[This message has been edited by 88 Silver Formula (edited 09-13-2007).]

ok something odd... bout five min ago.. went for a lil ride.. started up fine.. idles great.. i go about 3 miles and then back home.. and it surges idle.. bout 1500 to normal.. only does this warm not cold for me anyways..

I apologize for a silly question, but i was browsing alldata the other day and theres a technical service bulletin for the fuel pulsator, says it causes "prolonged cranking, no idle, stumbling, surging"

Has this been addressed?

fuel pulsator would have absolutly 100% nothing to do with it, on top of that i bypassed mine completly (it was a perfectly good working unit) and had no change what so ever....it may cause pro longed cranking but nothing to do with idle hunt.

hobodude34 yours does the same as mine. here is a video of what mine does...this is at operating temps in park..

http://s153.photobucket.com...current=DSCN2352.flv

88 how do you get yours to rev that quick? mine never falls below 1000 ive also got a 5spd.. shouldnt really matter tho.

[This message has been edited by hobodude34 (edited 09-13-2007).]

One thing I have found with mine is often when it's hunting if I give the gas peddle a quick tap so it opens a bit and then snaps shut.
That often makes it stop. I once read that if your TPS is not at the correct voltage for idle it can cause the hunt.
I know mine is just a little high but I have not taken the time to adjust it yet. Need to do that but bracket orders seem to take to much time...

Sorry to dredge up a older topic , but I needed to give props to Dodgerunner and 3800superfast . Dodge was nice enough to help with the IAC setup for a new replacement and 3800's walk through with ecm reset worked like a charm . My car on start up idles about 900 now maybe a fuzz less when warm and a hard drive but still very smooth. Idles about 1000 @ stoplight now , I am grateful to have a smooth idling Fiero now thanks to these two

how do i get it to rev that fast? that was only 1/2 throttle, i dont know its been super fast since the 3.4 swap., yeah thats right i swap engines and STILL has that BS idle

Hi

Hopefully, just a simple query re ALDLView - is there a size limit on the log file you import?


TIA

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The Madscanner
'85 SE 2M6 Auto

I've not run into one yet and I've done some over 1/2 hour logs before.
If your having problem opening the log it's usually because of trash that has got into the file while it was recording. Which causes error when it is trying to open.
When that happens I open the file in excel or OpenOffice Calc and clean out the offending junk and then they will open.

Thanks DR

I've got one file, about 20 Kb, but logged when static, idling, which loads fine. I've got another one which is 300Kb, which won't load (the application just goes "not responding"). I've cut it down several times, but no luck yet.

I've not sure what I midght need to do to tidy it up.

I have, however, run up an Excel files, cleaned up, and with a couple of graphs - just need now to understand what it is telling me.

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The Madscanner
'85 SE 2M6 Auto

Hi DR

It occured to me that, having installed a new EGR tube and checked over various cables and pipes, I should re-set the ECM, so did that today.

Have also checked if I'm getting any errors - after jumping the A + B connectors in the OBD1 socket, the only error code I'm getting is 12, which is normal with the ignition on, engine off.

Will take the car out for another run soon and run another log... Maybe some day when it's not raining here (could be a while!).

BFN

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The Madscanner
'85 SE 2M6 Auto

I don't know if it will help anyone or not but here goes. My 87GT runs just fine; starts just fine but when I stop like at a traffic light it will surge from around 1100 RPMs to 1500 RPMs back and forth,back and forth. It sounds like you're revving the engine slightly. What I found out was that if I'm running the ac or heat unit -this is when it happens. Was told to check ac freon(134) if it was low it would cause this surge when it kicked in and out. Freon was low; put freon in and problem solved. Hope it's that easy a fix for someone else.

[This message has been edited by NiotaFiero (edited 12-13-2007).]

I wish that this problem had been resolved. My 2.6L V6 idles fine when it's cold, but once it gets up to temperature, it starts hunting from 1100 - 700 and will occasionally stall. This is particularly frustrating at stop lights. If I rev the engine a little bit, the problem stops.

I have been following idle /loping/surging issues on this site for a few years now.
Yes years !!
This issue drives me crazy I have tried everything and I cannot find the cure.
It has to be the most frustrating thing I have ever come across with my 87 GT.
All I can say is @#$%^&**() !!
Now I feel better.
We need a Hero on this matter.
Whoever solves this will have to have a statue made in honour of this fix !!!!
Arrrggg.....

ChezFiero

I know what you mean. I have been working on it off and on for years also.
I have found I can make it somewhat better or worse at I tune my 3.4 but have not found a magic bullet.

If you want some interesting reading try this. I have actually been working in this area of the prom for the past year with mixed results. Ran across this post just a couple weeks ago. They mention hunting idle down the post a ways..

My current prom idles great until I reach full op temp then it starts to hunt. My last changes actually made it worse so maybe there is hope.

http://www.thirdgen.org/tec...rottle-follower.html

[This message has been edited by Dodgerunner (edited 11-21-2008).]

You guys are clearly the ECM/Sensor/Idle kings. I'm looking for some advice on what happens when the car goes into Diagnostic Mode, Field Test Mode or Closed Mode. My 87 V6 will idle at 900 on the dot in Diagnostic Mode, and when it's cold - so I'm assuming in Closed Mode. Once it is warm, it won't idle. Just drops to zero. Also, once it's warm, if I hold the idle at 500 for about 45 seconds (a long time if you're just sitting there), it seems the computer finally realizes the car should be idling higher, and it pulls up the RPM and idles (and will stay at idle indefinitely - or as long as I've waited). But, if I hold it above 900 rpm, no matter for how long, if I let it drop it will stall. I have a cable on the way to see what's going on with all the sensors. But, I just made contact with someone who has the EXACT symptoms as mine. He said it idles fine when the computer is hooked up - which I understand is the Field Test Mode.

He has also had another Fiero that idled perfectly and he swapped all the sensors, ECM and everything back and forth. His car still wouldn't idle and the other one would. I've already replaced the common culprits: IAC, TPS, and O2 (for good measure), done the grounds, checked the timing, and various other non-common culprits. But, since he is having the same problem and has already tried the rest, it actually seems it may be harness related. I know mine worked fine before it sat for many many years - however I've checked all the connections and they looked spotless.

I was excited to get the WinALDL cable on its way. But, now that I learn it too puts the ECM in a mode that might mask the problem, I don't know what to think or do. Is there some way to better understand what is changed in these modes that would stop the lack of idle problem? Or even in the Field Test Mode I may be able to see something wrong?

Thanks for any help.

My 3.4 is still hunting also. I've been playing with the tps idle voltage setting and can actually make it worse but have not made it better. I picked up a new cap and rotor today and am going to replace the pick up coil and the fore mentioned parts to see what might happen.
The theory I'm working on is that at idle I think I start to get a small miss. It might cause a rich condition that causes some kind of feedback loop to start. IE richer, idle drops, ecm speeds it up, clears the rich, idles down, repeat...

Just an idea I'm going to try..

As far as the cable making a difference, sometimes it will make mine settle down and other times after it gets to op temp it will still do it even running on the cable. I do know I run very rich at idle and it varies how rich. Idle INT will run anywhere from 70 to 120 depending on how it's running.

Well I found something interesting when my 3.4 warms up it also hunts from 1300 to 500 if i unplug my oxygen sensor it goes to 900 and stays put. I have a new egr valve new egr tube new oxygen senor and iac as well as a new distributor and plugs wires coil etc. No vaccum leaks either I had it put on a smoke machine at my friends shop after I replaced the crappy lines as well as all intake gaskets. So I'm interested in the cure for this as well

I don't know if this will help anyone. But, I was flipping through the factory service manual and found a section on idle issues. There is also a page with the range of correct readings from a WinALDL test.

Here is the complete section they had on idle issues. It certainly contains things I've seen around about idle issues. But, since it had things I don't think I've seen before, I'm posting it here in case it will help someone.

Here it is:

ROUGH, UNSTABLE, OR INCORRECT IDLE, STALLING

Definition: The engine runs unevenly at idle. If bad enough, the car may shake. Also, the idle may vary in RPM (called “hunting”). Either condition may be severe enough to cause stalling. Engine idles at incorrect speed.

Check:
- Park/Neutral switch circuit. See CHART C-1A
- For injector leaking, Check Fuel Pressure CHART A-7.
- If a sticking throttle shaft or binding linkage causes a high TPS Voltage (open throttle indication) the ECM will not control idle. Monitor TPS voltage. “Scan” and/or Voltmeter should read less than 1.2 volts with throttle closed.
- EGR “ON” while idling will cause roughness, stalling and hard starting. CHART C-7.
- Battery cables and ground straps should be clean and secure. Erratic voltage will cause IAC to change its position resulting in poor idle quality.
- IAC valve will not move if system voltage is below 9 or greater than 17.8 volts.
- Power Steering – CHART C-1E. ECM should compensate for Power Steering loads. Loss of this signal would be most noticeable when parking and steering loads are high.
- MAP Sensor – Ignition on engine stopped. Compare MAP voltage with known good vehicle. Voltage should be the same +/- 400 mv (.4 volts). OR Start and idle engine. Disconnect MAP sensor electric connector. If idle improves substitute a known good sensor and recheck.
- A/C compressor or relay. If inoperative, refer to CHART C-10.
- A/C Refrigerant Pressure too high. Chick for overcharge or faulty pressure switch.
- Cooling fan inoperative – See CHART C-12.
- PCV valve for proper operation by placing finger over inlet hole in valve end several times. Valve should snap back. If not, replace valve.
- Run a cylinder compression check. See Section “6”.
- Inspect oxygen sensor for silicon contamination from fuel, or use of improper RTV sealant. The sensor will have a white powdery coating, and will result in a high but false signal voltage (rich exhaust indication). The ECM will then reduce the amount of fuel delivered to the engine, causing a severe drivability problem.

[This message has been edited by Alpinej (edited 02-14-2009).]

That is my problem, the power steering is doing it.

But really I think the O2 does fit into the problem somehow be it a rich condition, exhaust temp dropping to the threshold of the O2,
etc.

[This message has been edited by Dodgerunner (edited 05-29-2009).]

I just posted this separately. But, I thought I'd throw it on here too in since this seems to be a good thread on idle issues and worth sharing here.

As I indicated, my car idled ok when cold, then after warming up during the freeway portion of my daily drive, when decelerating on the on ramp, I would pretty much always throw a VSS code (24) and then it would not hold idle. I tried all sorts of things, chasing down all sorts of bad signals. But, yesterday it appears I accidentally stumbled on the cure!

This is on a car with a 1987 Fiero GT V6 engine, ECM, wire harness, sensors, etc., in a VW based kit car.

I was under the dash testing the VSS buffer and trying to yet again find out what was wrong. According to the test I just did, as listed in the Factory Service Manual, my ECM needed replacing. While looking around under the dash, I happened to glance at the radio amp. I knew that I wasn't using the amp, but that it was still wired up. So, I decided to disconnect it while I was down there. I didn't think anything of it. Then today, on the way to work, it idled and idled and idled. It didn't know how not to idle.

I believe the amp was sucking in lots of power even though the radio was not on. My only guess is that somehow this pulled down the voltage on the VSS which is supposed to alternate between less than 1 volt and over 4 volts. I don't know for sure. All I know is that it was all I changed and it's working now.

That said, I still find it hard to believe and fully expect it to not work right on the way home.

So, thanks to everyone. If anyone else is having such a problem, I guess look for big electricity drains.

Hmm. Well i have a code 32 on my 2.8 and here is what happens. When I start the car it will rev to 1500 and drop to 500ish occasionally stalling. If it doesnt stall it will sputter between 500-1200 rapidly untill i give it some gas then it will level out for a bit then go back to the erratic idle. It does this while either warm or cold. This is all while either idling or at a stop light. It also wont kick the engine light on untill it is at normal operating temp. And finally while I am driving it if I hold the RPMs at 1900 or 2500ish it will surge as well. Any ideas?

Just to add to this thread, If you have an 85, that ECM does NOT need the 10k resistor to spit out data. It would help logging for this problem.

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"DRIVE IT LIKE A FIERO"
'84 Fiero, engine to be determined
'87Blue GT 3.4L Swap Completed!!!!!!!! Boosted!!!!!!!
^^^^ Now in the Construction Zone^^^^
Las Vegas Fiero Club
Fiero Road Club Of Northern Nevada