I recently had the same thing you are going throught and i replaced everey sensor exept the egr selenoind and still same problem. But then i pulled the intake off of the car and throughtly cleaned it with carb cleaner to get all the gunk out of it. It was really dirty even on a 60k mile car. But after that it didnt do it as much. It still wavered so then i made sure i had good ground on my ignitian module and then replaced the coil pak and wahala no more wierd start up and it idles much better. purrs at 1100. Now if i canonly figgure out why it dies when the car is warm when i step on the brake and come to a stop??
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04:22 AM
tjm4fun Member
Posts: 3781 From: Long Island, NY USA Registered: Feb 2006
I can be another tester. I do have the idle hunt on a cold engine. ignition off, back on restart and it runs perfectly.
Let me know if I can help.
Sure. do you have winaldl or a scanner or at least a decent meter? if you have winaldl or a scanner, when car is cold, hook it up and note the mat sensor and cts temperature it is reporting. if you don;t have winaldl or a scanner, use an ohmmeter and measure the resistance of the mat sensor on the air cleaner with the cable unplugged. you may have to reverse the leads to get a value, one way will show an open, the other will show the reading. it should be under 20k ohms with the temps now, unless it;s really cold then it could be over. the resistive value will be fine, se can figure out the temp reporting from the charts. This is still working to confirm the root cause, then we can try some workarounds. one thing is we want to be sure that the cause is the same, and go from there. there could be differrent causes, so that would be a necessary part of determining if any fixes we come up with will work for everyone.
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02:54 PM
Dan010 Member
Posts: 776 From: Katy, Texas USA Registered: Oct 2001
bahhhhhhhh! i'll be sidetracked. %$#%$#!!!! clutch line has a leak. not sure where yet, but foward of the driver's seat. nothing like driving 4 miles in local rush hour stop/go traffic with no clutch. Hoping it will hold for the run to work and back tonight, then I'll spend tomorrow on the fix. then back to reassemble part of the 18 ton crane I took apart for parts rebuild. (must be fixed by satruday morning. ) I have to clone myself.
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08:47 PM
Oct 13th, 2006
RhinoDj Member
Posts: 246 From: West Covina, CA Registered: Oct 2005
I had searching idle for months with my car. I replaced the plugs, wires, coil, IAC valve, air filter, oil and a couple other things I cant think of right now. The last thing I replaced was the distributor. And low and behold...the wandering idle went away. In fact, my RPMs at idle went from about 1200 to 850-900. And it sits nice and smooth while running. I dont know if the internals of the old distro were so messed up that they made the car wander, or possible it was something else i did and dont realize...But im happy that it finally went away. It was the most annoying sound in the world to have my car wandering while sitting still. Maybe throw a new distro in there just for laughs. Couldnt hurt? And they arent that expensive. Got mine from Fiero Store for like $130 or something....It was worth it. You helped me with the install of the distro too, cause I was nervous about setting the timing...you really helped, thanks, I havent had ONE problem since I got my car running again.
not meaning to sidetrack the thread - but regarding the clutch line, when I was working at WCF we had purchased the last one in CA from the dealership ( Martin Cadillac ) about 5 years ago. The only option here is maybe a NOS part that someone might be hording, a donor vehicle, or an after market source. But I do know for a fact they are no longer available through GM.
------------------ Former West Coast Fiero Employee
Got it! do you want my 20 seconds of sensor recording or just the MAT? MAT was sitting at 58.8 degrees CTS 91.7
this is not from dead cold, I had to start the car a fwe times to get the dang aldl stuff to work right.
I will give a new reading on both in the morning when everything is nice and cold.
should I start and record for a minute for more diagnostics?
now that is good enough. your mat is at least pretty close to ambient temp. cts is ok for a few starts, as the hunt seems to be there until closed loop. thanks for that! Right now we are playing with a couple of workarounds, I want to find a something simple anyone can try, and then go with the results of that. Right now, the right way to do this is fix the coldstart fuel map, but burning chips for all the years/ and tranny types is impractical. I'd like to find a possible easy way to fool the ecm, as it seems the problem will only happen with temps in the 50-70 degree range seveverly, an leser when warmer and not at all when colder. if you built your winaldl adapter and have an extra 10k resistor, unplug the mat, pulg the resistor leads in the cable end, and start it and see if it hunts. if you throw winaldl on, it should show a mat temp of around 30-34 degrees. let me know what happens.
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08:56 PM
tjm4fun Member
Posts: 3781 From: Long Island, NY USA Registered: Feb 2006
not meaning to sidetrack the thread - but regarding the clutch line, when I was working at WCF we had purchased the last one in CA from the dealership ( Martin Cadillac ) about 5 years ago. The only option here is maybe a NOS part that someone might be hording, a donor vehicle, or an after market source. But I do know for a fact they are no longer available through GM.
hole located and fixed. if itpops another one, I'll remake the whole thing myself. I have about 5 places near me that do hydraulic lines for almost anything, so parts should not be an issue. Thanks, and no problme on the post. I don;t get upset, but it isn;t my thread.
quote
Originally posted by RhinoDj:
I had searching idle for months with my car. I replaced the plugs, wires, coil, IAC valve, air filter, oil and a couple other things I cant think of right now. The last thing I replaced was the distributor. And low and behold...the wandering idle went away. In fact, my RPMs at idle went from about 1200 to 850-900. And it sits nice and smooth while running. I dont know if the internals of the old distro were so messed up that they made the car wander, or possible it was something else i did and dont realize...But im happy that it finally went away. It was the most annoying sound in the world to have my car wandering while sitting still. Maybe throw a new distro in there just for laughs. Couldnt hurt? And they arent that expensive. Got mine from Fiero Store for like $130 or something....It was worth it. You helped me with the install of the distro too, cause I was nervous about setting the timing...you really helped, thanks, I havent had ONE problem since I got my car running again.
there are likely many causes of the hunting idle, we are looking for the fix for people who have replaced everything and still have the problem. and that is alot of people! I think you got lucky, but happy you got yours running ok.
tommorow morning is expected to be around 38 degrees. I will go out and get some reading and see if the hunting throttle is there at that low of a temp (we have been having snow/sleet every morning for the past 3 days here.) for verification for you. No problem helping, It's kind of fun!
Tim, If its 38 degrees --your car should not hunt idle, what your going to need to do is get a 50K-Ohm Linear-Taper Potentiometer , then set up your winaldl, run the program in the key on engine off postion, the pot will need to be set to bring up your cts to around 80.2 degrees, (for a average coolant temp reading) the 10k resistor will take care of the mat, or the 38 or below degrees will do that for you on it`s own. If it doesn`t you may need a new mat, or you can use the 10k resistor, which will set the may value at around 30 degrees, you can check on the winaldl, the outside temp + your mat + your cts should read about the same--with in a couple degrees, (the default on the mat is -37 degrees) . You can get another pot (highly suggested) to dail in both sensors to the set values or degrees, this is being done, mostly because the wheather at the moment seems to be colder every where --which in turn would make your car NOT hunt idle. I purchased both pot meters from parts express. You`ll need to solder 2 wires on the 3 wire terminals on top, use the middle one and either end one will work, then tine/solder the other 2 ends, so it will fit in the sensors plug ends easier, once you have them & winald in place with key on engine off --and running winaldl, you can turn the pot meter either way and you`ll see it raise or lower the cts, or mat. This will allow you to fool the ecm into thinking the engine is warmer or the mat is running colder--thats part of what we are after for this part of the testing. When you get your temps dailed in--go ahead and start the car, record what you set the values to. Give it a minute of run time, and watch for any hunting on idle, probally won`t do it at those settings, shut the engine off and record what happened each time.Your in Michigan so the cts reading and mat this time of year will be low, which (again) you should not have the hunt idle . To make it simple, you would be simulating a condition with the pots --that would be ideal wheather for the hunt idle to happen. Then simulating conditions--via using the pots for the hunt idle not to happen. In a post or two below I will put in some of my testing for an example, then we can go from there.
On mention that should be observed, when you use winaldl by crossing the terminals in the connector, with the 10k ohm resistor, it won`t allow the car to hunt idle, it actually bumps up the rpms and puts the ecm in field sevice mode, which would render any results use-less, as the car seems to run the way its supposed to and no given the chance to hunt idle for you. Also as tjm4fun has mentioned , don`t be to concerned with rpms raising right now--unless its something wild like 4000rpms on start, then you have another problem.
Some of the first test I used --some may seem a little or over done for this purpose , but the idea is to rule out other variables. Also these first few tests where done with out a pot meter to set the values in. And are rough notes made during testing;
Went out to the shop and ran some test --not real scientific, but I`ll post them then see what you think.
Car sat for 12-15hrs===cold
1.checked winaldl cts == 70.9 mat == 69.5 Started the car == it hunts idle==stoppped car right away. to be expected.
2. Checked winaldl again ==cts == 81.5 == mat == 69.8 started car again=== hunts again also worse when I tap gas pedal.
3. checked winaldl again == cts == 91.5 mat == 70.8 started engine === no hunting with or with out tapping gas pedal.
4. Experiment time, === cts == 47.1 mat == 71.1
Pulled cts connector, installed a good cts sensor on connector, cts is way low due to the extra testing sensor sitting in a cup of ice water. start engine, it goes strait to 1850rpms-2000rpms no hunting.with or with out tapping gas pedal. **to be expected**
5.put cooling fans on the motor, 2 hrs pass, check winaldl .... ..................................cts==81.5 mat == 69.8 start engine ==== no hunt ? but will start to raise rpms from 1500rpms to 1850 with in 45-60 seconds.
6. shut car down,check winaldl == cts ==124.7 == mat== 70.4 start car ,right away, no hunting with or with out tapping gas pedal --but goes to 1500rpms and stays on the 1500rpms all is normal .
Check the #`s 2. & 5 their the same, 2. hunts and is worse when pedal is tapped 5. has same #`s but their is no hunt at all, but rpms raise up from 1500rpm to 1850rpms with in 45-60 seconds. now check # 6. car is started right away , and goes to 1500rpms where it belongs and stays steady on it with or with out tapping gas pedal, its good to go. I disconected the winaldl between each test, so it could not interfer, as it will raise rpms in field service mode. The mat stays around the same, threw out all the test, but did check it to make sure it works and it does. In the # 6 last test --it does perfect and was done right after the # 5 test above, but starts and runs fine (this is the 2nd start that seems to work) we are talking about, the only sensor that changed was the cts and it was raised slightly to 124.7, again # 2 & 5 have the No hunt--but 5 has a hunt on tapping gas pedal, (just a little) and the values are the same.
One of the first test using pot meter : Comments from tjm4fun in-between tests.
Set p gauge on:
1. mat=31.0 cts=77.4 1. worked fine, went to 1500 and did not hunt.
2. Started 2nd time with p. meter like above, went to 1650 rpm blipped , then returned to 1650rpm==no hunt
that doesn;t seem to bad, a tad high, but would likely drop if the cts were really changing value.
3. Started 3rd time with same setings like above, blipped it went to 1750, blipped to 2000rpm came back to 1500rpms--then started to raise quiclky and stayed at 1800rpms
still unpredicatable, a warm motro with rich fuel mix due to cts not changing.
Set p. gauge on: 1. mat=80.4 cts-= 81.7 1. Started and it went strait to 1850rpms and stayed there. no hunt****
it should drop off that fast, I think the ecm is getting confused now. set p. gauge on : 1. mat=81.7 cts=92.7 1. went to 1650rpm and stayed there ==no hunt***
ok, better, your letting the cts start to act normal.. set p. gauge on:
1. cts=104.5 mat=81.7 1. went strait to 1950rpm, then fell back to 1750rpm stayed there no hunt***
that idle is just too high, there is something else handling all this as well as can be expected..
set p. gauge on: 1. cts=149.0 mat=81.7 1. went to 1200rpms stayed there--no hunt***
that's better.
set p. gauge on: 1. cts=203 mat= 81.7 1. went to 1000rpm stayed there==no hunt***
that's working right now.
set p. gauage on: 1. cts=107.3 mat was raised to mat=107.3==1000rpms no
hunt***==threw code 25 mat sensor
May have gotten a glitch where the mat showed open and it caught it... set p. gauge on: 1. mat=95.5 cts=203.0 === 1050rpms ==no hunt***
normal warm start doesn;t hunt, sounds ok.
> ------------------------------------------------------- *** took off p. gauge aldl read real #`s as :
1. cts =149.0 mat=80.4 ==== started and stayed steady at 1450rpm
Cleared the codes as when I turned up the cts p. gauge to 430 degrees or something like that for fun..lol.. then it set a cts code 25, recleared the codes, then checkd with
no p. gauge as:
1. real reading winaldl cts = 158.4 mat= 81.7 took off winaldl started it --went to 1050rpms then to 950-75rpm in gear--allmost perfect for that car.
well it is now a warm start, and most people don;thave hunting when warm. high idles, yes, but that is usually some missed vac leak or leaky egr.
Some more data and tests: Another note this is repetative but may be worth looking at for sensor value purpose usage and comparison.. 10/11/06 First start cold with P. Meter on: 1. cts- 153.1 mat- 82.4 ==== ran for a second then stalled did this 2 times.
2. cts- 153.1 P. Meter on: mat- 79.9 Started 2 times then stalled this is one stalls from above.
Turned cts down P. meter on: 1. cts-78.8 mat-77.9 ==== started perfect to 1500, then exactly 60 seconds later, the rpms raised to 1850 on their own = no hunt
Ok car still running , ran cts up to 2.cts-113.9 these #`s. Of course P.Meter on mat-77.9 idles perfect at 1500rpm= no hunt
P. Meter on 3.cts-113.9 Waited 2 minutes, re-started, ran mat77.9 to 1850rpm then fell to 1500 no hunt.
P. Meter on: Just for the hell of it to rule out fuel pressure-emptied shcader vavle.
1.cts-113.9 Did this 3 times, went to 1850 then mat-77.9 dropped to 1500--no hunt
Also 10 minutes have passed.
Raised cts: P.meter on 1.cts-155.8 went to 1650 on start, then dropped to mat-72.3 1350rpm --good idle--no hunt
2 final tests each time the same happened checked real temp, real sensors.
*P Meter off:::*
1. cts-173 Both times with out winaldl hooked up mat-74.8 but did check with winaldl between for real #`s on real sensors..Each time on start it went to 1500rpms then dropped to 1000rpms in Park and 950rpm in *D*
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03:00 AM
tjm4fun Member
Posts: 3781 From: Long Island, NY USA Registered: Feb 2006
I am just too verbose, ain't I???? I need to get my hands on a better explanation of the prom. the one I have does not mention the mat in anything other than some base settings and for code setting levels. The only cold start map on the program I have shows it as cts vs map, but the curious thing is the temps coincide with effects seen at mat temps. Since you can more easily reproduce this, tell the cts it is 30 and the mat is 60, and see if it hunts. it shouldn;t If it does, let it cool and do the cts 40 and mat 60, it should not hunt. then try cts 50, mat 60. may hunt, not sure on this. for grins tho, could you also post your map value (in kpa) before you start? and maybe on a hunt and non hunt cold, also the map. I'm trying now to make sense of the cold start map. it is really a PITA to get mine to hunt, and it doesn;t do it as badly as yours when I do fool it. I think that is due to the motor being damn near perfect running as it is so fresh. I'm still looking at the porr man's fix vs a prom reprogram. I want it to be something you hook up and forgert about, but I don't think that is going to happen.
Here is apic of the coldstart map for air/fuel ratio:
[This message has been edited by tjm4fun (edited 10-14-2006).]
We need someone to try this **** could you also post your map value (in kpa) before you start? and maybe on a hunt and non hunt cold, also the map.***** My winaldl (hooked up ) will not allow for the engine to hunt ...I can grab the kpa when cold --non hunt--or warm/hot non hunt.. But it won`t allow it in winaldl for the **During Process** ===while the hunt is actually happening, if I would have been able to do this, this problem would have been figured out a couple years ago.*** crazy laughter in the back round --as he pulls his cape up over his face and heads for the laboratory/shop*****mu ha mu ha ha ha ha
a prom reprogram should not be expensive. eeprom programmers are dirt cheap on ebay and the blank chips are also cheap. TunerCAT is good enough for doing this right? I have a electronics lab in the basement and a eprom-eeprom programmer and probably have a couple of proper chips in either a blanmk state or can be erased for this use. if someone can give me links to software to do the modifications I can help. I have a 86GT and a 87GT ECM with chip here so I can cover 2 years, someone get me the chips for the 85 and 88 or the bin file from those chips and I will be happy to put in numbers you guys provide and send out chips to test.
I think we can come up with a solution we can simply post the bin files after we have success and people can download and make their own chip or pay a tiny fee for someoen to do it for them.
[This message has been edited by timgray (edited 10-14-2006).]
Tim , I have a 1988 chip, its the one that we have been doing the testing on, I need more keywords or data from you to find the software needed, Iv`e been on this since you posted.
Well the sun came out and I had to drive the fiero as she hasn't been driven for 2 weeks. Temp was below 40 degrees and when I started it, low and behold, a nice stead and solid idle.... that verifies that my idle hunt problem is dead on with everyone elses here so far.
tunercat and the fiero GT def file for the 1227170 ECM is only $89.00, but I will try to grab a copy of that other app and see what it allows to be changed. UPDATE: Gmepro is $100 + def files, it is no longer free in any way, way more money than tunercat. I'll go with tunercat and save money.
I find it funny that 18-20 years later a programming bug is found in our cars that should have been taken care of a long time ago. I wonder how many GT's were into the dealers for this problem and never were resolved.
[This message has been edited by timgray (edited 10-14-2006).]
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09:27 PM
Oct 15th, 2006
tjm4fun Member
Posts: 3781 From: Long Island, NY USA Registered: Feb 2006
Tim, looke here, it has alink to the shareware version: http://fp.enter.net/~rockcrawl/EPROM.html you can alter things and save them, but things like the hex editor are not useable. you can use any hex editor tho, once you find the layout of the prom.
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12:27 AM
Oct 16th, 2006
tjm4fun Member
Posts: 3781 From: Long Island, NY USA Registered: Feb 2006
tried to compromise the trouble temp range by richening it up by 1 point. I don;t know if this will be enough, but I think it would be. it seems to be very temp specific when this happenst, and it's in those 2 rows where it first jumped to 10 and higher. the lower number will be richer, so worst case is you run rich for 5 minutes until you are in closed lop, then that table is out of the picture.
I will attempt to look through the bin files of my 86 to try and find that table to edit, otherwise I will have to wait until next week to buy my copy of tunercat and the def file.
I wonder if the 88fiero bin file that comes with gmepro is the same as 3600's 88 chip in his car. I did a ton of research last night on the fiero ECM and I did not see anything that mentioned different versions of prom for different years but then, you never know.
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06:41 AM
tjm4fun Member
Posts: 3781 From: Long Island, NY USA Registered: Feb 2006
note that ties size dictates a differrent prom, as well as whether it is a california car or other area of the country. there are mor links in that page that covers schematics and some offset info ant prom type. not everything you need, but it's a start...
if you want to find that table in the a raw hex dump, use gmepro and alter every byte to a distinctive pattern. for example, make them all 0's save the file, open a hexeditor, compare the 2 files and it will list the block if it is set that way.
this is another freeware bin editor for gm ecm's: http://www.passtimeracing.com/eric/Cars/EFI/index.htm it will use the ecu file from tunercat, saving the cost of the program. els try a 0, 255 alternating in the editor and look for the 00 ,ff alternating in the hex dump.
It seems that the copy of gmepro I downloaded is allowing me to edit that table directly which should be all we need. I am playing around with the 88fiero.bin that came with it and it seems that it is happily letting me change the number to match what you are suggesting.
I am going to save it and then compare the two in a hex editor to see if the changes stuck and to see the location in the bin file they are. if this is working as is, the hex editor part is not really needed for this fix. very cool all these links, I pretty much have what I need now. Thanks a ton! you have kick started me faster than I though I could get there. Very cool and a + for you!
I am ordering some new chips. The two I have here are in a unknown state. I did erase them and they show erased but the pins are not in the best shape. $5.00 each is a bit expensive for them but well worth it for this testing.
Quick question, someone here was selling adapter boards for the ECM, anyone hav his name or a link to his post about them? I think I might want to buy a couple if we need to ship chips back and forth to make testing easier.
[This message has been edited by timgray (edited 10-16-2006).]
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08:19 PM
tjm4fun Member
Posts: 3781 From: Long Island, NY USA Registered: Feb 2006
I have to go thru my stock of chips, I don;t know how many 2732's I have. I have a ton of 2764 equivalents, but tht would require an adapter. actually burning a chip does me no good anyway, as I don't have the problem. I've been working with 3800superfast as a test bed to try to isolate this, as he has one that does it consistnetly. even tricking mine with very specific parameters only cause a slight hunt and bobble. in our many emails, I have wondered how the map effec on this is tied in, that would be the variable that might be why some have it and some don;t. it might be a combination of the vacuum levels on your motor & the map sensor calibration pushing the cold start map to the lean side. that;s getting carried away, we would need to have calibrated test equipemnt at multiple places to confirm it. we know fooling the mat stops it. so a reburn is the equivalent, and more correct way
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09:25 PM
Oct 18th, 2006
triker Member
Posts: 454 From: Yreka, Ca. USA Registered: Apr 2000
the problem is when you hook up winaldl the hunt problem eases, according to 3800superfast. the hunt becomes smaller in range, and the idle rpms alter. hooking up any scanner does effect the way the motor runs. Maybe one of those guys has a log of it when it is in the sort of failing state.
As tjm4fun mentioned --no matter which way you try , when the winaldl program is hooked up--it won`t allow for the hunt/idle to occur, even with blipping the gas, (which would usally through the iac in to a tizzy), I`m accounting this for mostly that the ecm (while winaldl is hooked up) is in the field service mode, which would make allowances for certain sensors, ect. To add to the above--I`m able to trick the mat sensor as mentioned--also the cts sensor into stopping the hunt idle, now tjm4fun and Tim have found a coralation that may bring the map into the picture as well, I`m working on the physical side of that too--where-as they are going for the burn, which would be the ideal way, so far there are 3 to 5 different ways to get the hunt idle to stop--we are shooting for the easiest application for the Fiero community...
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02:07 AM
cptsnoopy Member
Posts: 2585 From: phoenix, AZ, USA Registered: Jul 2003
Edit: I found the data I recorded on December 14, 2004. I was not able to glean much info from it so if I get a chance I will see if I can get more current data. I am using the Auto X-ray6000.
[This message has been edited by cptsnoopy (edited 10-19-2006).]
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02:37 AM
Oct 20th, 2006
tjm4fun Member
Posts: 3781 From: Long Island, NY USA Registered: Feb 2006
any info would be good to have. i could do more to pd this if I could get mine to do it to the extreme that most people have. I have alot of test equipment I can hook up to various sensors to get exact pictures of how they are reacting while in failure mode. I would love to see the map in realtime on a scope, and the iac drive, and injector pulse durations. the more I thinka bout this, I think I had the issue on my 86 but that was in the early 90's, no winaldl at that time, I did all the troubleshooting with a scope and a meter.I know I had to replace the map for an idle issue, the new one helped it, but then it died and I put the old one back in and did something else, modified the signal circuit I think. too bad that was a dozen years ago....
tjm4fun & timgray, That ecm is learning something as it goes, it has to be getting into the map somehow, as mentioned above I`m good with 10K for 4-5 days strait, then all the sudden its back, the new map is doing a better job. Its the ecm, 10K, or the fact that the mat is a glorified thermistor and picking up moisture, air density or something else is going on, I`m going back to dailing in with the pots on both sensors to see if that will settle it back down. Dodgerunner had a great idea for the problem of testing this--as we know we only get one shot at it, or until the 02 sensor takes over --which is pretty fast, he mentioned just un-plug the 02 for testing purposes--where was I at on career-day--I should have caught that...
