This is my continuing saga of learning for 4.9 liter owners that have yet to encounter the problems and people considering the swap. Recently, I experienced a complete loss of “punch” power from the motor. I replaced every electronic item between the distributor and the spark plugs with no success. ($250.00) I learned (from a Caddy mechanic) that there is a fuse (50 cents) which, when failed, results in the transmission reaching the default setting of 3rd gear. This was exactly the initial symptom which I experienced. Since all my fuses were older I went ahead and replaced them all…problem sorted.
At one point during my troubleshooting I had disconnected the negative terminal to attempt a computer reset just in case it was an ECM type electronic “hiccup”. By doing this I have inadvertently reset my idle function. Result: 1600rpm idle coast until coming to a full stop. There is a solution to the problem however one of the necessary components is the AC control head from the Caddy….conspicuously absent from the Fiero. I’ll keep you posted on how my new Caddy mechanic friend helps me sort through this problem as he already has an idea to take care of resetting this feature and tuning the idle.
Other problems with my swap? Well, there are a few minor tweaks that need to be made but I hope to sort most of these at Ed Park’s Fiero Factory swap meet!

They include:

Cruise control doesn’t work
Slight squeak from the FRHS suspension and a jingling change-like sound from same area
Slight brake pulse (I will have rotors turned this week)
You have to press the brake pedal deep on initial application to get any bite
I can’t remove the stereo…one of the retainers from the pullout system is hanging up a bit
AC is showing a full charge but no cold air blowing (possible low or high pressure switch failures?)
Tiny crack in the RHS wing stand
Oil leak from the cork oil pan gasket…needs replacement

I love the car and it is mechanically & cosmetically sound so no thoughts of it leaving…mostly just some teething difficulties. I need to get it sorted before I start on my next project: 1988 Formula w/350v8 power!

quote Originally posted by johnyrottin: At one point during my troubleshooting I had disconnected the negative terminal to attempt a computer reset just in case it was an ECM type electronic “hiccup”. By doing this I have inadvertently reset my idle function. Result: 1600rpm idle coast until coming to a full stop. There is a solution to the problem however one of the necessary components is the AC control head from the Caddy….conspicuously absent from the Fiero. I’ll keep you posted on how my new Caddy mechanic friend helps me sort through this problem as he already has an idea to take care of resetting this feature and tuning the idle.

I appreciate the feedback.

Many discussions about the "Idle Learn" procedure. Interesting to note it's different from the "TPS Learn" procedure which you usually perform first. But the "sail on" condition that the 4.9 is so prone to is caused by the ECM putting in a funky value for the idle throttle position.

I don't know what causes it to do that, but supposedly if you idle in park for 10 minutes and then idle in drive for 5 minutes it's supposed to reset to a better value. You don't need the AC control head for this, but having the on-board diagnostics does help in the "TPS Learn" procedure.

My car is a 6 speed so it's permanently in drive, which I think doesn't allow it to ever pick a better Idle throttle position.

Just for fun I'm going to try and hook up the AC control head along with a Fuel Display Center and BCM to see if I can get the on board diagnostics working.

I have a copy of the Cadillac repair manual from the dealer pertaining to this. From 1993 the manual titles it "TPS/Idle learn procedure". It eludes to the fact that although they are different routines technically, both are learned by the same procedure. The procedure described lets the PCM "learn" the proper closed throttle angle and throttle angle offset for the particular throttle body. I'll try to scan and post the page.

quote Originally posted by johnyrottin: It eludes to the fact that although they are different routines technically, both are learned by the same procedure. The procedure described lets the PCM "learn" the proper closed throttle angle and throttle angle offset for the particular throttle body. I'll try to scan and post the page.

The 1991 book clearly states they are two separate processes, although the words and descriptions generally have them one right after the other such that it's not clear you are performing two processes.

The TPS Learn is the process where you check the base timing, short the alternator, retract the ISC, Adjust the TPS, extend the ISC, check the TPS, adjust ISC if necessary, put everything back together, turn the key on then off twice.

The Idle learn all you have to do is disconnect the battery, reconnect and idle the car in park and in drive for a certain amount of time. The computer is supposed to start using the right throttle angle offset after that.

[This message has been edited by jscott1 (edited 04-15-2009).]

This is from a 1993 Cadillac Service Bullatin,
"Group Ref.: Engine

Bulletin No.: 316006A

Date: November, 1993

SUBJECT:
SLOW DECELERATION WITH CLOSED THROTTLE ABOVE 5 MPH
(READJUST AIR RATE)

MODELS:
1990-93 CADILLAC DEVILLES, ELDORADOS, FLEETWOODS, SEVILLES, AND SIXTY SPECIALS (EQUIPPED WITH 4.5L OR 4.9L ENGINES)

THIS BULLETIN IS BEING REVISED TO CORRECT THE WARRANTY STATEMENT, AND CANCELS AND SUPERSEDES BULLETIN 316006 PUBLISHED OCTOBER, 1993.

Some owners may comment about slow deceleration with closed throttle above 5 mph. This may be particularly noticeable after performing bulletin T-93-44 (Corporate bulletin 016540R) even though all engine adjustments have been set according to published service information.

To correct this condition readjust the minimum air rate to between 400 and 450 rpm, the TP Sensor setting to .55 volts, and reset TP Sensor/idle learns using the procedures listed in the appropriate Service Information Manual.

For warranty purposes use:

Labor Operation: J6358"

quote Originally posted by johnyrottin: Cruise control doesn’t work Slight squeak from the FRHS suspension and a jingling change-like sound from same area Slight brake pulse (I will have rotors turned this week) You have to press the brake pedal deep on initial application to get any bite I can’t remove the stereo…one of the retainers from the pullout system is hanging up a bit AC is showing a full charge but no cold air blowing (possible low or high pressure switch failures?) Tiny crack in the RHS wing stand Oil leak from the cork oil pan gasket…needs replacement

Well, I cant help you with the engine problems right now, but I can help you solve some other problems if you arent already aware.

Squeak from suspension: Probable a worn bushing if they are the originals. Being 21-25 years old, all kinds of squeaks and rattles can pop up though. Best thing to do is jounce the suspension while standing next to the wheel to pinpoint where the sound is coming from.

Brake pulse: sounds like you got that covered already

Brake pedal depression problem: You probably have a master cylinder going bad. See if there is any moisture around it or any of the calipers, but most likely the master.

AC blowing warm: Best place to start is to see if the compressor clutch is even engaging. If its not, you will need a wiring diagram to trace where the power comes from and what switches and relays it passes through. I just went through this with my duke and it turns out my low pressure switch was bad and my high pressure switch is intermittent. I have rigged both of them for now until I get replacements.

You may already know these things but maybe someone reading doesnt and this could help them out. Good luck.

-Joe

FWIW, its usually better to replace warped rotors rather than turn them. CHP did a study in the past discovering that 1) turned rotors warped again fairly quickly, and 2) it was more cost-effective just to replace them.

I do agree with that to some degree. When rotors are "turned" they are basically cut down to create a smooth surface again which results in a thinner rotor. If the rotor is already warped for some reason, making it smaller will most likely allow it to warp again in a shorter period of time. However, some manufacturers make their rotors incredibly thick with a lot of play between factory thickness and minimum thickness. In these cases, shaving a little off will probably not hurt it as long as it is well above minimum.

Then again there are some cars such as the Saturn L Series off the top of my head that almost require new rotors every pad change. When it came time, if you grab the rotor you can feel quite a large lip from just outside where the pad rides from the rotor material wearing away. Not sure if they did that on purpose or not but all the customers would whine about a $400 brake job.

The minimum thickness is stamped usually on the inside of the rotor hat, take some calipers and measure the thickness of the rotor as it is, if it is anywhere near that, just get new ones.

-Joe

I agree with the brake issue. Have you seen the prices they want for Fiero brakes? Huge dollars at Autozone, Advance, or O'Reillys. If I am going to do a full replacement I think I just may make a brake improvement like Grand Ams or something like that. As far as the TPS/Idle set procedure, I can't speak to the 1991 book as I have never seen it. However, The one that I photocopied from a 1993 manual (since my motor is a 1993) specifically states the procedure. I will give it a go but jscott1 please let me know what happens with attaching the ac unit. I may have to end up going your route and doing them individually if this doesn't work. Cheers guys and I appreciate all the help.

quote Originally posted by johnyrottin: As far as the TPS/Idle set procedure, I can't speak to the 1991 book as I have never seen it. However, The one that I photocopied from a 1993 manual (since my motor is a 1993) specifically states the procedure.

I found that page in my book last night, I'm going to scan it, but to Idle learn they tell you do perform the TPS learn first then the idle learn. But I don't know that you have to.

My understanding is the TPS learn is done by the PCM everytime the ignition is shut off. This is suppose to compensate for carbon buildup in the throttle body. It resets the closed throttle TPS value. If you had you foot resting on the throttle or the cable (or something) didn't allow the throttle plate to close fully it would change that value. I'll have to double check the FSM tonight to know for sure. Either way you shouldn't have to do anything but make sure the throttle is closed fully and let it reset again.

Mine says same. I will give it a go without the AC module though as I don't have one. If it doesn't work my Caddy mech friend says he has ideas for work-arounds and we will try them. Jscott ar eyou coming to the Fiero Factory on the 24-26 weekend? Might ask you to bring an AC head with you if yours works!!!

quote Originally posted by johnyrottin: Fieroseverywhere...just want to make sure I understand. Are you saying disconnect the neg terminal again allowing the system to reset again. Then do the normal 10 minutes in idle no load, 1 min in idle drive, and 1 min idle drive with ac? (or whatever the appropriate numbers are from the book)

Going from memory here (not as good as it used to be ). I believe disconnecting the battery cable only initiates the idle learn procedure. TPS learn is done by the PCM everytime the ignition is shut off.
I would just do the whole idle learn from the beginning one more time. Doesn't take that long and should eliminate any possiblity of a problem with the system. Not really much you can do for tuning the idle except adjust TPS settings and such. Unfortunately I've done this so many times with my 4.9 by now that I can make it idle just about anywhere I want.

With ISC fully retracted set that minimum idle to as low as possible without the car dying (~450rpm or less). It won't idle good but as long as it doesn't die its fine. Set closed TPS value to .55 volts. Set ISC maximum extension (TPS value 1.16 volts). Make sure the ISC is fully extended. They like to extend then click and drop back a bit. Initiate idle learn. Follow the FSM procedure but use these settings instead of whats in the book and it will work better with less sail-on. Joseph already posted the service bullatin with these same values earlier in this thread.

quote Originally posted by Fieroseverywhere: Going from memory here (not as good as it used to be ). I believe disconnecting the battery cable only initiates the idle learn procedure. TPS learn is done by the PCM everytime the ignition is shut off.

You remembered correctly!

quote Originally posted by jscott1: You remembered correctly!

Amazing. Guess it happens sometimes.

Second paragraph says when the battery is disconnected the TPS throttle angle is set to zero. So if the throttle plate was stuck open slightly when the battery was disconnected it would have thrown off everything. If everything else is already set properly (min idle & ISC max extension) all that needs to be done is to disconnect the battery and let it idle as the FSM says. Best of luck on it.

[This message has been edited by Fieroseverywhere (edited 04-16-2009).]

quote Originally posted by Fieroseverywhere: Let me know if you get this working.

I'm still waiting for the Climate Control to show up...but the wiring seems pretty straightforward. I'll keep a lookout for the missing grounds. Thanks.

Ahhh it seems I have sweet success, at least on the surface...time will tell. Here is what I did. I had to fake the computer into thinking it was in the diagnostic mode. I did this by jumping the A and M terminals in the OBD plug (2 terminals on the passenger side, bottom to top rows). Then I shut the car off (Fully hot after drive home...important to be at temp). Gave it about 20 seconds to ensure that change had taken place. Repeat. Then started the engine and ran it for 5 mins in park. into drive for one min, then with ac in drive for one min...all this with no feet on gas peddle. Now into park and turn it off. Done job. Set your controls where you want them and good to go! It works so far...I'll post update.

quote Originally posted by johnyrottin: Ahhh it seems I have sweet success, at least on the surface...time will tell. Here is what I did.

This is good information. If you have long term success then it will be helpful to have a script to follow precisely. I just need to get around to adding the "park" switch.

I will be driving it a few times tomorrow so I will give a first impression. Jscott you comin to the swap meet at Fiero Factory?

[This message has been edited by johnyrottin (edited 04-18-2009).]

quote Originally posted by johnyrottin: Jscott you comin to the swap meet at Fiero Factory?

Nope, sorry I won't be at the swap meet.

Good ride today. Car is running great. Idle is sitting at 750ish and is coasting at 1300 but drops down much earlier than before. I may try a few more runs at the prodcedure to fine tune it more but it is far better than it was before.

quote Originally posted by johnyrottin: Good ride today. Car is running great. Idle is sitting at 750ish and is coasting at 1300 but drops down much earlier than before. I may try a few more runs at the prodcedure to fine tune it more but it is far better than it was before.

Congrats! Hope your enjoying you new car.

quote Originally posted by johnyrottin: Good ride today. Car is running great. Idle is sitting at 750ish and is coasting at 1300 but drops down much earlier than before.

That would be great if mine would do that...mine is at 1300 ish the whole time. I still haven't added that park switch such that I can implement this procedure.

Update: Seems to have settled on 750 when stopped but on coastdown it sits between 1200 and 1300. AC now sorted out and believe it or not there was an effect on idle stability. Time for atacking all the small jobs on the beast now.

This ISC is about the biggest PITA I've ever seen. I'm about ready to install a toggle switch to move it manually.

Finally sound the jingle that sounded like loose change. I'll try to describe it because I don't know the technical name. On the drivers side, the sway bar comes near the lower portion of the wheel. A bolt of sorts goes through the bar and up to a portion of the suspension. Over this bolt is a metal sleeve and a large washer. On top of this washer should be a bushing (it is on the left wheel)...no bushing and the tube and washer jingles all over the place! NOISE! Now that I have found it I am going to have to find the part and install a new one...then another one is off the list.

Got it..page 219 in the Haynes Fiero manual...stabalizer bar link assembly. A couple of grommets are missing.

[This message has been edited by johnyrottin (edited 04-24-2009).]

quote Originally posted by johnyrottin: Update: Seems to have settled on 750 when stopped but on coastdown it sits between 1200 and 1300. AC now sorted out and believe it or not there was an effect on idle stability. Time for atacking all the small jobs on the beast now.

Ever get this issue sorted out? What did you set the min idle screw to? Service manual says 500-550rpm but a service bulliton put out at a later date says use 400-450 and adjust TPS value to .55volts. This should help a bit. Hope its working well for you.

I did...not perfect though. It still has about a 25ish rpm hunt but reading some caddy forums they had that as well. It is smooth though. I found in my paperwork directions for setting the timing. We did this and then let the car computer do its thing...it adjusts a slight bit every time you drive. We also did the learning procedures that my caddy mechanic friend Toni came by and walked me through. That helped immensely. So I should be close now. Thnaks for following up with me!

Now only a couple small problems left:
Remove and replace the cork oil pan gasket...junk...with a good one
AC has stopped working...need to investigate

I have a Fiero Factory conversion...
I have a 5 speed.

What am I supposed to do?

I see the term "AC" used here. It can't mean air contitioning can it?

Right now it's running pig rich where it hurts your eyes. Just swapped in a new block. Using Allante intake incase that means anything. HELP!

quote Originally posted by lou_dias: I have a Fiero Factory conversion... I have a 5 speed. What am I supposed to do? I see the term "AC" used here. It can't mean air contitioning can it? Right now it's running pig rich where it hurts your eyes. Just swapped in a new block. Using Allante intake incase that means anything. HELP!

Allante intakes are reputed to run pig rich on 4.9s.

The Allante MAT sensor is in the upper planum while the 4.9 MAT sensor is in the lower intake.
My MAT temps run around 140-170 with the Allante intake.
With those temps, your ECM thinks your engine is still cold and is giving it the appropriate fuel for those temps.
You probably need the Allante MAT/VE table.

In closed loop, my BLMs are running 126-130.

Hi,
I haven't been here in a while. but I have an '86 with the 4.9L and Caddy trans. Completed it a couple years ago. Anyway, the following paragraph is from a conversation with Rockcrawl about how to set the idle learn procedure correctly....This always got me pretty close, Then someone sent me the sevice bulletin which is the second paragragph, this set the motor really well..... to make a long story short, set the idle to 400 to 450 rpm instead of 525 rpm when doing the idle learn.

"Qouted from Rockcrawl"
The first thing you should do is set the base idle speed and ISC plunger length. Set the TPS as part of that process as well. Make sure the throttle plates and bores are clean before you start. Also make sure you don't have any vacuum leaks. Jumper ALDL A and B to enter the set timing mode. Verify timing at 10* BTDC and remove jumper. Disable the alternator by grounding the small brown wire, there should be a green connector inline if it's anything like a Cadillac harness. Disconnect the ISC motor where the main harness attaches to the sub harness. Attach two jumper wires to the blue wires of the sub harness. Connect one jumper to ground and the other to bat positive momentarily until the ISC is fully retracted. If it extends, reverse the polarity to make it retract. When it is fully retracted, the throttle lever should be resting on the minimum idle screw. If the throttle lever is touching the ISC plunger at full retraction, use a pliers to turn the plunger in until it's not touching. Use the minimum idle screw (recessed torx) to set the idle to 525 rpm. With the throttle lever resting on the minimum idle screw, set the TPS to .50 volts. Now you can extend the ISC by reversing the polarity of the jumpers. At full ISC extension, the TPS should read between 1.15 and 1.20 volts. Adjust the ISC plunger in or out with a pliers to obtain the correct TPS voltage. Retract the ISC. Reconnect the ISC to the main harness. Turn the key off and wait 20 seconds to allow the ECM to perform a TPS learn. Cycle the ignition on and off once more. It takes two cycles for a sucessful TPS learn. Perform and idle learn. Run engine until coolant temp is greater than 176*. Allow engine to idle in park for ten minutes. With brake applied, allow engine to idle in drive for at least three minutes. This should eliminate any coast down sail-on or stalling.

Second set of info:
Service bulletin:


Group Ref.: Engine

Bulletin No.: 316006A

Date: November, 1993

SUBJECT:
SLOW DECELERATION WITH CLOSED THROTTLE ABOVE 5 MPH
(READJUST AIR RATE)

MODELS:
1990-93 CADILLAC DEVILLES, ELDORADOS, FLEETWOODS, SEVILLES, AND SIXTY SPECIALS (EQUIPPED WITH 4.5L OR 4.9L ENGINES)

THIS BULLETIN IS BEING REVISED TO CORRECT THE WARRANTY STATEMENT, AND CANCELS AND SUPERSEDES BULLETIN 316006 PUBLISHED OCTOBER, 1993.

Some owners may comment about slow deceleration with closed throttle above 5 mph. This may be particularly noticeable after performing bulletin T-93-44 (Corporate bulletin 016540R) even though all engine adjustments have been set according to published service information.

To correct this condition readjust the minimum air rate to between 400 and 450 rpm, the TP Sensor setting to .55 volts, and reset TP Sensor/idle learns using the procedures listed in the appropriate Service Information Manual.

For warranty purposes use:

Labor Operation: J6358

Labor Time: Use published labor time


Good luck and get that thing running right!!!!
Dragon1/Brian

[This message has been edited by Dragon1 (edited 09-14-2010).]

I have used Rockcrawl's TPS setting procedure for years on my 4.9. I have no problem with sail on or high idle. You need to be very precise with the voltage measurements even a little out side the voltage range can make a big difference. Another item to check is the O2 sensor. The 4.9 does not like Bosch O2 sensors, I had problems with getting my 4.9 to idle properly until I removed the Brand New Bosch O2 sensor I had installed and replaced it with an AC Delco unit. After I did that my 4.9 with an Allante intake idles at 750 rpm.

Good Luck
Joe Sokol

------------------
85 SE Daily driver with a 3.4 DOHC OBD II
88 Formula/GT 4.9 Allante Intake (My Baby)

All this is great...
...none of this addresses how to put a 5speed into "Park"...unless neutral is good enough.

Lou_Dias check this thread https://www.fiero.nl/forum/Forum2/HTML/098096.html. It tells you how to wire your ECM so that it thinks it in any gear you want.

Joe Sokol

------------------
85 SE Daily driver with a 3.4 DOHC OBD II
88 Formula/GT 4.9 Allante Intake (My Baby)

With a manual trans puting it in "park" is not necissary. Though if it makes you feel better you can do as fiero King suggested and fool the PCM.

After doing the idle learn mine settles in at around 1400-1500 rpm. After a week its dropped to ~1200rpm. After a couple months its right around 1100. I'm not entirely sure why there is a delay but I suspect it has something to do with an intermittant connection from my VSS that I have. I will be correcting this over the next week. For the time being as long as I don't disconnect the battery again its stays right around 1100.

I've spent some time playing with TPS settings while doing the many idle learn's. I've ranged the settings from .7v to .45v. While some are better in certain respects they all adversly effect others. From my experiance the absolute best settings are the ones listed in the last service bulletin. **Setting the min idle to 400-450 rpm (or as low as it will still run) and setting the TPS to .55 volts while the throttle plate is resting on the min idle screw.** The absolute most important part is the TPS voltage range with the ISC extended. With ISC extended the TPS voltage should be between 1.15-1.2v. The closer to 1.15 the lower the coast idle. Once everything is set you need only disconnect the battery to initiate a new idle learn. You should never need to mess with the TPS, ISC screw, or min idle screw again.... with the exception if throttle body replacment. It works everytime for me.

One other thing I have found that you probably wont find anywhere is an issue I've had with added electrical load. Cooling fan, headlights, high power stereos, ect. When doing the idle learn you want to get near your max load at some point. The added load causes the PCM in "switch on" the alternator and can really bog down the engine. If its done while the idle is learning it can better compensate later. For me the cooling fan has been especially annoying. When it kicks on the PCM switches on the alternator and it causes a sudden drop in idle speed. The engine usually catches it and brings the speed back up but there is still an annoying delay. After idling for a couple minutes unloaded load everything you can up while its learning the idle... AC on, cooling fan or fans (should come on with AC), headlights, stereo blasting, trunk blower if equipped, ect. Everything electrical or mechanical that can put extra load on the engine.

[This message has been edited by Fieroseverywhere (edited 09-15-2010).]

quote Originally posted by lou_dias: All this is great... ...none of this addresses how to put a 5speed into "Park"...unless neutral is good enough.

Technically your car (5 speed) will never be in neutral as far as the ECM is concerned - always in drive (if wired correctly)...

Park is not needed, all the service manual is telling you to do is apply different loads on the engine as part of the learning proceedure - since you have a manual you can not simulate the load on the motor with it in drive and the brake is on. You also turn on the AC to add more to the load as well. If you hear differently, I would like to know.

HOWEVER, if you feel you must try it and put your car into park, all the info is in "my 4.9 wiring thread" ( thread here ) on how the ECM determins what gear the car is in, to simulate park - just wire it up so that the ECM thinks it is in park vs drive.

Here it is *again*

quote Just an FYI on how the ECM determines what gear the car is in: F8, C10, F7 and A2 provide a binary code input to the ECM to tell it what gear the car is in - code 91 indicates a unknown code is inputted. SpECiFiCLlY: in this order of F8, C10, F7, A2 P = 0100 R = 0011 N = 1010 D = 1001 3 = 0000 2 = 0101 1 = 1100 So, in a manual car when you tie C10 and F7 to ground (the pins are tied high internal to the ECM) inputs 1001, which tells the ECM it's in drive. Technically speaking A2 is what GM is calling a parity bit and you have a 3 digit binary code.

Edit: opps, Fieroseverywhere beat me to it - obviously types faster than I do.

[This message has been edited by Mickey_Moose (edited 09-15-2010).]