4.9L Cadillac - I have three PCM for the car. Let's call them Abel, Baker and Charlie. Abel and Charlie have stock PROMs. Baker has a PROM reburned by Sinister Performance to disable the VATS and few other things. The car is also wired with a Baker Electronix signal generator to disable the VATs.
Abel was in the car for a couple of years with intermittent driving. I jumped in the car one day and it started then quit. Try to restart and it would fire and quit. Put a noid light on one of the injector connectors and had the wife crank the engine. The light blinked once and quit, Multiple retries and the same thing. So I say it must be a VATs problem. Could be the Baker Electronix box or the PCM. Let's give Baker a try. He has the VATs disabled. The car starts right up and I drive infrequently it for a month. This week I get about 400 yards from home and the car quits. Put it in neutral and try to resart. Fires once and quits. Fortunately, I am on a small down hill incline and so I coast in the driveway - dead stick landing. Abel is sitting in passenger seat and the console is off. So let's give him another try. Same problem, fires once and quit. Very curious two PCMs with same problem. Charlie is resting in the garage so I grab him. Swap Charlie in and the car starts right. Being the curious type I put the Baker PROM in Charlie and the car starts right up. Being even more curious, I swap Abel back in and the car starts right up. Then Baker and the car starts right up. Then Charlie and the car starts right up.
Grab an analog ohm meter and test light. Check all the ground wires on the PCM plugs and get about 0.5 ohm - doesn't sound like a ground problem. Put a test light on wires that supply power to the PCM and it lights up brightly - doesn't look like a bad connection on the power supply. For good caution I grab a can of QR electronics cleaner and spray the PCM pins and plugs and then work them in and out a few times.
The car is starting but my confidence is pretty low on whether I have found the root cause of the problem.
------------------ formerly known as sanderson 1984 Quad 4 1886 SE 2.8L 1988 4.9L Cadillac 1988 3800 Supercharged
I had the console out of my 4.9 car, to install a Double-DIN skeleton. Shortly after putting it all back together, I noticed that it wasn't starting and idling as smoothly as it had been. Even stalled once, and was a bit "grumpy" on the restart. This started when I was looking at stuff with a scan tool. Okay... whatever. Figured it was just "a thing". A few days later, I was going to a local event. Got about 4 miles from the house and it started sputtering and bogging, and it finally stalled. Similar to how it acted when I was scanning it. I coasted into a driveway to ponder the situation. I disconnected the battery (front mounted... there's a knife switch) and reconnected it. Started it back up, and it ran normally, all the way back to the house. (**More about this, in a minute.) My EPROM is one that I programmed, to accommodate the Allante manifold, and the manual trans, but it has run just fine for a long time. It's mounted in a socket that I soldered into my "MEMCAL" in the same position as the stock EPROM. I removed the MEMCAL, removed the chip from the socket, and reflowed all the solder connections, where the socket is soldered into the MEMCAL. Plugged the EPROM back in, and plugged the MEMCAL back into the PCM, making sure to seat it solidly. Also made sure all the PCM connectors were well seated. Tugged a few wires, looking for a loose connections. All good. Started it back up, and it's been fine, ever since. I'm not sure exactly where the problem was. I just hope it doesn't return.
**Bear with me... There are five different definition files for the 4.9. They are apparently different enough that the wrong file just won't work, when programming a 4.9. Before I made all my "Allante and manual tranny" mods, someone gave me a tune that had worked well for them. When I plugged it into my PCM, it seemed to run fine. The first time. The second time I started it, it acted like it was in "limp home" mode. The trans started off in 2nd gear. The engine had significantly reduced power. If I floored it, it backfired. What this leads me to believe is that, if you don't disconnect the battery, the ECM runs on the last tune that it had stored when it was shut off. Good, bad, or indifferent. The next time you start it, it will load the "new" tune. The only way to get it to load the new tune, right out of the gate, is to disconnect the battery, and force it to load, fresh. (I had a Fiero "programmer" to tell me that I didn't need to disconnect the battery, every time I changed the chip, as long as the key was off. This was apparently the result of that. Lesson learned.
BTW... my EPROM has VATS turned off, but I also left the VATS "resistor module" plugged in. Figured I wasn't hurting anything.
Anyway... a long rambling post. But I think lots of issues can be caused by loose connections, either at the PCM, or at the EPROM/MEMCAL. But the Caddy PCM (not sure about others, but I wouldn't be surprised) can "throw you a curve", too. Doesn't make a lot of sense, just what I observed.
[This message has been edited by Raydar (edited 01-14-2023).]
Sounds like if it happens again I should disconnect the battery and see if that cures the problem.
Before I bought the Baker Electronix black box, I had someone burn a PROM with the VATS disabled. Got it back and the car ran in limp home mode. Didn't know there was such a thing as limp home mode until that happened. I then bought the Baker Electronix box and installed a PCM (Abel) with a stock PROM. The car ran reliably for several years but with not a lot of miles on it. For lack of a better hypothesis I'm leaning towards iffy electrical connections.
All three of the PCMs are 16132240's. As far as I know any 161632240 should be able to run any of the PROM's that are intended for the 16132240. Tunercat shows 16 different PROM's (broadcast codes) for the 16132240 and as you said 5 different definition files (I now own three). But I think as long as the correct definition file is used for the broadcast code then you shouldn't get in trouble. Most of the time the PROM won't read if the definition file is wrong. I have my car wired per the 92 Deville factory service manual. Maybe there are some small wiring difference if using a PROM from a different year that could create trouble. Or maybe there are wiring differences between a 92 Deville and 92 Fleetwood.
------------------ formerly known as sanderson 1984 Quad 4 1886 SE 2.8L 1988 4.9L Cadillac 1988 3800 Supercharged
[This message has been edited by sanderson231 (edited 01-14-2023).]
Ditch all the ECMs and get a Microsquirt. It'll work wonders]!
Way too many other nagging Fiero issues to even think about it . Like where is the small vacuum leak on my 3800 S/C that makes the car lean at idle despite the integrator going to 182.
------------------ formerly known as sanderson 1984 Quad 4 1886 SE 2.8L 1988 4.9L Cadillac 1988 3800 Supercharged
The PROM can sometimes be read with the wrong definition file. But it may load non-sensical data into the fields. I've seen that. I have speculated that the main differences between the different definition files (and its associated broadcast codes) is automatic transmission wiring, and maybe gear ratios. The 2240 should be able to run any broadcast code written for it. But that's not to say that all of the data is handled the same, or is input/output on the same pins.
In your case, I would suspect an intermittent wiring or connector issue. This, since your issues seemed to occur across Abel, Baker, and Charlie. Followed by a bad connection at the EPROM/MEMCAL. (That would be an odd coincidence, however, for the same reason.)
What is the tach doing during all of this? Reason I ask is that the injectors are triggered by the ignition pulses, so it might be an ignition related issue. That would help with the issue being random and across 3 separate PCMs.
What is the tach doing during all of this? Reason I ask is that the injectors are triggered by the ignition pulses, so it might be an ignition related issue. That would help with the issue being random and across 3 separate PCMs.
Since the would fire a quit I was thinking fuel but I like where you are headed with an ignition problem
------------------ formerly known as sanderson 1984 Quad 4 1886 SE 2.8L 1988 4.9L Cadillac 1988 3800 Supercharged
Hi slightly off topic Does anyone have contact information for someone that still is programing the obid 1 chips to run the 4.9 ? I had Westers in Alberta put a tune in for my 4.9 swap ( came from a 94 Deville stock 5 speed trans and hooking up the ecm to speedo killed the output to the dash). It runs but not great, looking for a tuner with similar Fiero 4.9 swap experience. Local speed gurus are saying to dump the gm ecu and replace it with a link system $$$$. I appreciate help I live in BC Canada.
Hi slightly off topic Does anyone have contact information for someone that still is programing the obid 1 chips to run the 4.9 ? I had Westers in Alberta put a tune in for my 4.9 swap ( came from a 94 Deville stock 5 speed trans and hooking up the ecm to speedo killed the output to the dash). It runs but not great, looking for a tuner with similar Fiero 4.9 swap experience. Local speed gurus are saying to dump the gm ecu and replace it with a link system $$$$. I appreciate help I live in BC Canada.
The VSS that came in the 4T60E auto that came with the Cadillac has an entirely output than the VSS from a stock Fiero 5 speed. Do not connect the output of the Fiero VSS to the 4.9L PSM. I would run it to the dash through the C-203 connector the same as in the Fiero. If the 4.9L has not been modded, I doubt there is anything to be gained in terms of max power by a custom tune. There are perhaps some parameters to that would help driveability with a manual transmission. We need Raydar to chime as he has done a 4.9L w/ 5 speed. Do not spend money on an aftermarket ECU - entirely not necessary. We'll get this worked out.
------------------ formerly known as sanderson 1984 Quad 4 1886 SE 2.8L 1988 4.9L Cadillac 1988 3800 Supercharged
Thanks Sanderson 231, I have done exactly that vss goes to the dash direct and the speedo is working, I read online that in order for the engine to run correctly it needed the vss feed back (this was a Fiero Factory 4.9 conversion post). My car is idling ok but running really rich stinks of unburned fuel. This is why I'm looking for someone that has experience with this swap to check out my current program for errors that maybe causing my drivebility issues. Any help is appreciated. This is not a race car and I have no intentions of modifying the engine further, Just looking to get it running correctly. 200 hp should be plenty. Also a shout out to member Mickey_Moose who's posts were invaluable to me going it this far
Thanks Sanderson 231, I have done exactly that vss goes to the dash direct and the speedo is working, I read online that in order for the engine to run correctly it needed the vss feed back (this was a Fiero Factory 4.9 conversion post). My car is idling ok but running really rich stinks of unburned fuel.
The PCM needs to be "faked out" by grounding a couple of the auto trans wires, to make it think it's in Drive. I don't remember which two wires, but I can dig it up if I need to. Since the Caddy never came with a manual, it's hard to figure out what to tweak. I bumped up the idle speed a bit, and did a few other things, but nothing I can point to. The 4.9 is difficult to tune because there are at least FIVE different files that could be used to tune, depending upon which year and model the donor was. You have to use the correct one, or the data will be nonsense.
But about the rich running... Make sure that your O2 sensor is good. They can fail, indicating "full lean", which will cause the PCM to dump fuel in. It can even kill your catalytic converter, if you have one. (Don't ask how I know this.) You can test it by unplugging it, and then resetting the PCM by disconnecting the battery. The engine will run on pre-programmed, default values. If the rich condition goes away, you've probably found your culprit. I used an NTK replacement part. (Advance Auto is where I found mine.) Also, if you have a scan tool, you should make sure that the PCM is seeing the correct values for coolant and air temperature. If they're reading very cold, it will also cause rich running. Third... make sure the power steering input on the PCM is jumpered. If not, that can also cause it to run rich.
Regarding the wiring, if you got your info from Mickey Moose, everything I suggested checking is probably already accounted for.
There are a couple other "gotchas" that happen if you're using an Allante intake manifold. Since you didn't mention that, I'll assume that you are not.
[This message has been edited by Raydar (edited 01-31-2023).]
Thanks for that Raydar. I pretty much used Mickey Mooses wire post as the schematic for my build grounding as described also installed the security chip defeat device. O2 Sensor is new but I will try what you have suggested and see what happens. Unfortunately the company I sent my chip to changed out the stock fuel map for one they said was more suited the Manual trans. Any idea if that fellow "Rockcrawl" is still programing? All the posts I have see him mentioned are years old. I will open up the ecm and see what numbers are on the chip and get back to you in a bit, unless it turns out that the O2 sensor is the culprit then the problem will be solved. thanks again. Brad
To diagnose the rich condition you really need to get a scan tool on it or datalog with a laptop (free software is available). The short term fuel trim (aka integrator) should be bouncing around 128 with a stock tune if everything is right. If it is reading low the O2 sensor is seeing a rich condition and it is biasing down the fuel injectors to try to correct the rich condition. But the integrator can only adjust so far and if it is bottomed out the engine will run rich. Of course your chip is not stock and whoever messed with the tune may have created the rich condtition.
I have seen a lot of plugged 4.9L fuel injectors. If the engine has sat around, I recommend pulling the fuel injectors and having them professionally cleaned. Mr Fuel Injector in Idaho does it for $18 each. A partially plugged fuel injector can cause a rich condition. One cylinder runs lean and pumps excess O2 into the exhaust and then the PCM makes the other cylinders run rich to try to get back on ratio.
As I recall Mickey_Moose wires the cars as a 1992 Deville. In 1992 a 16132240 PCM was used. From what Tunercat has on his website, a 1994 uses a 19196347 PCM. There may be some wiring differences. The 16196347 may not be entirely compatible with 1992 wiring. Please tell us what PCM you have (label on outside of the box) and what broadcast code the EPROM is (four letter code such as BWYZ on the EPRM itself).
I was thinking that it might be necessary to adjust the decel enleanment and decel fuel cut-off parameters in the PCM for a manual transmission. I see no reason to mess with other parameters that effect the fuel trim.
I can burn a new electrically erasable EEPROM. You would have to buy an adapter to install this. I do not have a UV eraser to modfiy your old chip.
Raydar, I checked my 1992 Deville factory service manual. From what I see in order for the PCM to think the transmission is in drive, the following is necessary:
PCM wire F8 needs to see an open PCM wire C10 needs to be be grounded PCM wire F7 needs to be grounded PCM wire A2 needs to see an open
Thanks for bringing this up. I'm putting the final touches on a 4.9L manual for a friend and I'm sure he missed this.
------------------ formerly known as sanderson 1984 Quad 4 1886 SE 2.8L 1988 4.9L Cadillac 1988 3800 Supercharged
To diagnose the rich condition you really need to get a scan tool on it or datalog with a laptop (free software is available). The short term fuel trim (aka integrator) should be bouncing around 128 with a stock tune if everything is right. If it is reading low the O2 sensor is seeing a rich condition and it is biasing down the fuel injectors to try to correct the rich condition. But the integrator can only adjust so far and if it is bottomed out the engine will run rich. Of course your chip is not stock and whoever messed with the tune may have created the rich condtition.
I have seen a lot of plugged 4.9L fuel injectors. If the engine has sat around, I recommend pulling the fuel injectors and having them professionally cleaned. Mr Fuel Injector in Idaho does it for $18 each. A partially plugged fuel injector can cause a rich condition. One cylinder runs lean and pumps excess O2 into the exhaust and then the PCM makes the other cylinders run rich to try to get back on ratio.
As I recall Mickey_Moose wires the cars as a 1992 Deville. In 1992 a 16132240 PCM was used.
Raydar, I checked my 1992 Deville factory service manual. From what I see in order for the PCM to think the transmission is in drive, the following is necessary:
PCM wire F8 needs to see an open PCM wire C10 needs to be be grounded PCM wire F7 needs to be grounded PCM wire A2 needs to see an open
Thanks for bringing this up. I'm putting the final touches on a 4.9L manual for a friend and I'm sure he missed this.
My Donor was a 1991 Deville. My PCM was also a 2240. I believe that most years/applications were 2240s. "C10 and F7 grounded" sounds strangely familiar. Possibly the same as mine.
Injectors... yeah. From the time mine was swapped in by the folks in Huntsville it had a bit of a skip to it. I finally replaced my injectors with the orange Bosch Type III injectors. The skip went away. Fuel Injector Connection (FIC) has them. https://fuelinjectorconnect...-iii-design-set-of-8
As I recall Mickey_Moose wires the cars as a 1992 Deville. In 1992 a 16132240 PCM was used. From what Tunercat has on his website, a 1994 uses a 19196347 PCM. There may be some wiring differences. The 16196347 may not be entirely compatible with 1992 wiring. Please tell us what PCM you have (label on outside of the box) and what broadcast code the EPROM is (four letter code such as BWYZ on the EPRM itself).
What he said - it has been a long time since I did this, but I do recall there was something with the 94 PCM that it was not a good choice to use at the time.
I might still have the files for the EPROM, but again this would only be for the 1992 PCM
They are in the \EPROM files\4.9l directory. Sorry I don't remember the specifics of the files other than the names that there are called. But includes both Rockcrawl and Stickpony images - you will have to load them into Tunercat and verify if the VATS has been disabled as I don't recall which had.
Stickpony was the go to person after Rockcrawl seemingly left the Fiero scene.
These are for the 2240 PCM (pre-94).
[This message has been edited by Mickey_Moose (edited 02-11-2023).]
I took a quick peak at the Rockcrawl and Stickypony calibrations. They both changed the pulses per mile for the VSS to 3975. The stock 4.9 BBXF calibration has 23754 pulses per mile. The VSS for the 4.9 outputs a square wave. The Fiero VSS outputs a sine wave of ~4000 pulse per mile. Despite the different wave forms this implies that the Fiero VSS can be wired to the 4.9 PCM if the speed pulses per mile is changed to 3975. But the 4000 pulse per mile square wave output from the 4.9 PCM would need to be converted to a 4000 pulse per mile sine wave to make it compatible with the Fiero speedometer. The circuitry to make this conversion consists of two resistors and one capacitor which is easily incorporated into the wiring harness under the console.
There were some small changes in the spark advance tables in the Rockcrawl and Stickpony calibrations. There were no significant changes that would effect air fuel ratio.
------------------ formerly known as sanderson 1984 Quad 4 1886 SE 2.8L 1988 4.9L Cadillac 1988 3800 Supercharged
Originally posted by sanderson231: But the 4000 pulse per mile square wave output from the 4.9 PCM would need to be converted to a 4000 pulse per mile sine wave to make it compatible with the Fiero speedometer. The circuitry to make this conversion consists of two resistors and one capacitor which is easily incorporated into the wiring harness under the console.
They are in the \EPROM files\4.9l directory. Sorry I don't remember the specifics of the files other than the names that there are called. But includes both Rockcrawl and Stickpony images - you will have to load them into Tunercat and verify if the VATS has been disabled as I don't recall which had.
Stickpony was the go to person after Rockcrawl seemingly left the Fiero scene.
These are for the 2240 PCM (pre-94).
I did look at the files you posted with Tunercat. The two stock calibrations opened OK. The four files that were edited all gave checksum errors. However I noticed in the text documentation that the checksum error (code 51) had been disabled in the switch table. Therefore I am assuming that files were edited without a tool that would recalcuate the check sum and that the files are not corrupt. I'll proceed with caution and try one out int the car.
I did look at the files you posted with Tunercat. The two stock calibrations opened OK. The four files that were edited all gave checksum errors. However I noticed in the text documentation that the checksum error (code 51) had been disabled in the switch table. Therefore I am assuming that files were edited without a tool that would recalcuate the check sum and that the files are not corrupt. I'll proceed with caution and try one out int the car.
Sorry, I cannot help on how they were originally edited, but the BIN files are as I dumped them using my programmer - however this was also years ago and maybe the files have been corrupted since then sitting on my hard drive? The text files are what I documented as to what the changes were at the time, so one can always create a new file.
The difference between the 2 Stickpony files is 1 was for a 4 speed car and the other was from a 5 speed car - no ideal if there are actual differences other than maybe the PPM calculation for different sized tires. But I have no ideal which one is which. lol
The Rockcrawl file was for the same 5 speed car.
The 4th file - I do not recall what car that was for...
[This message has been edited by Mickey_Moose (edited 02-14-2023).]
From what I have heard if I open the bin file with Tunercat and then save it back to my hard drive, Tunercat will recalulate a new checksum. So that the next time it is opened Tunercat will not give a checksum error. I have a couple of spare PCMs so I'm going to give it a whirl betting that the checksum error is just an artifact of the programmer that created the file.
------------------ formerly known as sanderson 1984 Quad 4 1886 SE 2.8L 1988 4.9L Cadillac 1988 3800 Supercharged
It's been a while, but I recall that if you are connecting the Fiero 5 speed VSS to the Caddy PCM, you may need to swap the VSS wires (purple and yellow). Without the swap, mine kept stalling everytime I pushed in the clutch and came to a stop.
Originally posted by Mickey_Moose: The difference between the 2 Stickpony files is 1 was for a 4 speed car and the other was from a 5 speed car - no ideal if there are actual differences other than maybe the PPM calculation for different sized tires. But I have no ideal which one is which. lol
The Rockcrawl file was for the same 5 speed car.
The 4th file - I do not recall what car that was for...
The key difference between the Stickpony and Rockcrawl file is the ignitiontiming advance. Rockcrawl stuck with stock timing. Stickpony advanced the timing at high MAP and high rpm's. For example the stock timing at 100 kPa and 4800 rpm is 35.9 degrees. Stickpony increased it to 41.1 degrees. I think that these values are delta timing i.e. the actual timing is the 8 degrees base timing in the distributor plus the value in the PROM. We don't know if Stickpony did this based on dyno results or it was just wishful thinking that more advance would make more power. 49 degrees of advance at 4800 rpm and 100 kPa seems like a lot.
------------------ formerly known as sanderson 1984 Quad 4 1886 SE 2.8L 1988 4.9L Cadillac 1988 3800 Supercharged
it had a bit of a skip to it. 
