ecm mods (Page 2/3)
cartercarbaficionado MAY 21, 02:27 PM

quote
Originally posted by 82-T/A [At Work]:
So, I kinda went over this in the other response to Yellow88. Full disclosure, I've never swapped out an ECM before... I mean... I've never installed an aftermarket ECM before. But I have done plenty of wiring harnesses and it's not too bad.

For me personally, I think re-doing the wiring harness and replacing the ECM with a more modern system is NOT bad advice. With everything being new, the Fiero runs quite well. But it was designed during a time when ECMs were really just starting to come into their own. The ECM we use in our cars was the first *real* computer control of a vehicle. The prior standard ECM that came in cars started showing up in 1980 with ESC (Electronic Spark Control) and usually controlled a fuel metered carburetor. Then they had some super-basic TBI-controlled ECM that controlled things like the Cross-Fire injected TransAm / Camaro and Corvette in 81-82, and controlled the TBI unit for trucks and a couple of passenger cars.

The MPFI system we used was first used in late 1983 in cars like the Olds-88 or the Cavalier... and it didn't really change through the entire production of the Fiero through 1988. Just a year later, 1989... they had a much, much newer and better designed system with the 7730. Just looking at how computers advanced from ~1984 to 1989... we went from an 8-bit Bus / processor with the 8088 microprocessor at 4.77 Mhz to a 16-bit bus and 32-bit processor with the 80386 at 33 Mhz. Literally worlds away in terms of performance.

The big thing that always seems to get harped on is that in order for a modern ECM to work well, the car needs to be running well already (meaning it can't have any timing, fuel, or compression issues). But... if the motor already runs "ok," then an upgraded ECM will definitely improve everything.

Anyone who's converted an older MPFI system to a newer ECM, or even upgraded to an SFI-compatible system will tell you the performance and drivability is night and day.


Below is a copy/paste (and slightly modified) version of what I posted to Yellow-88's thread.


the microsquirt is likely what I'll go with, or a mega squirt 3 to get a slight boost in the midrange rpm to deal with the cruising rpm needing to be around 3k to keep speed up most hills....until the ecu gives up I guess and gives it the whole hog and goes to 140 frightenly quickly at an 1/8th throttle
hence the just wanting to replace it since I'm not putting the effort in for a 7730 since it's only a bit more to throw a fully tunable ecu in to actually know what it's doing
82-T/A [At Work] MAY 21, 03:52 PM

quote
Originally posted by cartercarbaficionado:

the microsquirt is likely what I'll go with, or a mega squirt 3 to get a slight boost in the midrange rpm to deal with the cruising rpm needing to be around 3k to keep speed up most hills....until the ecu gives up I guess and gives it the whole hog and goes to 140 frightenly quickly at an 1/8th throttle
hence the just wanting to replace it since I'm not putting the effort in for a 7730 since it's only a bit more to throw a fully tunable ecu in to actually know what it's doing



This was my thought as well. Originally, I wanted to go the 7730 route too. It's still a good option... but it's basically replacing a computer from the 80s with one from the late 80s... literally. There's so much better technology out there now. For a totally stock 2.8, I don't really see much benefit at all. But converting to a MicroSquirt or one of these newer systems allows you to do so much more. You can convert to a MAF system if you wanted, etc. With the self-learning systems that many of them have now, you can literally just add engine modifications and it just figures it out.

You can still manually tune them too... but these self-learning systems get you 90-95% of the way there. It's really something else... a lot of people poo-poo them because they think that running on a dyno is the only true way to figure it out. But this is basic machine learning. If you want to optimize fuel across the entire fuel range, it can do this so long as your sensors are feeding it good data. Too rich here, too little timing there, it automatically adjusts that at the various RPMs and updates the fuel map for the next time you're in that rpm with TPS value and ambient temperature. They just work. MicroSquirt doesn't do any self-learning, FYI... but you can easily data-log off of it, and upload those logs into a system which will automatically optimize the fuel mapping values for you... which you then just re-upload.

Joe is right though, if you want it perfect... you need to have someone who knows where being a little lean can improve performance beyond sticking with a basic fuel optimization curve. And of course, you can only tell if that made a difference by running it on a dyno.

For someone like me though, I don't want the fuss... I want my cake and eat it too. I want to be able to install a new system, and just have it figure it out like machine learning is supposed to. So I'm going with the FAST EZ-EFI 2.0 system. People had problems with them in the beginning (lots of interference), but they fixed it in 2016, and I got mine in 2023 with the updated firmware that adds more self-learn optimization. I'm leaving a couple of horsepower out here and there, but it'll get me up running quickly, with a brand new harness. I bought the MPFI conversion kit, which comes with an entire harness for a standard TPI system (like our Fiero V6 but with 2 less injectors and plugs). The wiring harness already has all the factory Fiero plug-ends on them for TPS, MAP, IAC, IAT, etc... I literally don't have to change a single plug end... EXCEPT the one for the distributor (I'll be using the factory distributor with the MSD 6EFI system to convert it from analog to digital).

https://www.summitracing.com/parts/fst-30404-kit


What a lot of people do though too, is upgrade to one of these, and keep the stock ECM JUST to control spark timing. Seems to work well.


Snyderman did that for his 84 Fiero, and says he absolutely loves it: https://www.fiero.nl/forum/Forum2/HTML/144288.html
armos MAY 21, 03:54 PM

quote
Originally posted by cartercarbaficionado:

the microsquirt is likely what I'll go with, or a mega squirt 3 to get a slight boost in the midrange rpm to deal with the cruising rpm needing to be around 3k to keep speed up most hills....until the ecu gives up I guess and gives it the whole hog and goes to 140 frightenly quickly at an 1/8th throttle


I know you're probably joking, but the ECM can't cause any serious amount of "unintended acceleration". The only throttle it can control is the IAC valve, and that's not big enough to do anything real dangerous. But a vacuum leak could let in a lot more air than the ECM can.
If you put a paperclip into the ALDL connector like you do when checking for "check engine" codes, or for checking the base ignition timing - and then start the engine, then you should see the "check engine" light constantly blinking and it should stay at 1000rpm exactly. In this mode, the light comes on when the O2 sensor is reporting rich exhaust, and turns off when it's reporting lean. So the light should cycle on and off pretty rapidly, and it should stay on 1000rpm. If it doesn't then the ECM doesn't have control of the idle.

The 7730 swap has been on my long term "to do" list. I haven't tried yet, but I think the most logical starting point is probably the PROM from a 3.1L Camaro or Firebird. It's very similar to the engine and sensor configuration in our cars, moreso than any other 7730 application I'm aware of. It's the only 7730 car with an iron-head 60V6. The 2.8L Beretta is an aluminum head 2.8, not like our iron head engine. I don't know what sensor config the Beretta uses, but the 3.1L F-Body uses the same setup we do other than a different type of EGR and a knock sensor (both of which can be disabled or added).
However, from what I've read, none of the factory chips run great on the Fiero, so it will probably need a lot of re-tuning effort regardless.

I wouldn't erase a factory PROM. I'd save it "just in case". The chips used on these ECMs are off the shelf, they aren't unique but GM didn't show the underlying part number. You can buy EPROMs on eBay easily, the cheapest ones come from China but you can find US sources also. I don't remember what the correct chip type is for the 7730 - but 7730 swap threads should have that info. For the stock 7170 1986-88 V6 ECM it's a 2732A (I think the 1985 ECM is the same chip but not sure).
With a 7730 there's a separate chip that I think relates to the knock sensor and maybe some other details. So it matters what donor you use (I got mine from a 3.1L Firebird and have a knock sensor to match). There is some soldering involved to install a socket for easily replacing the EPROM.
I think there's some older threads that go into detail about all of this for 7730.

[This message has been edited by armos (edited 05-21-2024).]

Jason88Notchie MAY 21, 04:57 PM

quote
Originally posted by cartercarbaficionado:

I'm pretty much going to. my harness is correct for the stock ecu but it just keeps doing weird stuff. sometimes it sets the idle speed at 3k rpm and sometimes 750 at random with no code or explanation for it since I know it's not a vaccum leak, as far as I can tell the ecu just randomly starts to make up its own readings that have no basis in reality since all the sensors check out fine and it's a new replacement harness from a running driving 86 fiero



Ok. I hope you get it sorted out and start having fun driving the car instead of chasing gremlins all the time. That sucks.
cartercarbaficionado MAY 21, 08:16 PM

quote
Originally posted by Jason88Notchie:


Ok. I hope you get it sorted out and start having fun driving the car instead of chasing gremlins all the time. That sucks.


I mean it drove 30 miles to work today which it hasn't done in almost a year since it just straight up wouldn't run. the weird power loss is getting worse and it's starting to feel like my icm is doing weird stuff like it did before I put my new distributor in (I have the old one which was already a new style but I couldn't find a pickup to replace the one on it) so the timing is getting checked and I'll likely install my new 02 sensor and if none of that helps then I'm ripping the egr off and doing a chip to have one less thing that could be my issue
on the bright side it might help my terrible highway fuel economy (15 mpg. doesn't get worse or better depending on driving rpm or throttle position or even speed) but I'm not holding my breath. this car has been through alot and I'm gonna try to refill all the care that has leaked out over the years(like the coolant)
Yellow-88 MAY 21, 11:42 PM
Thank you Armos.

Most of what I see written is about 3.1 or 3.4 engine swaps using PROMs from 3.1 or 3.4 V6s. I was thinking that 2.8 5 speed Chevy was a closer match to our stock 2.8 5 speed. I have to wonder, how different are they really? I agree that no off the shelf PROM will be a" perfect" match for anything but the possessor itself was evolving rapidly during the last days of the Fiero. Too late for us. I'll go with the 7730 upgrade. ( that upgrade should have been a factory recall.)

I think to do it right, the engine harness should come out. It's a great opportunity to clean and inspect the engine bay and everything under the top plenum.
I imagine that spread out on the table is the best way to test and work on a harness. Just losing the EGR solenoid and its tubes is worth the effort.

A Sports Car can be defined as, having nothing on it that doesn't make it go. The EGR solenoid is just such a thing.

Yellow-88
82-T/A [At Work] MAY 22, 08:46 AM

quote
Originally posted by Yellow-88:

Thank you Armos.

Most of what I see written is about 3.1 or 3.4 engine swaps using PROMs from 3.1 or 3.4 V6s. I was thinking that 2.8 5 speed Chevy was a closer match to our stock 2.8 5 speed. I have to wonder, how different are they really? I agree that no off the shelf PROM will be a" perfect" match for anything but the possessor itself was evolving rapidly during the last days of the Fiero. Too late for us. I'll go with the 7730 upgrade. ( that upgrade should have been a factory recall.)

I think to do it right, the engine harness should come out. It's a great opportunity to clean and inspect the engine bay and everything under the top plenum.
I imagine that spread out on the table is the best way to test and work on a harness. Just losing the EGR solenoid and its tubes is worth the effort.

A Sports Car can be defined as, having nothing on it that doesn't make it go. The EGR solenoid is just such a thing.

Yellow-88




The difference between those other engines and our 2.8 is also in the sensors that it uses. Most of the newer V6/60s have a knock sensor. The only Fiero stock ECM I'm aware of that supports one, is the 85 V6 ECM, but it's disabled in the code (just need to enable it). This is not a bad thing though, because you can always wire one up. For the life of me though, I don't actually know where the knock sensor attaches to, but I assume somewhere on the side of the block.

I'm not trying to get you upset, but there's a couple of things that you should seriously consider. If your Fiero is not driving well (as you're suggesting), you need to get that fixed FIRST before you go swapping the ECM. A self-learning system can often improve this, but a 7730 doesn't do that. Swapping a 7730 on will likely only exacerbate the problem. I bought a very low mileage Fiero back in 1996, and I can tell you, it was anything but sluggish... and it was an automatic.

If any of your sensors are starting to fail, then the last thing you want to do is tune a new ECM to bad sensors. There's several sensors on the Fiero that begin to fail and don't really give error codes until they fail outright... such as the IAT / Intake Air Temperature sensor. This is the one in the air canister, and it can give false readings when dirty or corroded and can dramatically affect the performance of your Fiero. You'll never even see an engine error code for it unless it outright fails. The MAP can be similar as well.

Make sure all of these are "perfect" or new (to be honest), before you even consider swapping an ECM.


I get a "stubborn" vibe from you, and that's cool... nice to meet you, I'm the same way. But you'll want to realize that you're only going to cause more problems until you confirm that everything else is GOOD. I know you're looking for an easy button, and you've convinced yourself (respectfully) that the 7730 is that solution. But it's not. It's a good upgrade, yes... just don't skip steps... like ignoring a poor running engine thinking that the newer ECM will solve that problem.

But here's some advice you'll like. Several people have swapped in 7730s. I think you should have no problem being able to find someone who also / already has a tune specifically for our Fieros. There's a guy on here, DarthFiero I think is his name that does EPROM burns. You may want to reach out to him, or PM him and see if he already has one saved that he can burn to an EPROM for you (and sell it to you). Then all you need is the 7730 ECM (which you can buy all over the place on eBay and Rock Auto).

For the engine wiring harness... my personal opinion is that if you're going to take the wiring harness out... you might as well completely replace it. But that really depends on the condition of your car and where it's been. If the wiring is really solid, and not cracked or burnt anywhere, you can probably just clean and reuse it. But if when you inspect it, it's kind of nasty and every plug-end is destroyed... may be better to just replace it. There's a couple of companies that sell brand new MPFI wiring harnesses with all the GM connectors already on it. You can just buy one of those and manage the pinouts to the new 7730.


Also, while you're doing all this... you may want to consider the MSD 6EFI ignition box I mentioned earlier. It works with the 7730 (or any system you decide to use). It significantly improves performance and driveability.

"MSD 6EFI ignitions are capacitive discharge ignitions designed to work in harmony with electronic fuel injection systems. They come with detailed wiring instructions, making installation a breeze. Increased throttle response, smoother idle, quicker starts, and full ignition power throughout the entire rpm range are all benefits of adding these ignition controls to your fuel injected engine. They feature built-in rev limiters that will protect the engine in the event of a missed shift or driveline failure. If you have a 4, 6, or 8-cylinder engine with EFI, MSD 6EFI ignition controls will connect and fire it up!"

EDIT: You could even install the MSD 6EFI right now with your existing Fiero ECM, and it'll probably solve whatever concerns you already have. It's $239, and already comes with everything you need.

[This message has been edited by 82-T/A [At Work] (edited 05-22-2024).]

cartercarbaficionado MAY 22, 05:07 PM

quote
Originally posted by 82-T/A [At Work]:
The difference between those other engines and our 2.8 is also in the sensors that it uses. Most of the newer V6/60s have a knock sensor. The only Fiero stock ECM I'm aware of that supports one, is the 85 V6 ECM, but it's disabled in the code (just need to enable it). This is not a bad thing though, because you can always wire one up. For the life of me though, I don't actually know where the knock sensor attaches to, but I assume somewhere on the side of the block.

I'm not trying to get you upset, but there's a couple of things that you should seriously consider. If your Fiero is not driving well (as you're suggesting), you need to get that fixed FIRST before you go swapping the ECM. A self-learning system can often improve this, but a 7730 doesn't do that. Swapping a 7730 on will likely only exacerbate the problem. I bought a very low mileage Fiero back in 1996, and I can tell you, it was anything but sluggish... and it was an automatic.

If any of your sensors are starting to fail, then the last thing you want to do is tune a new ECM to bad sensors. There's several sensors on the Fiero that begin to fail and don't really give error codes until they fail outright... such as the IAT / Intake Air Temperature sensor. This is the one in the air canister, and it can give false readings when dirty or corroded and can dramatically affect the performance of your Fiero. You'll never even see an engine error code for it unless it outright fails. The MAP can be similar as well.

Make sure all of these are "perfect" or new (to be honest), before you even consider swapping an ECM.


I get a "stubborn" vibe from you, and that's cool... nice to meet you, I'm the same way. But you'll want to realize that you're only going to cause more problems until you confirm that everything else is GOOD. I know you're looking for an easy button, and you've convinced yourself (respectfully) that the 7730 is that solution. But it's not. It's a good upgrade, yes... just don't skip steps... like ignoring a poor running engine thinking that the newer ECM will solve that problem.

But here's some advice you'll like. Several people have swapped in 7730s. I think you should have no problem being able to find someone who also / already has a tune specifically for our Fieros. There's a guy on here, DarthFiero I think is his name that does EPROM burns. You may want to reach out to him, or PM him and see if he already has one saved that he can burn to an EPROM for you (and sell it to you). Then all you need is the 7730 ECM (which you can buy all over the place on eBay and Rock Auto).

For the engine wiring harness... my personal opinion is that if you're going to take the wiring harness out... you might as well completely replace it. But that really depends on the condition of your car and where it's been. If the wiring is really solid, and not cracked or burnt anywhere, you can probably just clean and reuse it. But if when you inspect it, it's kind of nasty and every plug-end is destroyed... may be better to just replace it. There's a couple of companies that sell brand new MPFI wiring harnesses with all the GM connectors already on it. You can just buy one of those and manage the pinouts to the new 7730.


Also, while you're doing all this... you may want to consider the MSD 6EFI ignition box I mentioned earlier. It works with the 7730 (or any system you decide to use). It significantly improves performance and driveability.

"MSD 6EFI ignitions are capacitive discharge ignitions designed to work in harmony with electronic fuel injection systems. They come with detailed wiring instructions, making installation a breeze. Increased throttle response, smoother idle, quicker starts, and full ignition power throughout the entire rpm range are all benefits of adding these ignition controls to your fuel injected engine. They feature built-in rev limiters that will protect the engine in the event of a missed shift or driveline failure. If you have a 4, 6, or 8-cylinder engine with EFI, MSD 6EFI ignition controls will connect and fire it up!"

EDIT: You could even install the MSD 6EFI right now with your existing Fiero ECM, and it'll probably solve whatever concerns you already have. It's $239, and already comes with everything you need.



some of us decided to swap in all new tested sensors to chase a wandering idle that ended up being the pickup in the distributor, I'm pretty sure this distributor is timed different to the last one since I just dropped it in same as the last one (rotor and body in same place) and it runs entirely differently. it's pretty cranky on cold starts needing a few seconds to start firing before it'll light off and stay at 500 rpm for a few seconds before going to high idle.
did that since I got it on and off so I'm sure something is messed up
Yellow-88 MAY 23, 01:40 PM

I get a "stubborn" vibe from you, and that's cool... nice to meet you, I'm the same way. But you'll want to realize that you're only going to cause more problems until you confirm that everything else is GOOD. I know you're looking for an easy button, and you've convinced yourself (respectfully) that the 7730 is that solution. But it's not. It's a good upgrade, yes... just don't skip steps... like ignoring a poor running engine thinking that the newer ECM will solve that problem.

Is it "stubborn" or just human nature to stick with the thing that's stuck in ones head? Either way you are right. I do intend to go to square one and check everything related to a smooth running engine. It's normal to "get used to" how things are and forget what they used to be. I do think that Yellow runs as good as it is expected to from the factory. I also think that Pontiac should have included the new technology into Fierro's as soon as it was invented. But of course, Fiero's were a "test bed" for other stuff, never intended to be "serious" cars.

Has anyone done a side by side comparison between a stock and a 7730 upgrade? From what I see written, there is a noticeable difference, and it's where I'm looking for improvement. Again, I agree, a crappy running engine runs crappy.

Yellow-88
82-T/A [At Work] MAY 23, 03:57 PM

quote
Originally posted by Yellow-88:
I also think that Pontiac should have included the new technology into Fierro's as soon as it was invented. But of course, Fiero's were a "test bed" for other stuff, never intended to be "serious" cars.



I'm not sure what you mean by this. The Pontiac Fiero was just as good as any other car that GM sold at the time in that price range. Pontiac didn't cut corners with the Fiero above any other vehicles at the time... so I don't really get what you mean about it not being a "serious" car. It was as serious as a Chevy Cavalier, or a Pontiac TransAm. GM's quality was generally less than great though in the 80s... so I don't know if that's what you mean?



quote
Originally posted by Yellow-88:Has anyone done a side by side comparison between a stock and a 7730 upgrade? From what I see written, there is a noticeable difference, and it's where I'm looking for improvement. Again, I agree, a crappy running engine runs crappy.

Yellow-88




I am not aware of anyone that took a 7730 ECM out of another car and just started using it on the Fiero without going through the effort of reprogramming it... there are some things you need to do in order to get it to work. But whether you use your current ECM, or a 7730... you'll gain a little horsepower if you have it fine-tuned to your specific car as there are definitely variances between production vehicles... and you can definitely lean it out in some places to gain a little more power (basically what Joe was talking about). If you don't want to do that... the closest 7730 ECM EPROM you'll want to likely use is the one from the 3.1 in the Third Gen Camaros and Firebirds (iron heads).

I think it's worth setting expectations on what you're going to get. The Fiero's technology is very old now, but the engine technology has more staying power. Like, I don't want to repeat all the things I said before, but with a new / new ECM, you can completely eliminate EGR all together (and your car doesn't have to choke on its own farts). You can also completely eliminate the cold start injector, and even convert to Sequential Port Fuel Injection which reduces fuel consumption and improves horsepower throughout the low to mid rpms.

A 7730 will give you some of these things, including eliminating the cold start injector and allow you to convert to a digital EGR (which only means less potential for a vacuum leak, and no need to use the vacuum regulator). Cold starts are some of the biggest improvements you'll get. It's more common on the 4 cyl Fieros, but they start at really high idle when cold, and as they warm up, eventually dip back down. You'll have less of that with the 7730. Another nice thing of course is that when you eliminate the cold start injector, you can now use that port as a nitrous port.

Based on what I've seen over the years, it seems most people convert to the 7730 because they're swapping in a 4-Speed automatic transmission and you don't have to struggle with swapping the VSS gears (it becomes programming on the EPROM at that point). But also... a lot of people switch to a newer 3.1 or the 3.4 V6/60 engine (which is effectively a drop-in replacement and you get to keep everything looking stock), and when they do that, they tend to want to convert to DIS ignition and get rid of the distributor. You can still use the distributor of course with the 3.1 and 3.4... but most people just want the performance and swap it out.

I think what you can realistically expect though, is improved cold starts, and a cleaned-up engine bay (no vacuum regulator and a few less vacuum lines, etc.). Piggy backing on my response in the other thread, if you're not real comfortable doing this yourself... then you can buy a harness online (a used one, or a replacement new one), and get it all wired up to your 7730 (leaving the factory wiring in place). Once it's all set, you can temporarily place the 7730 off next to the air cleaner (or something) and switch over the connectors from the new harness to the original harness. If it runs good... then you can go through removing the old harness and ECM. If it doesn't run at all, well... you can easily just reconnect the factory ECM and sensors and you haven't ruined anything.

It's definitely something you can tackle... but you'll want to take your time. Honestly though, don't get me started... if you're going through the hassle, you can swap in a 3.4 V6/60 and it would look totally stock... and magically more horsepower.