So, with my upcoming engine swap, I made a few 0-60 runs without short shifting (I never exceed 5000 usually haha), and as my calculations show 2nd should reach 60mph, and a 2 gear run is quicker than a 3 gear run, I decided to go for it, right to 6000, and see what happened. I've read several times on this forum that the rev limiter engages at ~6000, and cuts fuel until it slows to 4000, giving the user quite a scare. When I hit the rev limiter at ~6200 rpm, it was a much more precise limiter, it stops pulling entirely at that rpm, and just sits there, no oscillations, or noises, full power returning immediately at any lower rpm than the limit. Mine is the 1985 GT, which uses a different ECM than the 86-88 v6s, I think the rev limiter is another change between the two v6 ecms. Just an interesting piece of information I haven't seen here before.
Edit: never mind, rev limiter does operate like usual, off at 6200, back on at 4000rpm, I just was too impatient.
[This message has been edited by 1985 Fiero GT (edited 11-07-2024).]
I made a few 0-60 runs without short shifting (I never exceed 5000 usually haha)... When I hit the rev limiter at ~6200 rpm...
Remind us again if your 2.8 is entirely stock... but did it still pull half decently between 5000 and 6200 rpm?
A week or so ago I was merging onto the freeway, so I goosed the throttle in second gear... and wondered why the car appeared to be running out of beans a little early. Turns out I had been driving my turboed Subie a lot lately (8,000 RPM redline), and I sort of forgot I was driving my Formula. The 2.8 wound up nicely without missing a beat (1.6 roller-tip rockers, ported exhaust logs, power pulley), but it still doesn't have the necessary breathing capacity at higher RPMs.
[This message has been edited by Patrick (edited 11-04-2024).]
Remind us again if your 2.8 is entirely stock... but did it still pull half decently between 5000 and 6200 rpm?
A week or so ago I was merging onto the freeway, so I goosed the throttle in second gear... and wondered why the car appeared to be running out of beans a little early. Turns out I had been driving my turboed Subie a lot lately (8,000 RPM redline), and I sort of forgot I was driving my Formula. The 2.8 wound up nicely without missing a beat (1.6 roller-tip rockers, ported exhaust logs), but it jstill doesn't have the necessary breathing capacity at high RPMs.
Definitely not entirely stock, ported intake and exhaust, 1.6 roller tip rockers, power pulley (don't believe it does anything), msd coil, full "tune-up" (plugs, wires, filters, dizzy cap/rotor, pickup coil, most sensors). And it does certainly drop off at 5000 and above, but there seems to be a large dip between 4500 and 5500, either that or the scream of the engine and the exhilaration of never before reached RPMs made it feel like it picked back up a bit above 5500. Unfortunately 2nd gear just barely misses 60mph, would have gotten really respectable times for 1985 if it had the 15" GT wheels with the 4 speed (larger diameter, would have increased speed per gear) or a slight ratio tweak, to hit 60 at the very top of 2nd, and not need to take time to shift to 3rd for like 5 km/h. I got a GPS time of 6.11 seconds to 60mph (you don't have to tell me Patrick, I don't believe anything faster than a mid to high 6, as discussed in "oil in cylinder 5"), although it was below freezing, with surprisingly good traction on that run, so who knows.
I got a GPS time of 6.11 seconds to 60mph (you don't have to tell me Patrick, I don't believe anything faster than a mid to high 6, as discussed in "oil in cylinder 5")...
I don't think you'll ever entirely forgive me. lol
I don't think you'll ever entirely forgive me. lol
Oh I don't care/mind, I don't fully trust the results either, but 6 something is reasonable, even if not at all common, but with those certain common dyno proven upgrades, and a light Fiero with a low km, happy engine, and a very unhappy transmission haha! I just happened to have been reading through that thread to get some info for this one, and I know your memory with previous threads would have probably popped something up regarding the unreliability of the numbers haha.
Originally posted by 1985 Fiero GT: When I hit the rev limiter at ~6200 rpm, it was a much more precise limiter, it stops pulling entirely at that rpm, and just sits there, no oscillations, or noises, full power returning immediately at any lower rpm than the limit. Mine is the 1985 GT, which uses a different ECM than the 86-88 v6s, I think the rev limiter is another change between the two v6 ecms. Just an interesting piece of information I haven't seen here before.
Interesting. Years ago a guy was talking with me about a V6 Fiero he test drove. He asked if they have a speed governor (from factory they don't have it enabled) - because the one he drove just stopped accelerating at 80 or whatever he said. I used to think it might have been reprogrammed, but based on what your car did, now I wonder if it was an 85 and he was just on the limiter.
Interesting. Years ago a guy was talking with me about a V6 Fiero he test drove. He asked if they have a speed governor (from factory they don't have it enabled) - because the one he drove just stopped accelerating at 80 or whatever he said. I used to think it might have been reprogrammed, but based on what your car did, now I wonder if it was an 85 and he was just on the limiter.
Must have been in a lower gear or something, should and will go up to 120mph, and will be at about 5000 rpm (4 speed manual) the 2.8 is power limited not rpm limited.
Most of what I have to say is anecdotal, but I'd heard that of the ECMs, the 85 V6 ECM was really the better one to have... at least to start off from if you were going to wipe and re-burn the old EPROMs.
The 85 GT, among other things, also has the programming and provisions on the ECM for a knock sensor... though there's no wire in the harness to support it.
My 85 GT hit the rev limiter many times in two instances, unfortunately... because it had an aftermarket floor mat (that I got it with), and the gas pedal got stuck... I had to put it into neutral and it bounced off the rev limiter three times before I could turn the key.
To answer Patrick's question... on STOCK Fieros... meaning, the displacement was 2.8, and with a stock cam... my engine would continue to pull all the way to 6,000 RPMs. I never felt a loss of power. But as SOON as I started increasing the size of the displacement (like when I went to a 3.1)... immediately the car would feel like it lost power on anything above say... 5,000 rpms. I don't think it "lost power," but I think I'd gained power in the lower RPMs, and then due to the plenum restriction... it reverted back to what was otherwise totally stock performance above 5,000 rpms... so it just felt like I'd "lost power."
Originally posted by 82-T/A [At Work]: To answer Patrick's question... on STOCK Fieros... meaning, the displacement was 2.8, and with a stock cam... my engine would continue to pull all the way to 6,000 RPMs. I never felt a loss of power. But as SOON as I started increasing the size of the displacement (like when I went to a 3.1)... immediately the car would feel like it lost power on anything above say... 5,000 rpms. I don't think it "lost power," but I think I'd gained power in the lower RPMs, and then due to the plenum restriction... it reverted back to what was otherwise totally stock performance above 5,000 rpms... so it just felt like I'd "lost power."
I agree with this assessment, « hitting a wall » with a 3.4L and stock intake smells like BS to me.
Increasing displacement should not reduce performance anywhere.
Originally posted by 1985 Fiero GT: When I hit the rev limiter at ~6200 rpm, it was a much more precise limiter, it stops pulling entirely at that rpm, and just sits there, no oscillations, or noises, full power returning immediately at any lower rpm than the limit.
That phenomenon you are experiencing might be valve float, rather than a software feature of the ECM.
That phenomenon you are experiencing might be valve float, rather than a software feature of the ECM.
Really? Interesting, it was very precise, and it was immediate, didn't work it's way too happening, pulled all the way to it, then boom, stopped pulling at all.
A number of 3000 swap owners have told me that when they rev the engine in neutral they start hearing misses at around 3000 -3500 rpm. I tried it and confirmed it, There is no problem there as the rev limiter is just kicking in when the engine is revved at idle. Not sure if this happens with the Fiero 2.8L ECM.
------------------ " THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite. "THE COLUSSUS" 87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H " ON THE LOOSE WITHOUT THE JUICE "
Very weird, just did this in first gear (eased into it, not full throttle), and it stopped at 6200 and resumed at 4000, definitely not what I thought I experienced the other day, I don't know, I'll have to do another 0-60 and see what it does in 2nd gear again
Never mind me, I'm stupid, the rev limiter does work conventionally, power "off" at 6200, back when it reaches 4000, it just doesn't drop rpms as fast as I expected, so when I was doing it initially I didn't wait for the rpms to fall before getting off the gas, hence thinking that it held at that rpm, oh well.
IMO, if you keep revving that old 2.8 up to 6200 rpm, you're eventually going to start hearing Jehovah Witnesses.
Haha, it isn't that old in kms at least, and it only has about a week of driving left before it is out of the car, and the 3400 will be getting installed, so I'm not worried, man, the 2.8 screams above 5000 haha, I may or may not now be addicted to rpm haha!
Turns out I had been driving my turboed Subie a lot lately (8,000 RPM redline), and I sort of forgot I was driving my Formula. 
The 2.8 wound up nicely without missing a beat (1.6 roller-tip rockers, ported exhaust logs, power pulley), but it still doesn't have the necessary breathing capacity at higher RPMs.
lol
