Still working my daughter's car through it's paces after the engine rebuild and re-install. Car has about 25 miles on it since rebuild... engine drives fantastic, and we've been driving it mostly calm, but allowing it to climb in the RPM (up to 4,250-300 rpms)... now that I have a working tachometer (thanks Gunsett)!
Car doesn't smoke at all while we're driving it, or even when it's idling.
But if we let the car idle for a few minutes... like, maybe 2-3 minutes, and then I stab the throttle in idle (to like 2,250 rpms for a quick second), I get this huge cloud of greyish smoke. It doesn't smell sweet, so I know it's not coolant, but it's also not blue, and doesn't really smell like burnt oil. It's more acrid smelling.
Really, I have no idea what's causing it. Since the engine only has 25 miles on it, does it take time for the rings to properly seat?
I almost wonder if it's a combination of oil and too much gas. The TBI unit was completely rebuilt, new fuel pump, new lines, etc.
The only thing back there that's old is the EGR valve... but it seemed good so we just painted it and re-installed it.
Thoughts?
It doesn't happen every time I stab the gas... and in those other times, there's no smoke coming out of the exhaust at all... driving around, or even bliping the gas while it's stopped... no smoke at all. It's only when I've allowed it to sit idling for a few minutes (idling at like 800 rpms) and then I stab the gas... I get a big puff of smoke.
I'm wondering... is it possible that fuel is pooling in the intake? Thanks!
Since the engine only has 25 miles on it, does it take time for the rings to properly seat?
Two Methods to Seat New Piston Rings *Baby It - low RPS for XXX miles and step-up to midrange, finally higher RPS but to me - the piston rings will never seat properly. *Fast then Cool - accelerate rapid and vary the speed continuously under load to higher and higher RPS {until at redline} BUT at a very short time and then fully cool
This forces the rings against the cylinder wall during break-in.
To me, I use the latter than the former, the rings seat fast and better for the long haul; it makes for a tightly sealed combustion chamber, and less oil consumption too.
EDIT - second conventional oil change?
------------------ Original Owner of a Silver '88 GT Under 'Production Refurbishment' @ 136k Miles
[This message has been edited by Vintage-Nut (edited 01-02-2025).]
Hi Todd You put on a new cat didn't you. I am wondering if when it cools idling and then you hit the throttle that maybe it's clearing it's throat so to speak and burning off any buildup from idling. Just a thought. also it probably will take 500 miles to fully seat the rings and i think you said you used hastings rings which sometimes take a little longer than other brands I found when I used them in our shop. sleek
Originally posted by Vintage-Nut: Two Methods to Seat New Piston Rings *Baby It - low RPS for XXX miles and step-up to midrange, finally higher RPS but to me - the piston rings will never seat properly. *Fast then Cool - accelerate and vary the speed continuously under load to higher and higher RPS {until at redline} BUT at a very short time and then fully cool
This forces the rings against the cylinder wall during break-in.
To me, I use the latter than the former, the rings seat fast and better for the long haul; it makes for a tightly sealed combustion chamber, and less oil consumption too.
EDIT - second conventional oil change?
Thank you! I appreciate this response. I'll probably do the first since I'm going to have my daughter start to drive herself to school (and then we change seats) every day when we drop her off... and it'll be mostly slower / low-speed driving. I'll just calm down my upper rpms (which was rare anyway).
I have not yet changed the oil. I still have the original break-in oil that I purchased, along with all the mixed "other stuff" that's in with it... including the dry moly spray, and the assembly lube. The oil is still super-clear, so that's the only reason why I haven't changed it yet... but of course the filter is working well.
Should I have her change it now? Or should I wait a little longer? It's got about 25-26 miles since the very first startup.
quote
Originally posted by sleek fiero:
Hi Todd You put on a new cat didn't you. I am wondering if when it cools idling and then you hit the throttle that maybe it's clearing it's throat so to speak and burning off any buildup from idling. Just a thought. also it probably will take 500 miles to fully seat the rings and i think you said you used hastings rings which sometimes take a little longer than other brands I found when I used them in our shop. sleek
Hi, I totally did. It's a newer high-performance 2" Ocelot Catalytic converter which normally would be with the V6. I ordered the 2" piping because it fit over the original 1-7/8ths piping perfectly so I could weld it without any seams.
I also wonder if it has a lot to do with the fact that the car has barely been warmed up either... and the catalytic converter never reaching operating temperature? I drove it again today for a few miles, and it's been like in the low 60s outside. We turned on the heater, and we couldn't get much more than 75-80 degrees tops coming out of the heater core. It has a massive 6-core radiator, plus the radiator fan is running with key-on full blast. So I finally re-installed the 195 degree thermostat tonight. It's probably running so cold that it's just dumping fuel into it like crazy.
Thanks for the response!!! 500 miles shouldn't be too hard to get to. The car is a blast to drive, and we just submitted all the paperwork for a custom plate, so we should be getting that in the mail in the next couple of weeks (with a temporary by Tuesday). It definitely doesn't have the power of my V6 Fiero (or what it'll have with the 3.4), but the power is very smooth, and I can so easily toss it in the corners and it just takes it. Even with the totally shot front end (we haven't even touched the front end yet), it tracks really straight!
I'm not an expert with the Iron Duke motor, but in all my experience of rebuilt engines, the first several hundred km of run in will always send out some smoke. The acrid smell (eye watering!) seems to be a normal result. You did follow a good break in procedure? I informed my neighbours that I would be running an engine at 2500/3000rpm for 15 minutes to get up to operating temperature before driving out of the garage! After which it was several hundred km with constantly changing "mild" engine regime: no hard accelerations (just some throttle "blips") and no slow long idling/cruising neither. I changed the oil well before the 500km mark, but's that just me being over cautious.
------------------ "Turbo Slug" - '87 Fiero GT. 3800 turbo. - The fastest Fiero in France! @turboslugfiero https://youtu.be/hUzOAeyWLfM
Grey smoke is indicative of a rich mixture, typically.
The fact that you didnt have a thermostat in on 60 degree days, likely meant your car wasn't or was barely getting out of closed loop when driving. That would mess with you fuel tables and would cause what you are describing. . .
I'm not an expert with the Iron Duke motor, but in all my experience of rebuilt engines, the first several hundred km of run in will always send out some smoke. The acrid smell (eye watering!) seems to be a normal result. You did follow a good break in procedure? I informed my neighbours that I would be running an engine at 2500/3000rpm for 15 minutes to get up to operating temperature before driving out of the garage! After which it was several hundred km with constantly changing "mild" engine regime: no hard accelerations (just some throttle "blips") and no slow long idling/cruising neither. I changed the oil well before the 500km mark, but's that just me being over cautious.
Thanks Rafe, I really appreciate it... that definitely makes me feel a bit better about all of it. We drove it again today, and there was still "less" smoke than before. Only one belch of smoke after it had been idling for a bit.
As for break-in procedures... this engine has roller lifters, so I wasn't too concerned about a "proper" break-in. I know with flat-tappet that I need to do some crazy stuff with the engine (like you said, 2,500 rpms for 15 minutes), but in this case, I've just been driving it around and trying not to really abuse it.
I'll try to get to 100 miles, and then we'll change the oil. The oil is crystal clear so I've just been reluctant to do so... but I have fresh 5W30 that I'll swap in as soon as we do it. I'll eventually have my daughter go to synthetic, but probably won't do that until 5,000 miles.
quote
Originally posted by Dukesterpro:
Grey smoke is indicative of a rich mixture, typically.
The fact that you didnt have a thermostat in on 60 degree days, likely meant your car wasn't or was barely getting out of closed loop when driving. That would mess with you fuel tables and would cause what you are describing. . .
For sure, and the gas gauge went down fast too... I think it's definitely some of what Sleek said too with the catalytic converter. I put in the 180, just until I have a working temperature gauge, but I plan to run a 195 in it when everything is together. Especially because it's now got a 6-core radiator, which is wildly over-kill for this motor.
Figured I'd post this here. I had my daughter make a quick video (despite my daughter's protests) and posted a video of the engine running so everyone could see the puff of smoke, and / or hear the motor idling.
More information in the description, which I'll post below the video:
It idles and sounds a lot better than the video is giving it credit... there's no rattles or squeaks or anything bad...
- - -
I wanted to post a quick video that I felt might be helpful to others, and also low-key to show that I've actually been working on the car and made progress. I'll still continue to the show the progress in order, but wanted to post this for anyone who's curious what a properly stock / well-running Fiero should sound like on cold start-up and idle.
The engine has 25 miles on it since the engine rebuild, still has break-in oil in it with the assembly lube. There's a slight bit of smoke on start-up, which is normal for an engine rebuild, and usually results in a little bit of start-up smoke for the first 500 miles or so.
The engine has all the factory emissions systems installed, including: - Fully-functional ThermAC w/ manifold heat stove & ducting - Reconditioned fuel evaporative canister & new filter. - Ocelot (aftermarket) Catalytic Converter (replaces the pellet style) - Functional E.G.R. System
Content Timestamps: 0:00 Intro / Description 0:10 Engine Start-Up 0:23 ThermAC Adjusts Air Temperature 0:35 ECM Enters "Open Loop" Mode 1:20 Idle drops to ~1,200 RPMs 2:30 Idle drops to 850 RPMs
I saw the video just a few hours after it was posted on you tube and yes i did notice the puff of "smoke". I just figured it still needs broken in. With the rebuild your daughter did I would drop the oil around 500 miles then continue what ever break in process you prefer. I think the puff will clear up after everything gets seated. I am doing my break following by the baby it method. However my break in period is stalled out waiting on me to drop the cradle, find that oil seep near the rear main, fix, and reinstall.
We were at about the same stages on our rebuilds it is just you are getting yours done quicker than I am. My suspension rebuild is completed (still need to go to alignment shop). Paint will be next on my agenda, debating about changing the color from white to candy apple red on the base model I have. I would leave it white but I picked up an Indy a few years ago that is complete, in decent shape, does not run, and not been driven since 1997. No sense of having two white ones is there?
Good job on the videos and congratulations on keeping the 2.5.
It looks a little like oil leaking past a valve guide. Out of curiosity do the valves in your engine have the rubber umberella caps that fit over the valve stems? If so, are they all installed? Are any cracked or torn?
It looks a little like oil leaking past a valve guide. Out of curiosity do the valves in your engine have the rubber umberella caps that fit over the valve stems? If so, are they all installed? Are any cracked or torn?
They're there, but on the 84-86 engine, they're only on the intake side (if I'm not mistaken). All the valves though get a little O-ring that goes in the second slot below the valve locks. We used "Viton" seals. The exhaust valves don't have the machining for seals. The 87-88 heads install them on all valves.
She installed all of them in this video, including the O-rings:
Now that you located the issue the fix should not be difficult but the Duke engine had a few different head and manifold configurations . It was used on numerous cars and trucks in the 1980s and early 1990s with versions up to 110 HP (according to Wiki)..
------------------ " 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 "
If you want to swap a 3.4, I have one in my garage. Same price as the last engine you got from me(Free.99) Has lots of go fast stuff. Ported TB, gold roller rockers. I was told the block was sleeved. which could be a negative for a 3.4. It was in my parts car and ran when I pulled it. I drove it around the block, then pulled it.
If you want to swap a 3.4, I have one in my garage. Same price as the last engine you got from me(Free.99) Has lots of go fast stuff. Ported TB, gold roller rockers. I was told the block was sleeved. which could be a negative for a 3.4. It was in my parts car and ran when I pulled it. I drove it around the block, then pulled it.
Thanks man, I really appreciate that. I am definitely interested in the ported TB... but going into a meeting. I'll respond more in an hour... ugh. But wanted to say thanks again...
When I was doing a lot of swaps we did a cylinder leakdown test on the engine before installing it. Saves a ton of work. For the 3.4 P/R V6 engine to be swapped into a Duke Fiero the process as you may know is not that hard but replacing the bad head on the Duke may be easier and prove more reliable IF the new head is checked for straightness or milled to spec. Hope that the path you and AJ take works out well so we don't miss any of the GenZ garage episodes.
------------------ " 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 "
Now that you located the issue the fix should not be difficult but the Duke engine had a few different head and manifold configurations . It was used on numerous cars and trucks in the 1980s and early 1990s with versions up to 110 HP (according to Wiki)..
For sure! The cyl head came from CarterCarbs, and came off an 86, which is the same configuration as my daughter's 85. I'm extremely grateful that he had one, they're nearly impossible to find now. But yeah, she did all the work herself the last time, but I'm going to swap out the cyl head, paint it, etc., and get it back to how she had it.
The only changes we'll make is a ported intake, ported TBI (stock TBI unit, but ported to 400 TBI specs from an 84 Corvette), and a Fiero Store shorty header that's as close to stock looking as possible (it looks like the 88 heat shielding will even fit).
quote
Originally posted by KissMySSFiero:
If you want to swap a 3.4, I have one in my garage. Same price as the last engine you got from me(Free.99) Has lots of go fast stuff. Ported TB, gold roller rockers. I was told the block was sleeved. which could be a negative for a 3.4. It was in my parts car and ran when I pulled it. I drove it around the block, then pulled it.
Ok, out of my meeting. Just wanted to say, I'm extremely interested in the ported intake manifold, if you don't mind if I take that... but I don't want to steal an engine from you that someone else can desperately use. I actually already have a brand new (remanufactured) 3.4 that is sitting in a crate, so I don't want to hoard engines. But if you need someone to take it off your hands, I'll be happy to pick it up, and will probably give it to Villain (over in Ocala).
I also wanted to say how much I appreciate you giving us the 88 motor. Wanted to just lay out how we ended up using it. My daughter used all the brackets from the 88 so that she could convert her 85 engine to serpentine. We used the water pump pulley, the eye-hook brackets, the lower alternator bracket, the A/C brackets, and several other parts. The engine and cyl head itself, I then gave away to someone else who had an 88 Coupe with a blown engine, and he was able to install it in his car, transfer everything back over, and get the car back on the road. So thank you again!
Anyway, let me know... if you want to just get rid of the motor, I can find someone who wants a 3.4 in the area and give it to them for free. My daughter would lose her mind if I swapped out her Iron Duke though, she wants her Fiero as close to stock as we can make it. Haha. But I'm definitely interested in the intake plenum if you don't mind. Thank you... just let me know.
When I was doing a lot of swaps we did a cylinder leakdown test on the engine before installing it. Saves a ton of work. For the 3.4 P/R V6 engine to be swapped into a Duke Fiero the process as you may know is not that hard but replacing the bad head on the Duke may be easier and prove more reliable IF the new head is checked for straightness or milled to spec. Hope that the path you and AJ take works out well so we don't miss any of the GenZ garage episodes.
She loves the Iron Duke... haha... she gets suck a kick out of it, and I have to be honest, it actually sounds pretty awesome when we're driving and then take the foot off the gas and it decelerates from high rpm. This motor is not half bad. She did such a fantastic job rebuilding it, and man, I'll tell you... all the little things she did to it... it sounds really, really good inside the car. Like... I've had several Iron Duke Fieros in the past several years, and they sounded like a riding mower. This one sounds really, really good.
But yeah, there's no way she'll let me swap that engine out. But she does want to buy another Fiero and drop something crazy in it.
All she has left on the Fiero is to rebuild one headlight bucket, rebuild the front suspension / brakes, and then rebuild the doors (replace dew strips, etc.). Everything else is done. And when I say "done" I mean... she went nuts on it. Like... sanded down the whole underside of the hood, painted it the factory OEM satin black color, installed new underhood stickers, you name it. The thing looks brand new...
