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Discussion Starter · #1 ·
Hi all, I'm new to the community and am hoping someone can help me identify my engine. I bought an '85 Fiero that had a 3800 swap. I looked everywhere on the engine for some identifying marks but couldn't find any (it's in a tight compartment so I can't see all sides of the engine). I've attached a pic. Does anyone know what engine this is, and would you be able to tell be where I might find a number on the engine that would help confirm its exact year and model? Thanks so much in advance!
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There's a tiny tag below the #3 cylinder, near where the oil dipstick enters the block, but it's usually gone or ruined. Not sure how much that'd help.

The transmission, if it came with the car, has a tag near the dipstick entry that will narrow it down a bit, if you can get a pic of the numbers from underneath.

Unless they reprogrammed it with a generic 98-99 GTP file for tuning simplicity, the PCM may have the stock file on it, if you get that deep into messing with it, even if a nearby friend has HPTuners just to look inside without having to buy credits to tune it.

Things I see:
  • '99-03 W-body alternator (if original to engine... You can check MAF sensor style to see if it's '98 or '99+)
  • Gen 3 M90 from '98+ L67
  • HVAC port plugged on top of M90, meaning original car probably had vac line for HVAC (I forget which years/models)
 

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Discussion Starter · #3 ·
Wow, thanks, you're very knowledgeable! I'll look for those tags, but even of they're gone, you've given me a lot to go on, thanks!
 

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Thats probably a series two 3800SC engine. You can tell that as the Gen III Supercharger doesn't have the center bolt before the snout. The other possibility is that this could have been a "top swap" on a series III N/A engine.
 

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1998 GTP coupe. All stock and rust free. That will change soon.
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its most definitely a series II because of the SC cover boss on top. it also looks like a 98 style TB
 

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Ya, my note about the MAF would help the confirmation of that. You can either unscrew the sensor on top and check, or possibly see thru the inlet screen if you remove the intake tube.

1995-1998 Series 2 style
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(inlet with screen removed, not recommended)


1999-2005 Series 2 style
Camera accessory Input device Cameras & optics Material property Electronic device

Motor vehicle Automotive tire Automotive lighting Gas Auto part

(inlet with screen removed, also not recommended)


The 1997 & older Series 2 3800 M90's had this wonky vacuum tree, which we don't see in your image, hinting that it's 1998+...
Motor vehicle Electrical wiring Gas Auto part Electrical supply

(1998+ have a port in the lower intake under the supercharger snout that routs a U-shaped path of vacuum line around the top of the engine to the fuel regulator, bypass valve and MAP sensor... See next pic)

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