My 85 SE with the 2.5 Iron Duke and 5 speed doesn't pass emissions. The HC is way too high and idle but fine at cruising speed. I was too lazy to check the ignition timing (I thought it would be hard and time consuming... it was neither) but replaced the vacuum lines, cap, rotor, wires, and plugs. Went back and failed again. So, I checked my ignition timing and it was pretty high. I don't remember where, but pretty high. I adjusted it back to 8 degrees, which the motor was pretty unhappy with (CEL flashing, running rough) but left it, unplugged the jumper on the ALDL and it runs better now.

I checked to see what the ecm was doing to my timing, and it is ~27 degrees at idle! That seems really high, but I can't find a spec anywhere. Is that normal? What should it be at? What could cause that? I have 2 more retests, and I'd like to have more confidence it'll pass before I go in again...

Thanks!

1st, Did you jumper pins A and B before testing timing? Edit: Just noticed you mentioned the jumper. 2nd, You can go to the DMV in Utah and get a vintage vehicle registration and you won't need to get an emission test. You'll still want to chase down the high idle, but you will have plenty of time to fix it.

[This message has been edited by JMTUT (edited 10-19-2018).]

Yup, Wrong timing will often fail emissions but bad/missing Catalyst, EGR, etc, can fail too.
You need right base timing the ECM does the rest.
There is no specs for ECM/PCM timing in data stream to a scanner.

MIL light can/will flash when AB is jumped. Flashing is part of O2 sensor charts in FSM so you "see" the O2 sensor works.

If you have factory cat... "Pebble bed" cat used in 4cyl Fiero can wear out and doesn't work at idle or at all.

Antique tags...
While on https://www.dmv.com/ut/utah...vehicle-registration , can be hard/impossible to find on https://dmv.utah.gov/ ...
Most Historic/Vintage/Antique tags severely limits Driving because the tags have no inspection or emission testing.
Is often buried in state codes/rules that have to dig thru other state's web sections/sites.

From https://www.dmv.com/ut/utah...vehicle-registration

quote Utah antique vehicle registration plates are for vehicles dating from 1973 or before, while vintage registration plates are necessary for vehicles that are at least 30 years old and used as a collector’s item, or for participating in parades, exhibitions, tours, club activities or occasional, but not daily transportation. An antique car registration may be also needed for special interest vehicles that are at least 20 years old. The vehicles of special interest are classified as such because they are experimental vehicles, have a make that is no longer manufactured or is limited, are used for educational purposes, or are collected, restored, maintained by a hobbyist.

Meaning If you get stopped driving out of state, to local stores or work then you can lose the tag and worse for driving outside of antique/vintage rules.

Many places still require you to have all emission equipment for the year of car even when you have vintage et al tags. Everything after 1975 needs a cat and whatever else came with from the factory.

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Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave

I know about the antique plates, but I want to drive it daily without penalty and want to fix it because it is wrong.

I think the car has the factory cat, and I also think it is 'working'. The HC at cruise is great, and the CO is fine at idle and cruise. If the distributor advance was not computer controlled (mechanical or vacuum) the base timing is exactly what the advance would be at idle. Logically, it's supposed to run at approximately 8 degrees. I would even believe 10-12 degrees at idle, but 28 seems way off. I don't believe the EGR is active at idle, but is at cruise so I believe that is working as well.

The engine on the car was rebuilt ~8000 miles ago, but I don't know by who or how good of a job they did.