New here and first Thunder Bird 91 sc

Nice!
 
Took the car to work today got in 40 miles mix of city traffic and highway speeds.

In traffic ac on temp for to about 3/4 mark
a
It had a rough idle at stop lights but it drove fine.

It does smell rich at idle sometime ideas ???

Also it didn’t start right away a few times while it was 100 degree's and sat for 30/40 mins
It’ll try to start and die right away and it did it two or three times and then run great ?
 
You know the scene where they put the stoned guy in the back seat, and the other guy jumps in the car, and starts doing donuts, scaring the shit out of the stoner. My dad and one of his buddies used to do that to stoners in the 70's.
 
Part two
It failed smog was told the carbon and co2
Was high
 

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Fastymz, try primeing the fuel pressure, by listening for it to run when you first turn the key to run, letting it run, and doing it again. if it wont start, you need to use a fuel pressure gage.
 
rhat might be a symptom of a failed smog pump. (The air injected to the cat.)
 
I had an older tbird with a 5.0 that had one I know it wasn't the 63, lol. Must've been the 79.
 
I know that I had some hard starts where the car would almost lose its prime, I first did a new fuel filter and it helped a ton, now im trying to figure out the reason its still wants to die when its cool out. So I say a new fuel filter is a great and easy place to start
 
Grog6 said:
You know the scene where they put the stoned guy in the back seat, and the other guy jumps in the car, and starts doing donuts, scaring the shit out of the stoner. My dad and one of his buddies used to do that to stoners in the 70's.
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That was Super Troopers. You boys like Mexico?
 
I didn't realize it only ran 4 seasons, tho. I ran across it right after I woke up in the hospital after my stroke. I was thinking, "Weren't those guys cops?"

I think it credits 'broken lizzard' at the end, which is the same guys.
 
Still won’t pass smog,best I take it to a shop or sell it.
I’ve cleaned than replaced the maf , iac , plugs, wires. Can’t find any vacuum leaks , car runs good cruising , it is low on power but I’m not sure how powerful it should feel lol
Next is the 02 sensors
It starts cold great , once fully warmed up some times at a stop the idle will drop and it runs roughs , shifting between N and drive idle will drop , other times it’s great. It won’t pass smog because of the CO test it’s to rich.

Never over heats , ac blows cold, most everything works. I love driving it but can’t register it.
Due to nerve damage in both hands my ability to do my own are limited. But local shops are asking way to much to fix it
 
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Fastymz said:
Still won’t pass smog,best I take it to a shop or sell it.
I’ve cleaned than replaced the maf , iac , plugs, wires. Can’t find any vacuum leaks , car runs good cruising , it is low on power but I’m not sure how powerful it should feel lol
Next is the 02 sensors
It starts cold great , once fully warmed up some times at a stop the idle will drop and it runs roughs , shifting between N and drive idle will drop , other times it’s great. It won’t pass smog because of the CO test it’s to rich.

Never over heats , ac blows cold, most everything works. I love driving it but can’t register it.
Due to nerve damage in both hands my ability to do my own are limited. But local shops are asking way to much to fix it
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What did you replace the MAF with? Do you have a scanner that can stream data?
 
KevinVarnes said:
What did you replace the MAF with? Do you have a scanner that can stream data?
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I don’t have a scanner , or a garage right now.
So I found a shop that will evaluate it for a very reasonable price. Once I know what it is or was I’ll update on here maybe it’ll help someone else.

Once I get a quote then I can decide what to do with it.
I love the way the car drives especially on the highway.
But it’s really under powered for how heavy it is.
 
Fastymz said:
It won’t pass smog because of the CO test it’s to rich.
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It would be helpful to post the actual numbers and the maximum allowable limits on your smog inspection report.

The smog test is a 7 gas analyzer; but there are only 4 important values ( HC, CO, CO2, and NO(x) )

Fuel - Hydrogen and Carbon (HC)
Air - Oxygen and Nitrogen ( O and N )

When the fuel / air mixture is burned; the remaining elements are re-constructed inside the Catalytic Converters; most of the Hydrogen and Oxygen is is essentially burned away - so the remaining Hydrogen combines with Oxygen (H2O) .. the Carbon is combined with Oxygen (CO and / or CO2 ) inside the Catalytic converter .. Nitrogen combining with Oxygen is typically formed in the combustion chamber ( No(x) .. due to high Temps ) - that's another issue on its own.

So .. the critical points here are your engines ability to properly measure air flow ( MAF ) and engine temp ( ECT ) to deliver the correct mixture - and adjusted by the Oxygen sensors in the exhaust.

If your mixture were excessively "rich" as you say; the Oxygen sensors may produce a Check engine light on occasion - and excessive HC would be present in the exhaust; either due to faulty sensors, or an inadequate spark.

I'm leaning towards bad or inefficient Catalytic converters; if they can't turn the CO into CO2.

🤔
 
Idle speed CO 6.25%
High speed 7.23%
Idle speed hc 993
High speed hc 992


Hope that helps
And the check engine does come on and off while driving it, never stays on for long.
Also cold it starts and idles good , once fully warmed and sitting in traffic is when it idles rough and the rpm drop to about or below 500.
Hot restarts sometimes it fires right others it try’s and dies right away or I’ll have to crank it longer to get it to start. New fuel filter installed
 
Hopefully the picture uploaded
 

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Yeah .. that helps.

If you had the ability to pull the code when the check engine light comes on, it may point to either a bad sensor reading, or an excessive value condition ( unfortunately OBD1 doesn't store codes like OBD2 ) .. or stream live data like Kevin suggested above; from the MAF, ECT, and O2 sensors. It could be over fueling due to a weak ignition system, or a faulty reading from one of the above sensors ( most likely) .. the Engine Coolant Temp sensor the computer reads is different than the Cooling temp sensor for the dash gauge.

The ignition system on the early SC is known to have issues but that's not typically an intermittent issue. The old-school diagnostic for these type of computer systems was to tap, wiggle, or put a heat gun on components to see if it was related to heat or vibration.

When you reduce the excessive HC, the CO and CO2 numbers will come down as well.
 
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I get it , so it can be this or that. This shop I’m going is a friend of friend. He’s a ford guy and loves a mystery. So I feel comfortable he will sort it out .
And give me a decent price ? But I’ll have to see what that price is and if it solves the drivability issues.

I’ve worked on cars my entire life I’m 60 now.
But I don’t have a garage or the physical ability to do the work at this time.

That said I’m not a mechanic and not real knowledgeable of computers systems in cars.
I’m old school carbs guy mostly holleys !

But it’s all about fuel speak and air !
Than they added all these damn sensors lol
 
On the highway or above 1500 rpm it’s runs and drives so nice and super cold ac !
Hopefully whatever it is , if they fix it and solve the issues it also helps with the power output a bit ?
 
The shop is putting new plugs and wires on while it’s there.
I can’t physically do it myself
 
Plugs and wires are a pain in these cars - I remember when a lot of mechanics would refuse to do the work or charge upwards of $800 for the job ( in the early 2000s, California prices ).

A good mechanic should be immediately drawn to the components and diagnostics techniques described above. Shouldn't take more than a couple hours to determine which sensor is out of range if the check engine light is as consistent and easy to duplicate the conditions that cause it to pop up.

Air/fuel delivery is very critical on a supercharged engine; so the computer plays safe to run on the rich side when something like a sensor goes out of range.

Im sure you'll pick up more power when you get this issue worked out. You shouldn't feel like there is any power left on the table with the SC when it's in good running condition.
 
Please I don’t mean to offend anyone when I say the car is under powered.
It’s luxury vehicle and drives amazing.
So many cool things about it, but I grew up drag racing / street racing so I’m kind of used to more of a push you back into your seat !

This is my 23t that my dad and I built 15 years ago . We still drive and race it , it has a mild 351w / aod / 9” with 4:56 gears .
It goes lol
 

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Ah, I forgot SC's were OBD-I. Been so long since I've worked on non OBD-II cars. Some OBD-I cars can stream live data, but it can be limited. I've never tried streaming a SuperCoupe to see if they are capable. Without that you need somebody that can do real diagnostic work. It shouldn't be too difficult to figure out. You can retrieve codes on these with a simple jumper wire. Pulling a stored code could really help direct where to look.
 
Fastymz said:
Please I don’t mean to offend anyone when I say the car is under powered
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No worries here. And I agree; the SC in stock form has low HP numbers compared to most modern vehicles. The torque makes up for that a bit - It was pretty quick during its time.

The automatic leaves a lot to be desired as for driveability - night and day difference when you have the 5 speed version. The best bang for your buck mod to make the car feel quicker would be a set of rear end gears. 😉
 
dDUBb said:
No worries here. And I agree; the SC in stock form has low HP numbers compared to most modern vehicles. The torque makes up for that a bit - It was pretty quick during its time.

The automatic leaves a lot to be desired as for driveability - night and day difference when you have the 5 speed version. The best bang for your buck mod to make the car feel quicker would be a set of rear end gears. 😉
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If I decide to keep that was going to be my first upgrade too.
What gear have you had or heard give the best results with an auto ?
And I’m not worried about it loosing a mpg , just like to maintain drive ability .
 
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