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boosted running rich

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Old 09-10-2018, 09:59 PM
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dpower$
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Default boosted running rich

I have an early 86 that has a vortech supercharger. It smells VERY rich when idling. No intercooler, around 6psi. total boost. What should the A/F gauge read at idle? At 2500rpm on the highway? At full wail? Other than sharktuning, how can this be adjusted? I had it installed by a local shop, owner died, long story.
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Old 09-10-2018, 11:19 PM
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Does it still have an O2 sensor?

Could be a bad o2 sensor, a bad cat...cant believe a tune at idle would be pig rich on purpose..or even at cruise.

What DOES it say?
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Old 09-10-2018, 11:26 PM
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Haven't a clue...no cats, MSDS headers thru custom exhaust. Supercharger came with chips tuned for the 85/86 setup. Don't do my own wrenching. That's why I have several forunes
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Old 09-10-2018, 11:45 PM
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Well, then how do you know its rich?

No cats..gunna smell.
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Old 09-11-2018, 11:09 AM
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Forgive me. Should have read several fortunes tied up in this car.......Rich clues, burns eyes at idle
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Old 09-11-2018, 11:19 AM
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IMO, Idle and cruse should be ~14.7 AFR when hot, cold idle should be in the 13's, WOT hi 12's.
How old is the O2 sensor, and was it running OK, if so what changed?
Edit: also a bad ignition (cap/rotor and or wire or fouled spark plug would do the as you describe.

If you don't do your own wrenching, suggest you take it to another shop that has the tools and knowledge of custom Super Charged engines.

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Old 09-11-2018, 12:22 PM
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Originally Posted by dpower$ View Post
What should the A/F gauge read at idle? At 2500rpm on the highway? At full wail?
It would be helpful if you told us what the A/F gauge is currently reading at those points.

At idle, it should bounce around 14.7.

At 2500 RPM at cruise on the hwy, it should bounce around 14.7.
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Old 09-11-2018, 12:50 PM
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This could be way off base, but not much info to go on so far. Note that it "came with chips", but does that take care of all fuel enrichment on an 85-86 LH car?

My sc'd 84 uses an add-on rising rate fuel pressure regulator, and I've had a couple of incidents where one of the factory fuel pressure regulators has gone, which dumps fuel into the vacuum lines, which ultimately pegs fuel pressure in the rising rate regulator (and dumps fuel into intake) and it runs way rich.
Pull vac lines off fuel pressure regulators and see if you smell fuel to check.

Or as I said, this could be completely non-applicable to your setup.
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Old 09-11-2018, 07:05 PM
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Idle is in the 10's..... 2500 highway is in the 12's...... I don't think it ever reaches 14's
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Old 09-11-2018, 08:01 PM
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Originally Posted by dpower$ View Post
Idle is in the 10's..... 2500 highway is in the 12's...... I don't think it ever reaches 14's

Holy crap.

Hs it always been like that? Or until recently?

A parts list of all that was changed to install this would be helpful too..any fuel related pieces?
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Old 09-11-2018, 11:41 PM
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Supercharger setup was purchased from a rennlister 2-3yrs ago from Chicago "Tiburon" had it at one time. came off of an 85/86 setup with good results. Had everything I got installed. I think it has an adjustable fuel pressure regulator if that would change anything. Within the last 500 miles I have put $20k in the thing. Engine. out...., oil pan gasket, all new bearings, seals, WP, TB every porken item for an 86, headers, exhaust, elec fan, brakes, rotors, tires, wheels, alternator, battery, pwr st pump, on and on. Shop had it for 13 months. Owner of shop died during the build....real mess
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Old 09-12-2018, 01:50 AM
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Originally Posted by dpower$ View Post
Supercharger setup was purchased from a rennlister 2-3yrs ago from Chicago "Tiburon" had it at one time. came off of an 85/86 setup with good results. Had everything I got installed. I think it has an adjustable fuel pressure regulator if that would change anything. Within the last 500 miles I have put $20k in the thing. Engine. out...., oil pan gasket, all new bearings, seals, WP, TB every porken item for an 86, headers, exhaust, elec fan, brakes, rotors, tires, wheels, alternator, battery, pwr st pump, on and on. Shop had it for 13 months. Owner of shop died during the build....real mess
Oh dear, that is terrible.

Do you know what size injectors you are running? Also, do you know which chips are in it?

If they are Authority chips, immediately remove them and replace them with stock or shartuner chips and report back to us.
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Old 09-12-2018, 11:49 AM
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If the chips came w/ the SC setup, and it was reported by seller that all was good w/ the setup, don't change the chips!
Do not put in stock chips, this could cause the Timing to be too advanced under boost.

Take the car to someone who can actually start testing things, also try to get a list of what the setup came with.

AND some pic of the setup would really help us ID what you have (like a MURF kit),

side note: these cars are costly to maintain buy standard shops (as you have found out) so unless you do your own work or hold beer and BBQ party's for local 928 guys, these cars will cost a lot of $ to maintain (should have said a lot to get up to date) once up to date, standard maintenance, not so bad,
A custom SC car, that will require more $ no matter what you drive.

Get some pic's posted of the engine bay

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Old 09-12-2018, 02:24 PM
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The first thing I would do is remove the belt from the supercharger, and try to get the car running correctly without it.

Secondly, put the stock chips in, fuel pressure regulator, etc. If it still doesn't run right, at least you know it's not from the supercharger install, and can start doing 'traditional' troubleshooting.

Once you get it running correctly, then put the supercharger back on.

For only 5 psi of boost, arguably you only need a rising rate fuel pressure regulator. Best case scenario though is getting a proper tune.
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Old 09-12-2018, 02:25 PM
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If it does have an additional fuel pressure regulator added, then please do the simple check mentioned above to see if one of the factory regulators has gone. Pull the small vacuum line off the back of each one (2 regulators, 1 damper) and see that they are dry and not smelling of fuel on the vacuum side. Replace as necessary.
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