924Board.org

[ThePhotographersGarage]

Hello friends! So I'm fairly new to the CIS/931 game here, so bare with me for a bit, but I'm fighting to get my '82 931 to pass the strict smog test here in CA. I've had it at a local Porsche shop that has some time in it tuning it off the dyno (EG Off Boost/load) and while they can dial the CO adjustment in there just fine, it falls on it's face once loaded up on the smog Dyno. Blows about 2.3% CO at 15mph and 6.1% CO at 25mph. Both numbers should be just under %1. NOX and HCs are all great. New Lamba/02 sensor, cap/rotor/plugs and no dice. Seems to run pretty well over all, but I bought it w/o smog and haven't driven it blowing clean so not sure.

Current shop is a bit at a loss not being able to dyno tune it. All the local smog shops that have a tech worth their salt don't want to touch the car at any price, leaves me holding the bag.

Car has only seen about 1000 miles in the last 3 years or so, and while it seems pretty healthy, something clearly isn't quite right. I've got reciepts from a few owners ago and about 10k miles ago rebuilding the fuel dist, RR injectors with Bosch units, and other things. Also records of prior passed CA smog as recent as 2 years ago.

My gut tells me that something is up in the WUR. Maybe as simple as signal vacuum to the unit. If it passed a number of years ago and the only change done between then and now is time and limited miles, then it being out of adjustment and the car being completely USDM stock seems unlikely. Beyond confirming to major vacuum leaks and the like, what's the best way for a shadetree mechanic to start here? I'd like to get it to run perfectly, but most importantly get it to pass smog so I can drive it in general. Thanks gang!
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'82 924 Turbo

[Cedric]

Step 1 if it were my car, run the car with a wide band lambda sensor, its not expensive to buy and it will tell you alot. A dyno is not necessary it could be tested on the the road. Then you can see what kind of air fuel ratio the engine runs under load and whether the wur enrichment is working or over fuelling etc
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1980 924 Turbo
www.instagram.com/garagecedric/

[Fasteddie313]

CIS pressure tests and injector flow tests..
Make sure throttle switches are operating correctly..
Set AFR screw with the dwell meter method..

Keep the dwell meter hooked up and see what it is doing at these 15 and 25 mph ranges..
Adjust the AFR screw to get the dwell meter to read as close to 45-50 as you can while in these 15 and 25 mph load ranges..

Possibly find a smog shop that will let you adjust the AFR screw while on their rig to where it passes?
Adjust it while your there until the numbers pass?

Google says high CO means too much fuel.. Too rich?
Does your turbo smoke at all?

Also, I have seen it advised to get your car very hot before smog testing..
Go “blow out the carbon”, bunch of full throttle pulls on your way to the test..
Definitely don’t test on a cold or barely warmed up engine..

Move out of commiefornia..
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80 Turbo - Slightly Modified

[MikeDanger]

Heres how my buddy passed emissions.
However here in Denver, its just an Idle test (but they estimate higher rpms)

First you do need a wide band.

So what he did, is drained all the gas out, then put 1 gallon back in (should use almost all of it on the trip to the Test site) Drove to the test site.
Around the corner I parked, leaned the mixture a bit,

THEN, he put in a gallon of Straight alcohol. Picked up at home depot In the paint Isle. Its called "fuel" (for camping stoves and such)

passed with flying colors.
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It was either this or a giant box of legos