924Board.org

[Goldwolf]

Got my car at a local shop, not a P car shop but a good honest guy. He says injectors 1 and 2 are screaming, I think meaning they have fuel but are not opening. The car runs on 3 and 4, he said unplugging 1 and 2 make no difference on how it runs.

Should I assume that 1 and 2 injectors are bad and rebuild? Or can they still not have enough pressure to open? The car does drive, so I would think I have adequate pressure.

The other thing ,he said when the car gets up to temperature then it starts adding too much fuel and the smoke comes. I am not sure if these two issues are related.
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1981 Weissach Edition #179

[Eric P]

The injectors should squeal when they're spraying. You should definitely be able to hear them if you have them pulled out.

First, start with new spark plugs. They're cheap and may save you headaches down the road if it has been running badly for a while. Next, swap one of the "
bad" injectors out with a "good" one from another cylinder. Assuming that the injectors are your problem, the problem will move with the injector.

If you have 1 or 2 bad injectors, replace them all. The springs wear over time so they should be replaced as a set. If it were mine, I would just replace the injectors instead of cleaning them. You can have them cleaned for $15/each + shipping or just buy new ones for about $23 each. Don't forget that if one won't clean out, you'll need to buy a new set AND still pay for the cleaning. If you want new injectors, go on Ebay and search for "FJ46 injector". Those will be a direct swap into a '24. Also note that you should swap out the o-rings when you pull the injectors. Old o-rings can leak fuel and run the hazard of turning your engine bay into a huge fire ball. There's a 924 in a local junk yard that had an engine bay fire. Not pretty. It isn't worth the risk for a couple dollars in o-rings.

Definitely start by swapping injectors though. That should tell you if they need to be replaced.
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1980 924 NA, US model
1987 924S, US model

[Goldwolf]

Is pulling the injectors just a matter of undoing some brackets and pulling them out?

Plugs have been changed.
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1981 Weissach Edition #179

[Eric P]

Pretty much. There should be a couple clamps holding the lines down. You should be able to take out two little bolts in each clamp and then just pull out on the injectors (don't pull on the lines!!) You may need a pair of vise grips if they're really stuck in there. They pull straight out though. Then use two wrenches to turn the injector out of the threaded fitting on the line.

If you haven't yet, you can actually test the injectors for flow.

Pull all the injectors and place each one in a fuel resistant bottle,
Remove the air boot over your fuel distributor flow sensor plate
Jumper the fuel relay (far right and far left pins on the relay)
Lift the distributor flow plate to fire the injectors
They shouldn't spray or dribble until you lift the plate

All of your injectors should flow the same amount as soon as the plate lis lifted. You should see a nice fine mist in a cone shape. If you have lopsided flow or the injector dribbles, you have a problem with that injector. If the injector is spraying before you lift the plate, you have a problem with the distributor. When the injectors spray, they should "sing". You'll know what I mean when you hear it.

You can swap injectors to see if the problem moves with the injector (signifying a bad injector). When you're done, install new o-rings greased with a small amount of white lithium grease. The injectors should just pop back in and you can reinstall your line clamps.
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1980 924 NA, US model
1987 924S, US model

[Fasteddie313]

Wondering how he "unplugged" the injectors and noticed no performance difference... hmm

Do an injector flow test
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80 Turbo - Slightly Modified

[Goldwolf]

I think he just unplugged the spark plugs wires.
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1981 Weissach Edition #179