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Leaking injectors?

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Joined: 08 Sep 2014
Posts: 101
Location: Oklahoma City OK

PostPosted: Thu Nov 09, 2017 2:43 am    Post subject: Leaking injectors? Reply with quote

I've gotten the 924S to the point where it starts, runs and drives fine but it smokes. If I let it idle, it takes 10-15 minutes for the smoke to appear, whereas if I drive, it appears within 1-2 minutes. It's not white, nor blue..more of a light gray to brown vapor with quit a bit of water and soot. I guess my question is, when injectors fire will they "stick" and let more fuel into the intake manifold? I replaced the pintle hats and o-rings although the hats in the kit seemd to be a tiny bit longer I'm not driving it enough to tell anything regarding gas mileage . Should I pursue sending them to Witchhunter or should I be looking elsewhere? Oh, I also had to replace the ECU as mine had an intermittent. (Thanks John in CA) The O2 sensor measured good, as did temp sensor and AFM. Thanks for any input
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Eric P  

Joined: 21 Jun 2017
Posts: 169
Location: NY, USA

PostPosted: Thu Nov 09, 2017 7:40 am    Post subject: Reply with quote

There are two things on the top of my head that would cause this. One is water in the gas. Water settles to the bottom of the gas tank. It takes a few minutes to work through the system then makes steam and loosens up carbon in the exhaust. That steam causes sooty exhaust gasses.

The other thing would be oil in the exhaust from repeated failed attempts at starting/flooding. When I bought my 924, the previous owner had flooded the engine quite a few times trying to start the car with a bad fuel distributor. It had filled the crank case with fuel/oil mix and backed up the oil breather into the intake. It took a few minutes of running to get up to temp and start burning the oil out of the pipes. Once I got it on the road, it took a good 30 minutes of hard driving to clear the pipes out completely. I haven't had a puff of smoke since. If this is the case, you'll want to take it out on a desolate road in the middle of the night to avoid tickets- I'm speaking from experience here. Trust me, it'll smoke A LOT.

Change the oil and install a new set of plugs. .Assuming the gas is fresh, I would dump a bottle of techron in, top off the tank and take it out for a spin to get it nice and warm. As always, when running a car that's been sitting a while, watch the temp and oil pressure. Pull over and shut it off if anything goes awry. Check the oil for foam and gas smell after the first run. Then, check to make sure the plugs look good. You can tell a lot by looking at the color of the plugs after a good hard run

A lot can be solved by a few good drives though. These cars like to be driven and will resent you for ignoring them.

Just my .02
1980 924 NA, US model
1987 924S, US model
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