91 Talon REAL rich on startup

[Damned Talon]

hey when i first start my 91 talon tsi 2.0l turbo awd in the morning it is so rich that i completely fill my garage with black smoke in minuites. when i frist rev the engine up after startup it misfires and carries on around 3000 rpm. once the car is warmed up it smells like its still running rich but nothing like it does when its cold. im thinking maybe a leaking injector but all the plugs are soooo black its kinda hard to think its just one cylinder. i checked the ECT and its ok, no boost leaks.

the longer the car sits. the worse it runs when i start it up (VERY RICH) please please please help me give me some ideas.

 

[imnotdilbert]

Try replaceing the engine coolant temp sensor anyways. The ECU uses its reading to tell whether the engine is warmed up, and adust the fuel curve accordingly. If the sensor fails, the engine goes to default, which assumes that it is warmed up. I believe the engine "leans out" as it warms up. The part is only around $20.00, and takes a minute to replace, so its worth a try. Even if the reading is close, it could still be off.

 

[deusxmachina]

What's an ECT?

DSM's run very rich when cold, but that sounds severe. I'm curious what and how you checked for boost leaks.

 

[johnk]

I think he means the engine coolant temp sensor. That's what I replaced when I was having a rich startup problem. Mine was worse than yours I couldn't even start the car it just wreeked like fuel when I tried. Make sure that you checked the right sensor there are two coolant temp sensors. One is for the ECU and the other is for the guage. If your not sure try unplugging one and starting the car you should get a CEL if it's the ECU one and the temp guage won't read anything(if the car is warm).

Also check to see how bad your wires going to the sensors are. Mine the insulation hardened so bad it crusted off near the plugs and corroded and started breaking apart and shorting out no doubt.

 

[imnotdilbert]

FYI: The ECT for the ecu is the one with two wires. The single wire one is for the temp gauge. There is also a temp sensor for the A/C unit which has two wires. The wires on mine eroded away and broke inside the plastic cover. After I re-ran the wiring, my car leaned out quite a bit.

I also found that a bad isc can cause your car to run rich. Try testing all the coils and make sure they read at around 40 ohm's.