Running rough at startup.
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Joined: Sep 2003
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From: Chicago, IL
Car: 87 Monte Carlo SS
Engine: 350
Transmission: 200 4R
Axle/Gears: 3.73
Running rough at startup.
My car runs rough at startup, but then it runs fine after it warms up. Anyone know what this could be?
Senior Member
Joined: Mar 2003
Posts: 864
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From: Oakland Ca.
Car: 1988 GTA
Engine: 5.7L/L98
Transmission: 700r4
Typically when this happens the CTS is the place to start. Your car runs in open loop until your temps reach about 150. In open loop the ECM is taking readings from your CTS to adjust AFR. Often people with the cold running stumble or rough idle can fix it with the replacemnet of the CTS.
Thread Starter
Member
iTrader: (1)
Joined: Sep 2003
Posts: 229
Likes: 0
From: Chicago, IL
Car: 87 Monte Carlo SS
Engine: 350
Transmission: 200 4R
Axle/Gears: 3.73
Not sure if I'm running rich or not. Does the CTS control the electric fan also? That doesnt turn on by itself. It's wired up by a switch.
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Joined: Jul 2003
Posts: 4,803
Likes: 2
From: Grand Rapids, MI
Car: Z28
Engine: Sb2.2 406
Transmission: Jerico 4 speed
Axle/Gears: Ford 9" 3.60
The CTS does not control the fan. It gauges the engines temperature and tells the ECM what to do based on operational temps. Specifically, how much fuel. For example, if the CTS is reading lower than the actual temp, then it will the ECM "hey, engine is cold, inject more fuel." Thus, the ECM will tell the injectors to inject more fuel, moreso than what is actually needed, thus, making it run rich.
The fan switch (between #6 and #8 in the pass. side cylinder head) controls the fan.
The fan switch (between #6 and #8 in the pass. side cylinder head) controls the fan.
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