What makes a car run rich???
Thread Starter
Team Owner
Joined: Aug 2000
Posts: 28,015
Likes: 32
What makes a car run rich???
???? In our cars is it the ECM???
I'm thinking since I just popped code 33 again, and I have replaced everything in the troubleshooting except the ECM. Maybe the ECM is bad.
I'm thinking since I just popped code 33 again, and I have replaced everything in the troubleshooting except the ECM. Maybe the ECM is bad.
Intermediate
Joined: Aug 2001
Posts: 28
Likes: 1
From: Lewisburg PA
Re: What makes a car run rich??? (Old Sport)
For what it's worth, on an '89, the ECM varies the mixture based on the oxygen, mass air flow, manifold air temp, and coolant temp sensors. When I got my car the thermostat was stuck open and I was getting 18 MPG; with it replaced and the engine running above 190 degrees I'm getting better than 23.
Pro
Joined: Mar 1999
Posts: 532
Likes: 0
From: Cleveland Ohio
Re: What makes a car run rich??? (rmurcek)
Just a thought. Doesn't the O2 attempt to adjust the mixture too 14.7 or close to that number? Either it's unable to read the exhaust or the ECM can't react to it's findings. I'd bet the O2 is faulty but there are ways to be sure with test equipment. I think there only about $25 but it can be a bear to remove the old one.....Frank
Race Director
Joined: Mar 1999
Posts: 16,950
Likes: 0
From: Stafford, Virginia Kittah, Kittah, Kittah...
Re: What makes a car run rich??? (Frank C)
Just a thought. Doesn't the O2 attempt to adjust the mixture too 14.7 or close to that number? Either it's unable to read the exhaust or the ECM can't react to it's findings. I'd bet the O2 is faulty but there are ways to be sure with test equipment. I think there only about $25 but it can be a bear to remove the old one.....Frank
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Le Mans Master
Joined: Feb 2000
Posts: 9,715
Likes: 27
From: Kempner Texas
Re: What makes a car run rich??? (nobodyunknown)
The IAC, Idle Air Control, is actually a electrically controlled motor with a pintle that moves in and out and controls air movement into the throttle body to maintain the idle speed (RPMs) of the engine based on the programming of the PROM in the ECM.
The TPS is also electrical, but had no moving parts, as the IAC, does. It sends voltage info which the ECM interprets as the position of the throttle and fuel is added or subtracted based on the voltage reading it receives. The wider the throttle is open, the higher the TPS voltage reading.
All the while (in closed loop mode) the ECM is getting feedback from the O2 sensor and based on the mv reading it gets from the O2 sensor it adjusts the spark and fuel timings in an attempt to maintain 14.7 A/F ratio.
Jake
The TPS is also electrical, but had no moving parts, as the IAC, does. It sends voltage info which the ECM interprets as the position of the throttle and fuel is added or subtracted based on the voltage reading it receives. The wider the throttle is open, the higher the TPS voltage reading.
All the while (in closed loop mode) the ECM is getting feedback from the O2 sensor and based on the mv reading it gets from the O2 sensor it adjusts the spark and fuel timings in an attempt to maintain 14.7 A/F ratio.
Jake
