Does ECM use MAF sensor during open loop?
Thread Starter
Le Mans Master
Joined: Jul 2001
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From: Silicon Valley Kalifornia
Does ECM use MAF sensor during open loop?
Like title says. L98, 1985. I know it only starts reading off the O2 sensor when it goes closed loop (and of course the MAF sensor). ...but I'm wondering about MAF usage during "open" loop. TIA!!
Le Mans Master
Joined: Jan 2003
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From: Portland Oregon
Re: Does ECM use MAF sensor during open loop? (GRX)
You can once it starts and stops a couple times and goes into fuel back up mode. Then it reverts to Speed density mode and runs off the VE tables.
Thread Starter
Le Mans Master
Joined: Jul 2001
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From: Silicon Valley Kalifornia
Re: Does ECM use MAF sensor during open loop? (tjwong)
So it reads the TPS, RPMs and VE tables in open loop? This is an 1985...no MAP here...
[Modified by GRX, 7:00 PM 10/2/2003]
[Modified by GRX, 7:00 PM 10/2/2003]
Team Owner
Joined: Dec 2000
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From: SE NY
Cruise-In II Veteran
Re: Does ECM use MAF sensor during open loop? (GRX)
The only L98 engine control sensor that is ignored in open loop (such as at WOT) is the O2 sensor.
In this case the ECM reads and records the O2 sensor values as ususal but it sets two parameteres, the Block Learn Mode (BLM) cell #15 value and the Integrator value, to "neutral" value of 128. Since both of these values always read 128 in open loop, no modifications are made by the ECM to the A/F ratio. In closed loop mode O2 sensor readings are used to trim two parameters, which in turn trims the A/F ratio by adjusting injector pulse width to the correct values for driving conditions.
In this case the ECM reads and records the O2 sensor values as ususal but it sets two parameteres, the Block Learn Mode (BLM) cell #15 value and the Integrator value, to "neutral" value of 128. Since both of these values always read 128 in open loop, no modifications are made by the ECM to the A/F ratio. In closed loop mode O2 sensor readings are used to trim two parameters, which in turn trims the A/F ratio by adjusting injector pulse width to the correct values for driving conditions.
Melting Slicks
Joined: Jun 2002
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From: Phoenix AZ
Re: Does ECM use MAF sensor during open loop? (65Z01)
The only L98 engine control sensor that is ignored in open loop (such as at WOT) is the O2 sensor.
In this case the ECM reads and records the O2 sensor values as ususal but it sets two parameteres, the Block Learn Mode (BLM) cell #15 value and the Integrator value, to "neutral" value of 128. Since both of these values always read 128 in open loop, no modifications are made by the ECM to the A/F ratio. In closed loop mode O2 sensor readings are used to trim two parameters, which in turn trims the A/F ratio by adjusting injector pulse width to the correct values for driving conditions.
In this case the ECM reads and records the O2 sensor values as ususal but it sets two parameteres, the Block Learn Mode (BLM) cell #15 value and the Integrator value, to "neutral" value of 128. Since both of these values always read 128 in open loop, no modifications are made by the ECM to the A/F ratio. In closed loop mode O2 sensor readings are used to trim two parameters, which in turn trims the A/F ratio by adjusting injector pulse width to the correct values for driving conditions.
