MAF Sensor Voltage Dropping At High RPMs
Thread Starter
Melting Slicks
Joined: Jun 2013
Posts: 3,065
Likes: 39
Daniel,
You seem to have jumped right to "my injectors are too small". You guys need to look at the O2 sensor readings. When I see readings above 1 volt, that thing is running rich in WOT. So I see no evidence the engine is leaning out. If you adjust the tune to bring those down to upper .800's, you will see shorter pulse widths.
But if you like spending money proceed as you are doing.
You seem to have jumped right to "my injectors are too small". You guys need to look at the O2 sensor readings. When I see readings above 1 volt, that thing is running rich in WOT. So I see no evidence the engine is leaning out. If you adjust the tune to bring those down to upper .800's, you will see shorter pulse widths.
But if you like spending money proceed as you are doing.
Safety Car
Joined: Sep 2001
Posts: 4,157
Likes: 554
From: Glenbeulah Wi
Daniel,
You seem to have jumped right to "my injectors are too small". You guys need to look at the O2 sensor readings. When I see readings above 1 volt, that thing is running rich in WOT. So I see no evidence the engine is leaning out. If you adjust the tune to bring those down to upper .800's, you will see shorter pulse widths.
But if you like spending money proceed as you are doing.
You seem to have jumped right to "my injectors are too small". You guys need to look at the O2 sensor readings. When I see readings above 1 volt, that thing is running rich in WOT. So I see no evidence the engine is leaning out. If you adjust the tune to bring those down to upper .800's, you will see shorter pulse widths.
But if you like spending money proceed as you are doing.
Melting Slicks
Joined: Mar 2008
Posts: 2,141
Likes: 76
From: Santa Maria, CA
The question I asked and never got an answer to was how does Daniel know it was lean. I know he has a wideband but he never said what the AFR was at WOT.
Thread Starter
Melting Slicks
Joined: Jun 2013
Posts: 3,065
Likes: 39
In closed loop it will constantly transition between rich and lean. But in open loop (WOT) the ECM does not use the input to adjust fuel trim. So it will stay pretty constant. In Daniel's logs it is constant around 1v. I agree that narrow bands are not as accurate. But this O2 sensor would have to be way off to have a constant reading of 1v and a lean AFR.
The question I asked and never got an answer to was how does Daniel know it was lean. I know he has a wideband but he never said what the AFR was at WOT.
The question I asked and never got an answer to was how does Daniel know it was lean. I know he has a wideband but he never said what the AFR was at WOT.
Melting Slicks
Joined: Mar 2008
Posts: 2,141
Likes: 76
From: Santa Maria, CA
Before I adjusted my fuel pressure, it was 12.5:1 at low RPMs and 14.3:1 at high RPMs. When I adjusted my fuel pressure it was around 11:1 at low RPMs and 12.5:1 at high RPMs. When I adjusted the fuel pressure I also set the P.E. AFR vs Coolant temp table back to stock and left the 20% enrichment from 4000-6400 RPMs.
Thread Starter
Melting Slicks
Joined: Jun 2013
Posts: 3,065
Likes: 39
Yes I am. 12.5:1 is leaner than 11:1.
It was leaner with the lower fuel pressure and no matter what I did it would still not come down from 14.3:1 at high RPMs. So what I'm afraid of is now that I leaned out my MAF tables to accommodate the 50 PSI fuel pressure is that I will not be able to bring down the AFR at high RPMs to where I want it
It was leaner with the lower fuel pressure and no matter what I did it would still not come down from 14.3:1 at high RPMs. So what I'm afraid of is now that I leaned out my MAF tables to accommodate the 50 PSI fuel pressure is that I will not be able to bring down the AFR at high RPMs to where I want it
Melting Slicks
Joined: Mar 2008
Posts: 2,141
Likes: 76
From: Santa Maria, CA
Yes I am. 12.5:1 is leaner than 11:1.
It was leaner with the lower fuel pressure and no matter what I did it would still not come down from 14.3:1 at high RPMs. So what I'm afraid of is now that I leaned out my MAF tables to accommodate the 50 PSI fuel pressure is that I will not be able to bring down the AFR at high RPMs to where I want it
It was leaner with the lower fuel pressure and no matter what I did it would still not come down from 14.3:1 at high RPMs. So what I'm afraid of is now that I leaned out my MAF tables to accommodate the 50 PSI fuel pressure is that I will not be able to bring down the AFR at high RPMs to where I want it
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Safety Car
Joined: Sep 2001
Posts: 4,157
Likes: 554
From: Glenbeulah Wi
Yes I am. 12.5:1 is leaner than 11:1.
It was leaner with the lower fuel pressure and no matter what I did it would still not come down from 14.3:1 at high RPMs. So what I'm afraid of is now that I leaned out my MAF tables to accommodate the 50 PSI fuel pressure is that I will not be able to bring down the AFR at high RPMs to where I want it
It was leaner with the lower fuel pressure and no matter what I did it would still not come down from 14.3:1 at high RPMs. So what I'm afraid of is now that I leaned out my MAF tables to accommodate the 50 PSI fuel pressure is that I will not be able to bring down the AFR at high RPMs to where I want it
You want to target around 12.5 AFR, so if you can hold 12.5 at WOT to max RPM you would not have to change injectors.
Thread Starter
Melting Slicks
Joined: Jun 2013
Posts: 3,065
Likes: 39
