Air/Fuel ratio Gauge readings
05-11-2002, 10:21 PM
#1
Three Wheelin'
Thread Starter
Air/Fuel ratio Gauge readings
Hi All,
I installed a Autometer a/f gauge today and I'm wondering about the readings. At WOT it's showing steady rich all the way to redline. At idle and cruising it dithers back & forth from middle stoich to full lean. Cruising with throttle shut indicates nothing which is correct. Do these readings sound ok? I thought only the stoich lights should light during idle & cruise. Thanks.
Tom
'87 951 - new APE chips & LBE...WOW!!!!
'86 Supra - new head gasket
I installed a Autometer a/f gauge today and I'm wondering about the readings. At WOT it's showing steady rich all the way to redline. At idle and cruising it dithers back & forth from middle stoich to full lean. Cruising with throttle shut indicates nothing which is correct. Do these readings sound ok? I thought only the stoich lights should light during idle & cruise. Thanks.
Tom
'87 951 - new APE chips & LBE...WOW!!!!
'86 Supra - new head gasket
05-11-2002, 10:34 PM
#2
Addict
Rennlist Member
Rennlist Member
Yeah that's probably good with the APE chips. They run rich until the high RPMs then lean out a bit. My A/F is crazy at idle,,mostly lean to mid.
05-12-2002, 05:14 AM
#3
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The dithering between lean and stoich is normal. The DME doesn't run a fixed A/F ratio, rather it tries to average the A/F ratio into the stioch range when at idle or part throttle. There is a specific term for what this dithering is called, but I can't remember it off the top of my head. But what it's doing is measuring when the A/F ratio crosses 14.7:1. Every time it crosses this threshold it either richens or leans out the mixture depening of which way the ratio is heading, e.g if heading rich it leans it out.
05-13-2002, 02:13 AM
#6
Three Wheelin'
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I need an a/f ratio monitor.. what's the least expensive and how do you hook them up..
I'm also looking at the Apex'i S-AFC.. I think this monitor a/f also.. so I might just wait till I get that.. anyone know for sure?
Who's got and S-AFC.. recommended?
I'm also looking at the Apex'i S-AFC.. I think this monitor a/f also.. so I might just wait till I get that.. anyone know for sure?
Who's got and S-AFC.. recommended?
05-13-2002, 11:50 AM
#7
Three Wheelin'
Thread Starter
I got a Autometer from <a href="http://www.summitracing.com" target="_blank">www.summitracing.com</a> for $43. They had a cheaper one for under $30. Three wires: 12V+ (only when ignition is on), ground, and a third that taps into oxygen sensor wire at DME harness.
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05-13-2002, 12:23 PM
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[quote]Originally posted by Tom L.:
<strong>I got a Autometer from <a href="http://www.summitracing.com" target="_blank">www.summitracing.com</a> for $43. They had a cheaper one for under $30. Three wires: 12V+ (only when ignition is on), ground, and a third that taps into oxygen sensor wire at DME harness.</strong><hr></blockquote>
This reminds me of a situation I had last year. My car ('86 951) didn't have an O2 sensor (doesn't have a cat either) so I bought a generic, single wire (Bosch) one. Screwed it in and hooked it up to my ARM1. The ARM showed rich when under load and lean when backing off (so something was working) but strangely, never "dithered" but hung on the 2 middle lights (not pulsing but both on together) or, just on one of the lights.
Never understood this - it seemed like the DME just ignored the signal from the O2 sensor and ran a fixed map based on no O2 sensor present (it was spliced in correctly after *mucho* consultation on RENNLIST).
It's a Euro car (Switzerland), has US chips (APE II or HR - I have both and they work as advertised) and it's supposed to be a "world" vehicle. Perhaps you NEED a 4 wire sensor ... ?
Anyway, it's just one of the worlds great mysteries that will only jump up and bite me once I've purchased / installed over $1000 worth of MAF and ARC2
<strong>I got a Autometer from <a href="http://www.summitracing.com" target="_blank">www.summitracing.com</a> for $43. They had a cheaper one for under $30. Three wires: 12V+ (only when ignition is on), ground, and a third that taps into oxygen sensor wire at DME harness.</strong><hr></blockquote>
This reminds me of a situation I had last year. My car ('86 951) didn't have an O2 sensor (doesn't have a cat either) so I bought a generic, single wire (Bosch) one. Screwed it in and hooked it up to my ARM1. The ARM showed rich when under load and lean when backing off (so something was working) but strangely, never "dithered" but hung on the 2 middle lights (not pulsing but both on together) or, just on one of the lights.
Never understood this - it seemed like the DME just ignored the signal from the O2 sensor and ran a fixed map based on no O2 sensor present (it was spliced in correctly after *mucho* consultation on RENNLIST).
It's a Euro car (Switzerland), has US chips (APE II or HR - I have both and they work as advertised) and it's supposed to be a "world" vehicle. Perhaps you NEED a 4 wire sensor ... ?
Anyway, it's just one of the worlds great mysteries that will only jump up and bite me once I've purchased / installed over $1000 worth of MAF and ARC2
