Guys I've noticed over the past few weeks that when I start my car after driving it a few minutes prior (drive to grocery store, get groceries, get back in car and drive home) that the motor will run a little lean (between 15-16 afr ratio), and after a minute of driving everything will return to normal (between 13-14afr while idling and driving without boost). Anybody else experience this issue. Just seems a little odd. The motor doesn't sound funny while doing this, but it's just a question that I've had stuck in the back of my head for some time now.
3sgte Runs Slightly lean on hot start - 6G Celicas Forums
It happens because it does. Sorry ben. Had to get the dumb responce out of the way. My guess is heat soak. We need to verify this.
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Thats not "lean", its stoichiometric air fuel ratio for gasoline. At idle and cruising you should be at AROUND 14-15 afr.
http://en.wikipedia.org/wiki/Air%E2%80%93fuel_ratio
If are getting 13 afr at warm idle or cruise, then your o2 sensor may need to be replaced because its not doing its job of keeping the afr between 14-15
QUOTE (bsamps4 @ Jun 5, 2012 - 11:11 AM) 
>Guys I've noticed over the past few weeks that when I start my car after driving it a few minutes prior (drive to grocery store, get groceries, get back in car and drive home) that the motor will run a little lean (between 15-16 afr ratio), and after a minute of driving everything will return to normal (between 13-14afr while idling and driving without boost). Anybody else experience this issue. Just seems a little odd. The motor doesn't sound funny while doing this, but it's just a question that I've had stuck in the back of my head for some time now.
Thats not "lean", its stoichiometric air fuel ratio for gasoline. At idle and cruising you should be at AROUND 14-15 afr.
http://en.wikipedia.org/wiki/Air%E2%80%93fuel_ratio
If are getting 13 afr at warm idle or cruise, then your o2 sensor may need to be replaced because its not doing its job of keeping the afr between 14-15
15PSI - 30MPG - Megasquirt Tuned
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Makes sense. Ben have you replaced them sense you had the car?
QUOTE (lagos @ Jun 5, 2012 - 2:11 PM)
>>
Thats not "lean", its stoichiometric air fuel ratio for gasoline. At idle and cruising you should be at AROUND 14-15 afr.
http://en.wikipedia.org/wiki/Air%E2%80%93fuel_ratio
If are getting 13 afr at warm idle or cruise, then your o2 sensor may need to be replaced because its not doing its job of keeping the afr between 14-15
QUOTE (bsamps4 @ Jun 5, 2012 - 11:11 AM)
>Guys I've noticed over the past few weeks that when I start my car after driving it a few minutes prior (drive to grocery store, get groceries, get back in car and drive home) that the motor will run a little lean (between 15-16 afr ratio), and after a minute of driving everything will return to normal (between 13-14afr while idling and driving without boost). Anybody else experience this issue. Just seems a little odd. The motor doesn't sound funny while doing this, but it's just a question that I've had stuck in the back of my head for some time now.
Thats not "lean", its stoichiometric air fuel ratio for gasoline. At idle and cruising you should be at AROUND 14-15 afr.
http://en.wikipedia.org/wiki/Air%E2%80%93fuel_ratio
If are getting 13 afr at warm idle or cruise, then your o2 sensor may need to be replaced because its not doing its job of keeping the afr between 14-15
Makes sense. Ben have you replaced them sense you had the car?
Its hitting 15-16 on hot starts, and 13-14 on cold starts. The wideband sensor is brand spankin' new. The factory sensor is original. Perhaps a good cleaning is in order??? When i boost my afrs will drop into the 9-10.5 rangr beyond 4000 rpms. What should i clean the sensor with. Or if i need to replace it can i order the sensor from a 94 mr2?
Its hitting 15-16 on hot starts, and 13-14 on cold starts. The wideband sensor is brand spankin' new. The factory sensor is original. Perhaps a good cleaning is in order??? When i boost my afrs will drop into the 9-10.5 rangr beyond 4000 rpms. What should i clean the sensor with. Or if i need to replace it can i order the sensor from a 94 mr2?
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Then it sounds like everything is working correctly. There is no problem to fix here.
QUOTE (bsamps4 @ Jun 5, 2012 - 3:58 PM)
>Its hitting 15-16 on hot starts, and 13-14 on cold starts. The wideband sensor is brand spankin' new. The factory sensor is original. Perhaps a good cleaning is in order??? When i boost my afrs will drop into the 9-10.5 rangr beyond 4000 rpms. What should i clean the sensor with. Or if i need to replace it can i order the sensor from a 94 mr2?
Then it sounds like everything is working correctly. There is no problem to fix here.
15PSI - 30MPG - Megasquirt Tuned
yeah I generally get a 12-13 on a cold, and idle usually 14-15... however I do sometimes while idling the car will slowly drop to a low 16-18 range... which is a little annoying. but doesnt do it often and a little tap on the gas fixes it.
Kevin
Kevin
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Those small dips into the 16-18 range normally indicate a very small vac leak somewhere in your setup.
Most people don't realize this, but a wideband is a far better way of noticing vac leaks then your actual vac gauge.
QUOTE (Soulend @ Jun 7, 2012 - 7:44 PM)
>yeah I generally get a 12-13 on a cold, and idle usually 14-15... however I do sometimes while idling the car will slowly drop to a low 16-18 range... which is a little annoying. but doesnt do it often and a little tap on the gas fixes it.
Kevin
Kevin
Those small dips into the 16-18 range normally indicate a very small vac leak somewhere in your setup.
Most people don't realize this, but a wideband is a far better way of noticing vac leaks then your actual vac gauge.
15PSI - 30MPG - Megasquirt Tuned
why vac leaks? is this a gen 2 or a gen 3 motor?
Mike W1996 Toyota Celica ST205 GT-FOURGT2860RS turbine, TiAL mvr44, JE 86.5φ piston, Clutchmasters FX400, APEX P-FC269awhp / 273ft-lbs
Gen 3