Help! Air/Fuel ratio gauge acting freaky..
Help! Air/Fuel ratio gauge acting freaky..
Hello,everybody!I'm gathering parts for my KA-T project and I just have received Autometer air/fuel ratio gauge. Wanted to see what it does so I just hook it up to my engine. Reading were unstable through out entire rpm range, especially at idle. It says in the instructions that at idle it's normal to see a/f ratio change rapidly. But it says nothing about other situations. When conditions change from wide open throttle to closed the gauge indicates extremely lean condition. Probably it's bad O2 sensor, but "check engine" light is not on. If you have this gauge installed please share your experience. Thanks a lot.
Dude, your air fuel ratio gauge and oxygen sensor are working just fine. When your at idle and part throttle, the ecu is operating in closed loop. Basically, it reads from the oxygen sensor, and varies the fuel flow to get the best emmissions/mpg. Yes it's normal for the gauge to bounce around 95% of the time, and it should go lean every time you get off the gas because your injectors are not firing at all on deceleration. This is to save gas.
The only time your gauge will be somewhat accurate is over about 1/2 throttle. The ecu will go into open loop and just use the stock fuel maps, ignoring the oxygen sensor all together. This is when your gauge will level out, and you can tell if your running rich/lean/stoich.
In other words...ignore it most of the time.
The only time your gauge will be somewhat accurate is over about 1/2 throttle. The ecu will go into open loop and just use the stock fuel maps, ignoring the oxygen sensor all together. This is when your gauge will level out, and you can tell if your running rich/lean/stoich.
In other words...ignore it most of the time.
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Structure240sx
- Posts: 5615
- Joined: Sun Oct 06, 2002 5:04 pm
dont forget about the egt gauge. Fuel isnt the only thing that can effect your cars ability to detonate. Timing, which cant be monitored without a techtom or whatever, will make egt's different. An egt gauge is just as important as anything. Installed on teh 3rd cylinder is the best place--its the hottest cylinder in the firing order, thus yeilds the highest egt's to moniter this is the best way to prevevnt detonation by too high a combustion chamber temp.
i hate to sound like a moron but i got a question... i always read about how important the egt and wideband sensors are and i am completly agreeing but what are you looking for on them? i mean, for the 240, what reading would be considered starting to become lean on the wideband? when is it rich? what readings should you be shooting for off of the wideband if you want a reliable turbo setup that is not close enough to lean that on a bad day will blow it? what is a reading on the egt that is close to perfect? when is it to hot? i was reading another thread and (i cant remem who it was) said at idle their wideband read between 14.5-14.9 and somewhere in the 13s under heavier load. im not exactly sure when i get these readings how to interpret them (egt readings included). this really seems like something that would have been discussed before but i didnt see anything about this... maybe i missed it :help
ps go pistons (i bet there are a lot of cali guys on this board. haha)
ps go pistons (i bet there are a lot of cali guys on this board. haha)
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TrunkMonkey
- Posts: 3190
- Joined: Sun Aug 04, 2002 7:48 am
- Car: 2000 Lincoln Navigator
cylinder 4 is the hottest, it's the last one to recieve coolant.Projex240 wrote:dont forget about the egt gauge. Fuel isnt the only thing that can effect your cars ability to detonate. Timing, which cant be monitored without a techtom or whatever, will make egt's different. An egt gauge is just as important as anything. Installed on teh 3rd cylinder is the best place--its the hottest cylinder in the firing order, thus yeilds the highest egt's to moniter this is the best way to prevevnt detonation by too high a combustion chamber temp.
an egt gauge is almost usless. your EGTs will go up even when your running too rich.
putting the probe on a single runner isn't going to help if a different cylinder runs too lean. near the collector would be best. that way you can monitor the entire engine.
-demetrius
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TrunkMonkey
- Posts: 3190
- Joined: Sun Aug 04, 2002 7:48 am
- Car: 2000 Lincoln Navigator
dyno tuning is the only thing that can give you specific answers to your questions. you can get away with using AFRs and EGTs that someone with a similar setup has, but it may not be best. tuning on a dyno will tell you what the optimum timing, AFRs, and EGTs are for your engine. once you have this info, you'll know what to look for when your monitoring your engine via various gauges.kevdog240 wrote:i hate to sound like a moron but i got a question... i always read about how important the egt and wideband sensors are and i am completly agreeing but what are you looking for on them? i mean, for the 240, what reading would be considered starting to become lean on the wideband? when is it rich? what readings should you be shooting for off of the wideband if you want a reliable turbo setup that is not close enough to lean that on a bad day will blow it? what is a reading on the egt that is close to perfect? when is it to hot? i was reading another thread and (i cant remem who it was) said at idle their wideband read between 14.5-14.9 and somewhere in the 13s under heavier load. im not exactly sure when i get these readings how to interpret them (egt readings included).
-demetrius
demcj wrote:dyno tuning is the only thing that can give you specific answers to your questions. you can get away with using AFRs and EGTs that someone with a similar setup has, but it may not be best. tuning on a dyno will tell you what the optimum timing, AFRs, and EGTs are for your engine. once you have this info, you'll know what to look for when your monitoring your engine via various gauges.
-demetrius
so how exactly does everyone tune their setup with just the wideband and piggyback setup? im sure there are plenty of people here who have not used a dyno to tune their fuel setup. isent the wideband giving you the same readings as the dyno. i mean im sure the dyno gives you a lot more readings and detail but shouldnt the wideband be plenty to setup a turbo system? so there are no basic numbers to shoot for? i know i saw on some other thread the guy was shooting for between 14.5-14.9 at idle and i think he said somewhere in the 13s when it was boosting? honostly i dont know exactly what im talking about since i havent played with this stuff yet. just dont want to blow my engine when i do.
also, everyone says that the first thing you should do is set the system rich so that it doesnt blow and fine tune it by making it leaner. how rich are we talking? i could see myself making it way to rich since i dont know the point of being a moron when it comes to tuning turbos yet. i dont want to try to tune it and destroy my spark plugs the first time.
sorry for the basic boring questions.