Please help: Idle Air/Fuel way too low
01-08-2007, 03:58 PM
#1
Please help: Idle Air/Fuel way too low I have had THREE different tuners work on my car to get the idle air/fuel to 14.7. They both tried doing it the way it works on every other car and then they both tried putting band aids in the tune to see if they could change it manually. Nothing works. The car is tuned fine for the street and WOT so it doesn't seem that my computer is bad. My tuner said that it could be bad O2's but they have less than a 1000 miles on them and are a good brand.
The funny thing is, when you start the car for the first time that day, it will idle at 14.7 for the first 5 seconds, then it will very gradually lower itself to 11.5 to 11.8 over the next 30 seconds.
My gas mileage sucks around 11.0 mpg and I was wondering how bad it is to have an idle air/fuel that low, if it is washing down the cylinders. What could it be?
The funny thing is, when you start the car for the first time that day, it will idle at 14.7 for the first 5 seconds, then it will very gradually lower itself to 11.5 to 11.8 over the next 30 seconds.
My gas mileage sucks around 11.0 mpg and I was wondering how bad it is to have an idle air/fuel that low, if it is washing down the cylinders. What could it be?
01-08-2007, 07:08 PM
#3
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If your turbo and cam let you blow a lot of air through
the overlap then this would happen by fooling the O2s
with excess oxygen.
But 5 seconds into it, the car shouldn't even be in closed
loop. So that may not have anything to do with it, until
later when hot.
Can you see the commanded AFR and the wideband AFR,
whether this is a purposeful thing or somebody's just
confused?
the overlap then this would happen by fooling the O2s
with excess oxygen.
But 5 seconds into it, the car shouldn't even be in closed
loop. So that may not have anything to do with it, until
later when hot.
Can you see the commanded AFR and the wideband AFR,
whether this is a purposeful thing or somebody's just
confused?
01-08-2007, 08:36 PM
#5
Wait4me: Wires can't be backwards, no O2 extensions, just aftermarket sensors.
Jimmyblue: Can't be too much air, restrictive log manifold turbo kit and stock cam.
Black98WS6ta: I'll try replacing them but I don't think its going to help.
Jimmyblue: Can't be too much air, restrictive log manifold turbo kit and stock cam.
Black98WS6ta: I'll try replacing them but I don't think its going to help.
01-08-2007, 08:51 PM
#7
Sounds like you have both 02's in the downpipe. The pass side should be in the normal position (after pass. manifold)and the driver side should be in the downpipe.
I'm just guessing because I've seen this before on other turbo cars.Some people put both 02's in the cross over pipe or the downpipe.They have to be split up.
I'm just guessing because I've seen this before on other turbo cars.Some people put both 02's in the cross over pipe or the downpipe.They have to be split up.
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01-08-2007, 09:08 PM
#8
What do the long term fuel trims look like? Are they maxxed out in a effort to correct the rich condition? Does the car idle richer in open loop before the car gets up to operating temp? If it does lean out after in closed loop, how much does it change?
01-09-2007, 02:41 AM
#9
Slowhawk: Pass side O2 is in crossover just after exhaust manifold and BEFORE the first 90 under the tranny. Driver side O2 is in the downpipe at the back of the oil pan. The Wideband is also in the downpipe one inch from the driver O2.
Black98WS6TA: I'll let my tuner know but I think he may have already tried that. I trust him obviously, I let him tune the car. I was hoping someone else might have experienced the same thing and had the solution.
Black98WS6TA: I'll let my tuner know but I think he may have already tried that. I trust him obviously, I let him tune the car. I was hoping someone else might have experienced the same thing and had the solution.
01-09-2007, 05:34 AM
#10
Originally Posted by SStolen
Slowhawk: Pass side O2 is in crossover just after exhaust manifold and BEFORE the first 90 under the tranny. Driver side O2 is in the downpipe at the back of the oil pan. The Wideband is also in the downpipe one inch from the driver O2.
Black98WS6TA: I'll let my tuner know but I think he may have already tried that. I trust him obviously, I let him tune the car. I was hoping someone else might have experienced the same thing and had the solution.
Black98WS6TA: I'll let my tuner know but I think he may have already tried that. I trust him obviously, I let him tune the car. I was hoping someone else might have experienced the same thing and had the solution.
How is the car being tuned? SD or closed loop?
