FD Running Lean? Remove air pump with gutted cats?
01-30-09, 07:48 PM
#1
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Thread Starter
FD Running Lean? Remove air pump with gutted cats?
Does anyone know if running a Apexi cold air intake and having gutted cats will make a FD rx7 run lean? Is there any simple way to resolve this? Also will a Greddy Type RS BOV help things out because the car should run rich when the throttle is released. Thanks in advance.
Can I safely remove the air pump if I have gutted cats? Will this also remove and mooing noises from a Apexi Cold Air Intake? Thanks in advance.
Can I safely remove the air pump if I have gutted cats? Will this also remove and mooing noises from a Apexi Cold Air Intake? Thanks in advance.
Last edited by Sgt Fox; 01-30-09 at 08:28 PM.
01-30-09, 10:26 PM
#2
Yeah, probably. Opening up the exhaust system on a turbo car will usually bring boost creep, which can overwhelm a stock fuel system. Do you have a boost gauge in the car? Find out if you're building more than 10psi (stock). If you are, the wastegate will need to be ported.
A BOV has nothing to do with running lean under acceleration. When you let off the throttle completely, fuel is cut and the pressurized air is vented off to prevent compressor surge.
Why do you think you're running lean anyway? Do you have a wideband reading 12.0 AFR or higher at WOT?
A BOV has nothing to do with running lean under acceleration. When you let off the throttle completely, fuel is cut and the pressurized air is vented off to prevent compressor surge.
Why do you think you're running lean anyway? Do you have a wideband reading 12.0 AFR or higher at WOT?
01-30-09, 10:52 PM
#3
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Technically yes, anything that makes the car breathe with less resistance will make the car run leaner.
However, any EFI equipped car should adjust the fuel maps accordingly, unless your mods make the car require more fuel than your injectors can supply. In the case of your gutted cats, the post cat O2 sensor should also throw a CEL but is unlikely to lean out your mixture. You can solve this by using an "O2 simulator" or by simply using your catalytic converters like you should and not polluting
As far as any aftermarket air bypass valve or BOV goes, this won't really effectively change anything concerning your mixture because 1) you already have an air bypass system of some sort and 2) you are not going to be off throttle enough for it to make a difference.
Basically, I think your problem is somewhere else.
However, any EFI equipped car should adjust the fuel maps accordingly, unless your mods make the car require more fuel than your injectors can supply. In the case of your gutted cats, the post cat O2 sensor should also throw a CEL but is unlikely to lean out your mixture. You can solve this by using an "O2 simulator" or by simply using your catalytic converters like you should and not polluting
As far as any aftermarket air bypass valve or BOV goes, this won't really effectively change anything concerning your mixture because 1) you already have an air bypass system of some sort and 2) you are not going to be off throttle enough for it to make a difference.
Basically, I think your problem is somewhere else.
Last edited by BomberMan; 01-30-09 at 10:57 PM.
01-30-09, 10:58 PM
#4
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Thread Starter
No I don't have a boost gauge but I should get 1 along w/ a air/fuel gauge.
I'm not positive that its running lean because the exhaust still smells gasoline/rich like but I read in a Sport Compact magazine that quote
"The FD (Mazda's designation for third generation RX-7) comes equipped with a MAP (Manifold Absolute Pressure) sensor, not a typical MAF (mass air flow) sensor" states Brian, "This mean that the stock ECU does not readily compensate for increased flow caused by exhaust back-pressure reductions or a intake upgrades. Reading only manifold pressure, the stock ECU relies on fixed maps that no longer deliver the required fuel for the increase in volumetric efficiency. Under this situation, a momentary lean-run condition can easily lead to detonation and apex seal damage."
so I'm just wonderin if any1 had experience w/ this b/c a friend I talked to on facebook said that this setup may lead to detonation and his friend has a rx7 that had a similar setup plus a aftermarket intercooler and his engine broke within a week of installing the mods
I'm not positive that its running lean because the exhaust still smells gasoline/rich like but I read in a Sport Compact magazine that quote
"The FD (Mazda's designation for third generation RX-7) comes equipped with a MAP (Manifold Absolute Pressure) sensor, not a typical MAF (mass air flow) sensor" states Brian, "This mean that the stock ECU does not readily compensate for increased flow caused by exhaust back-pressure reductions or a intake upgrades. Reading only manifold pressure, the stock ECU relies on fixed maps that no longer deliver the required fuel for the increase in volumetric efficiency. Under this situation, a momentary lean-run condition can easily lead to detonation and apex seal damage."
so I'm just wonderin if any1 had experience w/ this b/c a friend I talked to on facebook said that this setup may lead to detonation and his friend has a rx7 that had a similar setup plus a aftermarket intercooler and his engine broke within a week of installing the mods
01-30-09, 11:06 PM
#5
Full Member
Thread Starter
Technically yes, anything that makes the car breathe with less resistance will make the car run leaner.
However, any EFI equipped car should adjust the fuel maps accordingly, unless your mods make the car require more fuel than your injectors can supply. In the case of your gutted cats, the post cat O2 sensor should also throw a CEL but is unlikely to lean out your mixture. You can solve this by using an "O2 simulator" or by simply using your catalytic converters like you should and not polluting
As far as any aftermarket air bypass valve or BOV goes, this won't really effectively change anything concerning your mixture because 1) you already have an air bypass system of some sort and 2) you are not going to be off throttle enough for it to make a difference.
Basically, I think your problem is somewhere else.
However, any EFI equipped car should adjust the fuel maps accordingly, unless your mods make the car require more fuel than your injectors can supply. In the case of your gutted cats, the post cat O2 sensor should also throw a CEL but is unlikely to lean out your mixture. You can solve this by using an "O2 simulator" or by simply using your catalytic converters like you should and not polluting
As far as any aftermarket air bypass valve or BOV goes, this won't really effectively change anything concerning your mixture because 1) you already have an air bypass system of some sort and 2) you are not going to be off throttle enough for it to make a difference.
Basically, I think your problem is somewhere else.
I'm only running no cats b/c my cats were clogged but I am planning to get high-flow cats
01-31-09, 07:23 AM
#6
Yes, removing the air pump will stop the mooing sound.
A BOV will not do anything for boost control. Boost control is done by a boost controller. Get one, install it. Even manual boost controllers ($50) work really well. If you're running no cats and don't have a boost controller, you're probably in a very dangerous situation (dangerous to your engine)
On an FD the boost level is the primary driver of your AFRs. Install a boost controller, set it to 10psi for a stock ECU and make sure it does not exceed that amount. As long as boost stays where it should be your AFRs should be fine under load.
A BOV will not do anything for boost control. Boost control is done by a boost controller. Get one, install it. Even manual boost controllers ($50) work really well. If you're running no cats and don't have a boost controller, you're probably in a very dangerous situation (dangerous to your engine)
On an FD the boost level is the primary driver of your AFRs. Install a boost controller, set it to 10psi for a stock ECU and make sure it does not exceed that amount. As long as boost stays where it should be your AFRs should be fine under load.
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