injectors not closing on deceleration
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injectors not closing on deceleration
Just wondering if anyone has noticed that the injectors don't fully shut down on deceleration. Since I have installed my Wb, I notice that sometimes when I let off the throttle the injectors will shut off like all my other vehicles and sometimes the injectors will keep functioning and keep the afr's a little on the rich side.
#2
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are you seeing this at high load? when the engine temps are high and the load is high, I think this happens as a cooling precaution. unburnt fuel removes heat. I know some DSM's used to actually fire the injection during the intake AND exhaust cycles under high load/heat conditions. Horrible for fuel efficiency, but great for not melting and having a minimal impact on performance Can anyone confirm that the evos also do or don't behave like this?
If they do, this should also only happen during open-loop operation, where there is no feedback from the o2 sensors. So the ridiculously rich AFRs don't matter so much since they are not totally the byproduct of combustion, even though the exhaust stream will see rich afr pocket spikes.
If they do, this should also only happen during open-loop operation, where there is no feedback from the o2 sensors. So the ridiculously rich AFRs don't matter so much since they are not totally the byproduct of combustion, even though the exhaust stream will see rich afr pocket spikes.
Last edited by blk-majik; Aug 21, 2009 at 03:48 PM.
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I know that my dsm does not act like that. My dsm is a 90 and as soon as you let off the throttle the injectors close.
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i have notice such behavier when the car is fitted with VTA BOV. is this your case?
many cars i tuned with aftermarket BOV are recording rich AFR in the overrun period (off throttle.
many cars i tuned with aftermarket BOV are recording rich AFR in the overrun period (off throttle.
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Its because you are running the car on a MAF and during light throttle decel (prior to decel fuel cut) the BOV is bypassing counted air, the air reaching the cylinders is much smaller in volume than what the MAF says, so it runs rich, regardless of recirc or open BOV venting. The further you get away from the factory parts/calibration, the worse it can be.
Its very possible this is one of the functions of the MDP sensor, as there are illogical areas between intake manifold pressure and MAF airflow where you can apply a negative fuel trim and eliminate this phenomenon entirely if you have an ECU that will allow it.
Its very possible this is one of the functions of the MDP sensor, as there are illogical areas between intake manifold pressure and MAF airflow where you can apply a negative fuel trim and eliminate this phenomenon entirely if you have an ECU that will allow it.
#11
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I see this once in a while too but it's hard to duplicate. I'm using a Works BOV which is a slightly stiffer spring than stock but still recircs. If I can catch the behaviour on a datalog and compare it to normal decel where the injectors shut off we might be able to tweak the tune to make it more consistant.
Last edited by Hiboost; Sep 15, 2009 at 05:50 AM.
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Wow had not seen this thread in a while.
For those that asked, I am on a stock everything.
With the injectors closing it is very and I mean Very unpredictable. I can actually feel them close when coasting to a stop.
Aaron email me your number and the next time I am in town I will give you a call and see if you have any free time.
For those that asked, I am on a stock everything.
With the injectors closing it is very and I mean Very unpredictable. I can actually feel them close when coasting to a stop.
Aaron email me your number and the next time I am in town I will give you a call and see if you have any free time.
Last edited by droppinbottom; Jul 28, 2010 at 03:50 PM.
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This past weekend I actually kept a close eye on my afr and around 3500rpm to 3000rpm my afr goes to around 11-12 afr and then goes back to normal. When I was stock I never noticed this. Im Cobb stage 2 now.
#15
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Its because you are running the car on a MAF and during light throttle decel (prior to decel fuel cut) the BOV is bypassing counted air, the air reaching the cylinders is much smaller in volume than what the MAF says, so it runs rich, regardless of recirc or open BOV venting. The further you get away from the factory parts/calibration, the worse it can be.
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