running rich; had to turn down fuel pressure
09-14-2008, 12:26 AM
#1
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running rich; had to turn down fuel pressure
As of late my car has been running richer as per my wideband.
It's basically right across the rev range and any intake manifold pressure.
I'm fortunate to have an adjustable FPR which I turned down about 7 - 8 psi to bring it back to where it was before (actually still a little richer than it should be)
So, I'm thinking: what would cause this?
My "shut-off valve" for the gastank vent system was bad; replaced it with no change.
Checked fuel dampener and the AFPR; both good.
Tested recirculation valve; it's good.
Can't be vacuum/pressure leak because it would show up as vacuum lean and boost rich.
Can't be leaky injector; after shut-off holds pressure in the rail.
All spark plugs look the same.
The only thing that was slightly off was the engine temp sensor; reads 230 ohms at 77* celsius (about 170 degrees F.) which is a little low according to the manual.
Could this be the cause? Seems unlikely. Anybody?
Running a Vitesse MAF.
It's basically right across the rev range and any intake manifold pressure.
I'm fortunate to have an adjustable FPR which I turned down about 7 - 8 psi to bring it back to where it was before (actually still a little richer than it should be)
So, I'm thinking: what would cause this?
My "shut-off valve" for the gastank vent system was bad; replaced it with no change.
Checked fuel dampener and the AFPR; both good.
Tested recirculation valve; it's good.
Can't be vacuum/pressure leak because it would show up as vacuum lean and boost rich.
Can't be leaky injector; after shut-off holds pressure in the rail.
All spark plugs look the same.
The only thing that was slightly off was the engine temp sensor; reads 230 ohms at 77* celsius (about 170 degrees F.) which is a little low according to the manual.
Could this be the cause? Seems unlikely. Anybody?
Running a Vitesse MAF.
09-14-2008, 05:11 AM
#2
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Are you using the SMT6?
09-14-2008, 06:49 AM
#3
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Tommy, since your car was running good AFRs and without any modifications the AFR changed, I would look at ground, sensors,.. As I recall you do not have a PiggyBack so nothing you could have changed (except for FQS setting) that will change the AFR.
The engine temp sensor will affect the AFR. The DME will richen the mixture when the engine is cold.
The engine temp sensor will affect the AFR. The DME will richen the mixture when the engine is cold.
09-14-2008, 07:17 AM
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"The engine temp sensor will affect the AFR. The DME will richen the mixture when the engine is cold."
Yes, but the ohm reading is low, so according to the manual, the DME would think the engine is running hotter than it actually is.
Yes, but the ohm reading is low, so according to the manual, the DME would think the engine is running hotter than it actually is.
09-16-2008, 04:10 AM
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I have the same problem as Turbotommy for some time now. Cant find someone who can slowe it. I am thinking to start replacing sensors. Where should i start?
09-16-2008, 04:17 AM
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I think I can shine alil light here im not running that setup my is of different make but how old is your wideband sensor? I have noticed as they start to go the reading get different but the car acts the same. I keep trying to tune my car to get it "in spec" and it slowly got richer but it wouldn't run correct with the right tune in then i changed my wideband and I was back to nornal with my orginial setting/tune.
my 2 cents.
my 2 cents.
09-16-2008, 11:00 PM
#7
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Well, I also thought that my wideband might be off.
But, if it was, then my car would be running actually lean when I turn down my adjustable FPR. If it was running lean (about 8% less fuel) I would notice a loss of power and jerking at part throttle. But, the car runs great (with the lower fuel pressure) and spark plugs all look good and even.
But, if it was, then my car would be running actually lean when I turn down my adjustable FPR. If it was running lean (about 8% less fuel) I would notice a loss of power and jerking at part throttle. But, the car runs great (with the lower fuel pressure) and spark plugs all look good and even.
