Ms3orDie
Greenie Member
unfortunately im not having any luck.
RPM and Speed bounce/boggles
- Thread starter Ms3orDie
- Start date
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unfortunately im not having any luck.
The_big_dill
Greenie Member
What was the last thing you did on your car prior to this problem?
From your log, my observations tell me your ECU is pulling a ton of fuel and your system is reporting extremely rich when you let off the gas. Your system is responding to it, but the readings are extreme for the conditions.
Typically this would exhibit a boost leak, but the problem seems to exist in vacuum conditions.
Have a look at this snippet from your log:
The key here is to remember that you have a steady throttle position and APP, steady vacuum/boost, steady fuel pressure. However, if you look at your AFR, it is jumping from 12 to 26 to 9 in a matter of milliseconds and eventually recovers closer to what it should be under these conditions (~stoich).
You can confirm that your system is appropriately compensating for that with the fuel trims, when the AFR jumps around, so do your short trims.
My next diagnosis would be based on changes on your car. But to me this looks like an intermittent sensor malfunction, potentially due to damaged wiring or a malfunctioning sensor. My guess would be your O2 sensor with the information I have.
Do you have a full throttle (WOT) log?
From your log, my observations tell me your ECU is pulling a ton of fuel and your system is reporting extremely rich when you let off the gas. Your system is responding to it, but the readings are extreme for the conditions.
Typically this would exhibit a boost leak, but the problem seems to exist in vacuum conditions.
Have a look at this snippet from your log:
The key here is to remember that you have a steady throttle position and APP, steady vacuum/boost, steady fuel pressure. However, if you look at your AFR, it is jumping from 12 to 26 to 9 in a matter of milliseconds and eventually recovers closer to what it should be under these conditions (~stoich).
You can confirm that your system is appropriately compensating for that with the fuel trims, when the AFR jumps around, so do your short trims.
My next diagnosis would be based on changes on your car. But to me this looks like an intermittent sensor malfunction, potentially due to damaged wiring or a malfunctioning sensor. My guess would be your O2 sensor with the information I have.
Do you have a full throttle (WOT) log?
Last edited:
Sho
Silver Member
Do you have a VTA BOV? If so, the spring inside is too weak. If adjustable, you need to turn it to tighter setting. If not, stiffer spring.
For example. I run a tial Q 50mm valve with a -12psi spring. I run that particular spring as my car idles at -10.5psi and pulls -11.9xpsi vac during engine braking.
A weaker spring such as the -10 exhibits the same symptoms youre having
For example. I run a tial Q 50mm valve with a -12psi spring. I run that particular spring as my car idles at -10.5psi and pulls -11.9xpsi vac during engine braking.
A weaker spring such as the -10 exhibits the same symptoms youre having
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