Quick question about vacuum leaks
Thread Starter
Melting Slicks
Joined: Jun 2013
Posts: 3,065
Likes: 39
Quick question about vacuum leaks
Hi all.
I have a quick question about vacuum leaks, which is going to be simple to understand after you read through the whole post.
Anyway, I had tuned my own 1985 Corvette. When I installed the new MAF sensor, there is a leak between the sensor and the intake snorkel.
I accidentally tuned my ECU over this vacuum leak. The car was dynoed and everything on this tune.
I fixed the leak and my BLMs dropped down to 115-119. Essentially this means that the tune is now slightly too rich for what the engine wants, and the computer is correcting for it.
Obviously, I will have to retune this to bring it back to around 128 BLMs.
So, getting to the actual question... How much do vacuum leaks affect fuel trim across the whole board?
Am I going to have to retune every load percentage or just part throttle, cruise and idle.
Does it affect the air/fuel ratio at WOT, or is it insignificant to affect it?
The vacuum leak was not very large, in fact, you could not even hear it. I didn't notice any performance issues.
Basically, the questions summed up, how much tuning should I expect to do?
Thanks for any advice!
I have a quick question about vacuum leaks, which is going to be simple to understand after you read through the whole post.
Anyway, I had tuned my own 1985 Corvette. When I installed the new MAF sensor, there is a leak between the sensor and the intake snorkel.
I accidentally tuned my ECU over this vacuum leak. The car was dynoed and everything on this tune.
I fixed the leak and my BLMs dropped down to 115-119. Essentially this means that the tune is now slightly too rich for what the engine wants, and the computer is correcting for it.
Obviously, I will have to retune this to bring it back to around 128 BLMs.
So, getting to the actual question... How much do vacuum leaks affect fuel trim across the whole board?
Am I going to have to retune every load percentage or just part throttle, cruise and idle.
Does it affect the air/fuel ratio at WOT, or is it insignificant to affect it?
The vacuum leak was not very large, in fact, you could not even hear it. I didn't notice any performance issues.
Basically, the questions summed up, how much tuning should I expect to do?
Thanks for any advice!
Team Owner
Joined: Aug 2000
Posts: 40,156
Likes: 45
From: San Pedro CA
first, it depends on the size of the leak... but introduce too much air, you get a problem.
I had a lean condition caused by a leak on the vacuum lines to the EGR... that small a leak leaned me out and caused my car to fail smog.
I had a lean condition caused by a leak on the vacuum lines to the EGR... that small a leak leaned me out and caused my car to fail smog.
