Strange sound behind the dash at high rpm

evilcw311

Most Evil Member!
SN95 Supporter
Joined
May 9, 2010
Messages
7,459
Reaction score
2,101
Location
Louisville, KY
Hi all so far everything seems to be working great now I’ve fixed that vacuum line but I am a little confused about the LTFT and STFT. Now before I fixed the vacuum line the LTFT at idle was at +5 on both banks and STFT was floating between -2 to +5 on both banks but now the LTFT has gone to -8 on bank one with a STFT of -2 to +2 and bank twos LTFT is at -3 with a floating STFT of -2 to +3.
All this is at idle and the STFT are more in the negatives than positives. What is this tell me ?
Is this all because of that vacuum leak or is something else going wrong?

Thats more for those who mess with tuning. You should definitely see a change but I’m not sure how those numbers would swing. While you were fixing the one line did you take the time to verify there was no other leaks??


Sent from my iPhone using Tapatalk
 

Adam Vinnicombe

Active Member
Joined
Jun 28, 2019
Messages
498
Reaction score
69
I’ve look all over the car now and have not found any other vacuum leak at all. What I did do as an experiment as I am still learning the basics here was to plug in my data logger and watch the fuel trims at idle, then I pulled the blue vacuum line back of and watched the STFT instantly react by going +8 while at idle and slowly decrease back to +1 as the rpms went up. So I can definitely say that that little vacuum leak was messing the fueling up when at idle
 

evilcw311

Most Evil Member!
SN95 Supporter
Joined
May 9, 2010
Messages
7,459
Reaction score
2,101
Location
Louisville, KY
I’ve look all over the car now and have not found any other vacuum leak at all. What I did do as an experiment as I am still learning the basics here was to plug in my data logger and watch the fuel trims at idle, then I pulled the blue vacuum line back of and watched the STFT instantly react by going +8 while at idle and slowly decrease back to +1 as the rpms went up. So I can definitely say that that little vacuum leak was messing the fueling up when at idle

You can’t do a visual check for vacuum leaks. Either get a smoke machine to test it or do what I do and get a cigar and do it the cheap easy way.

Smoke test is your easiest way to verify no more leaks.


Sent from my iPhone using Tapatalk
 

Adam Vinnicombe

Active Member
Joined
Jun 28, 2019
Messages
498
Reaction score
69
Right today I’m going to go and see if I can buy me a vacuum gauge but as I said I’m still learning here where is the best place to plum it in ?
 

Adam Vinnicombe

Active Member
Joined
Jun 28, 2019
Messages
498
Reaction score
69
Well some good news done the cigar smoke test and found no leaks anywhere which was nice but my fuel trims are still negative at idle but all jump to a constant 0 to +3 just above idle when in neutral
 

vitory34

New Member
Joined
Dec 15, 2020
Messages
1
Reaction score
0
I found interesting information about information about Torque of differential and driveshaft , and also how the Temperature can affect to the performance.
www.motorcloud.com
 

Forum statistics

Threads
74,882
Messages
1,452,553
Members
13,569
Latest member
94StewFord

Members online

Top