Quote:
Originally Posted by razthecat
Hey guys, long time lurker of the forums, new to posting. Before I even mention anything I just wanna say I appreciate any of you who will take the time to help, means the world to me.
Recently, like a day or two ago, my car went from sometimes overboosting over target on MHD 2+ to boosting 1-2 pounds under target. Not sure why it happened, I could physically feel the car feel a little bit more held back. My initial worry was compression and/or turbos, so I bought a compression tester which I will use today to figure out if my engine is healthy. The turbos were a concern because during the transition from a stop to low speeds I see a small puff of smoke out of the left pipe whenever I’m watching someone else drive away in my car. I decided to log my car before testing or changing anything and did 2 pulls in 3rd gear from around 2-2.5K RPM to redline. Here is the link : https://datazap.me/u/farazt123/tryna...og=0&data=3-16
Right about where boost first loads in, right after I stamp the throttle, the car will start pulsing, or hesitating, like it’s missing, but I don’t get any codes other than 2C7B which I believe is my downpipe O2 sensor going out, but it never threw a light so I figured it’s unrelated. At the same time it starts pulsing, rail pressure drops, all my cylinders get timing corrections, low pressure fuel pump starts acting weird, fuel trims go down. By the end of the WOT pull it seems like my LPFP touches 50PSI. I was desperately hoping this was my cause since it would mean a lot cheaper than an engine or turbos. If any of you are willing to go back to a log on my account that is called HPFP testing, you’ll see I did another pull, not sure if I did it properly but it seems like my LPFP doesn’t go anywhere near as low. Thanks again! Sorry for the huge post.
TLDR;
https://datazap.me/u/farazt123/tryna...og=0&data=3-16
Weird hesitation right after I open up throttle, cars boosting 1-2 psi under target after a few months of boosting over target sometimes. Haven’t done compression test yet, will today, but logs make me think potentially a LPFP.
Edit : did a compression test and here are my numbers.
Cyl #6 160 psi
Cyl #5 165 psi
Cyl #4 165 psi
Cyl #3 165 psi
Cyl #2 165 psi
Cyl #1 170 psi |
Your HPFP doesn't drop below 2000psi, that's healthy. Concern is when it drops below 1500psi. Your LPFP could be weak but it also doesn't drop below 50Psi. I don't think either of them are causing your boost fluctuations or off target issues.
It could be your boost solenoids playing up causing the boost fluctuations, also looks like you have a boost leak, as your WGDC is climbing to 80%+ and only reaching around 13psi.
Have you changed your vacuum lines recently? If not, a good idea to change them, Check charge pipe, DV connections, vacumn canister connection points for any cracks, FMIC connections.
You could also do a smoke test to help point out any possible leaks.