Bad Boost: VIDA TCV, TPS, and O2 log

SantaFe75 · Post by **SantaFe75** » 16 Jul 2017, 21:12

I'm having a hell of a time trying to figure out where my boost is going.

When I accelerate hard my boost will rise to 9-10psi then just as fast drop to 1-2psi.

I spent the day tracing and fixing even the smallest leak in the hoses. Oil, plugs, coils, ECT, all filters and nearly every hose are new.

I just ran out with the VIDA and ran up the Highway to check the duty cycle on the TCV. It looks like the duty cycle is dropping off while still under full throttle. This can not be normal, right?

download/file.php?mode=view&id=35741

Anyone have experience with boost drop-off? Please help.

Thank you

Post by **abscate** » 17 Jul 2017, 04:48

The CBV diaphragm could have a hole in it and is dumping too early, but usually it's hoses or an aged TCV.

How old is it? Performance drivers will replace at 100k miles. They get tired

SantaFe75 · Post by **SantaFe75** » 17 Jul 2017, 05:38

I have no idea on age. I was thinking the same thing with the TCV. I ordered a new Pierburg from IPD w/silicone lines, should be here today.
Looking at the log I thought I wasted my money on the TCV. I'm not sure but, it does look like it is working. Just dropping off for some reason. I will post back after work when the new one is in

SantaFe75 · Post by **SantaFe75** » 18 Jul 2017, 05:38

I am still waiting on the USPS to drop off my TCV. I decided to log a trip and watch the cam. It seems a little erratic to me. Of course I'm used to the good ol 350, where the only "ECU" in the thing is between your ears.

Is this cam angle movement normal? If it's not, could this cause the ECU to cut boost?

download/file.php?mode=view&id=35744

It seems to bounce around a lot with boost pres. & TCV % flat .

SantaFe75 · Post by **SantaFe75** » 18 Jul 2017, 19:07

Solved...so far.

download/file.php?mode=view&id=35750

The new TCV came in. The red compressor line is a PITA. Went for a run and there's no surging or fluctuation, just a smooth climb to 7psi. Happy day!

Post by **vtl** » 20 Jul 2017, 08:09

> When I accelerate hard my boost will rise to 9-10psi then just as fast drop to 1-2psi.

Sticky TCV solenoid. I had the same with IPD HD TCV (relabeled universal TCV made in Taiwan), which failed within the first year.