Loses Boost, don't know what to do to fix it.....TVS VMP

[Baby J]

So I am losing boost around 5000 to 5200 RPM's, can watch the gauge build up to almost 18psi and then just steady bleed off. I know that it has something to with boost bypass actuator, I know this because I used safety wire to hold the actuator closed and everything worked as it should. So I gave Justin a call at VMP, he said no problem he sent me another one, swapped it out today and i am still have the same problem. I am all out of ideas and so is Justin after calling and talking with him today.

What wondering if anyone else has been having this issue, and if so what did you do about it.


******SO everything is fixed, checked all the vacuum lines and found no issues, talked with TRBO VNM and also i believe Justin told me this as well, But basically adjusted the bypass actuator down (the bracket is sloted) preloading the bypaas and the problem is now solved. Car is back running like a champ.*****

 

[spray'n mach 1]

I was getting belt slip around the same rpm could that be it? if yours is doing a steady bleed off then that's probably not it unless it's just a slight slip. keep us informed what you end up finding out.

 

[03cobra#694]

EGR delete car? Which is obvious with the VMP. Just asking regarding your previous set up

 

[Baby J]

no not belt slip like said everything works great with actuator wired shut

yes egr delete,

 

[03cobra#694]

Vacuum line issue then.

 

[Alfie]

Did u bypass the solenoid for the supercharger ?

 

[03cobra#694]

Did u bypass the solenoid for the supercharger ?

EGR delete makes that go bye bye.

 

[Alfie]

What are u using to actuate the bypass ? Between the TB and blower or are u using manifold pressure ?

 

[Baby J]

Vacuum line issue then.

i am guessing, i have looked at the lines and cant find anything wrong i guess the next step is to just replace the lines

Did u bypass the solenoid for the supercharger ?

no i just wrapped safety wire around the actuator arm that is connected to rod that comes out of the SC and then wrapped the wire up behind the actuator braket so it held it the down closed position

What are u using to actuate the bypass ? Between the TB and blower or are u using manifold pressure ?

The SC itself does it not following you

 

[Alfie]

The vacuum source ? Stock the lines comes from top port which either has vacuum or under load has neither vacuum nor pressure. So the spring in the actuator is what closes the valve. Now if you use the same port as the FRP it will get pressure under load and have more closing strength . I may try this since u say you keep your pressure when u tied up the actuator.

 

[TRBO VNM]

It should have a boost source going to top port on actuator and bottom vented to atmosphere. That is how I installed it unless something has been changed since it left my place.

Dave, sorry, I was on the dyno all day and by the time I got home it was dinner time and had to get kid ready for bed.

I don't recall your gauge setup, do you have a boost/vac gauge? If so, what does vac read when idling? Have any surging or anything when idling? Taking the day off tomorrow from car stuff and taking the wife to a day movie and late lunch. You can try me in the morning if you want.

Take some pics of the vac lines and send them to me.

 

[Baby J]

Thats cool Jason Thanks, i understand about the family thing i'll get with you first thing in the morning. not having any surging that i can tell, yes i have the boost/vac gauge. i 'll get with you in the morning.

 

[Goose17]

Data log it and check your air fuel ratios - specifically check air/fuel commanded vs. actual air/fuel. In the GT500, if fuel supply becomes inadequate at upper rpm levels, the throttle will start to close and boost will drop. A GT500 owner had this problem last week and discovered his secondary fuel pump wasn't working when I told him to look at his fuel delivery.

 

[Baby J]

SO everything is fixed, checked all the vacuum lines and found no issues, talked with TRBO VNM and also i believe Justin told me this as well, But basically adjusted the bypass actuator down (the bracket is sloted) preloading the bypaas and the problem is now solved. Car is back running like a champ.

 

[03cobra#694]

Thanks for posting the fix.

 

[spray'n mach 1]

Thanks for posting the fix.

x2

 

[Goose17]

Glad it was relatively simple. Enjoy full boost!

 

[TRBO VNM]

You're welcome Dave. Glad it's fixed, now enjoy it before the bad weather comes.