VSV's!!!!!

[Bigin1987]

What are the vsv's and what do they do?

And can you bypass them?

I have one on the drivers side ofthe motor and the wires are broken.

I need help on my other post too.

 

[AJ'S 88NA]

http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?S=FI&P=1

 

[Bigin1987]

Ok that link told me the vsv is for (FPU) but what does it do and can you bypass it to get it to work?

And what does the (FPU) stand for?????

 

[hvyman]

Fuel pressure up. You need it.

Supposed to be a rear one for egr as well.

 

[Yellow 13]

Are you not able to twist the wires back together?

 

[Bigin1987]

Are you saying I can just twist those two wires together and just run a vacuum hose instead of the vsv???

Also the other vsv is still there but the guy who had it before me got rid of the egr system.

---------- Post added at 07:32 AM ---------- Previous post was at 07:31 AM ----------

The wires broke out of the plug that plugs into the vsv. That why I was asking if I could just twist the two broken wires together creating a solid current and just get rid of the vsv all together?????

 

[jetjock]

Twisting the wires together would be very bad. Has to do with that solid current thing you mentioned...

 

[kotu100]

would the vsv be required running an aftermarket AFPR?

 

[AJ'S 88NA]

would the vsv be required running an aftermarket AFPR?

I'd say yes, still have mine

 

[Bigin1987]

Does anyone know where I can get the plug that the wires broke out of?

 

[hvyman]

phoenixtuning.com. Will have to call.

 

[jetjock]

I'm not saying Toyota didn't put the VSV there for a reason or that you should yank it off but consider this:

Except during the first 90 seconds after the engine has been hot started the valve is always dormant. After those 90 seconds it contributes nothing to how the engine runs whether it's working or not and it does nothing at all when the engine is cold.

Logic therefore tell us that if you're not experiencing problems with hot starts (and if you are one would think you'd have mentioned it by now) you can remove the valve and run the vacuum line directly to the manifold without effecting engine operation in any way.

On the other hand if you are having hot start problems (by that I mean difficult starts 30-60 minutes after shutdown) then go ahead and repair it.

In other words yes, you can bypass it as long as you're not having hot start issues. Or just leave it in there. Because it's normally open leaving it results in functionally the same thing as bypassing. That said if you do decide to remove it insulate the wires that were broken off. Do not twist them together or bad things will happen...

 

[AJ'S 88NA]

I'm not saying Toyota didn't put the VSV there for a reason or that you should yank it off but consider this:

Except during the first 90 seconds after the engine has been hot started the valve is always dormant. After those 90 seconds it contributes nothing to how the engine runs whether it's working or not and it does nothing at all when the engine is cold.

Logic therefore tell us that if you're not experiencing problems with hot starts (and if you are one would think you'd have mentioned it by now) you can remove the valve and run the vacuum line directly to the manifold without effecting engine operation in any way.

On the other hand if you are having hot start problems (by that I mean difficult starts 30-60 minutes after shutdown) then go ahead and repair it.

In other words yes, you can bypass it as long as you're not having hot start issues. Or just leave it in there. Because it's normally open leaving it results in functionally the same thing as bypassing. That said if you do decide to remove it insulate the wires that were broken off. Do not twist them together or bad things will happen...

Does it have something to do with not pumping fuel if the engine is not running JJ? Or is that something else?

 

[jetjock]

Not sure I understand the question AJ. All it does it vent the regulator (disconnect it from the manifold and connect it atmosphere) for 90 seconds or so after the engine is started with hot coolant. In turn what that does is increase fuel pressure. The point is to help get rid of any vapor that formed in the rail while the engine was heat soaking after being turn off.

Fuel pressure will increase slightly because the manifold is no longer acting on the regulator diaphragm. It's no different than pulling the hose off the regulator with the engine running the way you'd do the fuel pressure checks specified in the TSRM. Same with having the engine off. Both cases cause the regulator to "feel" atmosphere and therefore set default fuel pressure.

The MKIII uses Toyota's Type A (36 psi) fuel system. The TSRM procedure for checking the regulator is engine off (regulator at atmosphere), fuel pump jumped on, and fuel pressure between 33-40 psi. Why that range? Because 36 psi falls right in the middle of it.

 

[AJ'S 88NA]

Yes, thanks JJ. I thought it was the safety feature that if the engine wasn't running that it cut power to the fuel pump, must be thing of something else.

I just think anything that has to do with fuel delivery should be there, for safety reasons unless you are absolutely sure.

 

[jetjock]

You're thinking of the fuel cut switch in the AFM of the 7M. In the GTE fuel cut off is done by the ECU through the Circuit Opening Relay when CPS pulses are lost.

I agree things shouldn't be messed with unless they're understood. Especially safety related stuff. It's not only my nature but the nature of my profession. I understand many owners these days live in a different world though.

 

[AJ'S 88NA]

You're thinking of the fuel cut switch in the AFM of the 7M. In the GTE fuel cut off is done by the ECU through the Circuit Opening Relay when CPS pulses are lost.

I agree things shouldn't be messed with unless they're understood. Especially safety related stuff. It's not only my nature but the nature of my profession. I understand many owners these days live in a different world though.

Some may live in a mushroom cloud if not careful

 

[Bigin1987]

Thanks for that info. But would that vsv cause it to stutter and all that or is that a different problem?

 

[jetjock]

Nah, you have other problems.

 

[Bigin1987]

But other than timing (which is set at the specs) what do you think would cause the high rpm stutter, hesitation and bad idle be caused by?

Take into mind that I checked all sensors except for o2 sensor? Could it possibly be caused by the aftermarket fuel pressure regulator giving it to much fuel (which would be why it's running rich) to cause these problems?