I am in the process of doing a wire tuck, and would like to know what this solenoid does. It is connected between the intake manifold and the FPR. My question, will megasquirt control this solenoid or can I get rid of it and it's connector? thanks

 

I have a similar question posted on the "other" forum
Probably the same function but placed at another place (between FPR and manifold vacuum).
I know I don't control it with my DIYPNP, so it will work with it disconnected (or removed and direct connection from the FPR to the manifold).

But it might have a function for cold start or something (since the JDM don't have it on the same year, and they have/had other emission standards).

 

it's for the "Vacuum Constriction Device". the hose needs to lead to somewhere under your steering wheel for proper operation.

 

I was going to ask over at clubroadster in the 'wire tuck' thread, but thought I'd get more help over here since it's more Megasquirt related. Now it wouldn't seem that way, judging by the 2nd response.

 

I removed if finally last week, still making 233rwhp so I suppose you can remove it Did it as I needed to retune fuel anyway.

I think it has something to do with idle control with the OEM ECU?

 

would you mind adding the year of your car to your profile somewhere or at least telling us what it is? then anyone can just pull up a manual and answer your question.

 

I believe it is the Pressure regulator control solenoid. I pulled mine off when I went full standalone with MS3. I also believe that it can be used as a vics control solenoid.

 

more than likely you could use is as a boost controller as well. Looks just like what the rx7 uses for boost control

 

That is very possible. I know when Braineack and I were trying to figure out what mine was, it did look a lot like a boost controller. Now we just need someone to try it.

 

if its like the rx7 one the top part is probably a cap
on the rx7 there is like 5 of these, soem are capped some aren't.
From research I think its 30hz for the rx7, have not tried it yet because I need the boost controller circuit pieces. but I will soon enough.

 

Oh sorry, I actually do have "1994" in my sig, but I have no idea why it doesn't show up.

After emailing DIYautotune, they told me that it is not used by MS. And after more searching it does appear to be PRC solenoid, although I don't know how or why it is controlled by the stock ECU. Either way, I too am quite curious if this can be used as a boost control solenoid.

 

I've been trying to figure this out as well.

With the Link ECU, the vac lines from mine are disconnected so it's just sucking air.

Went searching then found this


from M.net

The '96/7 PRC solenoid is intended to prevent fuel in the rail from boiling by keeping the pressure high in a hot restart situation. The solenoid admits atmospheric pressure to the FPR, instead of manifold vacuum, for long enough to get overheated fuel back to the tank. During this time the ECU leans the mixture a few percent to allow for the increased pressure difference across the injectors.

HTH
Rod

PS: for others who may be reading this ... on a boosted car with a parallel engine management system that is not aware of the stock ECU's PRC period, you can run into trouble because the normal fuel pressure increase (with boost) is absent during the active PRC period, making your fuel tables too lean ... so don't do a "quick get-away" on a hot-restarted engine. This can also apply to '96/7 + AFPR set-ups if the AFPR vacuum hose is tee'd-off after the solenoid.

 

So the whole hot restart lean threads we see around here could very well not be related to IATs but boiling fuel in the rail?

 

Late late bump. What did everyone ever figure out from that last post. I have hot restart issues with my ms2 and it's not mat issues at all. I'm wondering if removing this we'll help or make it worse?

 

I used it to control vics on eds motor.

 

So can pull mine off of my 94 since the ms doesn't use it and I'm not running vics

 

Just to update this. Yes I could and did pull it off.

 

Even later late bump.

I just wanted to confirm the MSLabs MS3 does not control this solenoid correct?

If you remove the solenoid do you just put a vacuum hose from the FPR to the intake manifold I assume?

 

no one controls it. I've wired it up on a few setups as I've wanted NB owners to start trying to use it to battle the hot-start issue...

 

Make your ASE and taper curve roughly resemble the side profile of the Eiffel tower and you'll solve your hot restart issues. ish.