Hey guys, how do I adjust when the VDI kicks in? Mine seems to be kicking later than what it suppose to, any idea on how to change that?

 

The VDI should kick in around 5500rpm. When is yours doing it?

 

5300-5600, I thought it kicks in at 4500 according to the RX-7 book. Well this isnt just for me, my friend's VDI kicks in at 6300

 

That might be the 6 ports that open at that time.

Someine had dyno'd a moderately modded motor with the shut the whole time and then with the VDI wired open. The findings showed that Mazda did a pretty good job determining exactly when they should open.

 

Mabye the actuator is shot. It colud be frozen up. I don't know, just a guess....

 

6 port kicks at 3800

 

How do you tell when the 6 ports and VDI open up?

 

Isn't that the secondary injectors at 3800?
I don't see how additional grounding correcting the 3800 hesitation have anything to do with the 6 ports opening.

 

6 port actuators arms will retract or extend depending on the year of the car. It is easy to see.

Grounding is for the ECU(?) not sure here. Yes, secondary injectors come on when the 6 ports open.

 

So look at it and have someone rev the car to ~4200?

 

No, it must be done under load.

There's several thread about what to do, but you won;t be able to find them until after the weekend when the server is upgraded and the search feature is turned back on.

 

That doesnt work, the engine has to be loaded.

Tmak26b, are you sure thats when the actuators upen up? You wont feel a hit when the VDI opens. It opens slightly before the it becomes most efficient. The jump in power you feel is when it comes into the VDI's powerband. And that is differnt for every car, depending on mods, engine condition, etc. My VDI doesnt get into the powerband until 6K. But it still makes more power from 5200 rpm(where it opens) than with the VDI set for low end.

 

Hi Adam, the VDI problem I have is not on my car. It's on my friends 91. The problem he has is that his car would drop off torque after 4500rpm, where on my car (and other 89+ NA) it picks back up at 5300 and then drop off again near redline. On his the torque drops from 4500 to like 6300, thats when his torque spikes all the way up. So his VDI isnt openng up as well as mine.

Today we both hooked up a boost gauge on our car and see if the actuator is getting enough psi to open. It turns out we both have the air come out at the same time (5300RPM). But it seems like his actuator is harder to move compare to mine. We did this by blowing air into the actuator. The actuator maxed out quickly, where on his he needs a lot more. So I am suspecting a half froze *** vdi actuator. Is our observation right, what do you think? Also what is the fix? Take it out and clean it? Is there anyway to do it without removing it?

Thanks

 

I understood that it wasnt your car, but it was your question, and youre who my response was directed to,

It does sound like a stuck actuator. Its probably carbon deposits around the rotating valve itself. I would recommend buying 4-5 cans of brake cleaner or carb cleaner(Brake cleaner leaves less residue, but doesnt dissolve the carbon so easily), take the whole manifold off, and clean the whole thing until the runners are spotlessly clean. Its really less work that it sounds like. Definately a good tune-up thing to do to make your car run best.

 

Oh yeah I understand you are trying to help, I was just telling you that it was on his car thats all. Anyway, do carbon actually get in the VDI actuators? Thats interesting I never thought anything is inside that thing. Also do you think the water trick can work with teh VDI or not really?

 

Water trick- Nope, it gets sucked in through a vacuum line, after the VDI.
The best way to clean it is to take the TB off, anf just spray away with carb cleaner down the manifold.
Try taking the actuator arm off of the VDI mechanism, and truning it by hand, seeing how free moving it is.

 

The water trick removed carbon from the engine. It does nothing for the intake manifold. The only good way to do it is to pull the manifold off and take a few cans of carb cleaner to it.

And I would recommend NOT doing this with the manifold on the car. You dont want all the crap thats going to come out of the manifold to run down into the engine.