That's the Vacc reservoir we're talking about it's bolted to the block on a bracket under the intake.
Fixing ACIS...
- Thread starter Ma70.Ent
- Start date
Its really hard to see, from the top or bottom. Look in the f/s section for someone in your area parting out an n/a, and see if you can go take a peek. If the intake is off, you'll be able to see it easy.
Cuel is right. I don't think I could see it with the intake in with out an array of mirrors and a flashlight.
If you think you've got a problem with your ACIS system pull the upper half of the intake manifold and replace the vacuum lines. The vacuum lines are the most common cause for failure, then the VSV (either the coil fails, or the plastic nipples crumble from years of heat cycling), then the reservoir (either plumbed incorrectly or damaged.
Easy enough?
If you think you've got a problem with your ACIS system pull the upper half of the intake manifold and replace the vacuum lines. The vacuum lines are the most common cause for failure, then the VSV (either the coil fails, or the plastic nipples crumble from years of heat cycling), then the reservoir (either plumbed incorrectly or damaged.
Easy enough?
Can you believe that while I was putting together my engine... someone pointed at my surge tank and said... oh man! This car has an easily accessible fuel pump! That is so sweet! I definetely just looked at him and said ahhh yeah... gotta love Supras!
pfffft... yeah wow.
Now something to add to the actual topic... can the opening of this valve be changed? I truly wonder if something can be done to make this system even more beneficial.
pfffft... yeah wow.
Now something to add to the actual topic... can the opening of this valve be changed? I truly wonder if something can be done to make this system even more beneficial.
Setheroo said:
It's been covered before... by someone.
Anyway, the ACIS system is controlled by the ECU. Barring hacking the ECU's ROM, installing a daughter board with an EEPROM and a new program the most you're going to be able to do would be to build a piggyback to delay the VSV coil from energizing and/or possibly hold it high for a set time longer (such as when you're letting off the throttle momentarily).
At any rate, it is possible. It's even possible to do a bit more intelligently if the trigger and hold system you are using is tied in to a more extensible fuel controller. However, until you understand all the factors you should refrain from screwing with it.
It was pointed out to me recently that someone said that, once you start modifying the intake, exhaust, etc., you should disconnect the ACIS. So, since I have upgraded the intake, OBX header, cat delete, and 2.5" exhaust, I figured I'd help out and test this theory. At normal operating temp., I disconnected the vacuum line from the actuator and plugged it, leaving the valve in tho open position, and took it for a drive. Didn't really notice a difference until I hit around 4k rpms at wot. Got the surge feeling. This was really noticeable in first and second, but not so much in higher gears. I went back to the shop, and zip tied the linkage to the intake runner(leaving the vacuum line off), locking the valve in the closed position(removed the inspection plate on top of the plenum to verify). Drove the car, with a very noticeable difference. Under 2500 at wot, the car responded ok, but flatlined after 3k or so; just wouldn't pull like normal. Went back to the shop, cut the zip ties, and hooked teh vacuum line back up. The difference between a functioning and not functioning ACIS is very noticeable, modified or stock. I have a ported head and "264" cams that I'll be putting on a freshly built short block soon(hopefully). I'll be changing to 3" exhaust then as well, and I'll try this test again after it's completed.
Cuel: Thanks that answers a question I've had for awhile!
(Always wondered if the kick at 4000 was Vacc/airflow pushing the valve open on it's own when the system is broken)
(Always wondered if the kick at 4000 was Vacc/airflow pushing the valve open on it's own when the system is broken)
Would be really interesting for someone with a functioning system to hook a LED up to the vsv and see where it switches and under what conditions!
The valve is spring loaded to hold it open. That spring is heavy, to. Closing it from the linkage was kinda tricky, and I had to use heavy ties to make sure they wouldn't break. On a system that isn't working correctly, the valve is stuck open, which would be causing a loss of low end performance. Not much maybe, but any loss on an n/a is not good...
IJ. said:
I don't think it just fully opens or fully closes all at once. By the way it acted when I had it locked closed, versus fully opened, I think it varies according to vacuum pressure. The rpm's where I lost power with it locked closed were significantly lower than where I gained the "surge" with it open. Maybe mount some type of switch to the linkage, and a meter to read when it starts to open, and how long it takes to fully open? I have no clue how to go about that, as its not in my usual range of "expertise."
I could "guess" that with it being open, you're not getting the full positive effects until around 4k, at which time you feel the "surge." I don't like guessing though. BRB.
I did, to. :biglaugh:
Same results. Removed vacuum line, and tied the valve closed this time. Cold, running up through first at wot, there is a definite surge, but cold isn't a good test. Took it for a run to get some bbq, let it warm up good, then stopped, and started again from a dead stop at wot. From a dead stop(1st gear) up thru the lower rpm range, its hard to tell a difference, but when it hits about 4k, it pulls harder than below. Hooked the vacuum line back up, cut the ties off, and drove it again. The difference, again, between a working system, and one that doesn't, is definitely there. I can tell, even by "seat of my pants", that there is a difference between a functioning system, and one that doesn't. The best test would be on a dyno, which could, hopefully, determine exactly how much of a difference, but I don't have easy access to one.
Same results. Removed vacuum line, and tied the valve closed this time. Cold, running up through first at wot, there is a definite surge, but cold isn't a good test. Took it for a run to get some bbq, let it warm up good, then stopped, and started again from a dead stop at wot. From a dead stop(1st gear) up thru the lower rpm range, its hard to tell a difference, but when it hits about 4k, it pulls harder than below. Hooked the vacuum line back up, cut the ties off, and drove it again. The difference, again, between a working system, and one that doesn't, is definitely there. I can tell, even by "seat of my pants", that there is a difference between a functioning system, and one that doesn't. The best test would be on a dyno, which could, hopefully, determine exactly how much of a difference, but I don't have easy access to one.
cuel said:
That (as you've already discovered) is a HUGE load of crap.
True as you modify the intake the HP and Torque curves (HINT: there are actually TWO of each thanks to the ACIS) do shift. Given the mods most of you make you'll NEVER see the difference while driving or on a dyno. While porting may have the effect of placing you closer to the calculated target the designers had in mind changing your air filter, shortening or lengthening the intake tract prior to the TB and removing the intake resonator/reservoir are all going to have little to no effect on the ACIS system's ability to modulate when the reverberating airflow will come back at the valves.
With that said, there is the possibility of tuning the plenum acoustics to your preference for a fair deal of benefit for your driving style. With the ACIS as the only form of acoustic modulation you have two points where you can make peak power or torque per each respective curve. Changing the timing of the ACIS valve won't change this peak at all, changing the diameter or length of the runners, the volume of the surge tank and the amount of air moving per RPM will.