View Full Version : Fixing ACIS...
Ma70.Ent
12-26-2007, 01:48 PM
I'm looking to add this info to the N/A Upgrade FAQ above this topic. So I'd like to know how you are supposed to fix the ACIS if it stops working? If you can, be as specific as possible, thanks.
BorHor
12-26-2007, 01:50 PM
Make sure the vac line is plugged in.
Making sure that the parts inside of the intake aren't all gummed up from the egr and pcv systems. Both of those systems need to be in good operating condition as well. The PITA part of it is that its hard to get to the components under the intake.
RazoE
12-26-2007, 02:15 PM
making sure your surge tank isn't missing (like mine) might be a good start, too...
BLACKCAT
12-26-2007, 04:33 PM
I might try to fit one on at a later stage but here is a chart that shows the impact on the torque curve.
Start by manually moving the linkage below the CSI. Then if that's good run a hose from a vacuum pump to the diaphragm (which moves the linkage) and check that it's responsive when vacuum is applied. Next test the VSV, this is covered in the TSRM. Those and vacuum leaks are the most common issues.
If anyone wants to flesh this out a bit better, have at it.
suprarx7nut
12-27-2007, 01:15 AM
CRE is online! :runaway:
On topic:
After seeing my slightly gummed up upper intake, I'd second the "check intake cleanliness" suggestion.
I'll have to take before and after shots when I clean out my intake mani this winter break. I bet I'll have a black spot the size of small car on the driveway.
Cleaning may make it more effective, but generally, if the butterfly valve isn't moving the car saw 200,000+ miles, all driven by a granny, all in 3rd gear, while cruising at less than 30MPH (Yes, Sparky, we're referring to your car here :icon_razz ) or something else broke first. Moving parts become impaired as debris builds, but they don't stop moving from it... at least not from this kind of debris, now rocks... you got rocks blocking it, then, then you've got a problem (and probably a mad neighbor who would like to know where his prized rock collection keeps going late at night). ;)
I'm not saying not to clean it out... not by a long shot. Mine was filthy and so was SupraRX7Nutter's. It's definitely worth cleaning out, but if that's all there is that's keeping it from moving then you've got something else to look for (see: cracked diaphragm and cracked vacuum hoses) as it should have a lot more pressure moving it.
making sure your surge tank isn't missing (like mine) might be a good start, too...
Or plugged in backwards as there's an IN and an OUT on them.
Or plugged in backwards as there's an IN and an OUT on them.
An EXCELLENT point. Rerouted vacuum lines are too common of a source of major grief... need to make sure VSV's are plumbed properly as well.
suprarx7nut
12-27-2007, 10:16 AM
Cleaning may make it more effective, but generally, if the butterfly valve isn't moving the car saw 200,000+ miles, all driven by a granny, all in 3rd gear, while cruising at less than 30MPH (Yes, Sparky, we're referring to your car here :icon_razz ) or something else broke first.
:rofl:
You funny motherfucker.
Ma70.Ent
12-27-2007, 09:29 PM
I've put a link in the N/A Upgrade FAQ to this topic.
Hopefully I'll figure out if mine works correctly or not. It probably does, but I'm paranoid and I HAVE to know :D
To add to the thread though, I assume I could just unplug the vac line then drive it and see if power is greatly noticeable at 4k+ rpm, then I'll know if it worked before or not.
suprarx7nut
12-27-2007, 09:56 PM
On mine, I can actually feel and hear a difference once it kicks in.
If I'm flooring it in 2ng gear i can feel a little bump of energy right at ~4200 rpm. I can't feel it in first or 3rd, but almost always 2nd.
Hmmm... I used to get that same thing in first and second. Found a thread over on SF on ACIS, so I went through the system, cleaned out the intake(the valve and linkage had sticky spots. I couldn't close the valve all the way by hand), checked all the vacuum lines. Now it pulls smoothly through every gear, and pulls well. If it isn't working correctly, I'd be very surprised.
My understanding of the system is that you only feel the 4000 rpm step when it's NOT functioning correctly, the transition is meant to be seamless.
suprarx7nut
12-27-2007, 11:46 PM
My understanding of the system is that you only feel the 4000 rpm step when it's NOT functioning correctly, the transition is meant to be seamless.
Hmmm..... well I'll be cleaning out my intake thoroughly sometime in the next few weeks, I'll update here if I notice anything.
Although I was pretty sure the valve abruptly opens and closes which leads me to think it would have a noticeable point of activation.
Ok, now i have a theory... I always seem to notice mine much more the first time I floor it beyond 4k. The subsequent pulls never seem to be quite as noticeable. Maybe it sticks or something the first time, after which it moves with more grace. :dunno:
I'm assuming that's what the Vacc reservoir is for to open at a set rate so you don't notice it snapping open....
ACIS lag? j/k
The coolant line for the ISC valve runs under there to. Could be heat from the coolant has slightly melted one of the vacuum lines under there if they where touching, either putting a pin hole in it, or maybe collapsing it. Just a thought.
need an "EACIS" controller!
"ACIS just kicked in Yo"
This thread popped up right in time. I'm looking for the part that's circled in black (disregard everything else). I've looked all over and found a few parts that look similar but don't have the nipples for the hoses. Does anyone have a picture of their engine showing where it's at? It'd help a lot with fixing my ACIS.
http://img.photobucket.com/albums/v633/DarkSaiyanWarrior/surgetank.jpg
That's the Vacc reservoir we're talking about it's bolted to the block on a bracket under the intake.
^^ Right above the motor mount
RazoE
12-28-2007, 11:05 PM
yeah, my car's missing that part too....
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?
Setheroo
12-29-2007, 01:43 AM
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.
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.
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)
Ma70.Ent
12-30-2007, 04:41 PM
I posted up Cuel's info in the N/A Upgrade FAQ too (he PM'd it to me at first) :)
Good stuff.
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...
So what explains the 4000 kick when you had the Vacc line off?
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!
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."
Hmmm, interesting point. Maybe I need to try tying it open, to make sure it stays open.
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.
LMAO Cuel heads off with a handful of cable ties ;)
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.
It was pointed out to me recently that someone said that, once you start modifying the intake, exhaust, etc., you should disconnect the ACIS.
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.
My favorite teacher once said, "Never believe anything I tell you is true. Go do your own research, and find results that are based on fact." It would be hard to argue the fact that it works exactly like its supposed to without testing it, and getting actual, real world results. I already had a pretty good idea that with just bolt-ons, there wasn't gonna be any change to how the ACIS operates, or the fact that it works quite well. Wonder what effects longer duration cams, with a higher lift, are going to have, if any.
I am curious about the 2jz plenum idea, though...
I suspect that different cam duration and lift may not change things too much. Different cam timing would probably move the peak of the curves to a greater and perhaps more noticeable degree.
What 2JZ plenum idea? GE or GTE? The GTE design seems a pretty poor idea for a N/A. They made so many changes from the MKIII to the MKIV and they kept the same style intake for the N/A. Now if someone's talking about fitting on a MKIV GE intake I'd be interested in knowing the differences.
TurboFreak
12-30-2007, 10:58 PM
So I was fiddling with this and I definitely fixed mine! It's a night and day difference. Even when I picked my brother up he mentioned my car felt better/faster/sounded better and he's not even into cars!
CRE: It was the GE plenum. It was being discussed over on SF. I'll have to find the link again. The ACIS system on it is supposed to be identical to ours, but a bigger valve or some such.
Edit: http://www.supraforums.com/forum/showthread.php?t=227121&highlight=ACIS--+acoustic+performance+thread
Defiant7M was talking about it, but not really in depth.
AJ'S 88NA
12-31-2007, 09:29 PM
I've noticed with the runs I've logged with the Maft -Pro that the ACIS at mid to WOT always opens at 4k. It makes quite a difference in the AFR when it does the lean direction.
I don't know what the AFR does with the stock ECU as I just installed my WB with the Maft-Pro.
Cre: You've run the stock O-2 with the Maft-Pro, have you noticed about 2-2.5 lean spike around 4k?
It's closer to 4200, and yes, as far as I recall I saw about the same.
I did mention that there will be some finer tweaking available for that soon, didn't I? First, you'll want to get the basis mastered. If I didn't tell you about that shoot me a PM or call me tomorrow.
YES, I'm bumping a very old thread.
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!
I'll go one better and log it.... granted I am N/A-T now so my results may be a bit incomplete due to higher manifold pressure at lower throttle, but it's a start. AJ could log his though for a closer image of things... his car's not stock either but it's closer than mine.
Does anyone know which pin at the ECU is the ACIS VSV? I'm assuming it's VSV1 or VSV2 next to the OX pin.
supraduper
11-07-2009, 05:28 PM
90 percent sure its vsv1
i glanced at the wiring diagram the other day in the tsrm
Yeah, I'm not even seeing VSV2 listed in the TEWD.
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