ISCV confirmed dead, buy new or used?

[mstgeer]

Completely disassembled, cleaned, inspected and lubed shaft with minimal amount of white lithium grease.

The shaft and pintle appears to slide easily when compressing by hand, and returns with just the spring tension, without the stator housing in place. And the bearing feel smooth.

Assemble it all back togather, test with + power to the 2 middle posts and ground applied individually one at a time outer 4 posts and it just clicks, not any visible movement.

Anyway, is this an item that is generally ok to buy used or just bite the bullet and get new?


Strange thing is before removing and cleaning car would not idle cold with it plugged in. Unplug it and restart and it would idle at approx. 1200 rpm.

 

[jetjock]

Sure it's not stepping? Helps to put a cable tie or wire on the pintle to see it.

 

[mstgeer]

no, not sure if it is stepping or not. How far does it move at each of the 4 activation levels? Not sure I undestand "put a cable tie or wire on the pintle to see it". Could you please elaborate a little?

Just for the hell of it, I just reinstalled it on the car and...same results. If the ISCV is plugged in and started the car will not idle. Unplug it and restart the car and it will idle relatively smooth at ~1500 RPM, but does NOT do the up and down to 2k RPM that I have read in other posts.

I assume it is moving some, otherwise why would there be a difference plugged in vs. not?

With it plugged in I do hear 3-4 clicks when the car is shut off.

BTW, thanks for responding, I was hoping YOU would.

 

[jetjock]

Putting a "tail" on the shaft or pintle magnifies its movement and allows you to see individual steps. Think about the hands on a clock.

Do the coils ohm out to spec? Sure it didn't get bound up during assembly? If it clicks it should step.

About this 1200 rpm thing. Are you unplugging the valve after engine shutdown prior to restart or before? I ask because the clicking you hear is it stepping wide open which will result in about 1200 upon restart. It may be opening but not closing.

 

[mstgeer]

could not remember sequence so went to garage and...
ISCV was unplugged, plugged it in and started, and immediately dies and hear clicka, clicka, clicka, turn key off
Try a second time, same result, turn key off.
Unplug ISCV, start car and it idles, flucuates 1100-1200 rpm, turn key off, do not hear clicka, clicka, clicka.

Came up to post this.

When I took the valve off the 1st time to clean it, it appeared the pintle was not seated.

I considered it might be binding when I reassembled it, so I took it a part a 2nd time, and only tightened the small flat head screw just till they seated.

 

[jetjock]

Then it all comes down to testing it off the car. Just be sure you're testing per the book (it appears you are) and there's definitely no movement. Odd that it would click and not move though. If the motor is good electrically and the bearings are ok no movement should be repairable.

If no joy my suggestion would be to buy used and then clean/lube the replacement. New is powerful spendy...

 

[mstgeer]

Also, don't know if this has anything to do with this, But I have a connector that is not connected to anything.
It is a grey female 2 wire, white/black and yellow/not sure maybe brown strip and has the braided wrap on it? It is behind the PS res and appears to come out of the harness at the same point the oil pressure sender(i think that is what it is) come out. I have been studying the EWD and can't figure it out. BTW the car is a '91 turbo 5 spd.

Should I still test the coils, as it appears to be isolated to the ISCV?

---------- Post added at 12:27 AM ---------- Previous post was at 12:17 AM ----------

I was testing it by using test wires with gator clips, one to + on bat to one mid post, another jumpered from gator clip on 1st mid post to 2nd mid post, and another from - bat post to the 4 other posts, one at a time.

During start and cold idle is the valve suppoed to be seated or open?

Chance it is being fed wrong info from another sensor? I don't really know what activates it, but assume the cold start time switch maybe?

 

[jetjock]

Yes, ohm the coils if you can and then test the valve under power again like the book says. If it clicks but doesn't move either take it apart to find out why or buy another one. Me, I'd want to know why it clicks but doesn't move and I wouldn't let go until I knew.

Dunno what that connector is. I'd have to look at the EWD. It's not the two wire connector for the coolant sensor is it? Not that it would cause this particular symptom but it still needs to be hooked up for proper idle control.

edit: Test it like the book says.

The valve is fully open when the engine starts. As rpm crosses 500 it closes X number of steps based mainly on coolant temp. Thereafter it slowly steps further closed until the cold idle strategy ends. The other sensors involved have only a minor effect and the cold start injector system isn't involved at all. It's for cold start enrichment, not idle.

 

[mstgeer]

I know how you feel, it drives me nuts not knowing why something does not work like it is supposed to.

I will check to coils tomorrow.

From a visual, it appears all of the wires are connected at the water neck.

Would a pic of it help you to maybe identify it?

 

[jetjock]

Sure, post one. If I don't see it someone else will. Btw you don't have any codes right?

 

[mstgeer]

I pulled it up from behind the PS res to get a good pic.

 

[jetjock]

Dunno. Doesn't look like the coolant sensor but are you sure it's connected? The sensor is behind the water neck on the engine side of the thermostat.

I ask because if the coolant temp sensor is open (code 22) the ECU defaults to thinking the engine is always hot. That means a cold start and cold idle will be problematic even with the valve working in that the valve will immediately step to the hot idle position. Add in the lack of cold enrichment (the coolant sensor is also used for that) and stalling usually results. As soon as the engine warms up these issues disappear because engine temp becomes equal to the default condition. Not quite the same as your problem but...

 

[mstgeer]

Sure, post one. If I don't see it someone else will. Btw you don't have any codes right?

No codes now, did have a 24 and 31, until I switched AFM elec. 2 days ago.

 

[jetjock]

Ok, then check the valve until you had a definite answer. Confirmed means confirmed. Good luck...

 

[TurboStreetCar]

When wiring my standalone to the valve i found the sequence that power needs to be applied to make the valve open and close. Ill find and post it.

Found it, It was on the EMS 8860 Tech forum.

Power The center "B" terminals with constant 12V

To open/close the valve you need to power the coils in this order: S3-S2-S4-S1 or S1-S4-S2-S3

This page shows the terminals of the connector: http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?S=FI&P=107

I know this sequence to be true as its what controls the ISC on my car and i have bench tested my ISC to find this out so i could wire the standalone properly.

I know it doesnt make sense but it works for me.

Another thing is that you need to do the full sequence. If the coil you energize isnt close enough to the position of the magnet it wont make a change. You need to power the coil nearest the magnet and to do that you need to keep with the sequence until you find it. It also moves very slow when testing in this manner.

 

[mstgeer]

is it different than what is listed in the TSRM?

 

[TurboStreetCar]

Tsrm says to go 1-4 in order. I found this order to work. Kind of against logic but its something else to try that's free, its the sequence my standalone uses to control my idle.

 

[mstgeer]

Well, it appears that the ISCV, was a sympton and NOT the ailment. I mounted it back on the car, except to the intake manifold, covered the hole in the intake manifold, and attempted to start the car.
The valve is clearly actuating, and returned to its seat when the key was turned off. I don't know why it did not react when tested per the TSRM.

So I hooked everthing back up and took the car for a drive, it was a little chilly so I turned the heat on full high. Drove around 10 miles round trip back home and...have a trail of fluid...antifreeze, WTF.

Pull the car in the garage and fluid is pouring out of the floorboard!!!! I have a severe sinus issue and never smelled the coolant in the car.

Appears the heater core is shot.

What I can reason is why that would effect idle?? Air in the system causing erronious signals from the temp sensors?

I bypassed the heater core, refilled the system and the car appears the ilde fine now. It was late, so I did not drive it, but did let it come up to op temp and it never stumbled once, and VF signal never went above 2.5v, from idle to reving up to 3k. It would drop down to 1.25 and 0 as rev'd and right back to 2.5 at idle.

Hope to get a chance to make another short run this evening.

 

[3p141592654]

Ref: http://www.supramania.com/forums/showthread.php?t=72109&highlight=stepper
Author: Figgie

The Toyota IAC is a 6 pole design stepper. Usually labeled S1-S2-S3-S4 for the switching ground and B1-B2 for the 12+ vdc. This automatically makes the stepper motor a unipolar designed stepper motor. What this means is that the stepper motor receives the the energy in only one direction... B1-> S1, B2 -> S2, B1 -> S3
To open the pintle the sequence would be
S4 B2
S3 B1
S2 B2
S1 B1
S4 B2.. x 125
this sequence is controlled by the TCCS. To close the pintle it would be the exact reverse.
S1 B1
S2 B2
S3 B1
S4 B2
S1 B1.. x125
According to all the research I did. The Toyota IAC shows 125 steps but in reality it has close to 255 steps. Also it is quick and if the standalone has adjustments it must be set to at least .25 seconds per step or 4 steps a second.

 

[mstgeer]

That is good info to know. Too bad toyota did not think it was relavant enough to put in the tsrm. It no wonder I could not see it move.

On a side note is the VF signal of 0 to 3.75 a definative indication that motor has a safe a/f ratio?