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View Full Version : TU Cal and hooking up to solenoid questions (VNT to TII)



kpic
08-30-2006, 07:38 AM
Don’t know if this is possible (or if I am in the right section).

What I have: 1990 Daytona VNT currently has a TII type turbo hooked up to a MBC along with a TU Cal.

What I would like to do: remove the MBC & hook up the wastegate to the solenoid allowing the computer to set boost as per factory setup.

1. I assume this would work but my spec sheet with the custom cal came saying this:“Boost setting 19psi (intended for use with manual boost controller)” guess I checked off MBC when ordering if there was that option? but I did give a max boost setting I wanted (19). Is this something that can be programmed? At one time I did hook the turbo to my VNT #1 solenoid but I only got 5psi or so. Maybe I hooked up something wrong.

2. If #1 is possible; Will the wiring connections I have now work with an earlier wastegate solenoid setup? Since I no longer need VNTs # 2 & 3 it would clean up the firewall a lot! Would I be able to plug the connection from my VNT #1 into say a 1989 wastegate solenoid??

3. Finally if I end up having to use the MBC only can I unplug the wiring from all of the solenoids and remove them (not sure if the computer checks for them?)

MiniMopar
08-30-2006, 10:07 AM
If it is truely a T2 cal, then it is only looking for one wastegate solenoid. Which one of the VNT solenoids, if any, is that hooked up to? I dunno...I don't have the 1990 wiring diagrams. You would have to plumb the solenoid just like the stock T2 setup, where you have the wastegate connected to the common (center) barb and the manifold connected to the bottom barb.

ShelGame
08-30-2006, 10:20 AM
The VNT and '90/91 2.5 T1 use the same codebase. Which means the T1 boost control routine is included in the VNT cals. So, it's just a matter of "turning off" the VNT bosot control and "turning on" the T1 boost control. But, the WG plumbing will NOT be like the T2, it will be like the T1.

That's all assuming Paul did the boost control swap and reconfigured the WG duty cycle tables for T1 boost control. Since the cal was originally setup for manual boost control, who knows if he did that.

MiniMopar
08-30-2006, 10:47 AM
Oh yeah, good call. In that case you need to block off the bottom barb and route the manifold pressure (or the turbo outlet tap pressure) to the wastegate. The center barb on the solenoid T's into this line via an orange restrictor.

kpic
08-30-2006, 01:55 PM
http://img226.imageshack.us/img226/6466/untitled1yi4.jpg

Ok maybe the link to a scan of the info sheet I got will help.
I think a while ago someone told me that the VNT #1 solenoid is the one that controls the boost. In the pics at the bottom of the sheet it shows the what I think is a standard TI or TII (are they different?) solenoid. Also in the pic it shows a line with a restrictor in it, I do not have that would I need one?

kpic
08-30-2006, 02:03 PM
If the use of a wastegate solenoid needs to be "turned on" and if my CAL is not provisioned this way can I then remove the solenoids?

MiniMopar
08-30-2006, 02:04 PM
It's hooked-up wrong in that picture. Yes, you need the restrictor. The late T1 style of boost control is literally a bleeder-valve setup but with a solenoid as the bleed. The restrictor evens-out the pulsing action of the solenoid.

1985 - 1987 T1:
http://minimopar.knizefamily.net/images/vac-t1-87.jpg

1988+ T1:
http://minimopar.knizefamily.net/images/vac-t1-88.jpg

MiniMopar
08-30-2006, 02:05 PM
If the use of a wastegate solenoid needs to be "turned on" and if my CAL is not provisioned this way can I then remove the solenoids?

Assuming that the diagnostic check for the solenoid has been disabled by the fact that the cal won't try to use the solenoid in the first place, then yes. You'll know...just disconnect them and see if it throws the code for the solenoid.

kpic
08-30-2006, 02:38 PM
Ok, so I am going to disconnect wirning to the solenoids if I get a code then I know the CAL can automatically use them (or does the CAL still need to be written to use them even though it sees that it is disconnected)

If it can then all I need is a TI (year specific?) W\G solenoid?

My hookup would look like this: Solenoid has bottom barb blocked, middle barb tees into the wastegate to vac source line (this is the line that would have a restrictor in it) and top barb would have that foam filter thing?

The middle barb of solenoid tees into a line that connects the wastegate with a vac source. Whew!

MiniMopar
08-30-2006, 02:42 PM
Yep. Basically the manifold source pressurizes the wastegate can (opening the wastegate) and the solenoid bleeds it off (closing the wastegate).

If you disconnect one of the "other" solenoids and you don't get that VNT-specific wastegate code, then you know that at least it doesn't think it's a VNT. If you disconnect the #1 solenoid that supposedly is the normal wastegate driver and you don't get a code, then you know it isn't trying to control the wastegate at all. You may have to drive the car each time to trigger the code, though

kpic
08-30-2006, 02:46 PM
OK, so I disconnected the 3 solenoids and got a check engine. Re-connected and it went out. So my computer is looking for them but again I guess I have no idea if it is able to use them just because it throws a code, is that right?

If so this is the worst of all situations as I have to leave all of the solenoids hooked up there even though they cannot do anything. And that would throw out my idea of just using a TI solenoid on it's own.

kpic
08-30-2006, 02:48 PM
Good idea , I'll just disconnect the #2 & 3 solenoids.

MiniMopar
08-30-2006, 02:48 PM
You can replace the solenoids with resistors if you really want to clean up the engine bay. Anything around a 500-ohm resistor (1/2 watt) will do.

kpic
08-30-2006, 02:59 PM
Well it knows it's a VNT. I dsconnected the #2 & 3 and got a CEL. So I guess I could hook up the VNT #1 solenoid to control boost but unfortunately the vac diagrams for a 90 VNT do not show a routing for the #1 solenoid? not in my service manual anyways. That is if it is even capable?

If I go that way I could disconnect the other two using the resistor method you described do you just disconnect and join each end with a resistor in the middle? Sorry , never used one before so not sure. Are they harmful to the computer or wiring?

kpic
08-30-2006, 03:12 PM
OK, further update I unhooked the #1 solenoid only and did not get a CEL. So my computer is not able to control it , Paul must have not enabled that circuit.

Guess I have to keep the MBC and use the resistors on the solenoids in order to remove them.

MiniMopar
08-30-2006, 03:13 PM
I'm wagering that it's not the #1 solenoid that the SBEC is trying to drive. A little more trial and error to see if it is #2 or #3 that is being used for the wastegate.

kpic
08-30-2006, 03:37 PM
You were right. The #2 & #1 disconnected does nothing. The #3 (the one next to the purge solenoid) sets a CEL.

In that case I can get a TI or TII bracket and place the purge and #3 solenoids in it and remove the #2 and #1 sols.

As for hooking up, the 90' vac diagram shows this solenoid going between one of the wastegate sources and the compressor side of turbo but no restrictor in line.
Since I do not have a VNT turbo anymore would I hook up basically the same way (w\gate to middle barb and vac source to top barb - diagram shows bottom barb open or blocked) or should I hook it up like the way described above as in a TI (would the solenoid be the same or do I have to obtain a TI solenoid?)

ShelGame
08-30-2006, 03:38 PM
I'm with Russ on that - I think the #2 VNT solenoid uses the same output as the T1 WG solenoid. So, if you can disconnect #1 and #3 and don't get a code, then the T1 control is probably enabled.

That doesn't mean that he configured the tables/constants for T1 boost control, though. The VNT uses some of the same table addresses as the T1. So, if he didn't re-configure those tables/constants, it still won't work under computer control even with the T1 boost control technically enabled...



EDIT: looks like you beat me to it. #3 must be the common WG output...

kpic
08-30-2006, 03:46 PM
Got it, I have to hook it up as a TI and try it out. If it is set up to control it I get the PSI it was programmed for and if it is not what would happen?

MiniMopar
08-30-2006, 03:55 PM
Well, either you will get very little boost (solenoid isn't opening), overboost (solenoid is not closing), or crazy erratic boost due to the issue Rob brought up.

kpic
08-30-2006, 04:04 PM
The 88'-up TI diagram shows two restrictors, one between vac source and w\g and the other between the w\g and solenoid. Any idea what the P\N is for them or are they the same?

MiniMopar
08-30-2006, 04:13 PM
I forgot about the other one. I think they are the same, orange restrictor...but my memory of my old 88 is fading. If that is the case, then you should be able to pick-up two restrictors of the same size and it should work OK. Sorry, I don't know the exact size offhand. Gus or somebody had a chart that showed the colors and sizes. Motormite (Help! or Vacu-tite or whatever) sells a restrictor that is roughtly the same size.

Also, my comment about that picture you posted being wrong is wrong. I thought they put the restrictor in the wrong place.

kpic
08-30-2006, 04:22 PM
OK, thanks for all the help! The pic of the w\g solenoid is correct then? Thats what I thought you meant was wrong.

MiniMopar
08-30-2006, 04:29 PM
OK, thanks for all the help! The pic of the w\g solenoid is correct then? Thats what I thought you meant was wrong.

Yeah, except they don't show the other restrictor between the solenoid and the "T". Also, traditionally the manifold pressure source for this setup is the tap on the turbo compressor outlet. It works just about anywhere as long as it is kept away from the vacuum source used for the sensors/FPR/etc.

kpic
08-30-2006, 04:30 PM
Appreciate all the help! I learned a lot today!

ShelGame
08-30-2006, 04:46 PM
Got it, I have to hook it up as a TI and try it out. If it is set up to control it I get the PSI it was programmed for and if it is not what would happen?

Just looking at the tables, if he didn't change them, then it looks like you'll probably get more sluggish boost response (hard to say if you'll actually notice), and probably at least some overshoot (showing up as creep) of the boost target. That's my guess.

You can tune the boost response to a certain extent using the restrictor between the WG can and compressor housing...

kpic
08-30-2006, 04:52 PM
You can tune the boost response to a certain extent using the restrictor between the WG can and compressor housing...

Mine would go between the can and a vac source as I don't have a stock turbo, but should not make a difference? Tune it as larger orifice restrcitor = more lag\sluggish and smaller orifice = quicker response?

ShelGame
08-30-2006, 06:08 PM
Mine would go between the can and a vac source as I don't have a stock turbo, but should not make a difference? Tune it as larger orifice restrcitor = more lag\sluggish and smaller orifice = quicker response?

Yep
- Bigger restrictor = less boost, sluggish
- Smaller restrictor = more boost, faster response