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1G IPS wire missing

Robert503

10+ Year Contributor
115
4
Oct 19, 2008
Newberg, Oregon
Trying to locate the wire that is supposed to be connected to my IPS.

The only wire (white with black stripe)I see nearby is hanging out of the harness on the fire wall near the throttle body.

Didn’t come across any wiring diagrams while searching. Any advice?

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19Eclipse90

DSM Wiseman
5,277
1,144
Sep 29, 2003
OKC, Oklahoma
Assuming this is the 1990 listed in your profile - the one you have pictured is the Engine Speed Adjustment Connector. The IPS wire should be coming from the connector for the throttle position sensor. This is originally grouped with a couple other connectors underneath the injector resistor pack (and its connection). The others are the CAS and the ISC connections.
 

Robert503

10+ Year Contributor
115
4
Oct 19, 2008
Newberg, Oregon
Assuming this is the 1990 listed in your profile

It is the 92 TSI sorry for the confusion. Does this info still hold true for a 92?

I’ll check it out once it’s light here in a little bit. Seems like I have a couple wires not in there homes then. The car runs good no idle surge, idle sits around 1050rpm once warm, never hesitates.

The only time I get a low idle/stall is when I am under moderate throttle/acceleration and then I let of the throttle quickly and put it in neutral (like trying to make it through a green light but it changes to yellow.
 

19Eclipse90

DSM Wiseman
5,277
1,144
Sep 29, 2003
OKC, Oklahoma
It holds true so far as that connector you have is still the Engine Speed Adjustment Connector.

The idle switch on '91+ had a single wire connector with a green wire. It should generally be in the same area as you're looking.

Refer to the diagram below: the connector [B-05] should be on a branch with the ISC control actuator connector [B-04], prior to the Knock (Detonation) Sensor connector [B-07] and EGR Temp Sensor Connector [B-08]

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wparks

10+ Year Contributor
63
23
Mar 19, 2012
Fort Collins, Colorado
When I rebuilt the throttle body on my '90 GSX I observed that the throttle position sensor wires and IPS wire were together on a short harness clamped on to the throttle body that came out to a common squarish connector on the side of the throttle body itself. Trace the wires from the side of the throttle position sensor down to that connector on the throttle body, and the IPS wire should be coming out of that connector- it could be hanging free down in there somewhere. (Picture of a crappy throttle body I had as a core- shows IPS wire coming down to connector)

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Also, a 1G wiring diagram is available on this thread (they have it posted as pdf on drive)

 

steve

DSM Wiseman
14,865
1,721
Feb 3, 2002
Boulder, Colorado
As shown above the 90 IPS wiring is part of the TPS connector. On a 91-94 the IPS wiring is part of the bundle that the ISC harness is in.

Here's a better picture of the 90 cabling, I looked and didn't find a good picture of the later harnesses.
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Robert503

10+ Year Contributor
115
4
Oct 19, 2008
Newberg, Oregon
Okay I found the green wiring hanging all lonely under the intake manifold, thank you I appreciate the help turns out it is hard to see in the dark and a flash light. I’m gonna hop in the car and see how it performs before adjusting anything.

Now for the Engine speed control plug on my firewall in my original pictures that I was mistaken about, any pointers on that? Thanks for the help
 

Robert503

10+ Year Contributor
115
4
Oct 19, 2008
Newberg, Oregon
Reconnecting the IPS definitely gives me a cold idle surge.

Edit - let it warm up and the surge went away. Took it for a drive and tried to get it to stall like I described before and it wouldn’t happen, it’s a lot happier finding it’s idle now. The cold idle surge worries me and I still need to figure out the engine speed adjustment connector before I try and tune anything in, that could very well have to do with the cold idle surge.

Also I’m not having much luck searching for engine speed adjustment. Is the engine speed adjustment and Idle speed control two different things?
 
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wparks

10+ Year Contributor
63
23
Mar 19, 2012
Fort Collins, Colorado
When the car is warm and all accessories are off, the idle should settle in around 750 RPM (your dash tach should be accurate enough to check.) If it is in the ballpark you should not need to do an idle speed adjustment.

It is likely it's time to pull your throttle body, (don't just spray cleaner down into it, there is a cavity and mechanism in the bottom that you don't want to get cleaner into.) The throat of the throttle body probably needs a good brushing/wiping out, and you can pull the idle speed control stepper motor and clean it's nose and seat in the throttle body as it's probably gummy.

The single terminal on the IPS will show continuity to ground when the throttle is closed. Make sure that you get good continuity to ground when the throttle is closed as I have seem many of those that get flaky.

I would also check the base timing- On the firewall near the speed adjustment connector is another connector that you connect to ground to measure this- Engine warm, all accessories off, timing light should show 5 degrees before top dead center. This adjustment is sensitive and has a big impact on idle smoothness.

BTW- you really need to try to find a factory service manual for the main car, and the second book for the electrical system if you can, Chilton, Haynes etc if you can't.
 
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Robert503

10+ Year Contributor
115
4
Oct 19, 2008
Newberg, Oregon
BTW- you really need to try to find a factory service manual for the main car, and the second book for the electrical system if you can, Chilton, Haynes etc if you can't.
Thanks for the reply, I will order the service manuals asap it is a early 92 with a 6 bolt so is there a specific one I should order? Or just the 92 talon manual?

Just checked the IPS since it was simple and that checked out. Continuity to ground when throttle is closed.
I will work on getting the throttle body off and cleaned up along with the idle speed control and test the motor as well.

Still confused on where my white with black stripe wire goes tho I can’t find anything on engine speed adjustment

I will check out the timing also. Not sure what connector you were referring to to connect to ground to check timing
 

19Eclipse90

DSM Wiseman
5,277
1,144
Sep 29, 2003
OKC, Oklahoma
The engine speed adjustment connector is not connected to anything in normal operation. It is available for diagnostic purposes, where one could connect an engine tachometer to this pin and get a engine speed reading.

The ignition timing adjustment connector is the one you need to ground when setting base timing.

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Robert503

10+ Year Contributor
115
4
Oct 19, 2008
Newberg, Oregon
The engine speed adjustment connector is not connected to anything in normal operation. It is available for diagnostic purposes, where one could connect an engine tachometer to this pin and get a engine speed reading.

The ignition timing adjustment connector is the one you need to ground when setting base timing.

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Thank you very much that clarifies a lot. Located the plug for checking the timing, the water proof cap seems to be missing unfortunately. Also came across a very useful thread for checking timing and setting biss

Previous owner seems to have used gasket maker on the throttle body and elbow and that stuff does not want to let go. I got the 2 nuts and 2 long bolts out, the bracket out of the way, 4 vacuum lines undone and cable undone Tapped on the elbow with a rubber mallet and it doesn’t budge
Got the elbow off and cleaned both sides of the throttle plate as I could with carb clean on a rag. Both sides shiny again with not much residue left. I’m sure I need to pull it off completely to clean it properly but hopefully this will help some.
 
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wparks

10+ Year Contributor
63
23
Mar 19, 2012
Fort Collins, Colorado
Since you have that ECU open, order a capacitor replacement kit like this one:
and have a local TV repair shop, friend, or someone at a local maker space replace the capacitors (unless you can do it properly yourself). Russian roulette if you don't.

The ignition timing adjustment connector (and the fuel pump check connector) are located on the firewall right next to the negative terminal corner of your battery as shown in the picture. The fuel pump test connector has one pin. You connect 12V to that to run the fuel pump.

The timing adjustment connector (A-60) right next to that is the one that has two pins- one pin will have a voltage, the other is disconnected. I'm sure someone will post the appropriate section of the manual, but in a nut shell, to adjust base timing:

Make sure the engine is warmed up, then shut it OFF. Use an alligator clip test lead to connect the pin that has voltage to ground. Connect up your timing light (make sure you use cylinder 1 closest to the accessory belt (I know you know this)). Start the engine, and check the crank pulley timing mark against the gauge. If it's not 5 degrees BTDC you will need to shut off the engine, loosen the cam position sensor can (keeping the two bolts slightly snug, rotate the can (very slightly) in the direction that you want the timing mark to move. It's pretty sensitive. Small moves and retest. Once it's there, lock it down, shut off the engine, then remove the shorting lead. Bingo. This is all from memory, so if I biffed it the guys will chime in.

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Robert503

10+ Year Contributor
115
4
Oct 19, 2008
Newberg, Oregon
Since you have that ECU open, order a capacitor replacement kit like this one:
and have a local TV repair shop, friend, or someone at a local maker space replace the capacitors (unless you can do it properly yourself). Russian roulette if you don't.

The ignition timing adjustment connector (and the fuel pump check connector) are located on the firewall right next to the negative terminal corner of your battery as shown in the picture. The fuel pump test connector has one pin. You connect 12V to that to run the fuel pump.

The timing adjustment connector (A-60) right next to that is the one that has two pins- one pin will have a voltage, the other is disconnected. I'm sure someone will post the appropriate section of the manual, but in a nut shell, to adjust base timing:

Make sure the engine is warmed up, then shut it OFF. Use an alligator clip test lead to connect the pin that has voltage to ground. Connect up your timing light (make sure you use cylinder 1 closest to the accessory belt (I know you know this)). Start the engine, and check the crank pulley timing mark against the gauge. If it's not 5 degrees BTDC you will need to shut off the engine, loosen the cam position sensor can (keeping the two bolts slightly snug, rotate the can (very slightly) in the direction that you want the timing mark to move. It's pretty sensitive. Small moves and retest. Once it's there, lock it down, shut off the engine, then remove the shorting lead. Bingo. This is all from memory, so if I biffed it the guys will chime in.

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Thanks for the info I’ll check it out after work. I got a set of 92 repair service shop manuals on the way
 

1990TSIAWDTALON

Moderator
9,685
5,524
Nov 14, 2013
Independence, Kansas
Well I got confused and removed the tps by accident hah got that all readjusted at .49 volts closed throttle on pin 19 at the ecu. Also took the opportunity to open the ecu and it’s a eprom! Also didn’t detect a hint of leaking or smell. Fresh as a daisy
TPS should be .63v at closed throttle position, 5v WOT. The idle voltage may vary when you start the car, a lot do by .01-.02v and end up at .65v.
Just FYI.
 

Robert503

10+ Year Contributor
115
4
Oct 19, 2008
Newberg, Oregon
TPS should be .63v at closed throttle position, 5v WOT. The idle voltage may vary when you start the car, a lot do by .01-.02v and end up at .65v.
Just FYI.
Dang idk how I came up with .49… it was an Interesting afternoon. Well it is an easy fix, I’ll double check what I have it set to and adjust accordingly. Thank you for catching that
 

1990TSIAWDTALON

Moderator
9,685
5,524
Nov 14, 2013
Independence, Kansas
Your WOT voltage may only go up to 4.8ish-5.00v and that is ok for full throttle.
 

Robert503

10+ Year Contributor
115
4
Oct 19, 2008
Newberg, Oregon
Still gotta re adjust the tps. Since I’ve been home I tested the ISC and it checks out
1-2 30.3
2-3 30.3
4-5 30.2
5-6 30.3

The only 6v I could come up with is 2 plc 3v batteries I had around that I ran in series to get 6v but that didn’t make the ISC vibrate or hum or anything, I tested my battery setup and it was only giving 5.8v. Hardware store run for some things and I’ll grab a camera battery to try it out properly. I’d love to get this thing to idle like it did from the factory
 

steve

DSM Wiseman
14,865
1,721
Feb 3, 2002
Boulder, Colorado
Dang idk how I came up with .49… it was an Interesting afternoon.

Because the specification in the FSM is 0.5v for a 1G +- 0.02v. The guys at ECMTuning suggest using 0.65v if your running DSMLink.
 

Robert503

10+ Year Contributor
115
4
Oct 19, 2008
Newberg, Oregon
Because the specification in the FSM is 0.5v for a 1G +- 0.02v. The guys at ECMTuning suggest using 0.65v if your running DSMLink.
Okay that makes sense. So to be clear I am not running dsmlink, so I should be just fine at .49? I will also check the wot voltage

Edit: I got a better connection and can now get the motor to bump just a little bit so I think it is functioning properly, I guess I will try plugging it back into the harness and turn the key to on and see what it does

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steve

DSM Wiseman
14,865
1,721
Feb 3, 2002
Boulder, Colorado
Replace it. That version of the ISC is know to fail and potentially damage the drivers in the ISC. The black plastic ones seem to be much safer.

It looks like the pintle is vibrating but not moving in and out which isn't good. Could just me my eyes, so you tell me.
 

Robert503

10+ Year Contributor
115
4
Oct 19, 2008
Newberg, Oregon
Replace it. That version of the ISC is know to fail and potentially damage the drivers in the ISC. The black plastic ones seem to be much safer.

It looks like the pintle is vibrating but not moving in and out which isn't good. Could just me my eyes, so you tell me.
Just vibrating back and forth with that terrible sound. No in and out motion at all. Perhaps I should open up the ecu again and check that area, I seen pictures of a bad one somewhere on here. Any suggestions on where to get the black plastic ones? Parts store wants $125 for one. Thanks again for the help

Also checked the tps voltage to be safe and it’s base setting is .49v and wot 4.98v 🤙
 
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