Irradic idle.

[Gasolinebaptism]

These are the first few days the car has been running for 7 years.
It idled when I started it up the first time just fine, bt after I drove it around at all it would die when I pushed in the clutch, or stopped. Then yesterday morning I hopped in and it was just fine, there wasn't an issue, it idled 800-1000 rpm. then I drove it later in the day and it wouldn't idle again, after awhile of driving I got it to idle once again, I adjusted the screw on the throttle body for it to consistently idle, even if it's high. The next time I ran it, it idles around 2 grand, I was just thinking it was because I adjusted the TB, I drove it home last night with that idle. I started it this morning and she ran great, all day when I wanted to drive it was perfect, with idle high around 2 grand, but sometimes it would calm down to 750 or so. I figured it had worked out it's issues so I adjusted idle back down to were it was originally. I hopped in it to go to safeways and it didn't start til the third time I cranked it, I held it at 1500 for a few seconds then it seemed fine, made it to safeways, left safeways and went to the post office, when I pulled in at usps, it died, and I couldn't get it to idle on the drive home either, consequently dying whenever I stopped.
It'll probably do about the same thing in the morning, run perfectly until afternoon. It's a bit frustrating, and ideas on what I should do?

 

[Gasolinebaptism]

I just read a thread on checking the IPS, but it gave me different directions, tell me if this means anything.
So with the TB plate closed, between that plug and ground I read 3 ohms, with the TB plate open I read an open line on every scale, because it is indeed an open line, but I did the multiple times and a few times when I closed the plate, I read higher resistance, all the way up to 26 ohms, this is again with the plate closed, then when I would open it all the way and let it close firmly, then it would drop back to 3-5 ohms. Sounds like a gunky TB. Agree?

 

[steve]

Very possible.
Do you still have the ground strap attached?

 

[Gasolinebaptism]

The ground strap is attached yes, now I just test that wire like you said, I'm not sure I did it right however.
With the wire off, I tested harness side with key on, 12 volts. Key on, TB open, 12 volts.

 

[steve]

The ground strap is attached yes, now I just test that wire like you said, I'm not sure I did it right however.
With the wire off, I tested harness side with key on, 12 volts. Key on, TB open, 12 volts.

With the wire off it should have voltage all the time the ignition is on.
Once it's connected to the IPS it should read close to 0v with the throttle closed and whatever you measured disconnected when the throttle is open. It should switch between the closed and open with little movement of the throttle.

All of these tests are to identify that all the peripheral items are working before pointing the finger at the ECU.

 

[Gasolinebaptism]

12.72 with throttle open.
0.042 with throttle closed.

 

[steve]

12.72 with throttle open.
0.042 with throttle closed.

Good, so the IPS is working. The ISC seems to be good. ECU is unknown.
The TB could be dirty, BISS out of adjustment, Some sort of vacuum/boost leak, or the ECU isn't able to drive the ISC.

 

[Gasolinebaptism]

Okay, I adjusted the BISS the proper way this time after I cleaned out the TB, I brought it down to about 900.
Now, tell me if this is normal. When I took off the ground from the diagnostic plug, the idle dropped about 200 revs, if I reconnected back to ground then it would pick back up, then when I went to the other ground behind the battery, when it was disconnected the revs picked up about 200, in essence evening out. Now that I think about it, it makes sense, it just caught me a bit off guard. but then again maybe there is an imbalance in the system.

It seems to be getting better, Since it was a tough start this morning and at my sisters, it hasn't had a problem firing up, again, idle was high after TB clean, and it's good right now. I'm just going to have to get out and drive some more to see.

I just gave the ECU a close look front and back. It looked to be in good shape. I payed special attention to the drivers, I didn't see a flaw front or back. It was rebuilt by microtech in 2004, there were a few changed connections on the back, I'm thinking that they were just channels that were affected by the leaky caps, and had to be made anew, it all looked to be in good shape.

 

[steve]

When you adjust the BISS you have two things grounded to put the ECU into the correct mode.
Disconnecting the the ground on mode pin changed the ECU mode from BISS adjustment mode to set timing mode. Disconnecting the ground from the set timing connector put the ECU in normal mode.

If you had disconnected the set timing connector first you would have switched the ECU into datalogging mode.

That fact that you weren't able to get the idle speed to 750 is a problem. You should be able to and still have a turn or two of adjustment on the BISS before it bottoms out.

What happens now when you turn on the AC or try and turn the steering wheel slightly when the car is running? Both of these are engine load inputs to the ECU that should cause a reaction.

You can see and smell the bad ones. I can smell burnt electronics before I even open the package sometimes but others show no outward signs until I test the drivers.

What I meant here was that you can see and smell the really badly damaged ECUs but there are quite a few where there is no user visible signs of damage. I've had to build test gear to check them.

 

[Gasolinebaptism]

I havn't sat and turned the wheel slightly or turned the AC on to see what would happen, I just havn't thought about it. I can in the morning however. And, I never bottomed out the BISS, so I can't say that it wouldn't drop to 750, I just wanted it at 850 or so because it feels more stable right now.
Is there any test I can do for the ECU with just a fluke?

 

[steve]

The ECU is programmed for a 750 RPM idle. In order to idle at any other speed you have to drive the ISC out of it's control range so that it can't bring the speed back down (or up) to where it's supposed to be.

So right now the ISC had closed off it's bypass trying to bring the idle to 750. It's not able to control the idle speed.

 

[Gasolinebaptism]

So perfectly adjust the BISS and quit dicking with it?
Drive around for a bit to let the ecu select a map, and possibly be good?
Big chance on the "possibly" though..

 

[steve]

You'll never know if it's working right until you set the BISS like it's supposed to be.

Later if you feel you need a higher idle speed for some reason like cams or such you'll have to get the ECU software changed to support it. That means EPROM ECU, software, and readjusting the BISS for the new target.

 

[Gasolinebaptism]

Okay, well it's spot on right now, idle at 750, I went and drove around, then adjusted it.
I have driven it since. It drops about 150 rpm with A/C and about 20-50 rpm with a load on the steering. Seems normal. It started right up this morning, and idle at about 2 grand til a few minutes after it was hot.
Then it progressively settled down. When I made it back to my place it was idling right where I set it, at about 850 revs.
Last night I went to a basketball game, so I drove there, and it had a high idle on the way there, and leaving, dropped a friend off about 4 miles from the game, when I left it died whenever I put in the clutch, then I got it to go, and did it again an hour or so later after I had been driving around.

 

[steve]

When you turn the AC on it should idle up not down, same for applying pressure on the steering.
At this point if it were here I'll pull the ECU and check that the ISC drivers are functioning.

 

[Gasolinebaptism]

Well, I havn't done the yet for the simple reason that it got put back together, as I need to drive it for awhile. may be a bad decision, but like I said I need it for awhile.
but anyways. I was checking out how the AC changes idle today, and I noticed when I turn the AC on, the idle dips a bit, it's not as much as it was, maybe 50 RPM, but the boost gauge moves up a bit. Goes from maxed out vacuum to 6lbs vacuum or so. now, this is the stock gauge, which I'm aware isn't a true boost gauge, I believe it's position is decided off of the tach and TPS. well how much gas you're applying that is.
This seemed peculiar because it would mean the throttle has changed, opened up a bit, even if it did idle down slightly, it tells me the ECU is doing its job. am I wrong? am I on to something? Last couple days it seems to be alright, Idles up when it's cold, sometimes 1200, sometimes 2000, but then settles. I've got a few parts coming, including a new exhaust mani, because I was going to change the O2 sensor and saw a crack that was about 2 inches long. I needed to replace the manifold gasket anyways, so I have both of those coming, injector O-rings, because there is a bit of a leak from when we tested the injectors. I can't tell if I'm running rich or am just losing quite a bit of fuel from the injectors, but it seems like I'm going through quite a bit of fuel, I won't know til I drive off an entire tank after I install the O-rings which should be here Tuesday. I expect the other parts to, so I will be sure and report back.

 

[steve]

I was checking out how the AC changes idle today, and I noticed when I turn the AC on, the idle dips a bit, it's not as much as it was, maybe 50 RPM, but the boost gauge moves up a bit. Goes from maxed out vacuum to 6lbs vacuum or so. now, this is the stock gauge, which I'm aware isn't a true boost gauge, I believe it's position is decided off of the tach and TPS. well how much gas you're applying that is.
This seemed peculiar because it would mean the throttle has changed, opened up a bit, even if it did idle down slightly, it tells me the ECU is doing its job. am I wrong? am I on to something?

The boost gauge is driven from the MAF. The load imposed on the engine will cause it to change.