IAC Motor Test

2 of them have there on prom. I does not.

I starting to wonder if the car is running in open loop. Is there a way to check for this. That would explain why the IAC motors would not reset. The other possiblity might be the speed sensor is not working properly.

Thoughts!
 
Another update,

Made some progress. I changed back to the 6026 computer to see if it would reset the IAC motors and it responded. When I got home I removed the air cleaner and I could finally see 1 of the pintles thru the IAC port. The manager at O'Reillys played with 1 of the motors. Could he possibly damaged it? When the engine is hot should the pintle be exposed, or retracted? The engine was running very flat, like 1 side of the motor wasn't getting enough fuel. The car still runs like shit, but progress. After stumbling home with a full tank of gas I proved 2 things.

1 is wasn't the fuel pickup, but it was very close. It looks like the fuel pump might be failing. :lol: I hooked up a gauge and I'm only getting 8 #'s at idle. I had a fuel gage port installed on the TBI's while they were off. If I'm reading off of the front TB, I think the fuel pressure is set on the rear TB. Could this be an adjustment issue, or is the fuel pumps failing.

2. The reman ECM looks like its got some type of problem. The 84 ( 6026 ) ECM seems to be working better.

We are getting closer to the problem, and the money pit is getting deeper!:lol:
 
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First off, you should use the memcal module programed for your cars engine. Do you know what the other one is programmed for?
IAC's are supposed to initialize and then proceed to a position determined by the ECT sensor, Open wider the colder the engine is at startup. After startup and at idle, it should be roughly 5-10 percent open. I am not an expert on crossfire so I am guessing a little here. From the wiring schematic it looks like the two IACs are wired in parallel and operate in unison. Sounds like they are not operating this way.
1) Didn't you say you purchased two new IAC's?
2) Do you have access to the schematic?
3) Have you checked for good power and ground connections and levels.
4) verify all sensor operation / interconnect. aka. TPS, ECT etc.
5) Proper injector commands and operation?

I have heard that these ECU's are notorious for bad interconnect at the connectors.

Keep trouble shooting, and look for discrepancies. So far, it sounds like IACs operating in unison and or fuel pressure.???

Bullshark
 
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The IAC's were set with the same spacing when I installed them. They are in parallel with each other. So 1 command should affect both the same. They are both new, and I tested them in the diagnostic mode before installing. Sounds like 1 might be damaged. I did wiggle all of the wires on the connectors looking for a bad connection. I think when hot the passage should be closed.

The ECM's I have used are the stock one for the 82, & the one for the 84 model with factory improvements over the 82 model. 82 was the 1st year with several problems from what I am told. The 84 model seems to be working correctly. It was one of the Christmas give aways from the DC. Darrow sent it to me.

Fuel pump seems to be my next problem. The motor was running flat on 1 side while starving for fuel. I'm not sure I can adjust my regulator to fix this or not. I have got to read up on it some. If I change it I will go with the 85 fuel pump.
 
Dirtbuster1 said:
I think when hot the passage should be closed.
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I don't think that is true. For all my aftermarket IAC applications the IAC should be slightly open at idle (This is so it can have some operation control range as the engine transitions to and from idle condition.) It then will follow throttle opening to a programed track function. A complex control function called PID (Proportional, integral, derivative gain) controls IAC response back to idle efficiently.

Dirtbuster1 said:
The ECM's I have used are the stock one for the 82, & the one for the 84 model with factory improvements over the 82 model. 82 was the 1st year with several problems from what I am told. The 84 model seems to be working correctly. It was one of the Christmas give aways from the DC. Darrow sent it to me.
Click to expand...

Two out of three bad ECU's....that seems like a long shot to me. I hope no compatibility issues have you chasing your tail. You know better than I.

Dirtbuster1 said:
Fuel pump seems to be my next problem. The motor was running flat on 1 side while starving for fuel. I'm not sure I can adjust my regulator to fix this or not. I have got to read up on it some. If I change it I will go with the 85 fuel pump.
Click to expand...

Sounds like an area to home in on, From what you say, there is only one fuel pressure regulator that feeds both throttle bodies. Hard to believe that there is a significant difference in fuel pressure with such a short distance between them.......unless there is a problem with one of the injectors.

Just some thinking out loud.


Bullshark

P.S. Wiggling the wires may open and close intermittent connections but that will not result in driving the IAC if the ECU isn't providing pulses. It thinks it has already drivin it to the proper position. In other words an intermittent connection will result in getting the IAC out of sync.
 
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I did not try one of the ECM's. It was the same model 6026. I just didn't change the prom.

1 of the IAC motor pintles is not visable, which means it probably wide open. The other could be possibly open some. It's not pulling much air if you stick your finger over the passage. The other ones sucking pretty hard.

I'm probably going to go ahead and change the fuel pump. After all of this I should be ok.

Thanks for the help!
 
Update,

I changed the fuel pump today based on 8 lbs. of pressure. I went ahead and converted to the 85 model pump that provides more pressure. Not to bad of a job, it took about 2 hours. I took my time not to screw up anything. Hit the key and 12 lbs. of pressure. That was a good sign, meaning I didn't waste another 70 bucks.

I pulled out the IAC again & reset them both to 11/8". After doing that I could see both pintals in the IAC paasage. I drove the car about 5 miles without the motor trying to shutdown. That was a relief. I will check the pintals again after the engine cools down to see if the IAC motors reset.

Thanks for all of the help!
 
Cranked the car again tonight & 1 of my IAC motors doesn't seem to be working right, I swapped the motors and the problem stays in the same place. I ohmed the plugs that are in parallel and they seem to be ok. I started pulling the harness apart and found where someone else had been in there. There was a vacuum hose rapped around the Iac motor leads. I removed that and found electrical tape, and slices in the wire. Cleaned everything up & traced everything up to the connection on the firewall. While tracing this out & found a ground that was hidden in the wires. I don't think this will make a difference but its connected now. I checked it out tommorow and see if I made any progress.
 
Dirtbuster1 said:
Cranked the car again tonight & 1 of my IAC motors doesn't seem to be working right, I swapped the motors and the problem stays in the same place. I ohmed the plugs that are in parallel and they seem to be ok. I started pulling the harness apart and found where someone else had been in there. There was a vacuum hose rapped around the Iac motor leads. I removed that and found electrical tape, and slices in the wire. Cleaned everything up & traced everything up to the connection on the firewall. While tracing this out & found a ground that was hidden in the wires. I don't think this will make a difference but its connected now. I checked it out tommorow and see if I made any progress.
Click to expand...

Ummm, sounds like bubba might have wired up one of the IAC's backwards. Better take a close look to see what's going on there.

Bullshark
 
Bullshark said:
Dirtbuster1 said:
Cranked the car again tonight & 1 of my IAC motors doesn't seem to be working right, I swapped the motors and the problem stays in the same place. I ohmed the plugs that are in parallel and they seem to be ok. I started pulling the harness apart and found where someone else had been in there. There was a vacuum hose rapped around the Iac motor leads. I removed that and found electrical tape, and slices in the wire. Cleaned everything up & traced everything up to the connection on the firewall. While tracing this out & found a ground that was hidden in the wires. I don't think this will make a difference but its connected now. I checked it out tommorow and see if I made any progress.
Click to expand...

Ummm, sounds like bubba might have wired up one of the IAC's backwards. Better take a close look to see what's going on there.

Bullshark
Click to expand...


As most of you all know, I had terrible idle problems and even run problems with my batch fire 1227730 speed density system, went on damn nearly 2 years.....time, money, effort, attitude, etc.....well, finally the cure was from DC yet.....run a bottle of Techron FI cleaner through a tank of gas, it took me two tanks/bottles, but can take 3, it worked....smooth as silk now....

not sure how the TBI is set up, with ONE 02 sensor in the pass bank I wuld guess, so to make sure it's not that, see what the tbodies are feeding one bank each or cross feeding both banks....so wonder if the O2 sensor is giving bad information.....scanner should say something about that....
 
I drove it to breakfast this morning. The engine ran good, with the exception of a rough idle. It did not crank at the 1200RPM it should have. It cranked at 650 RPM. My WinALDL cable hopefully will arrive today or tommorow. Then I can record all data while driving to see whats going on. Then I will post it for additional help.

I stopped and bought somemore contact clean, & Diaelectric grease. I'm going to work on all the connectors that this circuit connects to.

At least I can drive it & make it home without praying now.:lol:

Thanks for the help.
 
Both IACs are wired parallel, they are operated TOGETHER. Pull apart the harness and check if it's still wired properly. The schematic is in the download section.
 
Pulled the harness apart again today. Cleaned all of the contacts, ohmed, & installed Di-Electric grease in the connectors. Pulled the IAC motors again & set them both the same. Crank the engine and theres not high idle on cold start. Now one of the motors is in further than the other one.:eek:

I am clueless on what to do now. WinALDL didn't arrive again today. I'm hoping that will point me in the right direction. Is there another way that I can tell if the engine is in " open" or " closed " loop.

:sos:
 
Dirtbuster1 said:
Pulled the harness apart again today. Cleaned all of the contacts, ohmed, & installed Di-Electric grease in the connectors. Pulled the IAC motors again & set them both the same. Crank the engine and theres not high idle on cold start. Now one of the motors is in further than the other one.:eek:

I am clueless on what to do now. WinALDL didn't arrive again today. I'm hoping that will point me in the right direction. Is there another way that I can tell if the engine is in " open" or " closed " loop.

:sos:
Click to expand...

Whether or not you are in closed or open loop has no bearing on it. IAC's are positioned based on RPM, ECT, and Throttle position. I still think one of the IAC's has been wired bass ackwards. As TT said, take a close look at the wiring and see if the one that looks to be open way too far at full temp idle isn't wired backwards. Typically IACs should be ~5-10% open at full temp idle.
If all the wiring is correct, I would suspect the ECU

Bullshark
 
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NOT a doubt in my mind from reading this thread that the wiring is NOT identical, you should even check the colors and positions of each plug compared to the other....and figger out the correct sequence of pins and color codes.....olde tyme wiring will change colors so badly in a harness..you can't imagine....someone in the past got some colors confused....

probable blue to green or some such.....

:shocking::shocking::shocking:

PLEASE don't ask how I know this...

eh???:shocking::waxer:
 
The colors are faded but I have checked them from pin to pin & plug to plug. I was questioning if the ECM was going in to closed loop. I found the diagnostic check in the manual & have confirmed open & closed loop are functioning. Did the test to confirm the O2 sensor is also working. Unplugged the map sensor vacuum line & watched it stall the engine.

I keep asking myself why it is not idling at 1200 RPM when cold. The only 2 things that control that I think are the O2 & the CTS. I probably need to go back and check that plug connection to make sure it's still tight. If it was shorted it should be a code 14 & if open a code 15. I not getting either code. It also is not adjusting the IAC motors when cold. Hopefully when I get the ALDL cable, it will point out the problem.

Thanks
 
Went back to check the CTS sensor & one of the butt spice wires slid right out. That should make the car think it's colder ( more resistance ) but it might not had enough voltage to adjust the IAC motors. I want know until the morning when its cold, but it might just be the problem. Just enough connection not to throw a code.

The CTS sensor was putting out 270 ohms at around 180F. That sounds about right according to TT's fiqures in the CTS thread.

Maybe I get lucky!

:beer:
 
Dirtbuster1 said:
Went back to check the CTS sensor & one of the butt spice wires slid right out. That should make the car think it's colder ( more resistance ) but it might not had enough voltage to adjust the IAC motors. I want know until the morning when its cold, but it might just be the problem. Just enough connection not to throw a code.

The CTS sensor was putting out 270 ohms at around 180F. That sounds about right according to TT's fiqures in the CTS thread.

Maybe I get lucky!

:beer:
Click to expand...

Dirt, the one thing that you seem to be overlooking is that there is no logical explanation that would explain the fact that the two IAC's are commanded to different positions when they are wired in parallel and receive identical position commands. Bad CTS connection would affect both IACs equally. The fact that you said that someone has bubbaed the harness makes me think one of the IAC's could be miss wired. At this point I wouldn't go by wire color code. Need to check IAC pin polarity and actual IAC direction travel.

Bullshark
 
One of the new IAC motors was dropped and played with by the manager at O'reillys. I not positive if its good or bad yet. I can't seem to get the motors to move much the last 2 days. Thats when I installed them. After repairing the CTS connection tonight, I had to adjust one of them 3 times to get it to match the other. It had run out to a 11/4" while installed. It's know way that should have happened.

Hopefully I know more in the morning. I'm going to take it to be aligned. If they have a machine that could check the engine I will hook it up & take a look. I'm about ready to buy a new harness for under the hood. IT sure gets hot under there.
 
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