Have had the '82 for about a year now and the idle was always a bit high since purchase.
Have recently started to troubleshoot it after it sat for a few months and was not driven hardly at all. At that point it would not start easily and when it did things were very rough. Seemed like it was missing a cylinder.
Did some basic tune up things to the car.. new plugs, wires, dizzy cap and rotor. The rough idle went away with the new dizzy and rotor install.
Also had to repair a passenger side leaking exh manifold gasket.

Getting an intermittent code 15 from the ALDL which per the service manual is the ECT. The ECT had been replaced at some point since it had the 2 wire version on it.
What I am curious about and the manual does not explain at all is which wire goes to Pin A and which to Pin B on the plug. I can see after pulling back all the harness cover that Circuit 410 is the Yellow wire. This is connected to Pin A. Is that the correct configuration.

The car still idles way to high (1700RPM) but if I use my pinky finger to pretty much block the idle air circuit on the driver side TBI the idle drops several hundred RPM. I'm going to assume that the ECT still reads cold so the ECM never commands the IAC to close down??
Have added a few new parts along the way (IAC's, ECT and TPS) but don't want to replace any more without knowing it will solve an issue here. TPS voltage that last time I checked after install was about .528 vdc.

Car is hard to start from dead cold as well. Fires up easily when warm. Drives okay with some slight surges from time to time under part throttle conditions. Normal acceleration is fine and have not tried a WOT run yet.
Fuel pressure unknown at this time but spray pattern on both TBI's are nice looking cones.

 

either a bad tps sensor or blown throttlebody gasket . i would start there

 

B pin to circuit 410 and A pin to 452 to TPS circuit. If you have a two wire oem sensor the terminal in the center is the 410/B circuit.

 

I think wayoutthere has a good suggestion. The top plate gasket on the intake is known to be prone to failure on the passenger side rear next to the Exhaust Gas Recirc (EGR) valve due to the heat. Mine was cooked and sucked in along that border when I pulled my plate to rebuild my TBI.

When is the last time you put a gasket kit in your TBI? You may have some air leaks since you got an rpm drop when you blocked your flow.

Finally, do your headlights pop up strong? A vacuum leak can also cause a high idle.

L46 Man where are you?!?!?

 

Headlights come up pretty quick.
Noticed that the MAP vacuum line was routed to a fitting on the intake manifold but the pictures in the service manual showed that it should be routed to a port on the rear throttlebody. So I made the change to match the SM.
Still idles too high, so no change in behavior. Drove it for about 15 mins to see if an idle relearning would take place but non did.

Have not done a new intake manifold gasket kit yet. Was trying to avoid that unless evidence suggested it has to be done. I guess I might be there...
Odometer reads 98K miles at this point but I can see that the intake gaskets have been changed at some point in time because it is not just RTV.
The idle screws have all be tampered with at some point in it's life as well so I imagine that things are not factory set any longer.

I did change the ECT wiring, so thank you for that Gunfighter and the idle did improve a little bit, went down to about 1100RPM but then would surge back to 1500 only the drop back down to 1100. This was the action before the test drive.
Idles at about 1200 RPM now.... so I guess I must have a vacuum leak in the intake....argghhhh....

 

You may have already checked this, but just to eliminate a simple thing to check, have you taken a look at your Engine Control Module in front of your battery?
If you just got the car, are you sure it wasn’t swapped for a 1984 Manual Transmission unit?
If it is the original, it will be large, have lots of vent holes, and be numbered 1225550.
If it has been replaced with a 1984 it should be much smaller and numbered 1226026 with a PROM chip inside numbered CDR 3940.
A 1984 manual transmission unit will be 1226430.

 

You have a vacuum leak and the TB gaskets and the top plate are suspect and a good place to start. If you blocked the IACs and the idle came down, the motor is still getting air from somewhere in the form of a leak. Find the leak and your idle should come down to the normal cold start rpm of about 1100-1300 and drop down to stock idle within 45 seconds(ish) or wherever you have it set at. OR you still have an issue with the wiring maybe? Fuel pressure has NOTHING to do with a high idle, but should be checked. Set it at 13psi for a stock motor and you will be fine.

 

I did not block both IAC's at the same time, just the rear one which makes the most noise from the air being drawn in. The forward TBI does not have nearly as much vacuum draw on it. I think I will do that just to make sure the engine dies out rather quickly.
I'll also check the part number on the ECM just to make sure it is of the original type but I think it is by the description of a large metal box with lots of holes. I did look at it during all of this but didn't pay too much attention at the time. I'll report back with the details later on.

 

You have a massive vacuum leak! The MAF runs on vacuum as well.

 

Well, I checked on the ECM and it is a remanufactured unit, from Cardone... the p/n is 775550. Based on my research of the P/N online. The S/N leads me to believe it is from 2017/Mar.... but that is just a guess. So, maybe the ECM is okay and the issue is either a leak or bad wiring.

I took some cotton rope and plugged up the IAC intake tracts pretty tightly and the car then idles at 750RPM pretty steadily. So, I must have a vacuum leak going on somewhere if the engine will keep running without use of the IAC's and the TBI's are closed off. I know my closing process was not 100% effective but know should a 350 engine still run with all that air removed..
I've started the process of removing the intake. I'll report back what I find along the way. I hope I see the smoking gun after all this.......if for no other reason then just for some kind of reassurance.

More to follow and thanks for the replies...

 

Huh, just like I said, you have a vacuum leak somewhere that is pretty large. Just pull the top plate and replace that gasket and ensure it is sealed up properly. Next replace the TB base gaskets. Next, check your fuel pressure while your at it. If you need help with that PM me. Also have a good look at the IACs to ensure that they are both moving in and out. You can do that by shorting the ALDL connector under the ashtray, pins A/B. See if they cycle properly. I can help you out. GL

 

Okay, the top plate is off and all cleaned up. I also removed the EGR valve and was scared for a bit that one of the bolts was going to break off, but after some penetrating oil and back and forth action it did come out. Phew...
Removed a bunch of carbon crud from underneath the EGR tube inside the intake. Yikes...
Top plate gasket was very brittle and came off in a few large pieces. The back area around the dizzy and EGR was the driest I think.
New Mahle top plate intake gasket is ready to be installed. Once I get the intake back into place and torqued to spec I'll start to disassemble the TBI's to install new gaskets there as well since they are off and on the bench.

Lunch break over, time to return to the task.

 

This was mine before cleanup. Similar to yours, it sounds like.
Do you have your torque specs and a good, small torque wrench?

 

Off to the store to get an EGR gasket for the intake since my kit did not come with one.
Also the rebuild kit for the TBI's did not come with both of those little injector filters, only one of them in my kit.... figures....
At least the original ones looked okay but I'm just bummed that I got an extra of a couple items but didn't get one of an item that should be included.
Not the fault of a supporting vendor, because I know they don't package this stuff in house, they are just a middle man. Just a typical issue when you get a kit of something with many unique tiny parts.....

Yes, DWA the inside of my intake looked pretty much the same way as yours. The edges did not have any RTV around it, just an old brittle paper gasket.
Torque is done and got a few more things to button up before I start the car again, check for fuel leaks and see if my idle results are favorable.

 

Forgot to ask, did your kit come with the two oval gaskets for the air breather-to-Throttle Body? I understand those are important to prevent air leaks and high idle (Buccaneer or L46 Man please confirm).

 

The ONLY TB rebuild kit that I recommend which is complete is GP Sorensen, kit number 96-629 which can be ordered at Autozone. Their kit is a reliable complete kit and the FPR bladder is correct. There are kits out there especially online that are NOT correct and you WILL have issues with your FP and trying to adjust it. Also, DO NOT mix up the springs in the TBs, they ARE different along with the injectors, do one TB at a time. If you need help, PM me and I will give you my number. GL

 

Yes, it did have those. They are now on the car.

 

Thanks, yes I did notice that the bladders were different in the kit. Each went onto the correct TBI.
The initial start of the car after everything was back together did not go overly well at all. I did get the initial spray of fuel when the key was turned to On position. Then on crank it tried to start but could not really do well.
I had to follow the flooded condition to get the car started at the end of the day.
But, based on the issues I had after all the work was done I still think I have more troubleshooting to perform to figure out why the car does not want to run smoothly or reliably. Some of the behavior leads me to believe there are wiring issues of some kind in the harness.
Sometimes it idles fine, then other times it acts like one cylinder has been lost. Going to have to start on each subsystem to see where the culprits are and eliminate them one at a time.

The first will be fuel pressure. I have a fuel pressure gauge from my C4 days but I think a kit is in order that deals with lower pressure systems such as this car has. In the mean time I will verify the TPS is at .525 vdc or as close as I can get it.
I did a vacuum check last night and it was pulling 20 inches solidly, no bouncing or anything.

 

20 is good. I sent you a PM.

 

Started the car yesterday with it dead cold and the results were the same before the intake gasket change. Erratic behavior like surging and unstable, followed later with high idle once engine warms up.
But, the check engine light came on for a few minutes and the code is once again flashing a 15 which is for an issue with the ECT signal. Although it is possible I got a bad new part, I'm going to assume the problem is in the harness though.
I'm going to put an ohm meter on the sensor to see what it reads at garage temperature (60 degree +/- 5 or so). Then start taking readings further back into the system eventually ending at the ECM.