wandering idle

[H/O84]

Sweep dwell meters aren't easy to find these days. Some digital multimeters have a dwell function, but sweep is easier to read

I do have a sweep dwell meter I was going to use it last night but the garage filled with exhaust so I called it quits

It's an arcane system and you really need the factory shop manual

I have been trying to figure this out with the 84 chassis service manual, I think that's what you're talking about because it's got alot of stuff I'm still trying to figure out

Another issue may be the lockup solenoid in the trans, pretty common for them to fail and cause stalling problems at stops

That would make sense, when I bought the car it came with alot of extra parts, one of which was a tcc solenoid, hard to tell what it actually needs because the PO liked to replace alot of stuff just for the hell of it, he was dumping alot of money into it then parked it because he got busy. I'll figure out how to test that today and see if it needs it. Could that cause idle issues?

 

[Clone TIE Pilot]

It is possible it is the TCC.

I do have a sweep dwell meter I was going to use it last night but the garage filled with exhaust so I called it quits

I have been trying to figure this out with the 84 chassis service manual, I think that's what you're talking about because it's got alot of stuff I'm still trying to figure out

That would make sense, when I bought the car it came with alot of extra parts, one of which was a tcc solenoid, hard to tell what it actually needs because the PO liked to replace alot of stuff just for the hell of it, he was dumping alot of money into it then parked it because he got busy. I'll figure out how to test that today and see if it needs it. Could that cause idle issues?

It could be, the common symptom is after at least 40 minutes of highway driving, you come to a stop and the trans appears to downshift late causing a near stall or complete stall in really bad cases.

What carb rebuild kit did you use? Cheap rebuild kits do not have correct replacement parts. Every CCC Qjet uses a main body to throttle body gasket with a large triangular air bleed hole, sometimes rebuild kits include the wrong version of this gasket that does not have the proper hole blocking idle air bypass. Found this problem on my rebuilt carb.

The computer controls the fuel mixture in the carb, and will try to offset a problem. Using a dwell meter, you can read the fuel mix solenoid dwell on the 6 cylinder scale. Normally in closed loop, the dwell should hover around 30 degrees. If it below 30, it is responding rich to offset a lean problem, above 30 is a lean command to offset a rich problem. When the solenoid is off, the mixture is rich, when the solenoid is on the mixture is lean. Normally it should be an near equal amount of time of on and off, hence 30 degrees which is half of 60 degrees, the middle.

As for idle speeds, my Chevy 305 idles at 600 rpm stock when fully warmed up in drive, idles at 1k when still cold. A Olds 307 is probably similar. Chevy and Olds used different CCC setups.

 

[H/O84]

I have driven the car about a total of 4 miles so testing with highway driving isn't an option right now. Is there a good way to test the tcc without driving it? The gaskets I got from the rebuild kit matched what I took off the car.

 

[Clone TIE Pilot]

It really sounds like the engine is running lean, as a lean mixture hurts idle the most. When you rebuilt the carb, did you reset the adjustments correctly with gauges? You can make your own Qjet gauges from online information. You should hook up the dwell meter and see if you have a lean or rich problem. You should also test the TPS with a volt meter. A Haynes repair manual for your car has plenty of information on CCC systems.

Amazon sells analog dwell meters will are a required tool for working on any old engine. There is also a good deal of CCC information online with just a quick search. On one of the Third gen F body sites, a guy posted scans of a dealership CCC troubleshooting guide with logic charts. Alot of people just assume when their car isn't running right, its the computer at fault. What I found more often than not the source of the problem is the engine itself, not the computer.

 

[H/O84]

I already own an analog dwell meter, and the Haynes manual I have for the car doesn't tell me much about the TPS or anything related to that. I have been working out of the 1984 olds cutlass chassis service manual which has plenty of info in it. After following it's flow charts for code 21 it says that the TPS is in need of replacement. I didn't mess with any of the adjustment in the carb when it was apart, I only changed the needle and seat, accelerator pump, gave it a good cleaning and then put the new gaskets in. I don't see how it being lean would make the idle it go from 900 rpm to 1300 rpm by itself.

 

[Texas82GP]

A lean condition causes a faster idle.

 

[jiho]

I have been trying to figure this out with the 84 chassis service manual, I think that's what you're talking about because it's got alot of stuff I'm still trying to figure out

Good. You'll get it sorted out, then. Eventually. 😀

Just try to stay calm and enjoy. It really is an interesting system. 😕

 

[H/O84]

So I installed the new TPS today and its not throwing any codes and the idle sits in one spot and isnt hunting anymore. I am still having a problem, I can start the without choking it and it will idle great around 700-800rpm but if i give it any gas the high idle kicks in closes the choke half way and brings the idle up to 1300. When i had the ccc on my camaro it never did that. it would go into high idle before start up and wouldnt go back on unless the car was off. Anyone know why it wants to go back onto high idle when it doesnt need to?

 

[L67ss]

How fresh is the fuel pump?

 

[H/O84]

I believe the fuel pump is original. I found my problem I have a piece of linkage that was hanging up from when I put the carb back on