Fine tuning after my tuneup

[CorsePerVita]

Alright so the new clutch is fantastic, the car shifts nice and everything runs great after my massive tuneup but I have a few issues.

- My hunting idle HAS returned. It basically bounced violently and sometimes the car will die. Literally will drop below idle and gives itself a bunch of gas and it SHOOTS to 2-3k then DROPS again. It will do this over and over and over. Other times it stops and is fine. ONCE the car is WARM the issue stops entirely. If it's doing this and i come to a stop and push in the clutch, it just gives up and sometimes dies. Once warm, it's fine.

- My high idle appears to have gone away. It was going as high as 2000rpms. I gave the aux air valve a pb blaster squirt or two and it appears to have stopped. The idle goes to about 1300rpms when cold and no further... seems right to me?

- I could feel vibration through the shifter at times. I figured since the linkage is long that you'll feel the vibrations just as you did with any car. I put new motor mounts in and now it feels like the vibration is a lot harder. Car drives fine, shifts fine, is it just because they're solid? I know some cars vibrations get better and others get worse. It isn't like the shifter is vibrating, you can just feel it a little through the knob. Mostly in 2nd.

- The power feels great and the throttle response is much much better. However there almost feels like some bit of a hesitation. Now... I did gap the plugs at .44 is that too much? Or correct? figured maybe the gap was off.

- The shifting is butter smooth. However, I think I may be off JUST a little on the shifter adjustment. It goes into gears fine, however, before, it felt fairly loose when i moved the shifter to the left (as if i wanted to go to 1st or 2nd) whereas now it feels like there is just the slightest pressure. I read that I am supposed to turn the transmission shaft right (since when you move the shifter it sort of moves the opposite way) then move the shifter to the left and straight up. Then clamp it down. When I did that it felt pretty good but is that slightest amount of pressure normal? Keep in mind this is after I adjusted it assuming it was "normal" when I got it, it may not have been and perhaps my adjustment is. I am not sure.


Now a quick rundown on some things that I changed during my tuneup just so the variables of the issue are present.

- Spark plugs, wires, cap, rotor
- Plugs gapped at .44"
- Oil pressure switch replaced
- Aux air valve given a couple squirts of PB blaster due to it seemingly sticking hence my super high idle. Seems fine now
- Had a loose vacuum line where the cruise control was previously hooked up. My understanding is that one end went to the cruise control servo unit, the other went to the decel valve, and the other to the throttle body. It was connected to a T, both sides of the T were open (not connected to anything) and the beginning was connected to the throttle body. I removed the T and plugged the line since it was going to nothing.
- Did not end up changing any valves. Rechecked and they were within spec so I left it be. So valves being "tampered" with are NOT in the equaling since I did not change them. ( just clearing it up for anyone who may have read i was checking them earlier )
- New oil lines installed
- Throttle linkage given new bushings and regreased. I also noticed that when the throttle was "closed" that I was hearing no "click" from the throttle. I assumed this is a throttle position sensor? Or am I looking at something different? I readjusted it all and now it rests properly and can hear it "click" on the switch at throttle close. However I looked all over in the manual, as well as online and also searched parts and cannot find anything as to what this sensor/switch does, my assumption is perhaps this was another part of the cruise control system. it has a brown and green wire.

[Walter_Middie]

CorsePerVita,

My hunting idle HAS returned

I assume you are working on the 82 SC?

Sounds like you found a vacuum leak - Your hunting idle and dieing when coming to a stop are classic signs that you are running rich. I'd try leaning out the adjustment a little and see if that clears it up.

What usually happens is that your car develops a vacuum leak and it starts to run bad at idle, then the mechanic or previous owner makes the mixture richer. Then it runs better at idle, and rich at all higher RPMs. That's probably where you are now.

You also don't mention if you have an MSD ignition box. Even if you do, I think your plug gaps are too big. You need to have a really good ignition system (cap,rotor, and wires) to run this much gap. If you just have the regular ignition parts, I think your plug gap may be too aggressive.

[CorsePerVita]

Originally Posted by Walter_Middie

CorsePerVita,



I assume you are working on the 82 SC?

Sounds like you found a vacuum leak - Your hunting idle and dieing when coming to a stop are classic signs that you are running rich. I'd try leaning out the adjustment a little and see if that clears it up.

What usually happens is that your car develops a vacuum leak and it starts to run bad at idle, then the mechanic or previous owner makes the mixture richer. Then it runs better at idle, and rich at all higher RPMs. That's probably where you are now.

You also don't mention if you have an MSD ignition box. Even if you do, I think your plug gaps are too big. You need to have a really good ignition system (cap,rotor, and wires) to run this much gap. If you just have the regular ignition parts, I think your plug gap may be too aggressive.

Thanks for the help, yes this is my 82' 911 SC.

I am not sure where the vacuum leak could be coming from. I guess I will need to recheck things. I'll try removing the hose off the aux air valve since I did have it off and then reseat it to make sure it is seated properly.

As to the mixture I have not touched it since I owned it, however, it does not mean the previous owner didn't so this is definitely a possibility. Also one I didn't think of.

I have a brand new cap, rotor, wires and plugs in the car. However I have no upgraded ignition box. Where should the gap be? I'm happy to take the plugs out today and fix that.

[scotricker]

Me too , on the hunting idle.
After reading many comments for a long time, I finally started leaning my mixture with the tiny secret 3mm allen. After posting results and more questions, I was severely repremanded that we should never mess with the mixture without the correct specific exhaust gas analyzer equipment. So now what?
My mixture is leaner, but my idle still bounces when cold, and I have that super high idle just after starting. I'll use PB blaster in the AAR, good idea!
But some of the other comments were to check for a vacuum leak in the CIS with starter spray. Maybe I'll do that, too.

[Walter_Middie]

CoursePerVita,

You already said you found a vacuum leak.

Had a loose vacuum line where the cruise control was previously hooked up.

How long has it been like that? Could the previous owner have done this? Then richened the mixture? Or was the hose hooked up before and you unplugged it?

scotricker - I remember reading about your issue. It seems different from this one, and I think folks were nervous that you were just leaning out the mixture without doing some basic checks first - like CIS pressures. CoursePerVita sounds like he fixed a vacuum leak and is now running slightly rich. I could be wrong about both of you - the best advice is to check the CIS pressures, but if a slight change to the mixture fixes CoursePerVitas issue, I'm for that.

[CorsePerVita]

Originally Posted by Walter_Middie

CoursePerVita,

You already said you found a vacuum leak.

How long has it been like that? Could the previous owner have done this? Then richened the mixture? Or was the hose hooked up before and you unplugged it?

scotricker - I remember reading about your issue. It seems different from this one, and I think folks were nervous that you were just leaning out the mixture without doing some basic checks first - like CIS pressures. CoursePerVita sounds like he fixed a vacuum leak and is now running slightly rich. I could be wrong about both of you - the best advice is to check the CIS pressures, but if a slight change to the mixture fixes CoursePerVitas issue, I'm for that.

Well, it was like that when I got the car but I plugged the hose so it wouldn't be leaking. But it was literally hooked up to nothing, the hose was running to nada. It was like that for a while the way it appears. What if I open the hose back up?

Also found my gap on my plugs is wayyyy off so that explains why it's missing.

[CorsePerVita]

Ok quick confirmation I think i may have found the issue.

First off my plugs were fouled to hell due to the gap, i got new plugs and gapped them properly and kept the new crap gapped plugs as "backup".

As I am hooking it all back up and putting the new plugs in I notice a plug marked "AMP" on my warmup regulator is unplugged. Is this an issue?

[CorsePerVita]

Plugged it in and then double checked my plugs and wires one more time. As I did this I noticed the switch that closes as the throttle closes had a wire crimp that had come undone. I put a new connector on and she fired right up. Idle seems a tad high, not much. I am going to go drive it and see if the issue resolves or if I'm still chasing CIS demons.

[Walter_Middie]

I notice a plug marked "AMP" on my warmup regulator is unplugged. Is this an issue?

Many WURs have an opening to atmospheric pressure - they could be marked "Ambient Pressure". Just a guess - not sure. But I wouldn't assume it should be plugged. Can you read the part number off it - we can check against our database.

Stock plug gap is 0.031 inches?

[CorsePerVita]

Plugged it in, gapped plugs to correct gap (about .028-.030) and went for a drive. Car idles properly, warms up properly and she has her pep back Ah what a beautiful feeling. It's also running much better than when I bought it! These cars have got some balls. And that engine note.... ahhhhhh.

[wildcat077]

Happy to see you solved the mystery ... lol
Enjoy !

Cheers!
phil

[CorsePerVita]

Yeah what a weird issue. It explains why it's been doing it off and on since I got the car, wasn't plugged in the whole time! Sometimes it was just worse than others.

Thanks for all who gave advice and suggestions. Always appreciate any advice

[rusnak]

You might want to mark which vacuum line is going to the wur for future re-connects. Also, think about buying a used LM-1 fuel air gauge and a cis fuel pressure test kit. These make great requests Santa oh, 8 months early, haha. This is the only way to troubleshoot cis stuff.

Try adusting the shift coupler in 2nd or 3rd. Make sure the cone shaped setscrew is tight.

There is NO tuning of the clutch cable gap, once it Is correctly set.