My idle is hunting?

[Eric Mckenna]

Hey Fellas,
I have a question for ya,
I took my car out today for a spin.. it started right up like she all ways does for me.. ran up to 2k and once warmed up it dropped down to 1.5k which is normal for her.. she has always idled at that rpm range.. advanced timming. this is what i was going to a friends house to try to mess with .. adjusting the idle to back to around 1-900 rpm like it should.
Well while doing we also notice (using a o2 meter) that I was running a tad bit lean.. so we adjusted it out to 3.5% and the idle ran up higher which is normal...
but when we tried to lower the idle back to what it should be at say 900 to 100 it started to hunt on me and if you blipped the throttle it would rev up and then DIE!.. so we sped the idle up a bit more to keep it from dying but it still wanted to hunt and surge very bad.. SO I gues my question is ... is this a sign of a vaccum leak? some place? that would cause this hunting?
We think it is a vaccum leak.. but I wanted to see if you guys had any insight on the matter.
Thanks in advance... and is there a secret to adjusting shift linkage or is a simple keep messing with it until it's right sorta thing?
I thought we had finally got the shifting on my car dialed in but on the drive home from my friends house I started to nick third while shifing from 2nd anf even nicked first while coming from neutral.... what gives a( this was never a problem before I played with it.. I was simply trying to smooth out the 5 to 4th shift as it would grind a tad if i wasn't careful but all other ise to shift great.. a bit tight but never did they grind as they do now.. should i simply keep trying until i score... with getting them all right.

Thanks agaion guys for reading and helping me out.. I have no dout my friends and ne woun't get it sorted out but any help you guys may have to speed it uip a bit would be great!
Thanks, Eric
78SC

[dougcl]

Perhaps your O2 sensor is inaccurate. What kind is it?

Doug
1975 911S

[bigchillcar]

Hi Eric,

To answer your second question...yes, keep messing with it. I kept the screws out of the cover in the back floorboard for about a week and tried a couple of adjustments before I found my 'sweet spot'. In general, start with the shift lever in neutral and all the way to the left. From there you may want to try slightly up or slighty down from that position a centimeter or so. Then maybe a hair to the right with the lever if that doesn't solve it. I think all of our transmissions are going to vary a little from that basic starting point and I wouldn't buy anyone's argument that 'their position' works entirely for all others.

For the first question now...you can confirm whether or not you have a vacuum leak with the carb cleaner test. Are you familiar? Spray it in the engine compartment around your airbox, hoses, etc. If the idle speed jumps, you have a vacuum leak somewhere.

Does your year model not have the idle air bypass screw that my 2.7 with CIS has? My '74 is unique in that it doesn't have an auxillary air regulator...it has a hand throttle just to the left of the handbrake. Mine starts with it in the 'up' position and as it warms you gradually lower it. When fully warm, that lever is fully down (off so to speak) and idling at 900-1000. That's the time, at 180 degrees, to go to the back and turn the idle air bypass screw and ideally set the idle with a tachometer/dwell meter or just your tach. Hope this helps some.
Ryan

[Eric Mckenna]

Thanks guys! check into what you guys mentioned .. anyone else maybe have any insight?
THanks in advance if ya can throw anything into the mix here.. more ideas to work with is better than none

Thanks Guys..
Eric

Eric,
Was having the idle hunt and engine dying problem also. I leaned the mixture about 1/8 turn and it solved both probs. Worth a try.
Mark

[Eric Mckenna]

Mark,
So by leaning it out it took care of your hunting.. I thought that the reason it was dying was because it wasn't getting enough fuel.. starving it's self due to toomuch oxy and not enough fuel.. so I fattened mine up a bit to hit 3.5% .. I'll try to lean it out some and check that as well.
just to help me understand .. what does leaning it out .. well how does leaninf the fuel mixture out help eliminate the hunting.. i thought that if you leaned the car out it ran hotter and it wasn't too good for the motor.. but maybe i am thinking to the extreme side of it..I'll try the listed item and see what i can track down.
Thanks guys!
VERY much. I don't care what my cars looks like! but I DO care what it runs like and it's not running so good at the moment so the help you guys give is much appreciated.
I have a friend helping me out with this as well so with this bit of info I know we'll track the problem down.. anyone else have anythign else i should be checking on?

Thanks, Eric

[k9handler]

just disconnect everything! Pull motor! Insert 3.6! Ha Ha...I wish I had a better answer for you bro...but I am sure you can get it fixed.

Eric,
The way I verified that my car was rich was pulling off a vac from the decel valve. Immediatly, the idle leveled off. I searched the archives and found a post by John Walker (genious at large) that this indicates a rich condition. With a 3mm allen wrench, I turned the adjustment screw ~1/8 turn CCW. That's all it took. I'm not saying that it is at optimum setting, but it is drivable now. May not be your cars' problem, but it is easy to test. Good luck.
Mark

[Jbabic]

I think your friend is a complete idiot and should be taken outside and ran over with a set of 10" fuchs.

[Jbabic]

Eric,

My research on the BB is that 3-3.5% CO was where our cars run best. There are plenty of topics on this one.

Also we need to know where the timing should be set. If your at 5 deg BTDC your engine starts to hunt. your timing is at 10-5 ATDC...these facts will help fellow Pelicans help with this issue.


No worries, nothing can't be solved!! Except for living w/women!!

[Eric Mckenna]

HAHAHAH! Smitty I wish ! I could swing a 3.6 ltr . hahahah! but not yet, i have to simply keep the 3.0 ltr.
Mark, Thanks for the extra bit of info on matter I'll check all of this .. Thanks.
Jer, NAH! My friend isn't an Idiot at all! He happens to be one of the most helpful , knowledgable guys I know. I hope he knows that! I have NO dout that with his help we won't get all this sorted out.. but it's cool to also hear all the extra ways to trouble shoot, and pin point the problem.. If this damn snow would go away.. I'd be working on the shift linkage right now.
HAHA and oh yeah! Jerry, if I catch you bad mouthing the guy who is helping me with this one more time.. I'll have to ya!!! ok.. I don't like anyone talking crap about my friends!
were are gonna have my car running so sweet! you're gonna want to trade me! hahahahahah!

Laters!
Eric

[masraum]

Ssshhhhhhh, be wery wery quiet! My idle is hunting wabbit!



Sorry, I've been staring at this thread for days now wondering what your idle was hunting.

[Eric Mckenna]

Originally posted by masraum
Ssshhhhhhh, be wery wery quiet! My idle is hunting wabbit!



Sorry, I've been staring at this thread for days now wondering what your idle was hunting.

Steve, I don't know what it's hunting.. but I wish it would find it and STOP!!! .. cuz otherwise i am aafraid i'll be hunting the dreaded vaccumm leak!

Eric
78SC

[stormcrow]

Eric,

Try this to see if it will solve the problem. There is a throttle adjusting screw which is used to adjust the throttle plate. It's located right next to the idle adjusting screw. You will need a tiny screw driver to make the adjustment. It also has a lock nut on it so you must loosen it first.

Turn the screw out until the throttle plate is closed (it may already be closed). Next turn the screw in to open the throttle plate approximately 1/8" - just enough to allow air to pass by.
Tighten the lock nut and start the car.

If that doesn't solve your problem, then you need to check your fuel pressure. You may have a problem with your pressure regulator - this would also cause the idle to fluctuate because it has a direct effect on the fuel pressure.

If you havn't changed anything and the problem just started, then I would start with the pressure regulator and work from there but, you need a pressure gauge to troubleshoot.

Steve

"A Porsche does more then just go fast in a straight line"

[Jbabic]

Eric,

I have the fuel pressure gauge. I know what Stormcrow is talking about....all in all it could be a few things all together, or just one...but we will find the singing/hunting idle problem.

[Eric Mckenna]

Thanks, SCrow
I'll look into this as well .
Thanks Jer.. we will have to gather up at Carstons ona Friday or SAt.. hell even Sunday and this will allow us the time we need to really get in to it all..
Thanks for helping.
Eric

[Jbabic]

I am back in cold Cincy next weekend...Jen works Saturdays...so Brie and I can help out then....no pickup lines on Brie...ok?...she's only seven for God sake!!!

[Eric Mckenna]

HAHAHAHAHAHA! deal I promise! no pick up lines..
Sat, it is then...
laters, Eric
78SC