Karl_W944

During this winter I've been tasked with starting up our 911 to let it run and heat up to operating temperature over the course of 30-45 minutes at a time, at least once a month. Normally it would jump between 900-1100 at the start then settle in at 1000-1100rpm. On this last start-up, I used my regular procedure, pulling up the throttle choke to give it more gas rather than pumping the gas peddle. after about 20-25 minutes it, it warmed up to about 140 and jumped up to 2100rpm on it's own; without me being in the car or applying any throttle. After 5 minutes, it didn't settle back down to 1000-1100 like before so I shut her down for a minute, then turned her back on. She went back to a regular idle between 1000-1100, but as soon as the peddle was lightly pressed, it went back up to 2100rpm. I can't find a direct answer to this one, but I'm assuming it might have something to do with a sensor, or throttle linkage or throttle body, or valves? Has anyone had this problem or knows what the cause and solution might be? I'm not so mechanically inclined to sort through the car to find out. We're not taking the car out until it warms up a lot here so I'm also wondering how safe it'd be to drive to the mechanic if we cannot fix it in the garage?

I can put up a video if needed to better explain the problem.

Thanks
Karl

Karl_W944

Anyone please help? I've been looking around on here and PelicanParts and still cannot find an answer to this problem.
Bump!

Amber Gramps

I would say vacuum leak, but that doesn't sound right. Are you sure the throttle linkage or choke linkage isn't sticking?

Karl_W944

I'm not sure where to look or how to check. It's my dad's car and I've never down any more than start it up, let it run and basic TLC. I'm not really mechanically inclined as I've never worked on a car before; but if you could tell me where to look and check this, unless it's under the car, I can check right now.

redridge

does the idle change when you take the gas cap off?

Karl_W944

I'm gonna go start her up and let her run for about 20 minutes and see what happens.

Amber Gramps

Honestly, I'd not be to concerned about it right now. It would require a bit of tinkering and if you are not one to dive in with both hands....then maybe just keep her warm and cozy until the snow thaws.

...could be this:

(sorry about the MM link. )

Karl_W944

Actually, I may have been talking down to myself; I can do that! that does't seem hard. as a first student at an engineering school, it's about time I get my hands dirty!

Amber Gramps

Well, the guys that will know for sure what is wrong will be along when they get off work. ....unlike myself that just keeps myself entertained between naps.

If you can do that then checking compression and adjusting valves is only a few quick confidence building lessons down the road.

Karl_W944

Umm.... how do I check compression and valve adjustments?

Right now, it's been about 10 minutes since I started her up, throttle lever up, and she's stable at 1000rpm; but it doesn't sound pleasant. Almost rough as it appears that I can hear the fuel injectors(ticking or clicking sound?).

Update: at about 20 minutes now and the idle sounds much smoother than previously stated. Idle is now jumping between 1050-1100rpm, oil pressure is currently at 20.

Update 2: 25-30 minutes now and the idle is still smooth sounding, with a steady idle at 1150rpm(I reckon it's her happy idle point) with minimal movement. Oil pressure is still at 20 and engine temp. is at 130. Nothing else has changed yet

Amber Gramps

That all sounds normal. Oil will go to 4 bars when revving, it is most likely valve tappets you her clicking, also normal, .....so relax and enjoy the rest of your day.

Compression and all that was just me joking around.

Karl_W944

I just walked outside to shut the car off and as I opened the garage door it started to slowly rise to 2100rpm!!! Engine temp is at 150 ATM! What the heck just happened? Should I shut the car down?? I just shut her down out of fear

Sorry another update: I started her up again, this time with the throttle lever down and she idled fine at 1150rpm as always. But when I applied throttle it jumped back up to 2050rpm and refuses to go back down on its own.

Here are two videos I just made made:
This first one is startup with the throttle lever up, after a 30 minute warm-up period.
The second is with the throttle lever down. I applied very light gas when the rpm went up to 2000.

MUSSBERGER

How cold is it where the car is? Just letting it sit there and run isn't a good idea. Drive it to get it to operating temp.

rusnak

can you disconnect the throttle linkage at the motor and rev it by hand? That will at least eliminate binding in the tunnel or at the pedal.

Karl_W944

It's southeastern Michigan and both days, yesterday and today it was in the high 20s. I'd drive it if my dad would let me since there's currently no snow or ice on the road but we also take the insurance off it in the winter so should anything happen before April, I would rather not be held accountable.

I was always taught to let the car run for 30-45 minutes at least once a month in the winter so the oil and other such fluids don't freeze over too.

as for the throttle linkage, if it doesn't take a lift, specific OEM tools, or an hour, I'll try to do that tomorrow morning. I'll just need to find a tutorial and I should be all set.