sschultze09

Last weekend I started noticing my idle is over 1000 at times. Also when it drops below 1000 it seems to idle a little rougher than in the past. I did check the codes and I have a new one I have never seen before. In the Motronic mode #23 came up then it says regulation at stop (intake air leak?). Another thing I am noticing while writing this and letting my car Idle. It is making a popping sound out of the exhaust every few seconds. I can feel an increase in exhaust when it pops with my hand. Any Ideas on what I should me checking. Possible intake leak at the plenum somewhere?
TIA

lateforlunch

I'd check the idle control valve as they seem to get carboned up and stuck quite often. Intake air leaks could also cause this, if you have access to a smoke tester that might not be a bad idea to verify if your intake is sealed up good or not. Last but not least the fuel pressure regulator could also be faulty leaking un metered fuel into the intake.... potentially the source of your popping noise?

Let us know what you find

sschultze09

I cleaned the ICV a few years ago and will check/clean it again. It would be nice if it was that easy. I will search the fuel pressure regulator in here as it is running pretty rich right now. Thanks for the advice...

sschultze09

I saw another thread that said code #23 is most likely one of these.
cylinder head temp sensor and associated wiring/connector
throttle switches
high fuel pressure
a shorted O2 sensor wire
a bad O2 sensor
a mis-adjusted AFM
electrical noise entering the DME ECM harness from the spark plug connectors/wires
Does this sound right?

lateforlunch

fault code #23 regulation at stop is referring to the oxygen sensing regulation, sounds like yours is so rich its trying to drive it lean then and its at its limit? could be vice versa I suppose. All of the items you listed could affect the fuel mixure... time to start checking the items off the list. That can be time consuming, I like to keep things basic before I dive into pin checks and anything that requires alot of head scratching. Check for vacuum leaks first, head temp sensor resistance is easy enough to check too and could definetly cause you some running problems. good luck

sschultze09

Well I think I most likely found my issue. Could hear an air noise with the engine running and pushing down on the passenger side plenum the noise would change. took it all apart and this is what I found. luckily all the rubber is there and a chunk wasn't sucked into the cylinder. I would like to hear what the experts on here think. Split due to age or something more sinister going on? Anyway I have ordered 6 new ones and will report back once its all back together.

lateforlunch

Nice! glad to see you found the problem. All that plastic and rubber turns to stone with age and oil blow by, I dont see any reason to be alarmed... just some new parts needed. While you're in there replacing those plastic intake stacks and the rubber gaskets underneath would be a good idea too since Im sure its just as old.

Vandit

I'm in the middle of this, some of my stacks are cracked at the base where they fasten. Those intake manifold stacks are ~$90/each.


The gaskets on mine were falling apart.

sschultze09

Thanks, guys I will take a close look at the the stacks. Are the gaskets rubber?

BHCfarkas

Definitely wouldn't pay $90 for each of those. They appear to be rubber from the looks of it. I would make a trip to the hardware store and find a nice rubber hose that is the same inside and outside diameter and call it a day. Another thought, I bet someone of the silicone coupler companies make a similar sized option for you.

Vandit

These pieces are $90/each. Sometimes they crack. Mine are cracked at the base, around the fastener points.



The rubber couplings and the seal at the base of the manifolds are all relatively inexpensive. The seals have been superseded by 993 part #s.

sschultze09

Well my local Porsche dealership had one in stock so I just replaced the bad one and put it back together. Purrs like a kitten. I did check the stacks as Vandit suggested and no cracks at the base luckily at 90 bucks a pop. I am planning on replacing the O-rings this winter as preventive maintenance and also check/clean the mass air flow meter. For right now I am just going to enjoy the rest of the season. Thanks again guys for your help!

Navaros911

Glad to see it was an easy fix.

I think these cracks are quite common.

On mine I see small cracks too where they are fastened. Nothing too alarming to me, but I wonder if I should be.

Any advice?

sschultze09

Nav, are your cracks on the plastic stack or the rubber sleeve/coupling?