9 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHRough Idle
Leading reported evidence
Replace sparkplugs
Performed · outcome unconfirmed
No successful repair reported for this finding.
0
Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that performed work without a confirmed outcome
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Performed · outcome unconfirmed · Original poster
I had the sparkplugs changed, and it didn't affect the idle.
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Suggestion
It is extremely difficult (without proper testing equipemnt) to check the ICV for proper operation, However, when your engine is running rough, tap on the valve with the back of a screw driver and see if there is a change in idle.
Leading evidence: 'Replace sparkplugs' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Check icv' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
Source reports, not a diagnosis or a success probability. Counts refer to discussions and can overlap.
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that contain suggestions
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Suggestion
It is extremely difficult (without proper testing equipemnt) to check the ICV for proper operation, However, when your engine is running rough, tap on the valve with the back of a screw driver and see if there is a change in idle.
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that contain suggestions
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Suggestion
If the idle is lower than normal, check the Idle Control Valve on the side of the throttle body.
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that contain suggestions
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Suggestion · Original poster
Check all vacuum lines and throttle body connections for leaks.
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that contain suggestions
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
These are separate views of the same evidence. Frequency alone does not establish a fix, and these counts must not be added together.
Check icv
No successful repair reported for this finding.
0
Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
Discussions that contain suggestions
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Suggestion
It is extremely difficult (without proper testing equipemnt) to check the ICV for proper operation, However, when your engine is running rough, tap on the valve with the back of a screw driver and see if there is a change in idle.
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Suggestion
It is extremely difficult (without proper testing equipemnt) to check the ICV for proper operation, However, when your engine is running rough, tap on the valve with the back of a screw driver and see if there is a change in idle.
Counts describe captured discussions, not unique people or a diagnosis. Author identities are not reliably stored. Exact duplicate evidence is counted once across matching discussions; one discussion counts at most once per action/state. Multiple repairs reported together remain a combination. Suggestions and failed attempts do not establish a fix. Matches cover whole discussions and can include related faults, model variants and incomplete threads.
9 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
Rennlist: 1 discussions
0 evidence records excluded for query context · 0 excluded by outcome qualification · 0 adjusted by outcome qualification.
0 acknowledgements have no verified action link; they do not establish a repair result.
Generation: 20261027T150039Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources
Whuddup.
I have a '99 that idles a bit rough. It has 65k miles on it, but when I bought it with 54k I noticed it then, too. I had the sparkplugs changed, and it didn't affect the idle. It doesn't have a leaking RMS, nor has ever had the problem associated with the 3.4. When the old plugs got taken out I inspected them, and one of them smelled kind of funny. It's hard to describe the smell besides, "funny." They all looked similar, and none had visible problems.
Any ideas?
A bit rough compared to what? Have you sat in other 996s to compare? They tend to idle very differently than most "regular" cars. As far as a spark plug smelling "funny", I'll refrain from commenting
A bit rough compared to the '00 Carrera that my dad owned. A bit rough compared to the '02 x-50 he owns now. A bit rough meaning it the car vibrates too much at idle...and also it idles lower than it should...therefore it is idling a "bit rough."
comprede?
If the idle is lower than normal, check the Idle Control Valve on the side of the throttle body. Also, the temperture sending unit (directly below the air filter housing on the water pump) is known to cause these problems. Both can be slightly out of spec and not cause a CEL. Check all vacuum lines and throttle body connections for leaks. If you have a scanner, hook it up and see what the sensors might be telling you at idle. If you don't have a scanner, get one.
OK, that's a bit more clear. I don;t know if there are known idle roughness issues but I can tell you that my 1999 996 idled roughly compared to my 2004 with X51. It may be something inherent to that engine and its programming considering that it's a drive by wire, not e-gas.
Alon - Yeah, lol...I'm not a "new" Porsche owner, or anything. There is definetely something wrong with her as sometimes while idling at a light if you pick a note and sing monotonously it will be like yer talking into a fan.
Okay...well not
that
bad, but pretty bad irregardless. And, it is a 6-spd, btw.
The rough idle is not really consistent with certain type of driving, or only when it is cold. It just seems to idle rough when it wants to idle rough.
1999Porche911 - Okay, so on the "Idle Control Valve" on the side of the throttle body...what am I looking for in particular? Should I remove it and see if it is clogged? Should just replace it? Honestly, I don't mind spending money if it completely eliminates the possibility of that being the problem. (Unless I just check it for something in particular)
Temperture sending unit. Replace. Got it.
Check all vacuum lines and throttle body connections for leaks. k.
Scanner, eh? Where would I pick one of those bad boys up?
I have a scanner that is no longer made, but many people here have bought some and are happy with them. About $150 or so. Do a search.
It is extremely difficult (without proper testing equipemnt) to check the ICV for proper operation, However, when your engine is running rough, tap on the valve with the back of a screw driver and see if there is a change in idle. You can also remove the 2 screws and valve and spray the inside with carb cleaner and put it back on. All it is is a little verticle window that pivots open and closed based on how much air is needed to bypass the throttle body to keep the engine running. You can also temporarily increase the idle by putting a thin object between the throttle cable connector and plate. If the idle stabilizes, it may indicate a bad ICV. A new one is less than $150 and autozone carries them. Make sure your throttle body and intake are clean.
I would get the scanner, as it may showing you something obvious, such as an incorrect signal from the MAF. Even before getting the scanner, clean the MAF and see if improvement is noted. I would also run a few tanks of gas with some injector cleaner if you haven't done so already.
The 3.4 will idle rough at times, but seldom. It is normal for these cars to have the idle fluctuate +/- 40 rpm when warm.
Do you get a rough idle when you have the AC off? Try checking with the A/C on and off. I get a rough idle when I turn off the A/C. I believe that the A/C was designed to be on most of the time.
This is a source reference. Confirm exact model applicability in the original material.
