[s-cars] Short term rough idle - follow-up
Mark Strangways
MarkS1234 at spamarrest.com
Mon Jan 25 16:27:08 PST 2010
My best guess would be a bothersome injector leaking a bit into the IM.
Cleans up nicely once running for a bit as you have said.
Since you have the RS2 injectors your better off than my big Delphi ones, but this is where I get my "guess"
Best of luck with it,
Mark S
On 2010-01-25, at 7:08 PM, Robert Myers wrote:
>
> Dave,
>
> The most noticeable symptom is a slightly rough idle which smoothes
> out nicely in just a few seconds after start-up. I wouldn't really
> describe it as a miss. The rpms are pretty solid. It's not
> "seeking" like what usually happens with a sticky ISV.
>
> The engine sports a nice RS2 EM.
>
> Bob
>
>
> At 07:00 PM 1/25/2010, djdawson2 at aol.com wrote:
>> Bob,
>> I dont' really agree that you are just guessing when you see those
>> types of compression numbers. I'd also argue the #5 cylinder is
>> where you are going to see to most heat (not #3), especially if not
>> equipped with a good EM.
>>
>> The bottom end of these engines tend to be very durable. You're not
>> going to typically see a "miss" as a result of bad rings/cylinder
>> walls either... a "miss" (assuming your fuel and ignition systems
>> are working properly) is typically a symptom associated with
>> valve/valve seat wear... therefore, not sealing as well.
>>
>> Having a fresh head ready is always convenient on a high mileage car
>> (porting... no way). But yours looks pretty healthy.
>>
>> Dave
>>
>>
>>
>> -----Original Message-----
>> From: Robert Myers <bob at chips-ur-s.com>
>> To: Cody Forbes <cody at 5000tq.com>
>> Cc: S-Car-List at Audifans.Com <s-car-list at audifans.com>
>> Sent: Mon, Jan 25, 2010 4:34 pm
>> Subject: Re: [s-cars] Short term rough idle - follow-up
>>
>>
>> *This message was transferred with a trial version of CommuniGate(r) Pro*
>>
>>
>>
>> Hmmm... Sales pitch? Have a nice AAN just sitting around waiting for
>>
>> a suck.. er..., customer? ;-) Uh... How much? :-D
>>
>>
>>
>>
>>
>> At 02:29 PM 1/25/2010, Cody Forbes wrote:
>>
>>> *This message was transferred with a trial version of CommuniGate(r) Pro*
>>
>>> Nah, I'd say it's fine. Cylinder 3 runs the hottest and seems to wear
>>
>>> a bit more, but your numbers are reasonable. Without a leak down test
>>
>>> any statement as to why that cylinder is low (piston rings, grouved
>>
>>> cylinder wall, dirty/bent/burnt valve, head gasket, etc) is just a
>>
>>> wild guess at best.
>>
>>>
>>
>>> Time to take apart a running car? No.
>>
>>>
>>
>>> Time to casually search for a spare cylinder head to have rebuilt
>>
>>> (and ported hehe) and ready to swap on to the car on a lazy weekend?
>>
>>> Probably. Even better of course would be the same plan with a whole
>>
>>> fresh, tweaked, engine going in. Then sell the old stuff when you are
>>
>>> done and recoup some cost.
>>
>>>
>>
>>> -Cody (mobile)
>>
>>>
>>
>>> On Jan 25, 2010, at 1:37 PM, Robert Myers
>> <<mailto:bob at chips-ur-s.com>bob at chips-ur-s.com> wrote:
>>
>>>
>>
>>>> *This message was transferred with a trial version of CommuniGate(r)
>>
>>>> Pro*
>>
>>>>
>>
>>>> Yeah, Cody. You're right and I screwed it up. Now the question
>>
>>>> remains - do I need to get a new head gasket and/or valve job on the
>>
>>>> car?
>>
>>>>
>>
>>>> Bob
>>
>>>>
>>
>>>>
>>
>>>> At 12:46 PM 1/25/2010, Cody Forbes wrote:
>>
>>>>> *This message was transferred with a trial version of CommuniGate
>>
>>>>> (r) Pro*
>>
>>>>> Note that the compression gauge has a one way valve - it doesn't hold
>>
>>>>> pressure in the cylinders, only in the hose for the gauge.
>>
>>>>>
>>
>>>>> -Cody (mobile)
>>
>>>>>
>>
>>>>> On Jan 25, 2010, at 11:28 AM, Robert Myers
>> <<mailto:bob at chips-ur-s.com>bob at chips-ur-s.com>
>>
>>>>> wrote:
>>
>>>>>
>>
>>>>>> *This message was transferred with a trial version of CommuniGate(r)
>>
>>>>>> Pro*
>>
>>>>>>
>>
>>>>>> Original post:
>>
>>>>>>
>>
>>>>>> Hi Y'all,
>>
>>>>>>
>>
>>>>>> My well modified '95.5 urS6 has developed a relatively minor but a
>>
>>>>>> bit disturbing problem. On initial start-up the engine idles a bit
>>
>>>>>> roughly. The idle smoothes out again after a few (perhaps 10-15)
>>
>>>>>> seconds and becomes as solid as a rock. Obviously this is not, of
>>
>>>>>> itself, a major problem but it could be a portent of something more
>>
>>>>>> serious to come. Any ideas/suggestions?
>>
>>>>>>
>>
>>>>>> Other than the idle problem the car is running superbly. Let's
>>
>>>>>> see... modifications which might be related... Running the Dave
>>
>>>>>> Forgie 1.8t coil mod as expressed by Apikol. All the RS2 mods -
>>
>>>>>> turbo, ECU, EM, injectors. Stromung exhaust. Big FMIC, etc.
>>
>>>>>>
>>
>>>>>> Bob
>>
>>>>>>
>>
>>>>>> And now the follow-up:
>>
>>>>>>
>>
>>>>>> There were several suggestions ranging from "don't worry about it"
>>
>>>>>> to
>>
>>>>>> "try some Techron" to "check out the ISV" to "uh-oh might be a blown
>>
>>>>>> head gasket". (Oh joy. :-()
>>
>>>>>>
>>
>>>>>> OK, here's what has been done since the first post:
>>
>>>>>>
>>
>>>>>> Item 1 - a can of Techron has been added to a 3/4 full tank of fuel
>>
>>>>>> and about half of it has been burnt.
>>
>>>>>> Result 1: idle is smoother. Not perfect yet but improved. (It
>>
>>>>>> wasn't REAL bad to start with so...) Indicating possible dirty
>>
>>>>>> injector(s). I'm planning on doing the Techron bit again the next
>>
>>>>>> time I fill the tank.
>>
>>>>>>
>>
>>>>>> Item 2 - I pulled and inspected all the NKG plugs.
>>
>>>>>> Result 2 - They all looked the same - dry and with normal
>>
>>>>>> coloration,
>>
>>>>>> no excessive wear. They looked as good as any plugs of that age
>>
>>>>>> in a
>>
>>>>>> big boost I5. There is a hint of black deposit on the threaded
>>
>>>>>> portion of #1 well outside the internals of the engine area. It
>>
>>>>>> is a
>>
>>>>>> little greasy feeling and left a smudge on the fingers.
>>
>>>>>>
>>
>>>>>> Item 3 - The symptoms don't seem to indicate ISV troubles to me so I
>>
>>>>>> haven't messed with it (yet) - I will if the problem persists.
>>
>>>>>> Result 3 - none (yet).
>>
>>>>>>
>>
>>>>>> Item 4 - While the plugs were out I checked the compression of each
>>
>>>>>> cylinder (only one try - no repeated testing and averaging, cranking
>>
>>>>>> time was the same for all cylinders twelve pulses per cylinder) and
>>
>>>>>> found:
>>
>>>>>> Result 4 -
>>
>>>>>> Cylinder max pressure
>>
>>>>>> 1 150
>>
>>>>>> 2 150
>>
>>>>>> 3 135
>>
>>>>>> 4 160
>>
>>>>>> 5 155
>>
>>>>>>
>>
>>>>>> Additionally after cranking the gauge was just left alone while
>>
>>>>>> still
>>
>>>>>> connected to the cylinders. The pressure held and there was no sign
>>
>>>>>> of leakage - at least not in the short term (a couple of minutes).
>>
>>>>>>
>>
>>>>>> I'm not thrilled with #3 pressure but it is pretty close to being
>>
>>>>>> acceptable.
>>
>>>>>>
>>
>>>>>> OK, whadya think? Should I be making an appointment with my
>>
>>>>>> favorite
>>
>>>>>> independent Audi wrench or should I just quit picking at nits and
>>
>>>>>> get a life?
>>
>>>>>>
>>
>>>>>> Bob
>>
>>>>>>
>>
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>>
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>>
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