[ianreeves]

Hi, I wonder if anyone has any ideas ?



I have a 94 CS which when left for a few days and started it runs on 3 cylinders and chucks grey smoke out the exhaust. <img src="/forum/images/smilies/968/ohmy.gif" class="smilie" alt="" />



If you rev the car it clears and returns to idle.



The following are new;



Plugs

Plug Leads

Dis Cap

Rotor Arm

DME relay

Temp Sender Sensor

Fuel Pump

Fuel Pressure Regulator

Check Valve

( Injectors cleaned and tested )



Car is not using water, just rough as old boots when you leave it standing <img src="/forum/images/smilies/968/mad.gif" class="smilie" alt="" />



Any help is appreciated, and before anyone says.. I can't drive it every day !!! <img src="/forum/images/smilies/968/biggrin.gif" class="smilie" alt="" />

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[bob blackwell]

Well, I think gray smoke indicates oil consumption. Perhaps a valve is getting stuck open when it sits for a while and running the engine clears it up. I suspect valve guide seals or the valve guide itself is worn. Try running some chemical cleaner through the engine and see if it cleans out some builtup carbon deposits. If that doesn't work, it sounds like a valve job is needed. Good luck, Bob Blackwell.

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[TheMirror]

A few questions -



How many miles on the car?

Does it perform the same way every time?

Once warm, does it pass blue smoke on overrun?

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[ianreeves]

[quote name='TheMirror' post='34106' date='Apr 13 2007, 03:02 PM']A few questions -



How many miles on the car?

Does it perform the same way every time?

Once warm, does it pass blue smoke on overrun?[/quote]



Sorry also forgot to say



The car has had a full head re-build 1000 miles ago with new valves, seals, springs.. It did the above before the re-build though. Was rebuilt by a Porsche specialist.



The car has 88k miles - Full history



No to any smoke when its running. This is a intermittant thing, will be fine for a while then chug chug chug. Only smokes when in chug chug mode, when cleared, no problem.



Does not use any water or oil and gas consumption is about normal <img src="/forum/images/smilies/968/rolleyes.gif" class="smilie" alt="" />



Could it be a MAF fault or something to do with the cold start ?

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[flash]

i would definitely use a paper towel and catch some of the smoke to see what it is - if it's oil, you'll see and feel it - if it's fuel, you'll smell it



check the torque on the plugs - a loose one can do this - what happens is the compression drops in that hole, and unburnt fuel goes out the tailpipe - then the plug and the head heat up, and seal the gap



i would pull the plugs and look at them



a sticky injector can do similar things too - even if they were just cleaned, things go wrong



the next thing i would do is disconnect the plugs, one at a time, and see which hole is the one dragging its butt - be very carefull with this - the current going through the wire can kill you - insulate yourself from the wire, and do not let it go to ground

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[ianreeves]

Yes you can smell it.... The smoke is not at all blue, and the second it fires on 4 cylinders its gone.

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[flash]

sounds like fuel - check the plugs and such as indicated above

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[ianreeves]

Thanks will have a look over the weekend.



Quick question on the routes of the HT leads, are there any things that could be an issue ?



Either that or its a duff injector......

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[flash]

it's not likely a wire - the "clearing" of the symptom would seem to rule that out - but, the spark plug wires run under the vanity cover, so you could have knicked one - since you have to remove it anyway to be able to pull the wires one by one without electricuting yourself (i pull it just to be able to more easily pull the plugs anyway), i would take a good look at them - then, route them (and the cruise control cable) under there so they don't get pinched

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[ianreeves]

<img src="/forum/images/smilies/968/sad.gif" class="smilie" alt="" /> <img src="/forum/images/smilies/968/sad.gif" class="smilie" alt="" /> <img src="/forum/images/smilies/968/angry.gif" class="smilie" alt="" /> Well spent today looking and not sure what's going on...



Tested leads, all ok.. Then I took off the coil lead, and the ISV, MAF and throttle pos'n sensor plugs, and re-seated them..... Try and start the car then.. It didn't want to start at all. Turning oven then just about catching.... Lump Chug limp



Waited for a bit then started again and it ran fine <img src="/forum/images/smilies/968/mellow.gif" class="smilie" alt="" />



So not sure what that tells me.. Will see if I can pop down to the store and get a new coil-distributor lead.



Also took the the ISV valve off and cleaned that out, car is much smother on idle now.

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[ianreeves]

Well, still confused, but have noticed some other odd things ?



If I ever disconnect the MAF ( engine and ignition off ) the car struggles to start, is there some type of calibration it has to go though ?



Or



Is this an indication its on the way out <img src="/forum/images/smilies/968/mellow.gif" class="smilie" alt="" />



I have ordered a new ISV so will put this in anyway. The one odd thing is it doesn't appear to run on 'choke' when I start from cold the Revs only rise to about 1k then do drop to about 900 when warm ?



Still confused <img src="/forum/images/smilies/968/wink.gif" class="smilie" alt="" />

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[TheMirror]

Is there anyone nearby that you can swap your DME unit with? Just to eliminate the brain as a potential suspect.



-Mirror

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[ianreeves]

Any idea why you think it could be the Control unit ? Is normally fine... And when its going no problem what so ever.

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[TheMirror]

No, just an elimination theory.



If for some reason you put in a different DME and the problem disappears, its a fresh place to start.



FWIW, I had a 1995 2.0L Golf that did this, by the way. In 133K miles of ownership, I never did figure out why it did that and it never mattered. It could blow out big time smoke on startup if I juiced the throttle just right.



Let us know how it goes,

-Mirror

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