[T-Bone]

After sitting for close to a week, I started up the 968 today and it ran extremely rough. It didn't want to idle without my foot feathering the gas but after about 20 seconds it started smoothing out. I drove it for awhile and nothing else popped up. Starting it up again after it was warm was just as good as always. I am thinking MAF or something? I have some MAF cleaner but don't even know where it is on this car. Not sure what it could be. I don't know all the parts of this car yet. This is the first time this happened ('95 w/ 42K miles).

Any ideas?

Thanks,
T-Bone

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[S_Cal968]

Is this an isolated incident or does it happen every time it sits for awhile..? How often do you run an injector cleaner or when is the last time you had your F/I system serviced?

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[unknown4u]

step 1 replace dme relay. This because stage 2 of the relay is the circuit of the idle stabilisor it looks to me yours have those symptoms. Step 2 is the rest maybe a sparkplug?

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[T-Bone]

It's the first time and I replaced the DME when I got the car about 5 months ago. I do run Sea Foam from time to time in all my cars but have only done a can or so right when I got this. I have also replaced the spark plugs when I got it. I'll check to make sure they are all tight and that the wires are all connected well. As I said, the car ran great once the erratic idle mellowed out. I haven't popped the hood yet. I'll do it today.

Thanks

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[T-Bone]

One more possible piece of the puzzle. Started it this morning and went to the car show in Irvine. Car started and ran perfectly. When I got in, however, the inside smelled like gasoline. I remember this popping up in the past couple of weeks. When the car is closed up, it smells like gas when I open up the door. So, maybe the erratic idle in the beginning is fuel related?

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[S_Cal968]

Hmm, you may want to check the fuel line connections just below the tank. I also had a fuel odor and found a loose hose clamp close to the fuel pump. I'm not sure how it would come lose, but I haven't had a problem since. So, I'm wondering if there was air in your F/I system, [typically there's none] and it took a few moments to clear that out. If there's a leak, the cover shield will appear stained.
Another potential leak location is the inlet fuel hose, [runs from the filler to the tank].

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[xrad]

Idle speed/air bypass control or temp sensor?

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[sstman]

Just collected my 968 from the garage, have had the belts, chain, and slipper pads all replaced. the guys kept the car longer than anticipated, as they were not happy with the idle, once all back together. It seemed to hesitate every 3/4 seconds, with a vibration running though the chassis of the car. In fact they tore it all open again, as it was suspected that the exhaust cam have moved slightly?, when being lined up TDC?, any ways, they have checked everything, and although its better the second time round, there is still a slight shudder every couple of seconds on idle. the car pulls very well instant pick up on the throttle, no error codes on the diagnostic computer, so we are all stumped now! wish i had left the chains and pads, but they were pretty worn, and there was a leak on a cam seal anyway. any ideas guys?

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[Jamie '92 968]

<!--quoteo(post=71861:date=May 13 2009, 11:08 AM:name=sstman)-->QUOTE (sstman @ May 13 2009, 11:08 AM) <{POST_SNAPBACK}><!--quotec-->Just collected my 968 from the garage, have had the belts, chain, and slipper pads all replaced. the guys kept the car longer than anticipated, as they were not happy with the idle, once all back together. It seemed to hesitate every 3/4 seconds, with a vibration running though the chassis of the car. In fact they tore it all open again, as it was suspected that the exhaust cam have moved slightly?, when being lined up TDC?, any ways, they have checked everything, and although its better the second time round, there is still a slight shudder every couple of seconds on idle. the car pulls very well instant pick up on the throttle, no error codes on the diagnostic computer, so we are all stumped now! wish i had left the chains and pads, but they were pretty worn, and there was a leak on a cam seal anyway. any ideas guys?<!--QuoteEnd--><!--QuoteEEnd-->

Maybe this is too simplistic, and it doesn't fit at all with the fact that you just had this work done, but replacing my distributor cap and rotor two days ago made a huge improvement to my car's idle.
How long has it been since your's was replaced?

Jamie

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[Jamie '92 968]

<!--quoteo(post=67484:date=Feb 21 2009, 12:06 AM:name=T-Bone)-->QUOTE (T-Bone @ Feb 21 2009, 12:06 AM) <{POST_SNAPBACK}><!--quotec-->After sitting for close to a week, I started up the 968 today and it ran extremely rough. It didn't want to idle without my foot feathering the gas but after about 20 seconds it started smoothing out. I drove it for awhile and nothing else popped up. Starting it up again after it was warm was just as good as always. I am thinking MAF or something? I have some MAF cleaner but don't even know where it is on this car. Not sure what it could be. I don't know all the parts of this car yet. This is the first time this happened ('95 w/ 42K miles).

Any ideas?

Thanks,
T-Bone<!--QuoteEnd--><!--QuoteEEnd-->

T-Bone,

At the tech session in Hershey this year, Pete mentioned that a common failure mode of the 968s recently has been the cylinder head gasket.
My undersatnding of what he described was that the gasket develops small leaks, allowing a bit of coolant into the cylinder. He said that the symptoms are that the car will run very rough for a bit when you first start it up. I'd expect that the effect would be worse if it sits for a while and the coolant has time to leak.
This might be consistent with what you describe.

Jamie

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[Gotter]

<!--quoteo(post=71864:date=May 13 2009, 09:07 AM:name=Jamie '92 968)-->QUOTE (Jamie '92 968 @ May 13 2009, 09:07 AM) <{POST_SNAPBACK}><!--quotec-->T-Bone,

At the tech session in Hershey this year, Pete mentioned that a common failure mode of the 968s recently has been the cylinder head gasket.
My undersatnding of what he described was that the gasket develops small leaks, allowing a bit of coolant into the cylinder. He said that the symptoms are that the car will run very rough for a bit when you first start it up. I'd expect that the effect would be worse if it sits for a while and the coolant has time to leak.
This might be consistent with what you describe.

Jamie<!--QuoteEnd--><!--QuoteEEnd-->


Oooo... baaaaaad> I had this happen to my 944 a long time ago. I didn't even get the shudder/rough start. Ran fine, then one day the head warped and I was like Rally-X, shooting smokescreen as I went down the road (all the 30 yards I got...) Oil in the cooling system, coolant in the engine. 6 months and $7000 later, she ran beautiful. [img]style_emoticons/<#EMO_DIR#>/ohmy.gif[/img]

Jesus, the amount of ca$h I've thrown at these cars... [img]style_emoticons/<#EMO_DIR#>/laugh.gif[/img]


Anyways, If this is your deal, get it fixed yesterday! Your wallet will thank you.

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[sstman]

<!--quoteo(post=71863:date=May 13 2009, 05:01 PM:name=Jamie '92 968)-->QUOTE (Jamie '92 968 @ May 13 2009, 05:01 PM) <{POST_SNAPBACK}><!--quotec-->Maybe this is too simplistic, and it doesn't fit at all with the fact that you just had this work done, but replacing my distributor cap and rotor two days ago made a huge improvement to my car's idle.
How long has it been since your's was replaced?

Jamie<!--QuoteEnd--><!--QuoteEEnd-->

Thanks , Jamie, but yeah, the dizzy cap and rotor were changed at the same time with the belts (two weeks ago) the car ran great , huge improvement, the cam chain and pads were done over last weekend, because the fitter was waiting for the parts, so all the problems have started since the rocker cover came off the car .

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[Kim]

Mine did the head gasket thing and also was hard to start if it sat around a bit due to coolant inside the cylinders.

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[ds968]

Just had exactly the same rough , very rough , start symptoms this morning as described in T-Bone's first post , followed by smooth idle after about 20 seconds, and no problems at all driving it after that. The car sat undriven for two weeks prior to today. I recall this having happened only two or three times in the past ten years and just wrote it off as cold start gremlins which go away in a matter of seconds and ignored it.. as I probably will this incident also, but I was curious to see other's experiences and suspected causes so pulled up this thread....

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[Monstrous4Banger]

Does it die when you rev it, then abruptly cut throttle?

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[jfrahm]

I am often surprised people do not pull the plugs in situations like this. If you let the car sit and then pull the plugs you can look for coolant or gas in one of the cylinders, if need be with a q-tip taped to a bamboo skewer or something. The condition of plugs can also tell you a great deal, too-clean from water, black from fuel, etc.



If you do not find anything, start the car and shut it down during rough idling and pull the plugs again, if one is now wet with gas you found your problem.



You can also pull plug wires one by one to see of you can isolate the problem to one cylinder. Whichever wire has the least effect points to the problem. Often the car will run worse with the bad cylinder disconnected, but not as badly as it would with one of the good ones disconnected.



-Joel.

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[ds968]

[quote name='Monstrous4Banger' timestamp='1341119557' post='128823']Does it die when you rev it, then abruptly cut throttle?[/quote]



No.

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[ds968]

[quote name='jfrahm' timestamp='1341148913' post='128832']I am often surprised people do not pull the plugs in situations like this. If you let the car sit and then pull the plugs you can look for coolant or gas in one of the cylinders, if need be with a q-tip taped to a bamboo skewer or something. The condition of plugs can also tell you a great deal, too-clean from water, black from fuel, etc.



If you do not find anything, start the car and shut it down during rough idling and pull the plugs again, if one is now wet with gas you found your problem.



You can also pull plug wires one by one to see of you can isolate the problem to one cylinder. Whichever wire has the least effect points to the problem. Often the car will run worse with the bad cylinder disconnected, but not as badly as it would with one of the good ones disconnected.



-Joel.[/quote]





Will give that a try.

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[ds968]

Car started normally, with smooth idle this morning, but thought I should check the plugs nonetheless ; did not need to pull the spark plugs themselves out yet, I think I found the culprit while trying to remove the cap off the first one - the wire easily separated from the cap and the tip was completely frayed .

I presume that would explain the symptom, although, if it is that I wonder why a smooth start this morning ? Anyway, I twisted it back into the "pin shape" tip it should be and cut the also-frayed fabric around it so it probably will be fine as a temporary fix, for now. The other wires look good . Since I have the non- oem blue ones ( don't remember the brand, NOLO comes to mind but not sure that's it. ) I have to buy a whole new set, can't just replace one with another from of the oem set I kept. Just as well, if one went, the others can't be far behind..even if they still look fine at the moment.

The spark plugs look great, btw. Also I'm not losing any coolant. And when I say any, I mean not even a couple of millimeters drop from the fill line of the reservoir , after thousands of miles driven. So doubtful a leak, even a minimal one could be the problem.

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[flash]

yup - you found it

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