[mdss]

Hi all.



I have the above problem when the car is driven hard i almost get a little vibration through the pedals also it revs through the rev range fine but feels a little coarse.

Also when trhe car is at idle and i stamp on the accelerator i get a little miss before the engine revs smoothly, the car vibrates slightly before the rev needle flies up.

Dont know if these two are linked i thought maybe the balance belt may have jumped a tooth as the roughness may be coming from the engine harmonics not being in sync.



I do have a promax chip and have the drilled airbox as per flash's instructions, the car is certainly louder with the air box mod could this cause the vibration when the car is revved hard??



The car has had new plugs rotor arms dizzy cap. I have read a few post regarding DME relay not sure what dme stands for could it be this??



Any help as usual is warmly received and with the help i got from you guys last time regarding floaty steering the 968 forum is now stuff of legend amongst my "car friend"





thanks again

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[flash]

could be a loose plug or cracked wire. check the torque on the plugs (18-22ft/lbs). also fire it up in the dark and look for sparks jumping around at or around the wires.



also, when you installed the cap, did you also correctly install the spacers?



check the hall sender

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[mdss]

hi flash what is the hall sender?



when you say cap spacers what are they i had some idiot car detailer clean the engine bay and he managed to get water everywhere it started misfiring. i took all the plugs out and dizzy cap off and dried everything and sprayed it all with lubricating fluid and all seemed fine after that, but now you mention the cap maybe i refitted it incorrectly.



thanks again look foward to hearing what you think you are really MR 968

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[flash]

the rotor has 3 little spacers that go between it and the cam gear. people frequently lose or fail to install those. that leads to misalignment. don't guess on spark plug torque either.



also, check your spark plug wires. believe it or not these fail rather frequently.



the hall sender is at the rear of the distributor/cam housing, above the heater control valve and oil filter. you will find a connector on a little bracket there. it is well known for disintegrating due to heat (which is why i came up with the heat shield)

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[mdss]

Just did the 'in the dark test for jumping spark but nothing.'



How do i check the ht/spark leads what is the procedure??



I will check the hall sender tomorrow, how do you know if its gone is it simply a matter of having a look at the wires, i know its below the cam cover.



thanks again sorry for all the questions.

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[flash]

no worries



obviously check the connections of the spark plug wires. beyond that you need to check the resistance of the wires. i just replace them if i think they are bad, or are more than 3 years old, or have been removed more than a couple of times.



the connector at the little bracket is what usually fails on the hall sender. you should be able to easily see if it is crumbly.

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[Trueblue]

If you had a lot of mis firing after an engine wash, pay close attention to the entire high tension circuit, arcing can cause carbon tracking on various components, and this provides an easy path for recurrance. Had the same problem with mine after an engine steam cleaning, I dried everything in the HT circuit and all was well again. Soon thereafter I replaced all the plug wires and cap/rotor because I babied it home from the steam cleaner with that misfire, and also because they were of unknown age/history.



As to hesitation upon stomping the pedal, this could be caused by a vacuum leak somewhere, modern fuel injection systems try to compensate for this condition when the lambda sensor senses an excessive lean burn, and this could possibly be masking a problem.



I'm new to the 968, and no expert like many here, but this is my 2 cents on actions I would take..............

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

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[mdss]

Hi guys just a quick update i checked all the bits Mr flash told me too, finally after there was no improvement i managed to get a chap i know to let me plug the car into his autologic diagnostic which revealed if my memory serves correct fault code 34 hall sensor... so as usual it looks like flash may have diagnosed a problem from across the atlantic without seeing the car!!



I have ordered a senor and will fit it tomorrow any how to guides on how to change it?



The car never misfires when being reeved to the red line it just feels a little rough and flat did'nt realise the hall sender could have such an adverse effect on the car. will be interested to see if it cures the fault. I know these big engined 4cyl cars are a little coarse but not even my e30 m3 felt like this.

thanks again for all the help



will report back

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[flash]

glad you found it.



changing it isn't hard. you do have to remove the cam cover though to get to the screws, so plan on a cam cover gasket, some RTV for the corners, and the 4 circular gaskets that go at the bottom of the spark plug towers.



the bummer is that you also need to be prepared to have to replace the bolts that hold down the cam cover. they tend to snap easily. you may get lucky, you may not. usually you only snap 1 or 2, but it sucks when you do if you don't have any lying around (there are 2 different lengths too)

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[mdss]

thanks flash



only just changed the cam cover gasket 1 month ago when i had the head gasket done along will the four O ring gaskets the bolts should be fine also to be honest they came off fine last time what torque should the cam cover be tightened too ? 7ft/llbs??

Think thats what i did last time.



How long does the job take?



once again thanks your a pal.

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[Scott Collins]

I'll chime in if I may....





The valve cover bolts will "bottom out" - I'm sure there is a torque spec, but you can just feel for the stop when you turn them in and don't over-tighten past that. For instance, I would not use a 1/2 inch ratchet for this, because it is easy to over-torque with a larger handle. More leverage. I use a 3/8". I have never snapped one, but there is always a first time....



You'll see the shoulder of the bolt with you remove them, and be sure to lay them out in the order they were removed because they are different lengths depending on their location. Flash mentioned this, above.



It will realistically take about an hour, in part because you also have to remove the wire to the vario-cam solenoid that you see right on top center of the valve cover. It has a u-shaped metal clip that is squeezed and pried out.



Whenever I have done this, 3 times in the past year, I have had extra o-rings on hand and the paper gasket that seals around the vario-cam solenoid and as mentioned, extra RTV.

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[mdss]

Just was having a quick scan of all the info on the forum and came across flywheel vibration problem, what are your thoughts on this is what i may be experiencing that i have said is roughness, when i drove the car today i felt when it was being revved hard and i was changing gear there was vibartion coming through the clutch peadl.



Or is this being ott and this is simply a hall sensor symptom.



just a thought if i am being a fool feel free to say haha

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[Lear35A]

One more chime.

In case you do want to torque them, you are correct that it is 7 ft.lbs.

I just took a close look at mine. This is another case of not thinking out the design that infests this car. Just a couple of small reliefs in this valve cover and we would have been able to change this Hall sensor without removing the cover. Wouldn't have cost them a dime to make the casting this way. <img src="/forum/images/smilies/968/whine.gif" class="smilie" alt="" />

If your cover and spark plug rubber gaskets are relatively new, I wouldn't worry about needing new ones. However, the paper gasket and o-ring for the variocam solenoid are another matter. I'd have new ones ready for this. And, for me, it's one s of a b to get it lined up right.

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[DaveN]

Try not to break any cam bolts, one is 9.00 the other is something like 35.00!

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[mdss]

thanks guys will tackle it in the morning

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[mdss]

Hi guys changed the hall sensor was a pretty quick easy job under an hour and managed to do it without beaking any bolts.



The car feels much better and smoother although still alot of vibration when being driven hard so i think the balance belt has either been fitted wrong or jumped a tooth. the problem was a well known one the blance belt was whining alot as it was too tight so we kept loosening it till it stopped whining but now i fear we did this too much. so i will check this in a week.

But thanks to all of you for the help the car feels much better.



Also how have you guys timed the cambelt and the balance belt up as i think if i am going to do the balance belt i might as well check the cambelt?



thanks again

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[Lear35A]

Not much you can do with the cam belt short of doing the complete timing. That's a big job. Not too difficult to check to see if the belt has jumped a tooth. The balance shaft belt tension really needs to be set by the special Porsche 9201 tool.

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