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The hall sensor is 'easily' replaced when doing a tbelt replace project by removing a few more items
Remove the RH (passenger side in North American cars) cam gear then the back plate. Theres then lots of room to disconnect the HS connector, replace and reconnect.
Thanks Malcolm. If only I'd known this at the time! I had the gears off too to fut new ones, so would only have had to take off back plate.
Oh well the connector looked ok. I know they can crumble when they are actually disconnected, but I will leave testing connector till I'm back in there for another time, unless sensor fails sooner.
AFAIK you don't need to remove the intake to get at the two main ground points...
Thanks John. I understand the locations but it's the getting at them that is not as easy as it looks in the pic.
Fuel rails have to come off, MAF out is easy, but then I have to work at right angles over the end of the manifold to get the throttle cable pulley off ('off' is the easy bit), so since I'm this far in it's but a handful of easy bolts further to let me slide the manifold forward far enough to get at the ground points.
Was going to say I'd rather poke hot needles in my eye than remove/replace S4 manifolds. but then realised I've just had that done - ie a needle poked into my left eye to repair a detaching retina. LOL.
Will keep you posted.
Cheers.
(ps - retina ok now. Laser welding successful. Waiting for the gas bubble inside to dissipate).
how many miles are on the engine and has the intake refresh ever been done?
Its a safe bet that if you have over 50K miles and the intake is original then its time to refresh all of the parts under the intake ,
this would include the CPS, the knock sensors ,the Hall sensor, the flappy valve, the ISV and the TPS.
That said inspect the grounds and the CPS connector at the rear of the block ,
also look for a damaged harness as it crosses from the engine head to the firewall.
Thanks Mrmerlin.
Engine has 220,000 miles on it and I had the manifold off a few months ago.
Arrrggghh - if only I had known the significance of those two grounds. Never mind- I do now (but yet to be proven as the cause of the fault. Fingers X-ed).
To keep the car on the road I exchanged the GT manifold with my S4 manifold, and which is the one I modified so I call it my my 'fast' manifold. (The GT actually has S4 cams (thats another story) which is why I can accurately say the improvement is due only to the manifold changes. And gee is it still ever a FUN car to drive. Always get this all over my face whenever I touch the accelerator. Mwaaahh haaa haarrr).
Thanks John. I understand the locations but it's the getting at them that is not as easy as it looks in the pic.
Fuel rails have to come off, MAF out is easy, but then I have to work at right angles over the end of the manifold to get the throttle cable pulley off ('off' is the easy bit), so since I'm this far in it's but a handful of easy bolts further to let me slide the manifold forward far enough to get at the ground points.
Was going to joke I'd rather poke hot needles in my eye than remove/replace S4 manifolds. but then realised I've just had that done - ie a needle (not hot) poked into my left eye to repair a detaching retina. LOL.
Will keep you posted re the fault progress.
Cheers.
(ps - retina ok now. Laser welding successful. Waiting for the gas bubble inside to dissipate).
Don't ever let anyone tell you that getting at earth points MP-VIII and MP-IX (rear of the engine block S4 and up) is easy. (Well maybe on the engine assembly line). BECAUSE IT'S NOT. ARRRRGGGHHHHH!
- Intake manifold MUST be removed. (includes disconnecting idle air bypass motor).
- Ditto for fuel rail dampers and spider web of inflexible vacuum lines.
At this point you eventually sight the head of each bolt securing each earth and exclaim loudly (with Goldilocks-like innocence): "oh gee - there they are" or words to that effect.
Unscrew unscrew ... ... only to find the MP earth lugs are each clamped between each pair of harness clamp lugs and then on to the block. Too many metallic surface pairs between which corrosion/oxidation can occur, IMHO, and did.
Next reality check (after attempting to de-corrode, in place, the relevant contact surfaces):
- Heat hardened wiring harnesses are like old tree roots that you must work around.
Eventually (and after using many words unlikely to be heard at Sunday school), it dawns on this Braniac that it will be easier to remove the throttle cable idler-pulley bracket to the workbench. Dooo - oooh. Where much de-corroding and surface brightening happens.
Time to re-install: passenger-side (LHD) bolt: no finger room to start bolt into thread. Bolt underneath casting overhang on block.
I know: remove the idler pulley: BAAA-baaa. Wrong. Pulley impossible to remove.
Desperation Solution needed: ie cut slot into the side of the bolt hole in the mounting bracket: bolt can be easily started into the block; mounting bracket can slide under bolt head c/- side cut slot.
What were they thinking? Could tow a battleship with this lump of pig iron. LOL
If you're finding it difficult to visually untangle what you are seeing in these pics ... ... then it's because IT IS, and it's no easier in reality.
Replace your CPS and rear fuel lines. I'm with Stan: blob of red RTV needs 'splainin'.
I agree that cleaning these grounds is not easy. That's why it is usually doen as part of a full intake refresh. You are 1/3 of the way into a full refresh. You will have to do the last 1/3 to get the engine back together. Are you going to do the middle 1/3?
With hindsight would it have been easier to cut and splice a longer earth cable and ground it somewhere else?
Rgds
Fred
Was it ever Fred. And you're a master of understatement, btw.
Re your second point re ground locations: without being privy to Porsche's electronic design detail, it would be difficult to second guess their reasons for ground placements.
Longer earth looping away from the senor output wire allows more "decoupling" between sensor signals and their ground reference, meaning longer 'loops' can pick up unwanted other electromagnetic signals / electrical noise, that mix with the sensor output signals.
Maximum signal coupling (minimum looping) is achieved with the use of shielded signal cable or coaxial cable.
Problems occur when this 'noisy' signal is sent to a device like an ECU, which is expecting (up to a point), a 'clean' data signal upon which it can act.
Every electronic device is designed to read slighty noisy or distorted signals, up to a limit, but once this signal-to-noise limit is exceeded (for reasons set out above) the poor things simply throw their logic gates up in despair and sulk off into a tri-state corner. LOL.
I see one connector with red RTV coming out the sides could this be your CPS connector?
maybe the RTV is changing the signal
Ohhh geee gosh durn shucks ... ... ain't no gittin' away with anythin' on here is there? LOL
Yes it is RTV silicone. And it is holding the CPS connector/leads together. But being silicone-based it's a high value dielectric, ie, a non-conductor, so no effect on CPS signal.
Happened when re-fitting my then "experimental", but which now is my Whoo Hooo intake performance manifold, knowing that either way it would have to come out again in the near future for a tidy-up, including replacement of all those geriatric heat-hardened electrical bits.
Unfortunately the 'near' part of 'future' has arrived earlier than anticipated. LOL
Replace your CPS and rear fuel lines. I'm with Stan: blob of red RTV needs 'splainin'.
I agree that cleaning these grounds is not easy. That's why it is usually doen as part of a full intake refresh. You are 1/3 of the way into a full refresh. You will have to do the last 1/3 to get the engine back together. Are you going to do the middle 1/3?
CPS loop resistance is ok at 990 Ohms.
Rear fuel line replaced.
"Blob" has been 'splained. :-)
I'll worry about the middle third refresh once I'm finished with intake flow experiments.
Was it ever Fred. And you're a master of understatement, btw.
Re your second point re ground locations: without being privy to Porsche's electronic design detail, it would be difficult to second guess their reasons for ground placements.
Longer earth looping away from the senor output wire allows more "decoupling" between sensor signals and their ground reference, meaning longer 'loops' can pick up unwanted other electromagnetic signals / electrical noise, that mix with the sensor output signals.
Maximum signal coupling (minimum looping) is achieved with the use of shielded signal cable or coaxial cable.
Problems occur when this 'noisy' signal is sent to a device like an ECU, which is expecting (up to a point), a 'clean' data signal upon which it can act.
Every electronic device is designed to read slighty noisy or distorted signals, up to a limit, but once this signal-to-noise limit is exceeded (for reasons set out above) the poor things simply throw their logic gates up in despair and sulk off into a tri-state corner. LOL.
Ooops. Got a bit carried away there.
HTH.
I tend to assume that cables earthed to the chassis are not too sensitive whereas the "sensitive" ones are earthed directly to the kit they connect to- to avoid a false earth as it were. Not my strongest area of subject matter knowledge and generally defer to those who know better.
It might be interesting to see if there are other points of view on this subject matter..
Yes it is RTV silicone. And it is holding the CPS connector/leads together. But being silicone-based it's a high value dielectric, ie, a non-conductor, so no effect on CPS signal.
It's a dielectric and that's exactly why it would affect the CPS signal.
Between a return of the Black Dog, moving house, and getting over the loss of my old dog friend/companion of 15 years, the car is still in the gargage. Hoping to get back to it in the near future.
05-20-2015, 07:52 PM
all over my face whenever I touch the accelerator. Mwaaahh haaa haarrr).
