Fix the little things - PERFORMANCE MODS
Addict
Rennlist Member
Rennlist Member
Joined: Oct 2003
Posts: 17,322
Likes: 2,183
From: Gone. On the Open Road
Originally Posted by heinrich
Dave the wire was not busted but it did not clean it and performance was screwed.
Three Wheelin'
Joined: Jun 2005
Posts: 1,741
Likes: 1
From: Bournemouth, Dorset, UK.
Originally Posted by ew928
Twang.
Mine's got a nice K&N protective coating.
Be doing the MAF refurb real real soon.
Ernest (NYC)
K&N made a satisfying clang when it hit the dumpster.
Mine's got a nice K&N protective coating.
Be doing the MAF refurb real real soon.
Ernest (NYC)
K&N made a satisfying clang when it hit the dumpster.
Oil on the wire.....(personally I think the 928 breather system has a lot more to do with it )...
Dont blame K&N for oiled wire thats a fallacy in my opinion..I have used them for years in various cars......OVER OILING them can cause it....but you only reoil after at least 25 to 50,000 miles...and in my opinion they ARE worth a couple of hp and improve the intake flow slightly....
All the best Brett
PORSCHE 928 S2 AUTO V8 4.7 LTR 1986 IRIS METALLIC BLUE WITH X-PIPES ,RMB ,PROMAX CHIPS, KICKDOWN SWITCH.K&N.NITROUS KIT 150 HP.
PCGB UK 928 FORUM MODERATOR - Email managingdirector@pchealthcare.co
Addict
Rennlist Member
Rennlist Member
Joined: Oct 2003
Posts: 17,322
Likes: 2,183
From: Gone. On the Open Road
Originally Posted by Dannyfumi
Do 85s have hall and knock sensors?
The US version 85/86s used the LH/EZF combo of computers. The '87+ used LH/EZK. The "K" stands for knock detection.
Cannot say about ROW 85/86s...
Last edited by worf928; Sep 18, 2006 at 01:55 PM.
Rennlist Member
Joined: Oct 2004
Posts: 10,717
Likes: 58
From: Southern Alberta, Canada
Originally Posted by worf928
Theoretically there is an adaptor for those three-pin connectors so that you can hook an o-scope to them while the lump is turning. On a practical level if those sensors are more than about 10 years old when you disconnect them the sensor-side of the connector crumbles. All four have a bracket. Tech's seem to love to leave the connectors out of the bracket. When those connectors are not put back into their brackets they are subject to harsher vibration and impacts and degrade faster.
I always know that a no-start diagnosis has been performed on a 928 when I see that the impulse sensor connector is not in its bracket.
Here's my three-pin sensor methodology:
1) You will have to replace breather hoses under the intake. When you do , replace the knock sensors. (Chances are you will find that they are baked well-done in a coolant and oil gravy anyway from a leaky cross-over o-ring and/or filler neck gasket.)
2) When the passenger side cam cover comes off for powder coating or gasket replacement replace the hall sensor.
3) If the impulse sender is in its bracket don't mess with it. (Unless the supercharger kit you are installing requires that it be relocated or otherwise touched in which case you'd better have a new sensor handy. (Ask Olsen about that... ) )
The sensors are short money in the general scope of things. They'll add 10% to the parts bill for an intake refurb or an under/over cam cover refurb. That's when they are easy to get to. (Impulse sender is easy to get to in any case.) After 15+ years and 100k miles I think those sensors deserve to be retired.
AND since they are difficult to diagnose without a Hammer (or Spanner) or almost impossible to diagnose (on pre-89s) you will drive yourself nutso when they fail. I did - find my thread from a few years ago on "Powerless GT"
EDIT: The knock sensor and hall sensor failure modes are the hair-pullers unless you have a Hammer and your car has the diag connector. The impluse sender failure mode is pretty simple: no spark, no fuel, and no start.
I always know that a no-start diagnosis has been performed on a 928 when I see that the impulse sensor connector is not in its bracket.
Here's my three-pin sensor methodology:
1) You will have to replace breather hoses under the intake. When you do , replace the knock sensors. (Chances are you will find that they are baked well-done in a coolant and oil gravy anyway from a leaky cross-over o-ring and/or filler neck gasket.)
2) When the passenger side cam cover comes off for powder coating or gasket replacement replace the hall sensor.
3) If the impulse sender is in its bracket don't mess with it. (Unless the supercharger kit you are installing requires that it be relocated or otherwise touched in which case you'd better have a new sensor handy. (Ask Olsen about that...
) )The sensors are short money in the general scope of things. They'll add 10% to the parts bill for an intake refurb or an under/over cam cover refurb. That's when they are easy to get to. (Impulse sender is easy to get to in any case.) After 15+ years and 100k miles I think those sensors deserve to be retired.
AND since they are difficult to diagnose without a Hammer (or Spanner) or almost impossible to diagnose (on pre-89s) you will drive yourself nutso when they fail. I did - find my thread from a few years ago on "Powerless GT"
EDIT: The knock sensor and hall sensor failure modes are the hair-pullers unless you have a Hammer and your car has the diag connector. The impluse sender failure mode is pretty simple: no spark, no fuel, and no start.
BTW what are the symtoms of knock or hall failures?
Addict
Rennlist Member
Rennlist Member
Joined: Oct 2003
Posts: 17,322
Likes: 2,183
From: Gone. On the Open Road
Originally Posted by BRETT AINLEY
Oil on the wire.....(personally I think the 928 breather system has a lot more to do with it )...
..and in my opinion they ARE worth a couple of hp and improve the intake flow slightly....
I have asked that question a few times over the last few years. No one has yet posted a dyno chart - from a 928 - that shows a hp gain that is statistically significant. (A one or two HP gain in a few parts of the curve from one run of a K&N versus one run with a clean stock filter is not statistically meaningful. It's one sample set and the dyno would have to have measurement repeatability at every measurement (every 100 RPM) within 0.33 - 0.66%. )
EDIT: The above "0.33 - 0.66%" assumes that the CAR ITSELF would run in exactly the same way from run-to-run and that the environment in the shop is also static and unchanging.
I can post a dyno run (my '91GT) of a stock filter versus a new properly oiled K&N. Assuming no one cares about statistical significance or measurement repeatability then the K&N was worth one hp at peak RPM. However, the two curves across the RPM range cross from time-to-time - at some RPMs the stock filter made one more hp than the K&N and at some points the K&N made one hp more. So - we're back to significance and repeatability.
Note: I'm not saying that the K&N filter is a bad thing. It probably IS a good thing for some cars. But, no one will convince *me* that it is worth anything at all on a 928 until I see some numbers that make sense from a metrology standpoint.
Rennlist Stories
The Best Porsche Posts for Porsche Enthusiasts
Genius Porsche-Themed Gifts That'll Make Any Dad or Grad Smile
Joe Kucinski
10 Used Porsches Are Selling for Way Too Cheap
Joe Kucinski
Tuner Is Converting Porsche 911s Into Shooting Brakes
Verdad Gallardo
This Coachbuilt Creation Is A Modern Take on the Legendary Porsche 917
Verdad Gallardo
Is This Convertible Cayenne A Steal, Or A Returnless Investment?
Verdad Gallardo
10 Best Non-Flat Six Porsches You Can Buy For Under $100K
Joe Kucinski
Porsche's Top 5 Most Questionable Naming Decisions
Verdad Gallardo
Pogea Racing's 964 Porsche 911 Reimagination Stands Out in a Crowded Field
Verdad Gallardo
6 Convertible Top MYTHS Most People Don't Understand!
Michael S. Palmer
Addict
Rennlist Member
Rennlist Member
Joined: Oct 2003
Posts: 17,322
Likes: 2,183
From: Gone. On the Open Road
Originally Posted by the flyin' scotsman
Thx Dave............perhaps the intake removal will make this winters list.
BTW what are the symtoms of knock or hall failures?
As far as I can tell these sensors do not seem to exhibit simple - like the impulse sender's no-start - failure modes. In my case the Hall Sensor failure mode was dramatic. Others have reported less-dramatic hall sensor failure modes. Knock sensors seem to be the same way. John Speake has contributed to a number of threads on knock sensor failure modes. They should turn up with a search.
Pro
Joined: Oct 2002
Posts: 598
Likes: 0
From: New Hampshire
Originally Posted by BRETT AINLEY
Hi
Dont blame K&N for oiled wire thats a fallacy in my opinion..I have used them for years in various cars......OVER OILING them can cause it....but you only reoil after at least 25 to 50,000 miles...and in my opinion they ARE worth a couple of hp and improve the intake flow slightly....
Dont blame K&N for oiled wire thats a fallacy in my opinion..I have used them for years in various cars......OVER OILING them can cause it....but you only reoil after at least 25 to 50,000 miles...and in my opinion they ARE worth a couple of hp and improve the intake flow slightly....
Results
Stock Exhaust System: Maximum loss of 32 lb-ft and 28 hp. Average loss of 20 lb-ft and 18 hp compared to baseline.
Stock muffler & pipes: Average loss of 11 lb-ft and 10 hp
Stock dual cats: Average loss of 9 lb-ft and 8 hp
K&N air filter: Loss of 3 lb-ft of torque and 3 hp compared to stock filter.
Cat bypass vs 4” X: The X crossover gains 14 lb-ft of torque and 11 hp more than stock H.
Cat bypass vs 3” venturi: The venturi gains 19 lb-ft and 16 hp more than
the stock H.
Three Wheelin'
Joined: Jan 2004
Posts: 1,611
Likes: 13
From: Mosier, Oregon
Originally Posted by GT Jackson
I could be wrong but if I read the maint tips on track > exhaust systems, the specs there show performance down with K&N filter.
Results
Stock Exhaust System: Maximum loss of 32 lb-ft and 28 hp. Average loss of 20 lb-ft and 18 hp compared to baseline.
Stock muffler & pipes: Average loss of 11 lb-ft and 10 hp
Stock dual cats: Average loss of 9 lb-ft and 8 hp
K&N air filter: Loss of 3 lb-ft of torque and 3 hp compared to stock filter.
Cat bypass vs 4” X: The X crossover gains 14 lb-ft of torque and 11 hp more than stock H.
Cat bypass vs 3” venturi: The venturi gains 19 lb-ft and 16 hp more than
the stock H.
Results
Stock Exhaust System: Maximum loss of 32 lb-ft and 28 hp. Average loss of 20 lb-ft and 18 hp compared to baseline.
Stock muffler & pipes: Average loss of 11 lb-ft and 10 hp
Stock dual cats: Average loss of 9 lb-ft and 8 hp
K&N air filter: Loss of 3 lb-ft of torque and 3 hp compared to stock filter.
Cat bypass vs 4” X: The X crossover gains 14 lb-ft of torque and 11 hp more than stock H.
Cat bypass vs 3” venturi: The venturi gains 19 lb-ft and 16 hp more than
the stock H.
https://rennlist.com/forums/attachme...d=141006&stc=1
K&N filter.jpg
https://rennlist.com/forums/attachme...d=141007&stc=1
Porsche Filter.jpg
Last edited by Louie928; Mar 18, 2008 at 01:11 PM.
Addict
Rennlist Member
Rennlist Member
Joined: Oct 2003
Posts: 17,322
Likes: 2,183
From: Gone. On the Open Road
See - Louie has the right idea (as always): three runs back-to-back for each mod. From his charts you see that there are many rpm points with a 1 or 2 hp difference between runs with no changes to the car. So, when you compare one run of one mod with one run of no mods and see a 1 or 2 hp gain all you really see is 'measurement noise.'
Fleet of Foot
Rennlist Member
Rennlist Member
Joined: Aug 2003
Posts: 10,780
Likes: 51
From: We are there!(San Diego)
Originally Posted by worf928
I guess I should've asked: "Has anyone other than Heinrich had the ***** to clean one" 
What happened when you tried? Busted wire?
Instructor
Joined: Feb 2006
Posts: 101
Likes: 0
From: Finger Lakes region, New York
DON'T DO THIS- YOU'RE NOT SUPPOSED TO!
I found that out later, and apparently I just got lucky. I cleaned my MAF wire (86.5) with brake cleaner. Just removed the nets and sprayed it down a couple times. It had been coated with junk after sitting for years, and was causing a lot of problems. Tons of stumbling and hardly running at all. Connector also had problems- coating worn off to wires, and might have been shorting. I used liquid electrical tape. After those two things, it worked.
I'm not sure if it's in top condition. THere are plenty of problems with that car. But still, for 2500 initial cost and then I've put about 1500 into it since then, I have a fun 1986.5 green 928. Not the best, but I've enjoyed 900 miles with it. And we've spent so many hours together (electrical gremlins, windshield replacement, cv boots, radiator, timing belt, the list goes on....) that I've got ot say it was worth the price. MOST of those hours were some sort of fun.
I found that out later, and apparently I just got lucky. I cleaned my MAF wire (86.5) with brake cleaner. Just removed the nets and sprayed it down a couple times. It had been coated with junk after sitting for years, and was causing a lot of problems. Tons of stumbling and hardly running at all. Connector also had problems- coating worn off to wires, and might have been shorting. I used liquid electrical tape. After those two things, it worked.
I'm not sure if it's in top condition. THere are plenty of problems with that car. But still, for 2500 initial cost and then I've put about 1500 into it since then, I have a fun 1986.5 green 928. Not the best, but I've enjoyed 900 miles with it. And we've spent so many hours together (electrical gremlins, windshield replacement, cv boots, radiator, timing belt, the list goes on....) that I've got ot say it was worth the price. MOST of those hours were some sort of fun.
Rennlist Member
Joined: Feb 2002
Posts: 7,060
Likes: 42
From: Cambridge England
Cleaning the wire won't help, unless it is soaked with oil. The burn off cycle is on;y designed to clear very light deposits.
As DaveC syas, it is the burn off cycle that actually erodes the wire, and causes the gradual degradation.
But a 928 hot wire MAF will usually last 80k miles or so before it requires replacement. More recent cars like Boxster us a hot film MAF and they are failing as early as 30k miles. (also used in Mercs, etc)
I can supply MAF connectors, 2 & 3 pin male and female connectors.
As DaveC syas, it is the burn off cycle that actually erodes the wire, and causes the gradual degradation.
But a 928 hot wire MAF will usually last 80k miles or so before it requires replacement. More recent cars like Boxster us a hot film MAF and they are failing as early as 30k miles. (also used in Mercs, etc)
I can supply MAF connectors, 2 & 3 pin male and female connectors.