TheSamba.com :: View topic - Knock sensor added to stock Fuel injection

Wed Jul 17, 2013 7:50 pm

WOW... I'm super stoked!

I have mentioned my engine combo before, but I run a home brew 2.4 water boxer with 10.5\1 compression. Since I have built it, I've been trying to blow it up, just to find the week spot and correct it. I first added a Mann full crank case ventilation system including vented rocker covers. That system works unbelievably. The intake tract on any water boxer I've seen has a coating of oil after a few thousand miles. Mine is squeaky clean.. but this thread is not about that.

After break in, I realized that I could not run the timing as high as I'd like. I usually like to time wassers at 45deg at 3500rpm. With my engine I would need very high octane fuel to pull that. I've found that 38 or 40 is pretty good, but not as snappy. Then a few weeks ago, while pulling 5 motorcycles to the park, I experienced a tank of bad "premium" fuel. It would ping under almost any load. I detailed that experience in another thread.

I pulled the trigger and ordered a J&S safeguard knock system. It arrived in the post today... I almost had to leave work early to go home and open the box. It took about an hour to install and another half hour of driving around to play with the settings. This thing is incredible! I set my timing at 45deg, went to the biggest hills in my hood and started doing full throttle, full load runs. Turned off it would ping ping pow... hooked up there might be a hint of ping for one revolution then GONE.. the system is set to retard an offending cylinder by 2 or 4 degrees for each revolution until nothing is detected. It will then begin to increase that cylinder back to original over the course of several rotations if no further knock is heard.

Now, for me, this was a no brainer... bad gas, eh, oh well, full timing.... yea! more zing when available.. individual retard = more overall power at any time.

I can see this as a solution for anyone running a hopped up engine... stockers that want more advance for pep.. comfort for trips where quality of fuel is a question.. the list goes on.

I know there has been speculation on this forum in the past as to the performance of the J&S.... I can tell you with absolute certainty that is WORKS.. just like advertised... I mounted the sensor on the fuel pump block off plate. It even comes with its own bolt of just the right length. There is a monitor LED on the unit that will glow then flash then full on for the amount of retard applied\ping detected.. They also offer a dash mounted gage that will even tell you an offending cylinder

Cheers

Wed Jul 17, 2013 8:00 pm

Post up some pics! Interested to see the Mann system. Also interested in seeing performance data on your 2.4.

My i4 was actually altered to reduce compression from 10.5:1 (stock knock sensor) and therefore quite happy on regular fuel or premium if expecting full load/hot weather etc.

The J&s system perhaps should be standard on any gw 2.5 based on failure reports on that setup..

Wed Jul 17, 2013 10:27 pm

has anyone tried to adapt the knock sensing ignition that came stock on some of the inline vw engines? i believe the 1.8l 16v and cis fueled 1.8l 8v engines had this. these are found in the gti, gli and scirocco which are pretty abundant in most junk yards.

only issue i can think of is there is no adjustment to them at all other than spacing and positioning of the knock sensor which is designed for a cast iron inline engine. however i have seen some people 'tune' theirs on modified engines using aluminum spacers so maybe with some testing and tweaking this could be accomplished.

just don't expect anything but brainstorming on this subject from me as i'm going with a subie :)

Wed Jul 17, 2013 10:37 pm

Glad to hear of your positive results with the J&S. I was thinking of using it on the turbo system I am planning for my '85. $500 is a lot to spend without knowing how well it will work. I would also like to know more about your ventilation system.

Hans

Wed Jul 17, 2013 11:07 pm

Type17 wrote: has anyone tried to adapt the knock sensing ignition that came stock on some of the inline vw engines? i believe the 1.8l 16v and cis fueled 1.8l 8v engines had this. these are found in the gti, gli and scirocco which are pretty abundant in most junk yards.

only issue i can think of is there is no adjustment to them at all other than spacing and positioning of the knock sensor which is designed for a cast iron inline engine. however i have seen some people 'tune' theirs on modified engines using aluminum spacers so maybe with some testing and tweaking this could be accomplished.

just don't expect anything but brainstorming on this subject from me as i'm going with a subie :)

Most of the factory OEM knock control systems (except on high-end cars like MB, Porsche, Audi, Cadillac Northstar) use a knock sensor system that retards spark advance on all cylinders a similar amount even if only one cylinder experiences knock. The spark advance "add back" to spark advance is also very slow. The J&S system is cylinder-selective, the sensitivity to knock is adjustable, the rate of retard is adjustable, and the rate of "add back" is also adjustable.

Even the "high end" OEM knock control systems are not adjustable without extensive programming knowledge.

Kudos to the OP here for trying this out on the WBX! I used one on a DIY- turboed 2.4 toyota 22RE engine with the same excellent results. I ran a very tight deck clearance on that engine which made it very resistant to knock in the first place - - something a lot of "engine builders" (meaning engine rebuilders) don't pay sufficient attention to. While I am on my "anti-knock high horse", let me opine that any hot WBX build needs to include a tight deck clearance for best squish and quench and to make the heads work the way a "Heron" design is meant to.

Thu Jul 18, 2013 6:57 am

I'd love to hear some MPG numbers when you get some ore miles with the J&S, I've always thought it was a really cool piece of equipment!

Thu Jul 18, 2013 8:51 am

jackbombay wrote: I'd love to hear some MPG numbers when you get some ore miles with the J&S, I've always thought it was a really cool piece of equipment!

Not sure I'm a good bench mark. I am really really not nice to this engine. Drive it like you stole it. "Hit me Peter"!. Heavy Syncro Westy with 215/75/15's Tube steel and plate bumpers, 4kids, wife, dog, Moto's, camp gear..... the list goes on.

Thu Jul 18, 2013 9:20 am

hdenter wrote: Glad to hear of your positive results with the J&S. I was thinking of using it on the turbo system I am planning for my '85. $500 is a lot to spend without knowing how well it will work. I would also like to know more about your ventilation system.

Hans

I posted about the Mann Provent on this thread. So I provided an update. Just for Wildthings.
http://www.thesamba.com/vw/forum/viewtopic.php?p=6761938#6761938

Thu Jul 18, 2013 9:43 am

I've had a J&S single channel Safeguard since 2006 and have successfully used it on a bunch of engines I build (all air cooled).

How did you wires yours? With the Digifant I was concerned that delaying the spark even (raising dwell time, which is how the J&S works to delay timing) wouldn't jive with the stock ECU.

Thu Jul 18, 2013 9:50 am

Steve Arndt wrote: I've had a J&S single channel Safeguard since 2006 and have successfully used it on a bunch of engines I build (all air cooled).

How did you wires yours? With the Digifant I was concerned that delaying the spark even (raising dwell time, which is how the J&S works to delay timing) wouldn't jive with the stock ECU.

It's really quite simple. 5 wires. 2ea at Bosch sensor, 1 ground, 1 splice at coil neg, 1 splice at coil hot (for system power). As I understand it, the ECU doesn't even know it's there. It interferes with the signal to the coil. I was really skeptical even after speaking with John of J&S. You should have seen my face when I tried to start it after installing only to have the engine die several times... Ah, the old forgot to connect the vacuum line again.. This thing is like magic.

Thu Jul 18, 2013 10:13 am

what model do you have?

Thu Jul 18, 2013 10:21 am

It is the Vampire.

Thu Jul 18, 2013 10:59 am

Pictures or it ain't real!

Thu Jul 18, 2013 11:03 am

r39o wrote: Pictures or it ain't real!

Ha, Nice... not much to see really. The box is about the size of a USB external hard drive, I was surprised how small. I mounted it in my Westy closet cabinet. I can take a pic when I'm home with the van.

Thu Jul 18, 2013 11:10 am

jberger wrote: It is the Vampire.

There is only one coil in the WBX, won't the Universal version works better?

Thu Jul 18, 2013 4:44 pm

I have the J&S dash gauge display unit as well.

Moving the sensor from place to place on the engine will show different responses. I have my sensor threaded into a thick piece of steel that is bolted down by the distributor calmp hold down stud. It gets good response there on my hotrod Hot VW. That engine has slappy forged pistons and straight cut gears so I do get some false readings at times. With the quietness of the wasser it should really work well.

Thu Jul 18, 2013 7:11 pm

jberger wrote: jackbombay wrote: I'd love to hear some MPG numbers when you get some ore miles with the J&S, I've always thought it was a really cool piece of equipment!

Not sure I'm a good bench mark. I am really really not nice to this engine. Drive it like you stole it. "Hit me Peter"!. Heavy Syncro Westy with 215/75/15's Tube steel and plate bumpers, 4kids, wife, dog, Moto's, camp gear..... the list goes on.

As long as you have some consistent "before" numbers to compare to thats all that matters, but I am admittedly more of an MPG geek than most people.

Thu Jul 18, 2013 10:51 pm

Steve Arndt wrote: I have the J&S dash gauge display unit as well.

Moving the sensor from place to place on the engine will show different responses. I have my sensor threaded into a thick piece of steel that is bolted down by the distributor calmp hold down stud. It gets good response there on my hotrod Hot VW. That engine has slappy forged pistons and straight cut gears so I do get some false readings at times. With the quietness of the wasser it should really work well.

I believe this is the same spot...

Thu Jul 18, 2013 10:52 pm

This is the unit mounted in westy closet

Thu Jul 18, 2013 11:29 pm

Sexy!

Do you run an air/fuel monitor as well? I'd be curious to know if you can watch the ratio change while the system retards.

Neil