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boost sender wiring help...

...just purchased a new boost sender gauge and placed it on the Kokeln IC, where the broken one was...i understand its a white wire from the harness that is its mate...the white wire has been connected to another wire ( ground?) coming from the manifold...
...to anyone who isnt an electro-moron like myself, should i remove this ground connection from the manifold???does the new gauge need to be ground???or am i way off in right field altogether???
i appreciate all responses and advice...
AaRoN

Old 04-23-2013, 05:03 PM
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the ground wire was there to make the car run with a bad sensor. remove the ground wire yet you may need it again under a no start situation
Old 04-23-2013, 05:13 PM
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...for as long as ive owned the car, the boost has never worked...its always been pinned at 1 bar with ignition...how is it supposed to act???
Old 04-23-2013, 05:37 PM
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Your post is not clear to me. You mentioned replacing the boost sender "gauge", but it sounds as though you have replaced the sender unit (large orange rubber covered thing) that sends it's signal to the boost gauge in the cockpit. If so, they usually have just one wire connected to one of the spades. The body of the sender unit itself serves as the ground. Though to be honest I can't see mine anymore since I relocated it some time ago, but I seem to remember just the one wire (maybe there was a second wire for grounding, but it's really not necessary if I recall).

I think xbmwguy is talking about the overboost sensor switch, which also has a white wire to it that serves as a ground. For that unit, if the ground is open (such as when the switch trips due to over boost and opens the connection to ground) the engine will not run. If that unit is faulty, then removing the wire and connecting it to ground will bypass the overboost sensor.

But back to the boost gauge 'sensor'. If you were to ground out the white wire, it may peg the gauge. There are two spade locations on that sender if I recall. One is for an additional ground, and the other is for the sender connection. Perhaps you have the connections reversed.

Sorry, not much help since I can't see mine to give you better detail.
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Last edited by mark houghton; 04-23-2013 at 06:36 PM..
Old 04-23-2013, 06:32 PM
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here is the part i purchased: 993-606-103-01-M100

..i spoke with a phone rep regarding my boost gauge always maxing out when i turn the ignition...this was the part that was faulty, i assumed, because i suppose what was once the orange cap, was gone, exposing all the guts of the mechanism, and nowhere to connect...so ive forked over the 170 bucks, thinking it was a plug and play situation - and the boost gauge upfront still maxes out after replacing units and removing the ground wire...sorry for the confusion...i actually have my own nomenclature and only try to seem hip when exposing my naiveté on this forum...thanks guys for everything...heres some pics...
Old 04-23-2013, 07:16 PM
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These typically mount to the boost recirculation manifold, not directly to the intercooler. It will still read the boost signal fine on the IC, but there is the possibility that the sender is not seeing a good ground because the IC itself is not grounded due to the rubber o'rings and rubber grommetted mounts. Even though you have the white wire connected, you may also need to run a ground wire to the sender itself.
I should remember this stuff but time fades memory. It may be just the opposite of what I said earlier about the gauge pegging if you were to ground out the white wire. That sender is just a variable resistor that responds by changing it's resistance in response to boost air pressure. The higher the pressure, the more resistance. If the wire is completely disconnected (and that could be mimicked by no ground on the body of the sender) then your gauge may peg to max. In other words, try disconnecting the wire and grounding it somewhere, and see if your gauge returns to zero. If so, that's good news for the gauge. Then hook it back up and run a temporary ground to the sender and the gauge should stay at zero.
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Old 04-24-2013, 04:59 AM
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The wire to the boost sensor is brown with white stripe.
The wire to over-boost switch is white.
They both emerge from the harness at the same place and both have spade connector, so they are easy to mix up.
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Old 04-24-2013, 06:45 AM
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Quote:
Originally Posted by wholio94112 View Post
...just purchased a new boost sender gauge and placed it on the Kokeln IC, where the broken one was...i understand its a white wire from the harness that is its mate...the white wire has been connected to another wire ( ground?) coming from the manifold...
...to anyone who isnt an electro-moron like myself, should i remove this ground connection from the manifold???does the new gauge need to be ground???or am i way off in right field altogether???
i appreciate all responses and advice...
AaRoN
Do yourself a favor and disregard the boost gage inside the tach. It is fairly useless as it is inaccurate. Its hard to see as well.

The best thing to do is buy a VDO mechanical boost gage and install it in the clock location and tap into the brake booster line for a signal. Way more visible and 100% more accurate.
There is plenty of posts here on the forum discussing this gage and its installation.

You will be amazed at the difference in behavior of the 2 gages when you compare them while driving the car. The stock one you are correcting with the sending unit is way off.
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Old 04-24-2013, 07:49 AM
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Quote:
Originally Posted by fredmeister View Post
Do yourself a favor and disregard the boost gage inside the tach. It is fairly useless as it is inaccurate. Its hard to see as well.

The best thing to do is buy a VDO mechanical boost gage and install it in the clock location and tap into the brake booster line for a signal. Way more visible and 100% more accurate.
There is plenty of posts here on the forum discussing this gage and its installation.

You will be amazed at the difference in behavior of the 2 gages when you compare them while driving the car. The stock one you are correcting with the sending unit is way off.
I'm one of the exceptions, then. My stock gauge is actually pretty accurate compaired to my aftermarket gauge, but that gauge gives more accurate detail with more dial graduations.
For those with inaccurate stock gauges, I would place the blame on the sending unit aging in that hot engine environment over time. It's just a variable resistor after all, and the resistance curve is sure to change with age.
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Old 04-24-2013, 01:33 PM
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...okay guys, i tested the boost gauge and sensor...with ignition on, sensor NOT connected to brown wire, needle maxxes out...if i touch the brown wire to ground, the needle settles to zero...so gauge is good, problem is with sensor???how its brand new???and its not made by URO...does it need to be grounded???if so, how, with only one spade connection???
...sorry if its all elementary, i have never had a working boost gauge, so i dont feel i understand the turbo concept aty all when reading other posts...i drive by feel...but hell i wonder if the overboost sensor even functions...
Old 04-24-2013, 04:02 PM
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Quote:
Originally Posted by wholio94112 View Post
...okay guys, i tested the boost gauge and sensor...with ignition on, sensor NOT connected to brown wire, needle maxxes out...if i touch the brown wire to ground, the needle settles to zero...so gauge is good, problem is with sensor???how its brand new???and its not made by URO...does it need to be grounded???if so, how, with only one spade connection???
...sorry if its all elementary, i have never had a working boost gauge, so i dont feel i understand the turbo concept aty all when reading other posts...i drive by feel...but hell i wonder if the overboost sensor even functions...
Read what I said earlier. Mounted to the IC may not give good ground. Yes, rig up an external ground and it should work. Hell, just take one end of a large clamp (like a batter jumper cable) and clamp on to the body, with the other end to ground somewhere. That will settle the question.

Make sure you have the brown/white striped wire connected to the sender, and the white wire to the overboost switch...as Bill pointed out. As to the overboost sensor, it probably works fine but remember if you don't have the white wired connected to it then your car will not run. That switch provides a ground path, and will open when overboost situations occur, interrupting the ground and killing the fuel pumps.

You may have to remove your new boost gauge sensor, and see if there is a spot on the body where you can drill a small hole to mount a wire. Then run the other end to a good ground. You gotta ask yourself, "what would Fred Flintstone do"?

Hang in...you're almost there!
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Last edited by mark houghton; 04-24-2013 at 06:17 PM..
Old 04-24-2013, 06:08 PM
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I had a similar problem with grounding after fitting a new intercooler. Because it wasn't grounded, it acted like the over-boost switch was open - which means no spark. It took me a while to find the problem which I fixed with a small copper earth strap at the intercooler mount like this (at left side of pic).
This solved over-boost switch problem as well as boost sensor grounding.

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Old 04-24-2013, 07:45 PM
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...okay, im gonna give it a go and ground the sensor...here's the deal in the last 2 years of owning this car...the cap had been taken off the sensor, which was not hooked up...the overboost switch was hooked up, but to the brown wire - not the white one...the white one, i found to be a dangling finger of the harness, along with another brown wire and pink with blue striped wire - paired together further down the line of the harness...so with the overboost sensor switch hooked up to the brown wire, how'd the car run if its not supposed to???
...now ive got the sensor, the switch, and the wiring correct, and getting the same result, a fine running automobile with the boost gauge on the tach pegged up...
...fred flintstone would be runnin' from these bones by now!!!
...thanks for all your input gentlemen...i appreciate your patience...
Old 04-24-2013, 09:48 PM
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[QUOTE=wholio94112;7406355...so with the overboost sensor switch hooked up to the brown wire, how'd the car run if its not supposed to???[/QUOTE]

That's a good question. Both wires...the white one to the overboosdt switch and the brown one to the boost sender are pathways to ground. The OB switch provides the ground needed for the airflow sensor charging pressure relay (the yellow one) to activate, which in turn activates the two fuel pump relays. The brown boost sensor wire also provides ground for the gauge..that ground eventually running through the sensor's internal variable resistor and then to ground via the body of the sensor attached to your IC.

I could see where everything but the gauge would work correctly even if you had the location of the wires reversed, but only if your boost sensor was itself well grounded....which in you case it seems not to be. Hmmm....
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Old 04-25-2013, 07:38 AM
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Get the VDO clock boost gage, thats what Fred Flinstone would have done.

Seriously, it is alot better looking and easier to see while driving hard than the little dial in the tach.

Just my opinion.

B. Rubble
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Old 04-25-2013, 01:11 PM
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Mr. Rubble,

I hope you don't feel that my comments about Fred Flintstone had anything to do with you. Just a coincidence that your name happens to be Fred.
I used to be quoted as saying "what would the pioneers have done", then modified to say "what would the cavemen have done", and have now polished my witticism to reference Fred Flintstone....since much of what I do is admittedly Pleistocene era. Function before form is another one of my worthless words to live by.

Fer sure, a nice VDO is the ultimate ticket. But hopefully all this discussion will assist those who just absolutely must have a working stock POS gauge.
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Old 04-25-2013, 01:29 PM
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Mr. Rubble,

I hope you don't feel that my comments about Fred Flintstone had anything to do with you. Just a coincidence that your name happens to be Fred.
I used to be quoted as saying "what would the pioneers have done", then modified to say "what would the cavemen have done", and have now polished my witticism to reference Fred Flintstone....since much of what I do is admittedly Pleistocene era. Function before form is another one of my worthless words to live by.

Fer sure, a nice VDO is the ultimate ticket. But hopefully all this discussion will assist those who just absolutely must have a working stock POS gauge.
No problem man, I did not take it that way at all. I just thought it would be fun to add a little humor to all the posts. I take myself and life too seriously sometimes and thought it would be funny to start a little banter back and forth. I appreciate the apology but it was definitely not necessary.
I am surprised you noticed the B Rubble reference. I thought it was funny to sign it that way. I did not want to make you feel I was offended in anyway. Sorry bout that.
You always give good advice on the forums, but I hate to see this guy spend alot of time and cash on fixing the stock unit when I have found the VDO so much nicer. That said I do understand the desire to fix the stock components to make them work as designed.....its part of my German nature and stubborness.

Take it easy,
Fred
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---"When you're racing it's life! Anything else either before or after, is just waiting"

Last edited by fredmeister; 04-25-2013 at 04:04 PM..
Old 04-25-2013, 04:02 PM
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No problem man, I did not take it that way at all. I just thought it would be fun to add a little humor to all the posts. I take myself and life too seriously sometimes and thought it would be funny to start a little banter back and forth. I appreciate the apology but it was definitely not necessary.
I am surprised you noticed the B Rubble reference. I thought it was funny to sign it that way. I did not want to make you feel I was offended in anyway. Sorry bout that.
You always give good advice on the forums, but I hate to see this guy spend alot of time and cash on fixing the stock unit when I have found the VDO so much nicer. That said I do understand the desire to fix the stock components to make them work as designed.....its part of my German nature and stubborness.

Take it easy,
Fred
Cool Barney, I love the humor (it's in my nature, ya know?). Keep it coming! We get so serious here, so focused trying to help, but in the end it's usually a comedy of errors....or just a comedy all by itself. The banter is what keeps me alive.
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Old 04-25-2013, 06:10 PM
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The gauge should not move at all when the car is stationary or the ignition switch is on.

One white wire coming into the sensor and then one wire going to ground.

The boost guage sensor has one wire coming in and attaching to it. Mine is brown...
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Old 04-25-2013, 07:17 PM
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Originally Posted by wholio94112 View Post
here is the part i purchased: 993-606-103-01-M100

..i spoke with a phone rep regarding my boost gauge always maxing out when i turn the ignition...this was the part that was faulty, i assumed, because i suppose what was once the orange cap, was gone, exposing all the guts of the mechanism, and nowhere to connect...so ive forked over the 170 bucks, thinking it was a plug and play situation - and the boost gauge upfront still maxes out after replacing units and removing the ground wire...sorry for the confusion...i actually have my own nomenclature and only try to seem hip when exposing my naiveté on this forum...thanks guys for everything...heres some pics...
it looks like you have an exposed wire right at the big brown bundle..

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Old 04-25-2013, 07:19 PM
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