Boost gauge options in a '82 930

[saurkraut]

The boost gauge in my '82 930 is pegged full scale

I switched the gauge with a used one that was reported to be OK; still pegged full scale

Disconnected the wire from the transducer; still pegged full scale.

Grounded the wire on the intake manifold; still pegged.

Pulled the boot back on the wire, female connector is still securely attached to the wire.

So the wire is broken somewhere?

Can I run a new wire, or is the wire resistance part of the measurement?

Is there a boost gauge that will fill the clock hole in the dash nicely and to heck with the stock gauge?

[h20cooled7]

Yes, 934 or 935 boost guage will fit in place of the clock but you have to plumb it off the waste gate. Try Hollywood out in Cali ,Im pretty sure they sell them.

[x98boardwell]

If you install a manual boost gage as mentioned by h20cooled7 above you will not have to go all the way back to your waste-gate for a boost signal... unless the 82's do not have a brake booster off the master cylinder.

I added a manual boost gage (from Hollywood Speedo I think) and I plumbed it in to the brake booster in the trunk area just behind the dash with a "T" joint. Unless your year does not have that brake booster present then that may be the reason why you would need to go all the way back.

Keep us posted. I would like to know if you have that same booster... or an equivalent that will work.

Best of luck,
Bryan

[h20cooled7]

Very cool! mine had a adjustable boost knob plumbed in as well.

[saurkraut]

Ok Thanks. I'll search for "Hollywood Speedo" and go from there

[Turboo934]

It's North Hollywood Speedometer and you take the boost readings from the manifold not the wastgate.

[h20cooled7]

It was tied into the bottom of the wastegate to the manifold and they tied the port on top of the wastegate back into the boost knob and guage. Is that how it should be plumbed? I currently have the engine out and can plumb it correctly if this isnt how its supposed to go.

[turbobrat930]

I also have a 935 factory boost gauge (LED) for sale as well..... fits right into the the clock hole.... New, never used condition.....

[turbo nut]

My stock guage does the same thing mine is also a 82 if you figure it out please let me know what the cause is. Thanks

[gsmith660]

Originally Posted by saurkraut

The boost gauge in my '82 930 is pegged full scale

So the wire is broken somewhere?

Can I run a new wire, or is the wire resistance part of the measurement?

Is there a boost gauge that will fill the clock hole in the dash nicely and to heck with the stock gauge?

What I do to confirm a broken wire is run a wire from the gauge to the sender outside the car and if that fixes the problem then run a new wire through the tunnel and splice into the ends to maintain the original ends to preserve the color coding only if the wire I am splicing into is in good shape of course. Also check the ground on the sender.

[saurkraut]

Originally Posted by gsmith660

What I do to confirm a broken wire is run a wire from the gauge to the sender outside the car and if that fixes the problem then run a new wire through the tunnel and splice into the ends to maintain the original ends to preserve the color coding only if the wire I am splicing into is in good shape of course. Also check the ground on the sender.

I grounded the lead wire from the sender on the intake manifold and the gauge stayed pegged. Doesn't that confirm a broken lead wire?

I also tried swapping the gauge with a 'good' used one and it pegged too.

Is the 934,935 analog or digital?

[gsmith660]

Originally Posted by saurkraut

I grounded the lead wire from the sender on the intake manifold and the gauge stayed pegged. Doesn't that confirm a broken lead wire?

I also tried swapping the gauge with a 'good' used one and it pegged too.

Is the 934,935 analog or digital?

No the sender is grounded so sendin the lead to ground is only going to send the gauge to it fail position which is peg high I would guess if you run a known good wire to the sender from the gauge and it reads normal then that would confirm a shorted wire, a broken wire I believe would just do nothing to the gauge it would not respond. If hooking up a know good wire does not correct things then it is the sender since you have already tried a known good gauge.

[gsmith660]

What does the gauge do if you remove the signal wire while powered? and what does the gauge do when unpowered

[saurkraut]

When the key is turned on, both the original gauge and the replacement gauge peg full scale.

Including;

wire on sensor,

wire disconnected and not grounded,

and wire grounded to intake manifold.

The gauge remains at full scale.

Do I have a pinched wire?

[gsmith660]

Is it wired properly? Is this a factory 930 gauge if so I will go dig out the wiring diagram and help you check your wiring.

[gsmith660]

It is only 12 volt and a ground perse inside the gauge, the sender is a variable resistance coil and boost pressure moves the contact up and down this coil sending this resistance to the gauge I do not know if the default position for this gauge powered up is pegged someone with a factory boost gauge will have to answer this question. Does the gauge ever go to zero? try reversing the leads or make sure you have power and ground hooked up to the proper spade connector.

[spuggy]

Originally Posted by gsmith660

I do not know if the default position for this gauge powered up is pegged

If the factory boost gauge is not connected, it will peg high when the car is switched on, and drop to zero when connected to ground.

I think all the factory gauges do that?

[saurkraut]

So it sounds like a broken wire. It always stays pegged when the key is on. Grounding the wire on the sensor does nothing.

So its run a new wire, or put a mechanical boost gauge where the clock is.

(ending a sentence with a preposition -10)

I sent an email to North Hollywood speedometer about a gauge for the clock hole. No reply yet.

[sjf911]

I bought this one (type A) off of ebay and am very happy with the quality, fit, and appearance:




Porsche 930 Boost/Vacuume Gauge (Clock Replacement) : eBay Motors (item 200352383765 end time Mar-10-10 09:49:08 PST)

[gsmith660]

Originally Posted by saurkraut

So it sounds like a broken wire. It always stays pegged when the key is on. Grounding the wire on the sensor does nothing.

So its run a new wire, or put a mechanical boost gauge where the clock is.

(ending a sentence with a preposition -10)

I sent an email to North Hollywood speedometer about a gauge for the clock hole. No reply yet.

Its not hard to run a new wire but you can get a much more accurate gauge by installing 1 in the clock hole, I put an auto meter gauge in and run a steel line all the way back to the manifold leak cheacked and all.