Mechanical Boost Gauge

[mr299ron]

So I've just bought a mechanical boost gauge. I know where to install the gauge for the pressure, however I need to find a good power source for the backlight and how to do it.

Could I have some clear help from you guys?

Cheers
99ron

[parker455]

Cigarette lighter +12V or behind the dash clocks. Shinny has a good post on the OC about gauge wiring, have a gander here:

http://www.mr2oc.co.uk/forums/41/160627.html

[mr299ron]

Awesome, so it's just a matter of stripping the wires mentioned and adding the boost gauge's wires to them?

[parker455]

Yep! Just make sure you get a good earth and you should be good to go!

[mr299ron]

Awesome, thanks bud!

[2mad]

I found a wire that only went live with my lights on and hooked to that

[mr299ron]

Okay so I setup the gauge with the cigarette lighter wires. Easy as p1$$, just bodged on some spade connectors and wedged them in the plastic bracket that connects to the back of the lighter, then to keep them together I just taped them up. Sorted.

Took off the factory vaccum line from the boost sensor to the manifold and put my new hose on the manifold where the stock hose used to be.

Now, I know that when the car is cold/wastegate pressure it's supposed to be about 7psi. Now when the car had warmed up fully and the ecu allowed more boost, the gauge still read 7 maybe 8 psi.

I could swear the car was a little bit slower than it usually is.

Any advice?

And also, the gauge is reading 20-25 inhg at idle and when off throttle and moving it reads 30.. is this normal?

99ron

[2mad]

Sounds about right .. 11.0 to 12.0psi on boost your looking for .. up it to 15psi with a fcd ... have fun

[mr299ron]

But it's not reading anywhere near 10, only about 7psi!

[2mad]

But it's not reading anywhere near 10, only about 7psi!

7SSI is actator pressure mate .. spot on .. vsv should when walmed up hit 11.0psi .. investigation is needed mate.

[mr299ron]

Yeah I know that, as the car is evidently slower when cold, and then faster when warmed up.

However, when colder it just seemed to read 7 or lower (which i thought was fine) but then warmed up it wouldn't read much past 7.5 or maybe even 8psi :/

[2mad]

Yeah I know that, as the car is evidently slower when cold, and then faster when warmed up.

However, when colder it just seemed to read 7 or lower (which i thought was fine) but then warmed up it wouldn't read much past 7.5 or maybe even 8psi :/

Warmed up should be 11psi or more mate .. check your vsv .

[bobhatton]

Your stock boost control is not working and or the ECU thinks the engine is still cold via the ecu temp sensor.

[mr299ron]

Thanks bob, I'll have to get an mbc fitted soon and see.

[danjama]

And change your ecu temp sensor, as it's probably not been done since 1998.

[2mad]

And change your ecu temp sensor, as it's probably not been done since 1998.

Yeah should have checked that

[mr299ron]

But the thing is the car is noticeably different between cold and warm. The gauge reads 5 psi when cold and 8 psi when warm. The car feels noticeably different. I honestly think it's just a bad gauge now, as the difference in figures is the same from cold to warm.

I.e on my gauge it's 5 to 8 psi

the car should be showing 7 to 10 psi

Why would the car show 5psi, then up it 8 degrees when warm? Timing out?

[mr299ron]

Come to think of it, I think there's an issue with the vsv and/or spring that releases the boost pressure.

I reckon it's a little worn and won't open up as it should.

I'm going to install an MBC and disable vsv and see what happens.

[masterbateson]

And change your ecu temp sensor, as it's probably not been done since 1998.

re this above.

Is this the temp sensor on the engine bay hood/cover or something else? if so where is said beast?

In the mission to make mine run at its best, on my list of things to change are (ignition leads,coil pack,knock sensor) and now maybe one of these ecu temp sensors.
By coil pack i mean the doofrey that feeds the dizzy.
Dizzy and rotor plus plugs already been swapped.

[mr299ron]

And change your ecu temp sensor, as it's probably not been done since 1998.

re this above.

Is this the temp sensor on the engine bay hood/cover or something else? if so where is said beast?

In the mission to make mine run at its best, on my list of things to change are (ignition leads,coil pack,knock sensor) and now maybe one of these ecu temp sensors.
By coil pack i mean the doofrey that feeds the dizzy.
Dizzy and rotor plus plugs already been swapped.

This is the green ECU temp sensor and not dash sensor. I know where this is.

I have replaced plugs thus far, in terms of ignition. Looking to get a distributor cap and rotor arm soon. HT leads last once all is replaced.

But the thing is I don't think the car is underboosting because of all reasons mentioned above. I just think that the wastegate's spring is weak and allows air to pass through whilst the spring is supposed to be shut.