Guages - how to use them

[Oblivion]

(AKA The whats normal and whats not thread!)

After you've decided on what guages to put in and finally installed them so your interior is looking better, its time to put them to good use.
For any of them to be useful we first need to know whats normal and what should make your pants turn brown :P Add your wisdom and we'll edit it along the way :D

Below is a table of approximate values, for more info please read posts that follow :)
Values for stock standard car
Metric / Imperial

Warm engine at idle
Boost pressure: -0.7 bar (approx) /
Fuel pressure: 3bar + relative manifold pressure (eg @ -0.7 bar = 2.3 bar / 33 psi)
Oil pressure: 1.03 - 1.38 bar / 15-20psi
Oil temp: 100 deg c / 212 deg F
Water temp: 95 deg c / 203 deg F
Exhaust temp: 200-300 deg c / 392-572 deg F
Air / Fuel ratio: 14.5
Battery voltage: 14 volts

?anything else?

Maximum / Minimum warnings!
Boost pressure: 0.6 - 0.69 bar / 8 -10 psi (approx)
Fuel pressure: should remain consistently 3 bar (43 psi)+ relative manifold pressure
Oil pressure: 1.03 bar - 6.9+ bar / 15 - 100+ psi
Oil temp: 130 deg c / 266 deg F
Water temp: 105 deg c / 221 deg F
Exhaust temp: 700 deg c? / 1292 deg F?
Air / Fuel ratio: 13.5 (at WOT)
Battery voltage: 12 volts

[bradc]

The water temp normally stays just below 100C when idling or driving. The AFR when idle should be around 14.5 to 14.7. Oil pressure when you start the car and the engine is cold will be very high, but I beleive settles to around 15-20psi when idling

[Davezj]

on a motorway run oil temp is up to 120 C and if you thrash it 130 C.
round town about 100 C

EDIT:-
I would second brads oil pressure figures. Off the scale (100psi+) on initial startup but starts to drop quite quickly as the engine oil starts to warn, down to 15-20psi when hot.

[Oblivion]

hmmm I'm not sure my fuel pressure one is reading correctly at the moment, anyone know what it should be?

[Kenneth]

hmmm I'm not sure my fuel pressure one is reading correctly at the moment, anyone know what it should be?

3bar + relative manifold pressure. (so at -1 bar relative pressure, you should have 2 bar fuel pressure, at 1 bar boost you should have 4 bar pressure.)

[Kieran]

Thought it was a bit higher than that Ken? More like 2.3Bar @ idle under vacuum?

[Kenneth]

Thought it was a bit higher than that Ken? More like 2.3Bar @ idle under vacuum?

if you idle at -0.7bar (which I believe is about right) then you are correct.

to get -1bar you probably have to be decelerating. Either way the formular is still the same.

To calibrate your FPR you unplug the manifold pressure reference, at which point it should show 3bar.

[Oblivion]

To calibrate your FPR you unplug the manifold pressure reference, at which point it should show 3bar.

Sounds like what I need to do, mines only reading between 3-3.4 bar. Any clearer intsructions on this please? Unless its just my car being totally stuffed! /pan

[Oblivion]

List looks almost complete! :) anyone have figure for:
Normal exhuast temp/ warning limit
Air fuel ratio warning

[Turbo_Steve]

Any kind of AFR leaner than 13.5 at WOT is likely (but not guranateed) to see you with enormous EGTs and potentially a lot of preignition.

Partial throttle you can actually go quite lean if you're mapping for it (15.5-16) but the engine will tend to feel a bit gutless and run hot: will also usually fail emissions.

Factory map seems to have partial throttle adjustment enrichment to around 11.5 - 12 which is utterly ridiculous..or maybe my reg is getting tired.....

[Kenneth]

Sounds like what I need to do, mines only reading between 3-3.4 bar. Any clearer intsructions on this please? Unless its just my car being totally stuffed! /pan

Do you have a adjustable fuel pressure regulator? If so, start the car, open the bonnet, disconnect the vacuum feed to the FPR and then adjust the FPR until the gauge shows 3bar.

And you have written the pressure figure incorrectly.

The idle fuel pressure is "3bar + relative manifold pressure", NOT 2.3 bar.
The reason for this is that not all cars idle at the same vacuum level, which is entirely normal.
For some people this could be 3bar + -0.8 = 2.2bar, others 3+ -0.6=2.4

Adjusting your FPR to get 2.3bar on idle will likely result in incorrect fuel metering. You MUST set it with the vacuum feed disconnected and then set to 3bar.

[Oblivion]

Some great info coming through there :) I've added some imperial values that are in italics for the people using those type of guages.
?Vacuum in imperial units?