Fuel Pressure Gauge? A/F Ratio Gauge?

[Rider90]

I did a quick search around the net and around here, but could not turn up much information. I am looking for some gauges and I was wondering what the advantage is to have a fuel pressure gauge and the advantage to having a Air/Fuel ratio gauge. Can someone explain the two to me?

[MM03MOK]

It depends how you're driving your car. Street and drag racing? Steady highway travel? Also, do you have the ability to change these parameters yourself? Is your car tuned to begin with? You'd need more than the A/F gauge to do it right. You'll need a wide-band O2 monitoring system. There are more important gauges for all around use that would better serve you as performance monitors, such as a tranny temp gauge.

[fastblackmerc]

I'd go with a tranny temp gauge also. I don't think fuel pressure is of any help.

[Rider90]

Already have tranny temp

[Pat]

Rider90; a tranny temp guage was recommended but you already have that.
An A/F ratio meter to be of any value has to be of the Wide Band variety and cost several hundred dollars and requires new bungs in the left and right exhaust header down pipe if memory serves. The value is marginal for a street machine unless you have a turbo or supercharger and a tuner.

The fuel pressure guage would be a nice addition with a power adder, ie nitrous. Since I have a Zex nitrous system both a fuel pressure and nitrous gas pressure would be beneficial. I'm in the process of saving for these two items. I have the pillar pod already.

The oil pressure and battery voltages guages already in our cars can be upgraded.

So, for your instrumentation, upgraded voltmeter, oil pressure, fuel pressure and tranny oil temp would monitor your engine/tranny's health nicely.

[RF Overlord]

^^^what pat said^^^

Jason, do you have the OEM fake oil pressure gauge or the real one?

Here's another thought: how about a real coolant temp gauge, instead of the half-assed OEM? That would be of more value than either the fuel pressure or the A/F for a street-driven N/A car.

[Rider90]

I have the ScanGauge so I have Water Temp, Volts, Ignition or Load, and MPG.

I have a Tranny Temp Gauge, OEM Voltmeter which will be pulled since I have the ScanGauge voltmeter, and OEM dummy oil pressure.

I will have a real oil pressure, oil temp, tranny temp, and what else?? two more slots open.

Lets say I get boosted down the road, so maybe a boost gauge, now that leaves one more open?? This also means I would be forced induction, what other gauge should be neccessary?

[MikesMerc]

As has already been said, an AF gauge without a quality wideband would be pretty useless.

Fuel pressure is a great gauge to have if you have a power adder. I watch my FP gauge, not the boost gauge, when I'm "on it." A good FP gauge can save you when you're running a power adder.

For NA cars, I wouldn't bother with either. I'd focus on the temp and oil gauge upgrades, then go with a tranny temp.

[Warpath]

Fuel pressure gauge is nice if you have an upgraded fuel system. Some aftermarket pumps will burn out over time in the returnless environment. You don't have to worry about OE pumps like the Cobra or Focus pumps. The fuel pressure gauge will give you an idication that the pump is starting to go.

A/F gauge is nice if you are pushing the hp envelope or are blown. It will let you know if you have bad gas or something else going wrong. EGT will do the same. You can put the A/F gauge in one of the rear 02 sensor bungs if you have the OE sensors turned off.

Autometer is coming out with wide band A/F meters soon. So, you will be able to get one that matches the rest of your gauges (if you have Autometers).

[SergntMac]

Originally Posted by MM03MOK

It depends how you're driving your car. Street and drag racing? Steady highway travel? Also, do you have the ability to change these parameters yourself? Is your car tuned to begin with? You'd need more than the A/F gauge to do it right. You'll need a wide-band O2 monitoring system. There are more important gauges for all around use that would better serve you as performance monitors, such as a tranny temp gauge.

OMG! Spot on! My word, we have a gear head monster Bunny on our hands!

Honestly, I could not have said it better. I have a boost gauge because it came on the car, but I rarely look at it when into the boost because my attention is elsewhere, unless I'm on the race track in a controlled environment.

FP and AFR gauges are nice to watch. Very active...Keep moving around a lot. But, neither do much in providing advance warning of something gone wrong, with enough notice to correct the situation.

The only gauge I would like to add, would be tranny temp, but there is so much flexibility in my ScanGauge, I can pretty much tell when something is not right, so, I haven't gotten around to it yet.

If I were to gauge up (and I may) I would buy the Nexus stuff from AutoMeter. Only the best for my #1x.

[MM03MOK]

Originally Posted by SergntMac

OMG! Spot on! My word, we have a gear head monster Bunny on our hands!

The "gear head monster " has great mentors! And she's a pretty smart cookie to boot!

[Vortech347]

I run an AEM wideband and Autometer Electric fuel pressure on my stang. They match just fine. The new AEM's you can set up 6 different ways. Jegs has them right now for 280$!! Stay way from the POS autometer a/f gauges. (at least the older narrowband style) They read off your stock 02 and is not accurate for tuning.

DO NOT run an mechainical fuel pressure gauge inside the car unless you use an isolator (which are a pain to setup) . Its not legal at the track and stupid for street use. Electric ones are more expensive but they are much safer.

Here's a pic of the ones on my stang.

[martyo]

Since I have to take my glasses off to read the damn gauges, they are all a waste when I am driving.

I do use my boost gauge a lot, but mostly the recall function when I am at the track.

[sailsmen]

Our OEM Temp guage is useless, need 40+* to get it to move.

The FP is a good indicator on whats going on temp wise. As the temps in the heads increases the FP will increase.

[MikesMerc]

Originally Posted by SergntMac

FP and AFR gauges are nice to watch. Very active...Keep moving around a lot. But, neither do much in providing advance warning of something gone wrong, with enough notice to correct the situation.

Not true at all. The marauder is my third supercharged car and all of them had (have) fuel pressure guages.

I saved my motor in my blown 1991 Mustang LX 5.0 when I noticed the fuel pressure wasn't where it was supposed to be. After only a few months of use, the new Ford Motorsport 155lph in tank pump started to die and starve the T-Rex in line pump. This happened only on WOT conditions under boost. I would never have noticed I was running lean if not for the guage. My exhuast was loud on that car and any hint of detonation at WOT was inaudible. After noticing the pressure wasn't where it should be on WOT (gradually falling pressure under WOT), I laid off it and shut it down until I could get it to the shop. Sure enough, the pump was bad. Although the computer compensated as best it could, and that did indeed buy me time, the gauge saved my motor.