Gauges: What is normal?

[16949]

I didn't see a simple answer to this via search..

What is "normal" (or at least reasonable range) for the gauges to read while driving?

My Temp Gauge never goes above where it is in this pic. (I don't know the # since it says midway between 100 and 260 = 220? Delorean math?)

I know that the tachometer for mine is running high (post some other tweaks), where is ideal? I saw someone post 750, that seems low based on how mine runs smoothest.

Oil pressure: my oil pressure is all over the place when driving, is this common?

Battery: seems to fluctuate quite a bit but within normal range based on what the vehicle is doing (braking, ac, etc).

Thanks in advance-

[Michael]

That's a pretty open ended question. There are a lot that can cause erratic gauge readings, including the gauges themselves not being exactly on the nose.

For example, the oil pressure gauge had the incorrect sending unit (actually calibrated for a different car) installed from the factory which made the gauge peg out all the time. The correct sending units fixes the problem and will fluxuate quite a bit which is normal. ie, higher pressure at cold temps, lower pressure at idle and warm. Pressure climbs as RPMs increase.

The battery gauge has never really been accurate across the board. A good way to measure is check the voltage at the battery and compare to the gauge, and use that as a reference. Bad grounds can also cause low or incorrect readings.

Bad cluster ground can cause the temp gauge to peg out after shutting off as well, or since it seems to be working somewhat, it could be a stuck thermostat, or it could be the gauge, but I would look at the thermostat first.

A good way to check the tach is use a dwell meter hooked to the coil. The idle rpm is just not one of those things you check until ALL other problems are worked out and there is just a lot(too much to really list, idle computer, vacuum leaks, fuel pressure problems, incorrectly set linkages...the list goes on ) that can change idle speed.

A lot of people including myself bump the rest plate screws up a tad to help the charge rate at idle with A/C lights etc. on. My idle is set at around 900, but the plates are cracked to do that, idle is set by the idle computer.

[DavidProehl]

Aside from the idle looking a little high (mine idles at 750), the rest seems normal to me. As mentioned previously, gauges vary from car to car, but there isn't anything here that looks concerning.

Edit: Oil pressure will jump around a lot when driving. As long as it increases when accelerating, isn't 0, and isn't pegged you are good.

[Jonathan]

Was the car moving when you took that pic? I see the speedo at zero, but wasn't sure if that was working or not.

Assuming the car is sitting in one place...

Battery gauge looks fine. Mine sits about there too. It will dip slightly when things get turned on, using the brakes as you said... my car volts go down a tiny amount when hitting the brakes. The most noticeable dip will happen when your cooling fans up at the radiator turn on.

Speaking of cooling fans... do you know that yours come on from time to time? If they do, and that temperature gauge doesn't go above where it is because the fans are keeping things cool, then it is fine where it is. Mine shows a little higher when the fans come on, but I'd be more concerned with what that gauge does in relation to what it does on YOUR car at other times and then take note of anything out of the ordinary. That temperature reading is a different sensor than the one that actually turns your fans on (the otterstat decides when your fans need to come on). Could be some variance there in the accuracies.

The tach is a little high for the "proper" idle. Should be about 775 RPM +/- 50 as mentioned. If your car runs smoother at a higher RPM, then there is something else to address. Likely your mixture or lambda system. Very popular topic nowadays so you're not the only one trying to get it right on their car.

What concerns me more about the high RPM at 1,500 or so is that often you would see the engine oil pressure higher by this time. If the car is idling low, around the 775 design point, the oil pressure gauge will show a pretty low value. Not zero, but say around the 25% mark on that gauge. Once the car is in motion and up in RPM, it will rise to about the 75% mark on that gauge, which tends to be normal.

Two things about that:

Original oil pressure senders (the one reading the analog value on this gauge and which is the bell shaped one located just beside the oil filter right in the engine block) were not very well calibrated and often just sat pegged when the engine was running. The replacements were a more accurately calibrated unit and will actually go up and down as I just mentioned with engine speed.

The other aspect is that the low oil pressure warning light (with info from the engine coming from the sender on the driver's side of the engine, opposite the analog side one) is said to be more accurate for being made aware of problems. Meaning, if you see your oil warning light come on, it is a problem. Seeing a low reading needle in the gauge may not be telling you the whole truth. You will know if your warning light bulb is working or not as a test since it should come on when you turn the key in the ignition prior to starting the engine.

[dn010]

My oil pressure is always pegged at 80 while the engine is running but as mentioned it depends on the sender unit installed. Voltage will vary depending on what loads you have (lights, fans) and what RPMs you're at. Mine has never been able to get 13+ at idle, it is always under until I increase RPM above 800.

[bfloyd]

Reviving an older thread as opposed to starting a new one.

On the Engine temperature gauge what is normal? My car has been back together now for a year, and everything seems to be running fine. No matter how long I drive it, the temperature gauge never gets above the mark in-between the 100 and the 220. Is this normal? My fans do cycle on and off it it's idling after about 10 minutes. I have seen the car spit some coolant out of the overflow tube maybe once or twice, but nothing major, just a drop or two.

Also... the Oil pressure gauge. My gauge was pegging out at the top (12 o'clock) or would jump all over the place, so I bought a new sending unit from DMCH. Easy installation, but now the gauge just stays pegged at the 12 o'clock position with the engine running.

I have unplugged and re-seated all of the wiring connection on the bulk head,but nothing changed. What should the gauges read?

[Mark D]

My temp reading rarely exceeds the first tick mark on the gauge. It usually sits at or below that first mark when fully warmed up. It's not a linear scale on the gauge either so it's tough to say what the temp actually is at that line between 100 and 220. Splitting the difference evenly would give you 160 degrees, but then you have to consider the rest of the gauge only goes from 220 to 260 in the same amount of needle travel.

My oil pressure gauge is pegged at 80 when on the throttle and may dip slightly below at idle.



You can also reference this page for what is expected to be normal. Sounds like a corroded connection at fuse 5 may cause a low reading on the temp gauge or your thermostat may be on its way out if the gauge is reading really low all the time.
http://support.delorean.com/kb/a45/instrument-cluster-and-gauges.aspx

[AugustneverEnds]

Replacing the factory oil sending unit with one from DMCMW last year eliminated the jerky motions on the oil pressure gauge. Now it goes close to the top at start up and settles to ~60psi when driving steadily on the open road. Probably sits near ~20psi when stopped and idling.

Cleaning grounds and removing previous owners aftermarket stuff (alarm, radio, cruise control, back-up camera) improved the voltage reading from <13V to 13V> at idle. Of course turning things on brings this figure down but never to the yellow warning line anymore.

I had a high idle condition last year, would idle at 775RPM or so when first started then would climb to 1200RPM or so when warmed and in Park. Turned out the spring for the microswitch hammer was sticking and the hammer was not consistently tripping the idle microswitch. I have a good 775RPM idle now in all conditions.

My temperature gauge usually sits a hair below the first mark when moving steadily on all but the hottest of summer days. I think it gets to the first line on 90+ degree days.

All cars are different and of course this is subjective but I think my gauges move a bit more slowly and deliberately now since I replaced the old circuit board with DMC Europe's new design one and used brass washers and nuts instead of steel. Again probably more perception than anything on this one.

[Lwanmtr]

What would be an average rpm for an automatic when doing 60-70mph?

[whocruiser]

What would be an average rpm for an automatic when doing 60-70mph?

From daily driving VIN 1662 for about 13 years without a functioning angle drive, I developed the general rule of thumb that when in 3rd gear on an automatic transmission DeLorean, you'll be pretty damned close if you simply multiply the tach scale by 2.2. 20 = 44mph, 25 = 55mph, 30 = 66 mph, 35 = 77 mph, etc. At slower speeds in lower gears I've not the foggiest, and it generally doesn't matter much then anyway ;-)

So to more directly answer your question, that'd be about 3000 RPM give or take a wee bit.

[dn010]

What would be an average rpm for an automatic when doing 60-70mph?

http://dmctalk.org/showthread.php?118-RPM-to-MPH-Chart

[Lwanmtr]

Thanks. The one time (so far) i've driven at highway speed it seemed high. But I admit i could have been in 2nd the whole time, since most of the interior was disassmenbled, so I didnt know where the shifter was..hehe.

[Nate88]

Reviving an old thread.

My main concern is the battery gauge. When I start the car, the gauge is 13 volts maybe a hair more. However, as I drive it starts to dip a bit to a little under 13. Only load is radio, no interior fan or A/C, and no cooling fans. It gets even worse with the Headlights on (still with only the radio). One evening I was driving around with headlights on (all other exterior lights are LED's) and it was starting to dip lower than I have ever seen it, maybe 1/16" to 1/8" above 8. No issues with driving and the next time I started the car the volts were right around 13 again. RPM's while driving seem to have little effect. The example above was varied speeds from stopped, to 55-60mph.

Could this be the alternator going out or the gauge not reading properly? Belt tension is pretty good, it could be tighten slightly but there is no squeal.

[David T]

Reviving an old thread.

My main concern is the battery gauge. When I start the car, the gauge is 13 volts maybe a hair more. However, as I drive it starts to dip a bit to a little under 13. Only load is radio, no interior fan or A/C, and no cooling fans. It gets even worse with the Headlights on (still with only the radio). One evening I was driving around with headlights on (all other exterior lights are LED's) and it was starting to dip lower than I have ever seen it, maybe 1/16" to 1/8" above 8. No issues with driving and the next time I started the car the volts were right around 13 again. RPM's while driving seem to have little effect. The example above was varied speeds from stopped, to 55-60mph.

Could this be the alternator going out or the gauge not reading properly? Belt tension is pretty good, it could be tighten slightly but there is no squeal.

Check the belt on the alternator and get it tested.

[Michael]

Reviving an old thread.

My main concern is the battery gauge. When I start the car, the gauge is 13 volts maybe a hair more. However, as I drive it starts to dip a bit to a little under 13. Only load is radio, no interior fan or A/C, and no cooling fans. It gets even worse with the Headlights on (still with only the radio). One evening I was driving around with headlights on (all other exterior lights are LED's) and it was starting to dip lower than I have ever seen it, maybe 1/16" to 1/8" above 8. No issues with driving and the next time I started the car the volts were right around 13 again. RPM's while driving seem to have little effect. The example above was varied speeds from stopped, to 55-60mph.

Could this be the alternator going out or the gauge not reading properly? Belt tension is pretty good, it could be tighten slightly but there is no squeal.
The volt gauge is known to be inaccurate. Check your voltage at the battery with the engine running with a multi meter...compare to what the gauge tells you then you will know.