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Calibrating Autometer gauges?

85 Jimmy

85 Jimmy

Sheepdog
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I've had Autometer gauges in my truck for about 5 years now and they are starting to bug me.

First problem is, my fuel gauge does not read correctly. When I initially installed it, it was close to correct, but over the years it tells me that I have more gas then I actually have. For example, when it tells me I have 3/4 of a tank I actually have about 1/4 tank. Is there a way to fix this?

Another problem I am having is my oil pressure gauge reads backwards, and I hope it's not correct if it's backwards. At idle when cold it reads 75 psi, then when it warms up and is idling it reads off the gauge like it gotten more pressure. I have the gauge wired up through the ECM for my TPI, but I also have the sending unit that came with the gauge. Is there a spot I can hook up the autometer sending unit other than the back of the engine where it is in the stock location? it's kind of a pain to get back there, and I'm not sure I'll have the clearance with the firewall...
 
you should have a blocked off oil port on the side of the block above the oil filter...

usually misreadings are sender issues, not the gauge... especially fuel level... you can check the ohm's on the sender with a multi meter by manually moving it all the way down, and up...... so, removed from the tank...

the oil sounds like something in how it's wired...
 
I think the oil pressure gauge reading funny is how the TPI ecm is sending the signal to the gauge. I'll see if the port above the filter is the same size as the sender.
 
Pardon my ignorance, but how is your oil pressure gauge interfacing with the ECM? Maybe I misunderstand your statement. The ECM doesn't monitor oil pressure. I'm not aware of any TPI applications that monitored oil pressure, although I know the TPI Corvettes monitored oil temp for at least one year.

A 45 and 90 ohm resistor across the back of the gauge would verify it's accuracy (should be half and full or empty, can never remember what 90 ohms reads), however you could also measure resistance when the gauge is reading half and then reading full, and again you should get 45 ohms at half, and either 0 or 90 at full, whichever is right. This would be the easier way. If your sending unit wire reads 45 ohms when your gauge says half, you know the gauge is right, and the sending unit is reporting erroneous fuel levels.

This is why when I hear people say aftermarket gauges are more accurate than factory....yeah. Nothing can be considered accurate if it's not been checked for proper calibration.
 
I don't know on the oil pressure gauge. I know when I got my harness from street and performance, there was/is a green wire coming from the ECM that was labeled "oil pressure". that's the wire I used for the gauge. The ECM is a GM part #1227727 that came from a corvette.
But, I just installed the sending unit that came with the oil pressure gauge and I still get the same reading...... I guess I'll need to shoot Autometer am email.
 
All senders but the fuel gauge sender is specific to the autometer gauges, I can save you that work lol.

The oil pressure gauge needs a wire (assuming one wire) run straight from the pressure sender. Obviously power and ground too.
 
dyeager535 said:
All senders but the fuel gauge sender is specific to the autometer gauges, I can save you that work lol.

The oil pressure gauge needs a wire (assuming one wire) run straight from the pressure sender. Obviously power and ground too.
Click to expand...

The gauge has both power and ground, I just installed the sender that came with the gauge, re-ran the signal wire to it, and it still reads the same. I just sent autometer an email, hopefully they respond sometime soon. although, I've had this issue since I installed the gauges 5 or so years ago.
 
I just called them, they are sending me a new sender.

I also googled this to see if it's a common problem and it seems like it is. From my googling, Ohms at the sender with 0 pressure should be 230, I checked mine and it's 227.

I guess I'll find out if a new sender will fix it.
 
The funny thing is I sent an email with my problem before I called. One guy, that did zero diagnostics on the issue, just said "that's the weirdest thing I've ever heard, I'll send you a new sender."
Now I have a guy emailing me asking the resistance at the sender. Just so that I have those numbers down, with the engine off it's 227 and with the engine at idle it's 325. Now I'm waiting to see what he says.
 
IIRC if you play around on their website they list all the resistance specs for their senders. If he doesn't get right back to you.

That's a pretty small range, I'd think bad sender too. IIRC many of the AM senders have a (roughly) 200-1100 ohm range. I'm guessing the 325 is way too low.
 
I went and double checked the 325 ohms, it's supposed to be 32.5. You'd think if you pay the money for a fluke they'd at least get the decimal in the right location, but mine puts it where it wants to sometimes.
 
The tech guy says that 252 ohms should read 0 psi and 42 ohms should be 100 psi.
 
Exact opposite from what I thought, but that's good, your idle number is right, your high pressure number is opposite where it should be, so sender problem!
 
:haha:

Tech guy says he suspects a bad sender, but wants me to send in both the sender and gauge so he can bench test them together and see what the results are. He also said that since I bought them 6 years ago they may or may not be covered under warranty, so I may be charged if they need to fix the gauge. He does not know that I talked to another guy and all ready have a sender on the way...

What to do, send them in and see what they say, or wait to see if the new sender fixes it?
 
rampage said:
That gauge needs to be returned to sender. :whistle:
Click to expand...

Is the tech backwards?

And I wouldn't send them in IF they may or may not replace them. Then what? I mean if they are willing to credit your shipping or something towards a new gauge ok, but I'd think 6 years to be pretty poor longevity. Mine don't have a fancy name on them, but they aren't a day under 24 years old and they still work.

And additionally, not sure what he'd do on the bench that you can't do at home with your meter, other than eliminate you as an operator error. :D
 
The thing that gets me is that the gauge was doing the same thing when I had it wired to whatever the wire coming from the ecm was (I thought FI needed to see oil pressure to pulse the injectors). Then it read EXACTLY the same as before when I hooked up the provided sending unit. I'm not talking similar, the gauge read exactly the same with both setups. The tech guy keeps telling me that he thinks I'm using the wrong sender, but I have a problem with not throwing anything away, and I still had the box the gauge came in with the sender still in the box. So unless they packaged it wrong, it's the correct one.

I can understand if the sender is junk out of the box. With the luck I've had with my TPI swap, it seems like I get brand new junk parts that I have to swap out like 3-4 times before I get a good part.
 
dyeager535 said:
And additionally, not sure what he'd do on the bench that you can't do at home with your meter, other than eliminate you as an operator error. :D
Click to expand...

I was tempted to video myself testing the sender and attach the video to my email. :popcorn:
 
Yep, new no longer means it works. :(

I see autometer lists a couple of oil pressure senders, I tried to dig up the actual specs to double check what you were told, but I can't find the specs easily.

2242 is one of the senders used, this apparently shows what resistance should be for X pressure http://www.classictiger.com/mustang/oilpressuregauge/oilpressuregauge.htm
 
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