I have a full sweep electric autometer fuel pressure gauge. Connected to pin 10 and insert EIO input #2. Fuel pressure very erratic. Frame to frame drastic change. Is this normal? I only connected the + signal to the EIO.Thanks
I have a full sweep electric autometer fuel pressure gauge. Connected to pin 10 and insert EIO input #2. Fuel pressure very erratic. Frame to frame drastic change. Is this normal? I only connected the + signal to the EIO.Thanks
2003 5.7 RCSB 224/228 114 60lb MOTORONS LONG TUBE HEADERS CAT DELETE 4L80E 3.73
Hmm sounds like you answered your own question. Outputs have two wires, signal and return (ground).
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Do I get the ground from the EIO or anywhere? Would this also be true for my PLX wide band it only has signal hooked up and working fine?
2003 5.7 RCSB 224/228 114 60lb MOTORONS LONG TUBE HEADERS CAT DELETE 4L80E 3.73
The gauge should have a signal & signal return (ground) wire for it's output. Just have to look over the instructions to see which ones. Could also be the ground for the gauge itself. Not sure there without the instructions though. But yes you need to run two wires from the fuel pressure gauge to the EIO. One ground, one signal.
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Thanks Ill try that.
2003 5.7 RCSB 224/228 114 60lb MOTORONS LONG TUBE HEADERS CAT DELETE 4L80E 3.73
Ground hooked up and no change erratic behavior continues.Very short log.Originally Posted by EC_Tune
2003 5.7 RCSB 224/228 114 60lb MOTORONS LONG TUBE HEADERS CAT DELETE 4L80E 3.73
Yeah that's definitely erratic. I could see a couple PSI change over time but that thing is just flat noisy! In fact I would venture to say that the output is not damped at all or has other issues at hand.
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Bringing this thread back from the boneyard, as I have the exact same problem??
I have tapped into my Autometer Nexus sender Purple wire into the EIO aux input. The signal ground wire is not going through the EIO, it is sent to a ground lug which is grounded to the battery neg terminal. I tore into the wiring over the past couple days, removed all splices and went with soldered connections......same erratic results?
I have run my LC's and fuel pressure "inputs" into a DB-9 connector, all inputs are soldered to the pins. I can put a voltmeter on the sensor pin and its steady as can be. but plug it into HPT and it goes nuts? I have tried every conceivable configuration...I have changed aux input stations thinking maybe just one pin was bad on my interface....no change. tried different grounding configurations....no change. My last ditch effort was to eliminate the EIO interface, I soldered the right pins on to a test lead, ran a dedicated wire from my db-9 straight into the HPT interface.....no change.
I even logged raw voltage, and as would be expected it is very erratic. I did notice it tried to carry voltage numbers out to 3 decimal points???
I spoke with Autometer this morning, they state that their gages and a voltmeter simply are not as fast as the HPT data logging abilities. As such Autometer thinks this will not be improved upon without either some mod to the HPT sensitivity, or some way of filtering the input from the FP transducer??
Last edited by b727pic; 02-04-2011 at 12:43 PM.
2004 GTO M6, 403, Callies, compstar, wiseco, QTP HV oil pump, QTP 2 piece timing cover, EDC custom AFR 235's, LS6 intake, P1SC-1 Procharger maxed @ 13psi, 224/232 600/600 114 EDC custom cam, JBA shortie headers (thanks California) custom boost referenced return style fuel system with surge tank, walbro 255, staged magnafuel 4303, Dual LC-1, Dual Aeroforce Interceptor gages, Nexus fP and boost gages.
How does it look if you right click on the PID and tell it to only carry one place after the decimal?
your gauge signal ground needs to be the EIO..make sure it is not a power ground.
if its a power ground/common signal ground, then it needs to go to the chassis
as far as eratic... it wont be smooth... not feasible... you will see injector pulses in your log(jagged line)
also any lean or rich cells(commanded way different than the cells near it) may show spilkes.
unfortunately our LS1 cars dont have the greatest fule pumps and not the greatest regulators on them.
60lb motrons will definitely see some pulses in the fuel pressure data, and if you are using stock fuel rails, you dont have enough volume to dampen the pulses(thats part of the benefit of a larger fuel rail.
as far as a volt meter reading stable....its going ot unless you spend some big bugs on a meter.. most meters read very slow and do averaging to make it easy to look at...
spend $400 on a meter that can do peak and rms real time readings and you will see the exact same result.
theres a reason why we use a histogram that can average the data when trying to see what things are actually doing.
and the autometer guys have no clue when it comes to HPT, so dont ask them how to solve an issue that is not an issue... its just you thinking its supposed to be something its not.
Fuel pressure is not perfect, never will be, nature of fluid dynamics...
analog gauges read slow for a reason, so you dont see little variances like that
HPT EIO section always logs at 40 frames per second.. way faster than the autometer can output...
your data logging on your car will determine how much of that gets averaged.
the more PID's, the less frames per second, the longer the averaging time for the EIO.
-Scott -
I have tried everything from whole numbers only, all the way out to 9 decimal points......no effect.
2004 GTO M6, 403, Callies, compstar, wiseco, QTP HV oil pump, QTP 2 piece timing cover, EDC custom AFR 235's, LS6 intake, P1SC-1 Procharger maxed @ 13psi, 224/232 600/600 114 EDC custom cam, JBA shortie headers (thanks California) custom boost referenced return style fuel system with surge tank, walbro 255, staged magnafuel 4303, Dual LC-1, Dual Aeroforce Interceptor gages, Nexus fP and boost gages.
Thank you for your reply...
I do have a completely custom, boost referenced staged twin pump fuel system regulated by an SX performance rail mounted regulator. until I am at 3PSI boost, the intank Walbro runs at 13.1 DCV, at 3 PSI the voltage is kicked up to 16 DCV, then at 5.0 PSI the Magnafuel 4303 kicks in.
The histograms do log nicely, my issue was trying to read the chart during a boost run, I was trying to correlate small amounts of KR, to dips in the fuel pressure at any given moment. This led me down this road of trying to "stablilize" the fuel pressure being logged on the scanner.
as far as the signal ground goes, I have no idea. The documentation from Autometer does not explain in detail for the Nexus gages. Its simply a 3 wire lead that connects the transducer to the Nexus "brain box". Since the transducer is a 0-5vdc unit, I assume that one wire is the 5 volt supply, one is the signal output, and the other is signal ground? I will have to call Autometer to confirm....I am using an MPVI interface, according to the diagram I have pins 5 & 6 are grounds, I have pin #5 routed to a chassis ground lug, pin 6 is currently unused. Assuming Autometer confirms one of the 3 wires is a signal ground, I guess I should route that into pin #6?
So it sounds as if the issue at hand is not an issue.... it just is what it is. I certainly don't want to reinvent the wheel so to speak.
Thanks again, I appreciate your input.
Last edited by b727pic; 02-04-2011 at 05:47 PM.
2004 GTO M6, 403, Callies, compstar, wiseco, QTP HV oil pump, QTP 2 piece timing cover, EDC custom AFR 235's, LS6 intake, P1SC-1 Procharger maxed @ 13psi, 224/232 600/600 114 EDC custom cam, JBA shortie headers (thanks California) custom boost referenced return style fuel system with surge tank, walbro 255, staged magnafuel 4303, Dual LC-1, Dual Aeroforce Interceptor gages, Nexus fP and boost gages.
My fuel pressure log looks exactly the same. Smooth at idle and choppier as demand increases.
My fuel system is boost referenced but the regulator is near the tank where the stock fuel filter/regulator was. I swapped a non-regulating filter in and added a regulator right there. I was thinking maybe that had something to do with it but there is probably very little fuel being bypassed during the time the graph is choppy. I may go to custom rails with a bigger bore and see what happens.
1971 Corvette-LS3 swap with custom cam. Stainless headers and sheet metal intake built by the owner. 442rwhp.
2007 STS-V-Billet Precision 67mm turbo swap. 563rwhp@15psi.
1991 Camaro-6.0 swap with LS6 heads and custom cam. Headers and other swap bits fabricated by myself (wife's car)
It's quite likely there is significant rail pressure pulsation
at the injector firing rate, and the slow EIO frame rate
will "decimate" the real activity making a sort of regular
appearing jagged display ("aliasing"). More rail or close-in
volume is about the only thing to fix the magnitude of
pressure ripple. If the noise bothers you then you can
filter it but I think you just want to eyeball the center
line.
its not a problem with HPT or the FPsender, that is what the fuel pressure looks like. one way to solve this is to add a Fuel pulsation damper to the rail.
I have a Aeromotive Eliminator Pump and ID1000's injectors, big pulses..
-Carl
Last edited by carlrx7; 10-13-2011 at 02:24 PM.
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