Fuel Rail Pressure Gauge is here for bombers

[Matt400]

For that I think I would use a standard 217 that will say Boost on top and come with the transducer and then use label maker software or a print shop sticker that has "Drive" on it and just stick it on the face plate inside the gauge over the letters "Oil"



Probably would need to use a boost transducer on channel 2 also vs the OP sensor. I will check tomorrow if the connectors are compatible. Dleno would probably know if channel 2 pressure can be configured to use a boost transducer.

 

[SRadke]

Thanks Matt, I'll look into that.

 

[DLeno]

Matt, check with Matt @ spatechnique (US) or Mr. Cottier (UK) to validate this, but as I know, SPA uses one pressure transducer for all pressure channels. for example, the oil, drive, boost, and fuel are all identical and interchangable sending units. All you're doing with rail pressure is substituting this $120 sender with the Bosch sending unit on the rail, and calibrating the SPA gauge face to match. As I mentioned earlier, I approached them a year ago on this subject and they declined to work on a one-off! Matt (Reed) is really good to work with, BTW, I'm sure you've discovered that. keep up the good work; this will benefit a lot of bombers who like digital gauges and who wish to monitor rail pressure. The SPAgauges are head and shoulders above the rest, in my opinion. they are a measurement instrument, not just a guage.



meanwhile over the past few months I've been working on a couple of analog guage choices for those who prefer analog. my prototype is actually pretty fun to watch, as rail pressure fluctuates from under 5,000 psi to 26,700 or so with Quad's box on there. I'm still just a bit concerned about the readings you guys are getting though. I've been extensively testing with the fluke 189 in combination with the fluke formsview software, collecting real-time peaks and averages of the data over long periods of time. You can acheive sample rates and peak threshold values with the software that cannot be acheived with the 189 alone. I have never logged over 4. 590 volts on the highest peak. I also used the "fast max" peak detect on the standalone 189. still, 4. 590 is the max. Thats approximately 26,700 psi assuming sender linearity. could be truck to truck variations I suppose -- arn't you getting higher readings? On my truck the sender is saturating at something less than the supply voltage, which means that this sender is NOT a rail-to-rail sender (its output is not capable of reaching supply voltage). Above 4. 50 we really cannot assume sender linearity -- anything over 26,100 is just a guess, and I would suggest that rail pressure is actually higher than the gauge reads, simply because the sender is not linear in that region. In TDR issue 48 I briefly mention the limitations of the rail pressure sender for the purpose of characterizing a pressure box.



Anyway keep up the good work. We also need to validate that the rail pressure sender is electrically the same for 555s, 600s, and 610s. that would be a bad mistake to make if they are different!



-Doug

 

[Matt400]

I have never logged over 4. 590 volts on the highest peak.

I was able to log 4. 87v using a ramifier turned all the way up with a Snap On Vantage. I calculated that at just over 27,900 lbs.

We also need to validate that the rail pressure sender is electrically the same for 555s, 600s, and 610s.

Good point. I don't have the means to do that here. Tomeygun might be able to check if part numbers are the same.



I ran into another block with SPA- They either want me to buy all the gauges or give them a list of the people who want to buy. They feel posting a group buy over a period of time will cause conflict with their vendors.

Its starting to disappoint me after all this work. maybe Tomeygun would like to be a SPA vendor too!

 

[SRadke]

If they need a list of people who want to buy they can be the vendor and collect the funds themselves. That doesn't sound bad. We'd probably have to work the rail. pressure plug pigtail through a separate deal but it should work. I still have hope

 

[Tomeygun]

If they need a list of people who want to buy they can be the vendor and collect the funds themselves. That doesn't sound bad. We'd probably have to work the rail. pressure plug pigtail through a separate deal but it should work. I still have hope

So far it seems that Quad or myself are going to make a SINGLE large order on behalf of MATT400, enough to cover the demand, and the wiring harness can be bought if you want (details on that still in the works) from me or Quad



Please PM me if we can could you in, So I can get an accurate number



PS - the part # for the Fuel rail sensor is the same for 03-04, not I do not have the info on the 05, I bet the same though

 

[DLeno]

I was able to log 4. 87v using a ramifier turned all the way up with a Snap On Vantage. I calculated that at just over 27,900 lbs.

I dunno Matt, that number just does not sound right to me. Its lower than I think a 100HP pressure box will take the rail, and its higher than what I think the sender is capable of. you either have a noise problem or we're just seeing a difference in trucks. Its possible that your sender saturates at a higher pressure than mine. To validate the measurement we should compare Idle pressures and the AC component of your DC signal (at idle). Mine is . 02 volts RMS at idle.

 

[Matt400]

Its lower than I think a 100HP pressure box will take the rail, and its higher than what I think the sender is capable of.

Most maybe but what about the Ramifier? Its a pretty aggressive pressure box. TST told me it was capable of over 29,000. . being concerned they said since that only at WOT and not dead headed it shouldn't blow the valve.

we should compare Idle pressures and the AC component of your DC signal (at idle). Mine is . 02 volts RMS at idle.

Od, I measured . 002v at idle. Pressures at idle where very pulsy using the temp channel I have been working with ranging 4200 to 5200 that should smooth out using a boost channel

 

[DLeno]

yea I agree and thats my point -- If the gauge was accurate and linear, I would expect it to read more than 27,900 with a Ramifier, Bullydog, Volumizer, PPE, Predtor, etc. -- the aggressive pressure boxes that make an honest 100HP and connect only to the rail pressure sender and the MAP sensor. Those boxes I could see rail pressure slam up against the 26,000 psi saturation point at mid-rpms -- suggesting excursions well beyond that point.



its not just WOT -- is WOT plus high RPMs that cause the high rail pressures. Quads 100HP boxe appears to be gentler on rail pressure than any of the other pressure boxes I tested and reported on in TDR issue 47 and (soon to hit the streets) issue 48.



I'll measure my AC component again. The only other thing I can think of that would explain measurement differences is our hookup strategy. are you using signal ground from the sender or chassis ground?

 

[Matt400]

When I saw 4. 87v I let off and it was under a 0-60 run. I don't know where RPM's were. I used chassis ground to measure the ac.



I will re-run the tests again this weekend using a boost channel, I don't want everyone to buy into something that doesn't work right. For me it appeared it was fine.



In my initial testing I used my Snap On Vantage meter to analyze the transducers output which is simply a standard . 5 - 4. 5v sensor.

I just don't see that transducer hitting a wall a 4. 5v. The engineers at SPA helped me to configure their gauge to use the OE transducer in place of theirs. Actually something many SPA users do so they incorporated that function into the gauge.



My calculations showed from . 5 to 4. 5 it is linear. With most not wanting to run over 29,000 thats still under the supplied 5v. I do understand that from 4. 5 to 4. 8 is assuming, but with it being linear doesn't that make since.



One thing for sure is it would also be nice to see if pressures are also too low such as with a duration box. I don't see any trouble with reading below 4. 5v

 

[Matt400]

This thing just took a major dump tonight

DLeno- After realizing I would be tied up on Saturday I stayed after work to go over this stuff one more time and am glad you got me to.

I spoke with Quad over the phone today he even questioned how I was able to extract 4. 78v from the transducer and that they could not get any more than 4. 56v



I see that after going over my old notes and redoing the voltage tests once again on the transducers output I had been using the min/max feature on my Vantage only because it made driving more safe. Using that feature I was able to record 4. 78v output equaling about 27,900 lbs which is what had got my attention in the first place to get a gauge set up.



Running the tests without min/max proved what you have been saying- that the transducer gets saturated. Seems my Vantage would catch 4. 78v fast enough before saturation. Now I really feel like dog doo! and have to apologize to everyone for all my hype.



I guess what the gauge will do is warn duration box users if pressures are getting too low at super wide pulse width settings, on the other end of the scale the numbers are not accurate enough for monitoring high pressures.

I had been assured from good sources including SPA the OE transducer would not just stop at 4. 5v and since I recorded 4. 78 I went with it.



This could have been a major let down for many so thanks again DLeno for pointing this stuff out. I really feel bad.

 

[SRadke]

Don't beat yourself up Matt. What is the max pressure you see when you're NOT running a pressure box? Something significntly inside the range of the sensor I assume? Why would I want a box that pushes my CP3 so hard it is significantly beyond the scope of the very sensor that is designed to control it? Tell me how high I can measure accuratly and that's the pressure I'll stay below. That's my opinion. I still want one.



-Scott

 

[Matt400]

What is the max pressure you see when you're NOT running a pressure box?

To be honest I never really tried to see how high I could get it. Tonight I didn't do any box off runs. I do remember 19,500 about a month ago testing with a temperature channel.

Why would I want a box that pushes my CP3 so hard it is significantly beyond the scope of the very sensor that is designed to control it?

Good point and reason to buy from a manufacture that will be up front about pressures.

Tell me how high I can measure accurately and that's the pressure I'll stay below. That's my opinion. I still want one.

Well I know they are ready to order anyway but I should confirm the high end readings with SPA. Originally I was just using my Vantage meter and referencing the transducer specs dan. poitras posted to compare with and get my pressures. Later on I set up a SPA temp channel per SPA’s instructions and called it good. Tonight I ran the Vantage right along side a SPA boost channel and they didn't zive even though the SPA was set just the way the engineers said to.

• 0 psi = . 50 voltage return (VDC)
  
• 5801 psi = 1. 39 volts
  
• 10153 psi = 2. 06 volts
  
• 14504 psi = 2. 72 volts
  
• 20305 psi = 3. 61 volts
  
• 26107 psi = 4. 50 volts
  

Box maxed out I saw a solid 4. 56v (not in min/max mode) at WOT above 3000 rpm on my Vantage, looked over at the SPA and it was at 23,80.



This was with the SPA's FCS set to 261 and SPn set to 4. 5v so I should have seen at least 26,10



Something is wrong with that and I have sent off another email to John in engineering.

Also it’s possible the above spec chart is not correct. Chapter 14 page 69 of my factory manual states fuel pressure can be delivered as high as 23,206 so I am wondering now about that chart. I am going to send a PM to dan. poitras and ask about where it came from, it could even be a mis-print but telling the gauge to read 26,10 @ 4. 5v. and only seeing 23,80 at a true 4. 56v is wrong for sure.



I might do some more testing on Sunday. .

 

[rbattelle]

Also it’s possible the above spec chart is not correct. Chapter 14 page 69 of my factory manual states fuel pressure can be delivered as high as 23,206 so I am wondering now about that chart.

Are you implying the chart is wrong because it goes up to 26k psi? Of course you'd want your sending unit to be able to read pressures above the maximum pump pressure.

I am going to send a PM to dan. poitras and ask about where it came from, it could even be a mis-print but telling the gauge to read 26,10 @ 4. 5v. and only seeing 23,80 at a true 4. 56v is wrong for sure.

That's very odd...



-Ryan

 

[Matt400]

Are you implying the chart is wrong because it goes up to 26k psi?

Not really, just reaching at the possibilities. From what I saw on Friday night it was more like an error in the gauges settings. The chart should be right. Max pressure listed in the manual is 23,206 which just happens to fall right in the middle of the last 2 figures @ 4. 06v.

I will take a look again at the SPA settings on Sunday and from here on out I will always run my Vantage side by side to verify.

 

[Matt400]

Using the temp channel I see 4. 3-5. 5 at idle, and a max of 21. 5 at WOT (without pressure box) Is this low for an HO??

You might try this- change the SPn setting to 4. 0, this corrects an error I made about using 4. 5v from the chart because the span across that chart is 4. 0v



* 0 psi = . 50 voltage return (VDC)

* 5801 psi = 1. 39 volts

* 10153 psi = 2. 06 volts

* 14504 psi = 2. 72 volts

* 20305 psi = 3. 61 volts

* 26107 psi = 4. 50 volts



Using a boost channel is better because you can increase the averaging which smooths out the readings. I changed it from 400ms to 1 sec and that made a big difference vs using a temp channel that can't be changed.



Later in the week I will put a sensor simulator to use on the SPA and see just how exact I can calibrate it to the above chart.

 

[KYLE4]

I did not read all 90+ posts but I know someone running the fuel pressure/ oil combo guage right now. He uses fuel pressure for the lift pump and oil pressure to monitor his rail pressure so if this doesn't happen you can always use the guage and maybe have a new faceplate made most decal shops can do it for around 10. 00 bucks that will be the only difference

 

[DLeno]

To be honest I never really tried to see how high I could get it. Tonight I didn't do any box off runs. I do remember 19,500 about a month ago testing with a temperature channel. Good point and reason to buy from a manufacture that will be up front about pressures. Well I know they are ready to order anyway but I should confirm the high end readings with SPA. Originally I was just using my Vantage meter and referencing the transducer specs dan. poitras posted to compare with and get my pressures. Later on I set up a SPA temp channel per SPA’s instructions and called it good. Tonight I ran the Vantage right along side a SPA boost channel and they didn't zive even though the SPA was set just the way the engineers said to.

• 0 psi = . 50 voltage return (VDC)
  
• 5801 psi = 1. 39 volts
  
• 10153 psi = 2. 06 volts
  
• 14504 psi = 2. 72 volts
  
• 20305 psi = 3. 61 volts
  
• 26107 psi = 4. 50 volts
  

Box maxed out I saw a solid 4. 56v (not in min/max mode) at WOT above 3000 rpm on my Vantage, looked over at the SPA and it was at 23,80.



This was with the SPA's FCS set to 261 and SPn set to 4. 5v so I should have seen at least 26,10



Something is wrong with that and I have sent off another email to John in engineering.

Also it’s possible the above spec chart is not correct. Chapter 14 page 69 of my factory manual states fuel pressure can be delivered as high as 23,206 so I am wondering now about that chart. I am going to send a PM to dan. poitras and ask about where it came from, it could even be a mis-print but telling the gauge to read 26,10 @ 4. 5v. and only seeing 23,80 at a true 4. 56v is wrong for sure.



I might do some more testing on Sunday. .

Matt, the chart is correct for 03-04 (555) engines at least. I got those same numbers direct from Cummins.



The numbers you describe (23,80 at 4. 56) sounds like the SPA is expecting a 0-4. 5v sensor. instead of a . 5 to 4. 5v sensor. in fact, without further info from you I'd say 23. 8 is just what I would expect with the following sources of errors adding to each other:



1. incorrect slope: the SPA "offset" is either not set to . 5v (you have not zeroed the gauge), or doing so still does not impliment the mathematical slope (span) you want. Better double check this with SPA. Do you read zero when the key is on but the truck is not running? If yes, and you have the span and full scale set correctly, then the gauge is not implimenting the correct slope. There's some interesting 9th grade linear algegra here -- Make sure you are clear with SPA as to the function you want. Reading my SPA manual I was not convinced that the SPA could actually be calibrated for the correct slope, but I didn't persue it further. John should be able to sort it all out.



2. ground loops causing a voltage difference between chassis ground and signal ground. On my truck, chassis ground is lower than signal ground, which means if you measure signal voltage with respect to chassis ground you will get higher readings.



BTW, that the sender is calibrated for pressures beyond what it expects to see is perfectly valid. I think the only you need to solve/understand here is that the SPA slope behavior is apparently not what you want. That, and the difference between chassis and signal ground. -Doug

 

[Matt400]

Thanks Doug,

I do see where and error was made in the SPn setting. It should be 4. 0v and not 4. 5

I will go back and correct that on my first post.

The Span on the chart between . 5v and 4. 5v is 4. 0v

The FSC should be set back to 261 so I will correct what I told Bhaner about using 271

 

[Matt400]

Numbers of interest

Today I used my sensor simulator rather than the truck to input voltage from the transducer chart. Doing this confirmed the SPA's output more accurately.

• 0 psi = . 50 voltage return (VDC) Gauge reading = 0 psi
  
• 5801 psi = 1. 39 volts - Gauge reading = 5. 80 psi
  
• 10153 psi = 2. 06 volts - Gauge reading = 10. 20 psi
  
• 14504 psi = 2. 72 volts - Gauge reading = 14. 50 psi
  
• 20305 psi = 3. 61 volts - Gauge reading = 20. 30 psi
  
• 26107 psi = 4. 50 volts - Gauge reading = 26. 10 psi
  

While I was at it I plotted a couple others-

23206 because that is the max listed in my 03 shop manual

26700 because that is the point the OE transducer gets saturated

• 4. 06 volts - Gauge reading = 23. 20 psi
  
• 4. 56 volts - Gauge reading = 26. 70 psi
  

So the SPA they set up for us will read up to 26,700 psi accurately and is only limited by the transducer's saturation point. I continued to raise voltage inputs to the gauge till it maxed out at 29,500 psi.