Fuel Rail High Pressure Sensor Upgrade

[SSinstaller]

Originally Posted by djuosnteisn I'm just gonna throw this out there, and maybe it's rubbish, but if the SB ground is different that the ECU's ground or even the sensor's ground, you can get different voltages (much like the crank pos sensor issue chris). But it certainly seems like the sensor reads quite a bit over 4.5V.. which is a good thing. I'd just like to verify it.

I'm sure all the SB's measurements are a bit skewed, but I doubt they're off by more that a few hundredths of a volt... It would cause some serious issues if it was much worse than that..

Honestly, I'm more concerned with finding out where the sensor pegs than the actual pressure it represents.. I just want to make sure that whatever RV I end up with is set right about where the sensor pegs..

Also, my SB and the Aux Box are grounded directly to the main ECM ground bundle.. I have not had the MIL for the crank position sensor since I moved it to the ECM gound...

[djuosnteisn]

Yup. But that doesn't mean other people's SB's are. So your logs are probably a bit more accurate than other's right now. A few hundredths would be quite a bit of pressure on this sensor, possibly the differences we're seeing between AP and sb.... but who knows.


I've been clicking that datahseet in OP for like an hour and it won't fucking load. I only had a chance to glimpse it at work and now i can't get it... grrrrr.

[NJSPEED3]

Originally Posted by SSinstaller I'm sure all the SB's measurements are a bit skewed, but I doubt they're off by more that a few hundredths of a volt... It would cause some serious issues if it was much worse than that.. Honestly, I'm more concerned with finding out where the sensor pegs than the actual pressure it represents.. I just want to make sure that whatever RV I end up with is set right about where the sensor pegs.. Also, my SB and the Aux Box are grounded directly to the main ECM ground bundle.. I have not had the MIL for the crank position sensor since I moved it to the ECM gound...

Any chance you can get me some pics of how you did this please?

[Lex]

Most sensors can "read" outside the specified ranges. However near the top and bottom of those ranges their linearity starts to suffer as does their accuracy and this is why the spec calls for a range as well as a particular resolution that is maintained over that range.

[06Speed6]

That is true Lex, if the data sheet spec is 4.7v, we should try to keep our working pressure under that mark. This is really going to be critical if we are pushing the pressure limits of the injectors.

[SSinstaller]

Originally Posted by NJSPEED3 Any chance you can get me some pics of how you did this please?

Here is the MS3 diagram.



Pins 1AZ 1BB 1BG 1BC 1BH are the ECM grounds.. All you need to do is trace them back into the harness until you get to the junction, and ground your SB there...

[bnoon]

Originally Posted by forcedinduktion anyone else feel stupid reading this ?

Yeah, this is one of those moments where I'm happy I'm not on the bleeding edge. I get the jist of it as they're trying to increase the resolution of the sensor within a set working voltage range. I'm an electronics/network engineer and some of it still sounds like the parents/teachers on a Peanuts cartoon. WAwa wah wah wa wa... Yes ma'am, I know ma'am...

[djuosnteisn]

Okay, so i can open the datasheet at work.

The sensor is a wheatstone bridge... basically 2 voltage dividers, one with a variable resistor that changes with pressure. The difference voltage (usually less than 20mV) is amplified through some op amp gain stages and conditioned a bit i bet. That's why there's a pull up resistor on the signal line.

The amplification stages (op amps) run off the supply voltage, 5V according to the datasheet. And their maximum output is dependent solely on the supply voltage. There are two main types of single supply op amps, one's that can swing to only the low rail (ground) and about 1 diode drop below the high rail (like 4.5V), and then there are some that can swing completely to both rails. IIRC the ones that need to be able to sink an appreciable amount of current (like this one if they're saying you can use up to 16V as a pull up on the open collector output) usually don't swing all the way to the high rail, but i could be wrong. I'd have to check my electronics book at home.

Usually they will just flat line at a certain level.


Marcus... is the over drive part of the datasheet your talking about in the technical data section? Where it says, " Max. overpressure = 180 bar"? Cause in my mind that means the max amount of pressure the sensor can see before it becomes damaged or un calibrated. The other pressure is "Rupture pressure = 300 bar", which i interpret as physical rupture of the device.


On the characteristic curve graph... it does show the dotted line to 4.8V, and translates to upper area for signal range... but i'm not sure if this is evidence enough to say it'll read that high.


I'd like to see some SB logs with some readings over 4.5 V.

Also, judging from the way the AP will just clip the reported pressure, makes me think there is a hard voltage limit to the out put of these sensors.



I think the easiest thing to do at this time is just pick up the higher reading sensor, and put our energy into correlating some voltages to pressures between the two.

I mechanical tester jig would still be very useful for this... *cough* scott *cough*.

[SSinstaller]

Wow.. Should have kept my mouth shut. I just got the crank position MIL for the first time in months...

I guess it's still better than seeing it every other day..

[djuosnteisn]

Hahahahahaha, shit... tempted the god's.

[SSinstaller]

Ok, Rob(the_caruch) just sent me his log that he took that 2274psi screen shot from...

The max FP sensor output he hits is 4.85v (SB says that's 2274psi-but we know it's not that high), so even if it's off by .05v we know the sensor is good to at least 2219psi..

Originally Posted by djuosnteisn Hahahahahaha, shit... tempted the god's.

Yep, and my appt to get my safety inspection is at 11:30 tomorrow morning...

I have enough time to clear it and complete the readiness monitors before then... Thankfully I can still pass in NC with the crazy EVAP monitor incomplete...

[Lex]

If anyone has a spare sensor taking it apart is not too tough. There is a pressure transducer in the tip (variable resistor essentially) and a potted PCB inside the casing.

In heavy duty applications all sensors must be able to take above battery voltage even if they are rated for 5V and not break. This is a safety and reliability requirement and I am not sure if the same one exists in passenger vehicles. It seems that it may be the case.

Edit: Here is what it likely looks like inside. The diamond like resistor setup is the wheatstone bridge.

Edit 2: Better diagram.

[Lex]

On the other hand, the effort is probably better spent at adapting a new sensor and translating the voltage/pressure curves correctly to the control system so it can make use of them.

[djuosnteisn]

Originally Posted by SSinstaller Ok, Rob(the_caruch) just sent me his log that he took that 2274psi screen shot from... The max FP sensor output he hits is 4.85v (SB says that's 2274psi-but we know it's not that high), so even if it's off by .05v we know the sensor is good to at least 2219psi..

Here's a screen shot from that log:






Looks good to me.

[Burn69]

Nice

[the_caruch]

Did you guys want me to turn up the fuel psi in my Standback tune even more? Attached is my fuel psi table. I can bump those to -20 to see what voltage i get if it helps anyone out.

[SSinstaller]

Originally Posted by the_caruch Did you guys want me to turn up the fuel psi in my Standback tune even more? Attached is my fuel psi table. I can bump those to -20 to see what voltage i get if it helps anyone out.

You could try, but I'd watch the realtime graphs very closely..

I wouldn't add more than 1% at at time.

If you ever see the pressure flatline, let off asap, and remove pressure until you can make a full pull without the pressure flat-lining...

I don't think you have much sensor range left, and once your adjustment pegs the sensor the FP will just keep climbing until the injectors quit firing or something breaks..

[the_caruch]

Originally Posted by SSinstaller You could try, but I'd watch the realtime graphs very closely.. I wouldn't add more than 1% at at time. If you ever see the pressure flatline, let off asap, and remove pressure until you can make a full pull without the pressure flat-lining... I don't think you have much sensor range left, and once your adjustment pegs the sensor the FP will just keep climbing until the injectors quit firing or something breaks..

Ok cool, i'll give this a try when i can and keep a close eye on my realtime graphs

[Erich]

Originally Posted by the_caruch Ok cool, i'll give this a try when i can and keep a close eye on my realtime graphs

Your car will probably let you know before the realtime graphs do (was the case for me) but a good idea to watch them none the less.

[djuosnteisn]

Any news on your front erich? Valve still working? What pressure are you running and have you done anything about a sensor?

[Erich]

Never found a solution I liked for logging an extra higher pressure sensor. Still looking, but not real confident in getting something together before the new motor goes in.

Valve still works, though I only see 2073 in my logs on throttle off now. Have it now so I am running consistently in 2020 to 2040 range with the AFR's where they should be.

[SSinstaller]

Originally Posted by Erich Never found a solution I liked for logging an extra higher pressure sensor. Still looking, but not real confident in getting something together before the new motor goes in. Valve still works, though I only see 2073 in my logs on throttle off now. Have it now so I am running consistently in 2020 to 2040 range with the AFR's where they should be.

Are you logging with the SB or the AP?

I should have a valve on the way with a ~2300psi crack pressure, so hopefully the SB will let us know the OEM sensors max Vout...

If we have enough range for the full 2300psi, I don't think we'll need an upgraded sensor... It may just be an ECM limitation for the AP, and I'm sure Cobb can get fixed if there is enough interest/need...

[Erich]

AP, so limited to the 2073 the ECU provides.

[seshomaru7]

Probably bringing up an old thread but just asking if anyone has upgraded the HPFP then the safety relief valve to up fuel pressure to maybe 1900-2000 without problems? It would seem like the upgrades of the fuel rail/line and injector seals wouldn't be necessary at that pressure and I would only like to be able to maintain these pressures at WOT, instead of upping the pressures even more.

[djuosnteisn]

seals would still be necessary... that's a function of cylinder pressure, not fuel rail pressure.


You can control where the higher pressures occur (at wot) with either of the popular tuning methods.

[superskaterxes]

just updating this thread with some relevant info.

i just purchased my sensor today from here

All European

Mercedes PN is in the OP or u can use the Bosch PN. make sure you tell them you saw it online to get the $122 price.


i ordered the harness from here. it was free because you can ask to view "samples" of the products.

www.te.com




i also found the connector for the stock harness so you can make this 100% PNP. now im not sure this is the right connector but it looks to be correct. ill update this post when i actually get it. (note the first 3 parts in the list are put together in a "kit" which is what the last item is.) UPDATE: THIS CONNECTOR WILL FIT THE STOCK HARNESS

[m4tic]

i feel like i stole something

[djuosnteisn]

Tyco is used to that feeling.

[SSinstaller]

Originally Posted by bmorrisj i feel like i stole something

I'm sure they're going to catch on when 50 people sign up and request a free sample of that one plug...

[rudydecc]

Originally Posted by SSinstaller I'm sure they're going to catch on when 50 people sign up and request a free sample of that one plug...

If you buy them its $3.91 worth of parts w/o shipping.

I like the quantities for the sites that you can buy from, they go by the 1000s. lol. yeah, I need 1 lol.

[Erich]

I ordered mine on official Vanderlay Industries business.

[superskaterxes]

Originally Posted by SSinstaller I'm sure they're going to catch on when 50 people sign up and request a free sample of that one plug...

glad i got mine haha.

btw they ask you for the project your using them for and application, ect.

i put upgraded bosch FP sensor testing haha



P.S. dont go order all this shit cause its free when we havent even tested the sensor yet!!!!

[SSinstaller]

Originally Posted by superskaterxes glad i got mine haha. btw they ask you for the project your using them for and application, ect. i put upgraded bosch FP sensor testing haha P.S. dont go order all this shit cause its free when we havent even tested the sensor yet!!!!

I'm taking a break form being the guinea pig, it's too expensive...lol

[06Speed6]

I bought the crimp tool for those connectors for another project, its like $140 lol. Making custom connectors gets expensive quick. I have like 4 of those crimp tools now.

@superskaterxes I spy 247 phail!

[superskaterxes]

Originally Posted by 06Speed6 I bought the crimp tool for those connectors for another project, its like $140 lol. Making custom connectors gets expensive quick. I have like 4 of those crimp tools now. @superskaterxes I spy 247 phail!

lol hey! its good for FS thread trolling. dustin picked up a rail, 4 injectors, RV, stock pressure sensor, and harness for 75 shipped haha

[06Speed6]

Yeah that was some phail too, he sent his pm like 10mins before I did =P

[djuosnteisn]

[Dano]

Originally Posted by Erich I ordered mine on official Vanderlay Industries business.

great job there Costanza

[Erich]

Originally Posted by Dano2010 great job there Costanza

Hey, that's T-Bone to you.

[phate]

I need more pressure

Subbed.