Jump to content
HybridZ
Sign in to follow this  
Timecode

High fuel pressure on boost

Recommended Posts

So data points from what I can see on the video:

 

30psi fuel pressure off boost

 

62psi fuel pressure at what I am guessing is 30+lbs of boost, tapering to 61 psi as boost tapers down to 30psi (hard to tell on the gauge)

 

The only thing that seems odd is that when you hit what looks like 34-35lbs of boost your fuel pressure gauge does not go all the way up to 64psi it stays at 62 psi. Suggesting maybe you are maxing out your fuel pump or as mentioned above you are dumping fuel. 

 

Have a duty cycle table we can look at?

 

The pressure seems correct for the level of boost you are running assuming you are running a RRFPR or a FPC.

 

Its a 1:1 FPR.  If I turn up the boost more, the fuel pressure goes up accordingly, 1 psi per pound of boost

Edited by Timecode

Share this post


Link to post
Share on other sites

I think I get it now.

 

At idle 30psi of fuel pressure

 

At 20lbs of boost 61psi of fuel pressure. 

 

You are basically making 10psi out of step with your boost.

 

Playing the video really slowly screen by screen I am seeing the fuel pressure spike to what looks like 40psi at around 0lbs of boost. Then rising in a linear fashion with boost more or less. 

 

RRFPR's aren't suppose to play an affect under non boost conditions, but it seems like yours is going up 10psi before you actually get into boost.

 

That makes what NewZed was saying earlier suspect, where are you getting your vacuum/boost source for the gauges/FPR?

 

 

 

Edit: Disregard I'm an idiot, but I'll leave it up here.

 

At idle you are in vacuum which helps suck the fuel in basically equating to the base pressure plus the vacuum so 40ish psi.

 

At all points it seems like your system is functioning correctly

 

At idle with vacuum -10-15psi of boost 30psi of fuel pressure, total pressure at injector face 40psi

 

Starting to build 0psi of boost, 40 psi of fuel pressure, total pressure at injector face 40psi

 

Boost built 20psi of boost, 60psi of fuel pressure, total pressure at injector face 40psi

 

So the FPR seems happy and the fuel pump seems happy and it seems like your lines are working in this instance.

 

I'm kind of back on board with my original though of injector sizing or an injector fault. What are your injector duty cycles?

 

Another thought would be the charging system. Do you have a voltage correction table? Does your voltage in your system change at all while you drive? If you do have a mis calculated voltage correction table you could be compensating additionally which may cause the system to inject more fuel into the system.

 

Lastly was this car tuned? Since it seems your fuel system is functioning and if it isn't a fault then logic dictates that fuel should be pulled from the system.

Edited by seattlejester

Share this post


Link to post
Share on other sites

Video clarifies a lot of things.  FPR seems to be working fine. No over pressure that I can see. 22 lbs boost and 62 lbs FP. Perfect. Turbo spools quickly and FP keeps right up with it. 

 

Fuel Pressure at idle with Vacuum hose disconnected is 40 PSI correct? Add 22 lbs boost and FP should be 62 lbs. which is what we are seeing. 

 

Not seeing 27 lbs of boost in this video. Boost to FP correlation seems correct,

 

1: How tunable is the JWT ECU? Can you plug in, data log and tune with a Laptop or programming pad? I'd be looking at injector duty cycle closely. I'm not familiar with this ECU. If you can't program it with a Laptop or Pad, then you need a better ECU for a modification of this level.  

 

Edit: Found some info on the JWT 550 kit and reading . Looks like no data logging and no real time programming. In other words, 1990's technology. Not good.  IMHO, get a better ECU. If budget can afford it Haltech , AEM, MicroTech are all very good. If you're on a budget, go Megasquirt. Lots of good technology available these days. You sometimes find a good deal on used HalTechs on E-Bay. The Honda crowd are always updating to the latest and greatest systems. 

 

Most systems these days have " AutoTune" where you set the AFR required and system will self tune to that level. 

 

PS: Love how you've integrated the gauges. What pod did you use on the lower right side. 

Edited by Chickenman

Share this post


Link to post
Share on other sites

Just my 2cent. I have the same kit except mine is tuned for 420cc injectors. Now I have sunk ring lands on a forged pistons, but they were 10 years old and I had other issues. The JWT set is untunable the only thing you can do is adjust the Fuel pressure regulator. Thats is an impressive amount of boost I think you are pushing your set up . I assume you are logging through your boost controller ? perhaps look at duty cycle and make adjustments there? If your set up is like mine you are using a relay and not the ECU to control the fuel pump. I am interested to know more about your set up . what kind of pistons? head work ? how much boost /HP ?

Share this post


Link to post
Share on other sites

Video clarifies a lot of things.  FPR seems to be working fine. No over pressure that I can see. 22 lbs boost and 62 lbs FP. Perfect. Turbo spools quickly and FP keeps right up with it. 

 

Fuel Pressure at idle with Vacuum hose disconnected is 40 PSI correct? Add 22 lbs boost and FP should be 62 lbs. which is what we are seeing. 

 

Not seeing 27 lbs of boost in this video. Boost to FP correlation seems correct,

 

1: How tunable is the JWT ECU? Can you plug in, data log and tune with a Laptop or programming pad? I'd be looking at injector duty cycle closely. I'm not familiar with this ECU. If you can't program it with a Laptop or Pad, then you need a better ECU for a modification of this level.  

 

Edit: Found some info on the JWT 550 kit and reading . Looks like no data logging and no real time programming. In other words, 1990's technology. Not good.  IMHO, get a better ECU. If budget can afford it Haltech , AEM, MicroTech are all very good. If you're on a budget, go Megasquirt. Lots of good technology available these days. You sometimes find a good deal on used HalTechs on E-Bay. The Honda crowd are always updating to the latest and greatest systems. 

 

Most systems these days have " AutoTune" where you set the AFR required and system will self tune to that level. 

 

PS: Love how you've integrated the gauges. What pod did you use on the lower right side. 

Not looking to go standalone as of now.  The JWT tune runs so strong, its hard to justify right now.  The gauges are from Depo Racing, they come with the pod.  Good company that backs up their products.

Share this post


Link to post
Share on other sites

Not looking to go standalone as of now.  The JWT tune runs so strong, its hard to justify right now.  The gauges are from Depo Racing, they come with the pod.  Good company that backs up their products.

 

Seems like your best option might be to just stop looking at the AFR gauge.  You're tuning to an LED.

Share this post


Link to post
Share on other sites

The video is kinda old.  I have been slowly raising the boost to find the point of detention, I haven't found it yet, at least with race gas.  My point was that it still feed adequate fuel at that boost level.  It is scary fast at 27 psi, power unknown.  From third gear and up it pulled hard on a new ZO6. My GPS speedo clocked a 10.9 1/4, that was at 25 psi I think. I have turned it down to 23 psi because thats fast enough. The turbo is kinda small, T3/T04b turbocharger with a T04B compressor housing and V trim compressor wheel.  Ceramic ball bearing unit with a 57mm turbine wheel. The turbine housing is a .63 a/r. Water cooled as well. It's not that much psi for that size turbo. 

Share this post


Link to post
Share on other sites

You said it runs great, doesn't smoke, no real problems except an AFR number (the LED's on the gauge - my joke) that makes you uncomfortable.  But it's uncomfortable on the safe, rich, side.  I didn't go through your math, but at least two people did and said that there's no great mismatch between fuel pressure and boost pressure.  The numbers are right.  Basically, it looks like you don't really have a problem to fix.  And the only solution to fine-tuning your AFR's is to get a tuneable engine management system.

 

There's nothing that can be done here.  Stop looking at the AFR gauge and enjoy the car.  Or get a tuneable system.  That's all I'm saying.

Share this post


Link to post
Share on other sites

You said it runs great, doesn't smoke, no real problems except an AFR number (the LED's on the gauge - my joke) that makes you uncomfortable.  But it's uncomfortable on the safe, rich, side.  I didn't go through your math, but at least two people did and said that there's no great mismatch between fuel pressure and boost pressure.  The numbers are right.  Basically, it looks like you don't really have a problem to fix.  And the only solution to fine-tuning your AFR's is to get a tuneable engine management system.

 

There's nothing that can be done here.  Stop looking at the AFR gauge and enjoy the car.  Or get a tuneable system.  That's all I'm saying.

 

It definitely is better than lean and is why I still drive it.  In most of my experiences the issues I have are usually my fault.  Ben at JWT says it should be around 11.5-12 AFR on boost.  I still have an issue, at 8 psi you will see fuel pressure ramp up too much. Look at 20 psi, fuel should be at 56 psi but its at 61.  That's not correct.

 

Most of the electrical systems have all been replaced/upgraded with new wires, relays, and a 70 amp alt.

 

My setup: 83 auto F54 block, fresh stock p90 head, ARP bolts, unknown forged dished pistons, stock rods and crank, 2mm MLS head gasket, 7.4 cr, ported-polished-port matched intake manifold and exhaust manifolds, 2X Moroso oil separators, 240sx throttle body, Nismo 555cc injectors, Turbonetics TO4B, internal wastage hole enlarged, widemouth downpipe to V band stainless 3" with a Borla XR1 muffler, , Synapse BOV recirculating, Ford lightning MAF with my own custom intake with 6"velocity stack and 7" Amsoil air filter, Godspeed intercooler, Griffin super thick 2 core radiator, my own custom charge pipes, Setrab 25 row oil cooler with Misimoto thermostat and AN stainless lines, Aeromotive 1:1 FPR, 240x fuel filter, nissan 71c trans, larger than stock Spec clutch, alum flywheel, aluminum driveshaft, z31 CLSD 3.7 with cv's.  

 

There's more but my fingers are hurting.

Edited by Timecode

Share this post


Link to post
Share on other sites

I suggest reviewing the suggestions in this thread, addressing the potential causes, refocusing, and providing better information.  You got a bunch of ideas from your video but now you're saying the video is old.  All those people who watched the old video, wrote some numbers down,and did some math for you.  Are they going to do it again?  Who knows.

 

Here's another possibility for you - tiny, or clogged boost hoses.  Bad boost data.  Or a bad boost gauge.  I didn't watch the video (and won't now, because it's old) but if you're just shooting up in to boost zone and then back down, maybe there's a delay at your gauge.  Several people are questioning your numbers, you should verify that you're getting good data.  The fact that your pressure gauge company backs their products doesn't mean that they don't break.  Just means they'll fix them when they do.

 

Much of what your dealing with depends on good information.  You have a lot of sketchy numbers here.  Since the engine is safe, you can spend time making sure you have good data.  Millions, maybe billions, of hours have been wasted by people working with bad data.

Share this post


Link to post
Share on other sites

That makes so much more sense now. You are tuning via FPR...

 

Also the reason why you can't supply duty cycle numbers voltage correction etc. You don't have access to them.

 

Where is your boost reference to the boost gauge and to the FPR from, are they from the same spot?

 

Have you checked the oil? If the excess fuel isn't coming out of the exhaust via black smoke then it is being washed down into the oil. 

 

If you aren't going to switch to a tunable ECU which I think nistune would be the easiest and if AFR bothers you, turn up the boost. Granted if the ECU has  a boost scalar then you are never going to get ahead of it. Keep in mind if this is for a Z31 then it is for a different motor the VG30 which is going to have a different efficiency not to mention different displacement off the bat.

 

It really isn't running strong. Most turbo cars make the most power from 11.5-12.5AFR so you are definitely in the rich camp and probably leaving power on the table. You could actually be hurting the motor with that "tune" by washing the cylinders of lubricating oil and diluting your oil supply, I hope you change the oil often. 

Share this post


Link to post
Share on other sites

I agree with ZH. I wonder if you're chasing ghosts. Car seems to run strong??   You see no black smoke from tail pipe. Could be an instrumentation error. 

 

I've had O2 sensor get contaminated and give false readings before. It doesn't take much. Silicone used in the wrong place, leaded fuel ( race track fuel or Aviation Gas ) of course, over heating of WB sensor ( this is often over looked on Turbo cars ) will all cause inaccurate readings and drive you nuts. 

 

If it's really that rich (9.5 to 10 ) the plugs should show it. Pull the plugs and take a picture with a good quality camera. No flash. Flash will skew the colors. 

 

Have you ever done a WOT plug cut with fresh plugs? That will tell you what's really happening in the engine. 

 

For the gauges. I'm only seeing a Lambda gauge. ( Top dash panel left gauge ). Can't tell what the minimal reading is... but it looks like 1.0. Is that correct? As for the FP gauge, that is the left hand digital gauge in the passenger  foot-well correct?  

Edited by Chickenman

Share this post


Link to post
Share on other sites

I agree with ZH. I wonder if you're chasing ghosts. Car seems to run strong??   You see no black smoke from tail pipe. Could be an instrumentation error. 

 

I've had O2 sensor get contaminated and give false readings before. It doesn't take much. Silicone used in the wrong place, leaded fuel ( race track fuel or Aviation Gas ) of course, over heating of WB sensor ( this is often over looked on Turbo cars ) will all cause inaccurate readings and drive you nuts. 

 

If it's really that rich (9.5 to 10 ) the plugs should show it. Pull the plugs and take a picture with a good quality camera. No flash. Flash will skew the colors. 

 

Have you ever done a WOT plug cut with fresh plugs? That will tell you what's really happening in the engine. 

 

For the gauges. I'm only seeing a Lambda gauge. ( Top dash panel left gauge ). Can't tell what the minimal reading is... but it looks like 1.0. Is that correct? As for the FP gauge, that is the left hand digital gauge in the passenger  foot-well correct?  

Its see's nothing but race gas and I'm sure I heat it up the sensor plenty.  All plugs look the same, semi dark brown.  I'll find a pic. I want to do the WOT plug cut as I hear this is the only true way of determining how the burn is. 

 

All the gauge info you said is correct, min is 10 AFR.

Share this post


Link to post
Share on other sites

That makes so much more sense now. You are tuning via FPR...

 

Also the reason why you can't supply duty cycle numbers voltage correction etc. You don't have access to them.

 

Where is your boost reference to the boost gauge and to the FPR from, are they from the same spot?

 

Have you checked the oil? If the excess fuel isn't coming out of the exhaust via black smoke then it is being washed down into the oil. 

 

If you aren't going to switch to a tunable ECU which I think nistune would be the easiest and if AFR bothers you, turn up the boost. Granted if the ECU has  a boost scalar then you are never going to get ahead of it. Keep in mind if this is for a Z31 then it is for a different motor the VG30 which is going to have a different efficiency not to mention different displacement off the bat.

 

It really isn't running strong. Most turbo cars make the most power from 11.5-12.5AFR so you are definitely in the rich camp and probably leaving power on the table. You could actually be hurting the motor with that "tune" by washing the cylinders of lubricating oil and diluting your oil supply, I hope you change the oil often. 

 

Of course it could run even stronger, but right now it scoots, I just want to lean out the tune which, hopefully will be done by fixing all known issues first.  I'm on fuel delivery right now hence this whole thread. I don't want to blame JWT for a bad tune until I know all is well on my end.  I sure hope my gauge readings are correct or this is going to be a pain.  I did happen to replace the fuel pressure sensor and it is reading the same as the old unit. Precision Z verified my Wideband/gauge matches there test equipment so.....

You guys rock by the way, I've been so busy lately I needed an army to help me with this.

Edited by Timecode

Share this post


Link to post
Share on other sites

Obvious question, but is the Race Gas Lead free? If not O2 sensor is likely contaminated. What race gas is it. Is it E85 by chance? 

 

How close is the O2 sensor to the Turbo? You may need a Heat Sink for it. WB sensors are more sensitive to excess heat than NB sensors. I'll try and find a link.

 

Another question, and we need this one answered please. What was the exact pressure that the FPR was set to at idle and was the vaccuum reference line to the FPR disconnected or connected when you set the Fuel pressure? 

 

Curious. If you have a Lambda gauge and the minimum reading is 1.0. That equals 14.7 AFR with Gasoline. So how are you measuring any numbers less than that?

 

 

For the gauges. I'm only seeing a Lambda gauge. ( Top dash panel left gauge ). Can't tell what the minimal reading is... but it looks like 1.0. Is that correct? As for the FP gauge, that is the left hand digital gauge in the passenger  foot-well correct?  

 

 

All the gauge info you said is correct, min is 10 AFR.

 

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Sign in to follow this  

×
×
  • Create New...