kinser86

78 280z Severe Driving Problems

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    Alright, I got the some parts off the car and brought them home. I evaluated the gauge first before I do anything else. I had 100PSI on the compressor supplying the line. I swept it to 80-PSI before the video and also did a couple of these sweeps before recording. 

     

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    Update time. I had taken the injectors back to Fuel Injection Specialties and they agreed that two were flowing irregularly. They cleaned them again and got them back to flowing where they should have been. The discrepancy occurred because the cleaning solvent dried in the two injectors and clogged them back up. I took them back and did the same out of car test and got all of them to match volumes.

    scaled_results.jpg

    plot3.png

    After this, I put the rail back on the car and put in new plugs on every cylinder. At this point I felt the fuel pump was too much for the car and we pulled it and replaced it with a Delphi stock replacement. We hooked everything up, set the timing again, and tried to drive it again.

    From the video, the car is driving much better now. The resister between the coolant temperature sensor is turned all the way back as if it was never installed right now. With the stock pump replacement, the fuel pressure still seems a little high but not as high as with the previous pump. I pulled the plugs after we drove it around for a bit and took some pictures.

    new_plugs.png

    I need to put the AFM cover back on and clean up some of the engine bay before really driving it. Any thoughts on fuel pressure/vacuum reading?

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    26 minutes ago, kinser86 said:

    Any thoughts on fuel pressure/vacuum reading?

    Sounds pretty good.  Nice that the the fuel Injection guys owned up and fixed the injector problem.  Although, you'd think they would know better.

    I see 32 psi on the fuel gauge, and 20 inches of mercury on the vacuum gauge.  That calculates to about 42 psi fuel pressure with no vacuum.  I think that you can borrow a gauge from the local auto parts store, for a cross-check.  They require a deposit but give it back afterward.  Looks like you're still working with a gauge of unknown quality.

    Good luck.  Carry on.

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    sounds like its back firing? for the record my stock setup never backfires. Not sure what causes that, but was under the assumption that FI cars should not. I tried to find out by mr google, some said its a lean mix not igniting until got into the exhaust, some said its a rich mix not completely burning until the exhaust, others claimed all cars backfire unless they are de tuned, and a LOT of votes for it sounds cool. I remember it sounding cool when I would shut off the ignition with the key, wait a few seconds, then turn back on for a nice BOOM. real cool until I blew up my parents muffler, then not so cool. I am old now and prefer to not hear loud exhaust, at least not for extended trips. One last opinion was its the nature of the type of exhaust. I love google...

    Edited by Dave WM

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    2 hours ago, Dave WM said:

    sounds like its back firing? for the record my stock setup never backfires. Not sure what causes that, but was under the assumption that FI cars should not. I tried to find out by mr google, some said its a lean mix not igniting until got into the exhaust, some said its a rich mix not completely burning until the exhaust, others claimed all cars backfire unless they are de tuned, and a LOT of votes for it sounds cool. I remember it sounding cool when I would shut off the ignition with the key, wait a few seconds, then turn back on for a nice BOOM. real cool until I blew up my parents muffler, then not so cool. I am old now and prefer to not hear loud exhaust, at least not for extended trips. One last opinion was its the nature of the type of exhaust. I love google...

    I believe that may be the exhaust he is running

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    On 9/30/2018 at 8:06 AM, Dave WM said:

    sounds like its back firing? for the record my stock setup never backfires. Not sure what causes that, but was under the assumption that FI cars should not. I tried to find out by mr google, some said its a lean mix not igniting until got into the exhaust, some said its a rich mix not completely burning until the exhaust, others claimed all cars backfire unless they are de tuned, and a LOT of votes for it sounds cool. I remember it sounding cool when I would shut off the ignition with the key, wait a few seconds, then turn back on for a nice BOOM. real cool until I blew up my parents muffler, then not so cool. I am old now and prefer to not hear loud exhaust, at least not for extended trips. One last opinion was its the nature of the type of exhaust. I love google...

    I think it might be the exhaust you hear. It does have a header and exhaust system. One way to check would be to let it engine brake and see if it makes any noticeable sounds but again it might be the exhaust. 

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    So what's the bottom line? It sounds much better. Are you calling this a success now?

    The thread was about severe driving problems. Are you claiming victory? That would be sweet!

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    9 hours ago, Captain Obvious said:

    So what's the bottom line? It sounds much better. Are you calling this a success now?

    The thread was about severe driving problems. Are you claiming victory? That would be sweet!

    I still need to check if the fuel pressure is high or not. The gauge seemed to do fine with the compressed air sweep but still seems to read high on the car even with 20inHg at idle. If it truly is high, then I am not done yet 😞. I have blown through the fuel rail and hard lines on the chassis with compressed air at about 120PSI with a clean towel covering the outlets and did not observe any particulates. I need to try a different gauge and see if I get the same results.

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    I bought a differential pressure gauge. Hook one side to the fuel rail. Hook the other side to the intake manifold.

    My fuel pressure "seemed" like it was all over the place, but when measured differentially (as you really should), it was rock steady at 36psi even when you goosed the throttle. It's really deceptive when just measuring one side.

    So why doesn't everyone do that? Because they're expensive and delicate. I got lucky and found one on ebay for cheap. I'll post a pic when I get a chance.

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    Interesting. My setup will have a pressure gauge on the entrance to the fuel rail, and another at the FPR return. That should give me the same setup basically. Pressure before and after the rail.

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    Here's the theory for the differential pressure gauge I have. It's essentially just a piston (which also happens to be a magnet) sliding back and forth in a tube. That magnetic piston is coupled to the gauge needle so there is no process fluids (whatever you are measuring) in the meter movement area.

    Operates like this:
    orgauge1.jpg

    And this is hooked up to the car. Too big to leave in there all the time, but it's fantastic for diagnostic purposes. One side pushes while the other side pulls. The pressure reading would go down if you disconnect the vacuum side because that side isn't pulling:
    setup.JPG

     

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    11 hours ago, Captain Obvious said:

    Here's the theory for the differential pressure gauge I have. It's essentially just a piston (which also happens to be a magnet) sliding back and forth in a tube. That magnetic piston is coupled to the gauge needle so there is no process fluids (whatever you are measuring) in the meter movement area.

    Very interesting. There are some Ashcroft differential pressure gauges on eBay currently for a decent price. 0-60 PSI with a max pressure of 3,000PSI and 1/4"NPT(F). Something like this should work in this application correct? If so then it would be worth a purchase to have in the toolbox.

    s-l500.jpg

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    11 hours ago, wheee! said:

    Interesting. My setup will have a pressure gauge on the entrance to the fuel rail, and another at the FPR return. That should give me the same setup basically. Pressure before and after the rail.

    Actually this is not quite the same.  You need to compare pressure inside the rail to "pressure" inside the manifold.  The big confuser for the fuel pressure regulator operation is that they/we use vacuum for the measurement on one side and pressure for the other side.  Convert vacuum to pressure and do some math and you can see what's happening.  That's what I did in post #103.  But I have to go search around for proper values every time this topic comes up.

    CO's cool tool is a direct reading of what's happening.  But a calculator and two gauges will get you there too.

    Kinser you almost seem more interested in the measurement and diagnosis than actually driving the car.  You will do well here...

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    I didn't dig into the specs of that Ashcroft differential gauge, but the biggest thing you would have to watch for is something compatible with gasoline. The Orange Research gauge I have is all metal body and piston and has Teflon seals. It also magnetically couples the internal piston to the meter movement so the gas never gets to the needle. It's completely segregated.

    I don't know anything about the Ashcroft, but if it can handle the gasoline, then it should work fine.

    I don't remember what I spent on mine, but its very convenient having it at my disposal. No math. No units conversions. Direct reading.

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    40 minutes ago, Zed Head said:

    Kinser you almost seem more interested in the measurement and diagnosis than actually driving the car.  You will do well here...

    I think so too Zed. I plan my methods during the week and attack during the weekend. My hope is that any unfortunate individual who has to go through what I am/did with this car can reference this at some point and use the numbers to make the right decision rather than throwing money/time where it shouldn't go.

    4 minutes ago, Captain Obvious said:

    I didn't dig into the specs of that Ashcroft differential gauge, but the biggest thing you would have to watch for is something compatible with gasoline. The Orange Research gauge I have is all metal body and piston and has Teflon seals. It also magnetically couples the internal piston to the meter movement so the gas never gets to the needle. It's completely segregated.

    I don't know anything about the Ashcroft, but if it can handle the gasoline, then it should work fine.

    I don't remember what I spent on mine, but its very convenient having it at my disposal. No math. No units conversions. Direct reading.

    Fortunately Ashcroft has very good documentation on their website. The item currently on eBay is:

    Model: 25-1130FL-25S-XV2-60#

    25: Size (2.5")

    1130: Series

    F: Body Material (Aluminum) (The stainless bodies have a higher max pressure rating of 6,000-PSI)

    L: Case Fill (Glycerin Fill)

    25: Process Connection Size (1/4" NPT Female)

    S: Process Connection Location (In line)

    XV2: Options (1-SPST switch with terminal strip)

    60#: Range (60 PSI)

    More importantly, the o-rings are Buna-N so gasoline should not be a problem. For the cost it is worth a shot.

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    Well for twenty-five bucks, it's certainly worth a shot. If it works as well as mine, it'll answer any questions about the real pressure that the injectors actually see. I took a quick look at Ashcroft's website and I couldn't find a diagram that explained the basic theory of operation for the internals. I did see some mention of magnet(s), so I assume it's the same magnetically coupled meter movement concept as the one I have, but I couldn't 100% determine.

    11 hours ago, kinser86 said:

    My hope is that any unfortunate individual who has to go through what I am/did with this car can reference this at some point and use the numbers to make the right decision rather than throwing money/time where it shouldn't go.

    This whole thing sounds like a typical 280Z story to me.   LOL   Most of us have been through it. So far, you made a simple mistake and screwed up your ignition timing and vacuum hose routing, Your PO put in a fuel pump that was incompatible with the stock pressure regulator. And you paid for an injector cleaning that had to be done twice because the first time didn't work out as intended. Nothing unusual so far.

    Admiral goal to keep that sort of stuff from happening to anyone else, but I wonder if you're trying to prevent the un-preventable.  :beer:

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    Here is a snapshot of the mechanics of the gauge:

    image.png

    image.png

    Gauge Mechanics

    Gauge Datasheet

    I ordered the one from eBay and it is on it's way. I will post videos of course of it in action. For the time being, we are going to clean up some of the car and drive it some more and I will keep an eye on the plugs.

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    On 10/4/2018 at 7:16 AM, Captain Obvious said:

    Your PO put in a fuel pump that was incompatible with the stock pressure regulator.

    Actually, the pressure readings are the same before and after the pump change.  42 psi.  Hence the thought that there's a bad gauge somewhere.  It's been the same gauge reading fuel pressure from the beginning.

    The parts stores will loan a fuel pressure gauge, among other things.  I don't know why I don't take more advantage, they have quite a selection.

    https://www.oreillyauto.com/rental-tools

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    53 minutes ago, Zed Head said:

    Actually, the pressure readings are the same before and after the pump change.  42 psi.  Hence the thought that there's a bad gauge somewhere.  It's been the same gauge reading fuel pressure from the beginning.

    Oh.  I was going from the text above when the OP said "At this point I felt the fuel pump was too much for the car and we pulled it and replaced it with a Delphi stock replacement." and "With the stock pump replacement, the fuel pressure still seems a little high but not as high as with the previous pump."

    I didn't have time to sit and wait for all the videos to load and run calculations on multiple gauges and stuff. I was just going off the text and assumed there was a reduction in fuel pressure with the stock style pump.

    Edited by Captain Obvious

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    kinser, Thanks for the gauge details. I had found the datasheet, but didn't see that gauge mechanics document.

    It looks identical in theory of operation to the one I have. If it works as well as mine, you're gonna love it.

    So it sounds like the car is running well enough to drive it now? That's a great improvement from when you started!   :beer:  Your next task... Clean some electrical connections and double/triple check for vacuum leaks. It's likely you have several small leaks throughout the system.

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    17 minutes ago, Captain Obvious said:

    Oh.  I was going from the text above when the OP said "At this point I felt the fuel pump was too much for the car and we pulled it and replaced it with a Delphi stock replacement." and "With the stock pump replacement, the fuel pressure still seems a little high but not as high as with the previous pump."

    Kinser86 seems a bit like a fresh engineer itching to use new knowledge to solve problems as fast as possible.  Very detailed work but he has skipped the basics of calibration and verification.  

    No offense kinser.  Everybody jumps ahead to what "must be" occasionally only to find that what must be, wasn't.  Some people spend much time and money doing that.

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    On 10/4/2018 at 9:16 AM, Captain Obvious said:

    And you paid for an injector cleaning that had to be done twice because the first time didn't work out as intended.

    Just for future reference, Fuel Injection Specialties did not charge me the second time and were extremely diligent and supportive of my concerns towards correcting them. I don't want people to be discouraged from using them nor do I want to tarnish their name. In the end, I got the injectors flowing evenly. It could have been my fault letting the injectors sit to long before reinstalling them.

    11 hours ago, Zed Head said:

    Kinser86 seems a bit like a fresh engineer itching to use new knowledge to solve problems as fast as possible.  Very detailed work but he has skipped the basics of calibration and verification.  

    No offense kinser.  Everybody jumps ahead to what "must be" occasionally only to find that what must be, wasn't.  Some people spend much time and money doing that.

    None taken. Quality and cost go hand in hand which is why I keep opting to spend money on better testing equipment rather than throwing it at the car. Like you mentioned, I am more interested in the measuring than driving the actual car 😁. There doesn't seem to be any higher quality 1/4" NPT fuel pressure gauges readily out there. I am keeping my fingers crossed that the ΔP gauge will read better. Who knows, maybe the OTC vacuum gauge is incorrect and I don't really have 20inHg and I do have a vacuum leak somewhere which is why my fuel gauge is reading what it is. Time will tell, just have to wait for the gauge to come in.

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    16 minutes ago, kinser86 said:

    maybe the OTC vacuum gauge is incorrect and I don't really have 20inHg and I do have a vacuum leak somewhere

    This is what I have thought about a couple of times. I've never seen a stock L engine run at 20inHg. Not that it isn't possible? IDK. I just haven't seen it myself. But I have thought you should check it with a different gauge just to eliminate it.

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    Well I've kinda lost the pea on where the vacuum measurements are being taken at this point, but I've easily seen 20inHG when measuring on the port vacuum source at the throttle body. You get the throttle plate in the right position and that vacuum really spikes. Depending on how it's running and if you need the throttle open far enough just to keep it running...

    Interestingly enough, I don't remember if I ever measured a non-ported source on the main intake manifold log on my car. Not sure I ever needed to.

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