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kinser86

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About kinser86

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    San Antonio, TX
  • Occupation
    Mechanical Engineer

My Z Cars

  • Zcars Owned
    280z
  • About My Cars
    1978 280z CA Car

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  1. kinser86

    78 280z Severe Driving Problems

    I have been weighing some options here.. going back and forth between switching rails to a Pallnet style with an adjustable FPR or sticking stock. Right now a replacement fuel pressure regulator (Bosch 64018), is available from rockauto and Amazon Prime (believe it or not). If I can't overcome the fuel pressure, then a lower flowing pump would be in order, yanking out the walbro 255 to something less. This would only leave me with the injectors as the variable in the fuel world. Rockauto has a few injectors available, but I would not go re-manufactured if I'm trying to eliminate some variables of 'what ifs'. Granted I intend on running the same test as before prior to installing the rail. That will provide a degree of confidence. We have found some good symptoms with the high fuel pressure, unbalanced injectors, and vacuum advance routing. But what if after this next round of parts, the car is still rough. Is it then time to look for an ECU/AFM pair and try then? I'm trying to find the smoking gun between the lines, again going in circles as I do. Thoughts?
  2. kinser86

    78 280z Severe Driving Problems

    Thanks! Just let me know. I have been thinking if I am going to replace the FPR, that I should go with a Pallnet rail with an adjustable FPR. This was going to be a modification down the road but given the circumstances and cost associated with a stock replacement, the Pallnet rail would be closer. I would still use the factory barb style injectors. Just a thought.
  3. kinser86

    78 280z Severe Driving Problems

    I hope others can learn from this too. 👍 The statement in bold summarizes how I approached everything with respect to this car. 😂😂 Regarding the fuel pressure, really the only solution here is to replace the regulator on the rail or change the fuel pump back from the walbro. Considering they are about the same price, I would go with a regulator first to see if that helps. The injectors were at 2.4Ω and 2.3Ω, so they were definitely not 16Ω. Sorry those were not included originally, I need to update that data sheet. We had the injectors serviced with Fuel Injection Specialties and the nozzles were replaced as part of the service(they used to not be black tipped). That may explain the mist/vapor appearance versus the stream appearance. I would definitely be interested in a set of injectors that have a known past. PM will be on it's way shortly! Thanks for the input everyone, this is a journey 🙂
  4. kinser86

    78 280z Severe Driving Problems

    Alright here are the results. I had to assume 188cc/min at 12VDC so a 30 second flow should yield 94mL. We ran a couple of test, not much deviation between then data groups. The second video shows what the PSI at the rail was during the test as well as the quality of the return from the rail. I even mention it in the first video. The gas is not bad, it has some 102 octane in the tank, that is why it is orange.
  5. kinser86

    78 280z Severe Driving Problems

    We were able to perform the test tonight. I am going through the videos/data to do a formal post, I haven't given up yet.👍
  6. kinser86

    78 280z Severe Driving Problems

    Thanks for the clarification👍. I have an extra set of injector connectors I will put together in series for the volumetric test out of the vehicle. The parallel circuit was an example outside of the car (excluding the dropping resistor) but you are correct, about 1.7A in the vehicle with the dropping resistor.
  7. kinser86

    78 280z Severe Driving Problems

    For clarification purposes, when you say you wired the injectors in series, you literally meant in series? If yes, then this yields 833mA at each injector. Wired in parallel yields 5A at each injector. 😱 I don't want to let the smoke out, then they won't work anymore..... 😊
  8. kinser86

    78 280z Severe Driving Problems

    I performed a test swapping connectors during idle but I have not tried swapping injectors and starting the car again to see if it followed the injector or stayed at the cylinder. I am going to measure the volume of the injectors as Zed Head recommended and go from there.
  9. kinser86

    78 280z Severe Driving Problems

    Did you run the supply voltage through the dropping resistor? I was thinking of 80% duty with the mosfet. This will help keep the injectors cool and I could run them for a fixed time. I could be over thinking the test stand but I have always been advised to not run full 12VDC through the injector. I think this will be a better test. I was unsure if the test I performed would work as intended but I can run the pump like you said and manually pull vacuum again and see if it reacts the same. I will pull the oil pressure wire and run the pump that way.
  10. kinser86

    78 280z Severe Driving Problems

    Thinking of a way to do this using an n channel mosfet and arduino. When the pump is running, I have seen above 40PSI without the engine running. I saw it today when I would prime the rail before injector testing. Once the fuel pump shut off, it would drop below 40. I don't remember if its 38 or 36, I would have to capture that. All injector seals were replaced within the past few weeks when I put the injectors back in the car. I have tested vacuum leaks with carb cleaner but was unable to find any leaks. I have not tried using propane. I think I will create a test setup using a n-channel mosfet and an arduino to run the injectors at a reduced duty cycle rather than getting the wiring in the car involved. I don't have a spark tester but that is a good idea. I can do those test but I think first I will pull the rail completely and do some bench flow test. When spraying the injectors, the fuel pressure gauge would sweep to 0 when spraying. That doesn't mean it can't get stuck though. Fuel Pressure gauge of vacuum gauge? I don't smell or see fuel in the line connected to the FPR but I wouldn't rule out a stiff/rigid diaphragm. The vacuum advance diaphragm was cracked and damaged a while back which warranted a replacement distributor. There has been a lot of good comments. As everyone mentioned, I need to measure volumes. I will develop a simple test circuit using an arduino and n-channel mosfet and run the injectors at a duty cycle that is yet to be determined. The test rig will require some work as to how I will have everything setup. Once I have those numbers, I will see where we go from there. I am hoping #2 and #3 are low.
  11. kinser86

    78 280z Severe Driving Problems

    Time for an update. I ran a few test this morning. First thing I did was pop off the fuel rail to capture some video of the injectors. I made a quick ground interrupt switch to an old injector connector and tested the injectors. I sprayed all of them but focused the video on #1, #2, and #3. I disconnected the starter signal and would turn the key to prime the rail before each test. In my opinion, the spray pattern for #1 looks really good. #3 definitely looks suspect with defined spray trajectories columns rather than a large cloud seen in #1. #2 I think falls between the both in quality but I will let the video do the talking. The other injectors looked similar to #1. Next thing I did was pull all plugs and blow out all the fuel that got in the cylinders. I figured now would be a good time to do another compression check but the vehicle was not warm. Fuel was blown out of all cylinders before performing the test. Numbers again are high but they are still within 10% of each other. I then hooked up the FPR to a vacuum pump and put my vacuum gauge between the two to record FPR with respect to vacuum. Again, I charged the rail before doing this and slowly pulled vacuum until the pump couldn't pull anymore. It looks like 23inHG vacuum is only yielding 28PSI on the gauge. Is this an acceptable range? Now I made this chart for referencing fuel pressure with respect to vacuum. I read the FPR is to maintain a pressure differential of 36 PSI with respect to vacuum so if this chart is wrong, let me know. That is all I was able to do. I have a new set of plugs I will put in next time but the spray pattern on #3 is suspect to me right now. The rail is still loose on the car anticipating suggestions to replace the two. I did not check valve lash or fuel return due to some time constraints.
  12. kinser86

    78 280z Severe Driving Problems

    I was thinking more on the lines if the compression/leak down test are no good on those cylinders. I will do some test first and let those numbers dictate the next step in the process.
  13. kinser86

    78 280z Severe Driving Problems

    I did not try to drive it after #2 and #3 did not respond to injector connectors being pulled. I did check continuity to the ECU and dropping resistor for both connectors as a fail safe and they were both good. I can perform another leak down and compression test with a warm engine this time and also check the valve lash. If these numbers are good, then the only assumption would be the injector is truly not firing even though there is a clear audible clicking of the injector during idle. I marked the injectors prior to them being serviced so they went back to the cylinder they originally came from. One quick test would be to swap a known working to one of the #2 or #3 position and see if the issue follows the injector or stays with the cylinder. Right now a visual inspection on those two injectors is a good idea. I think switching positions will help determine if its an injector or the cylinder. Right now the priority list is: Determine why #2 and #3 injectors do not impact idle speed Warm Engine Compression test again Leak down test again Valve lash If out of spec, adjust and re-run compression and leak down Swap injectors with others on rail to see if idle speed follows injector or not If it follows injector, then bad injector If it stays at cylinder, something else is going on Vacuum pump test the FPR (still on the list but need to get #2 and #3 on board) I can't make any future decisions on next steps but if the numbers don't match up on #2 and #3 and injectors are good, then it sounds like the head needs to come off. As soon as I get those numbers I will post them up. I will take some videos and pictures again since they help so much. Thanks again for everyone's input, it is definitely helping! 👍
  14. kinser86

    78 280z Severe Driving Problems

    Alright here is an update.. We might be on to something but as promised let me check off the to-do list first. Verify vacuum line routing (Distributor) If incorrect, verify timing again (10°BTDC @ 800RPM) It was incorrect, vacuum source was after throttle body. I put it below the throttle body per the FSM. Timing/Idle speed adjusted back to 10°BTDC @ 800RPM. FPR exercise with hand vacuum pump I left this tool at home so I was unable to perform this exercise! 🤬 It stays on the list... Verify firing order (caps and plugs with pictures) 1-5-3-6-2-4 CCW As promised, pictures. Also a video of each lead with a new plug in showing spark. Verify AFM pins not popping out when plugged in Pins are solid in the connector when installed. I still have the AFM cover off right now so those terminals are easy to access with a multimeter and measure to the ECU connector. Review injectors firing (I have video below) unplug one at a time #2 and #3 did not have an impact on idle speed when removed. I swapped connectors from Injector #1 and #2 after this, and when I perform the test again with the swapped connectors, #2 still has no impact on idle but injector #1 (with #2 connector) will drop about 90rpms like it did with the original connector. screw driver to ear All injectors are clicking. #2 and #3 are clicking the same as other. Granted I am using a tall screw driver to my ear, when the connector from #2 or #3 is removed, the amplitude of the clicking goes down a lot. When the connector is installed, it has the same amplitude as the other injectors. Record video of RPM/FP/Vacuum See video below. So after this, I am really perplexed with #2 and #3 injector having minimal impact on idle speed.In the video you can definitely see about a 100rpm drop on all other cylinders. I have not been able to reduce idle speed yet but I forgot my vacuum pump to test the FPR. The EGR system has been removed and blocked off on the intake plenum. The AFM does move freely, I have never been able to get it to bind or feel any resistance in its movement. Spark Test Pulling injector connector test. (Apologizes for the shaky video at times, it is not easy handling all of these items at the same time.) Reemphasizing the impact #6 injector connector has on idle speed. FP/RPM/Vacuum Video:
  15. kinser86

    78 280z Severe Driving Problems

    A lot of good information here, let me see if I can answer them. I went through an exercise believing the oil pump drive gear was off a tooth, so I spent a day going one tooth left and one tooth right to see if I wasn't seeing a true 11:25. This resulted in a waste of time because it was correct to begin with. This is before the injectors were rebuilt. I will take a picture of it tomorrow but 1-5-3-6-2-4 on cap to the plug is what I have. When validating the timing marks on the crank pulley, I checked TDC on the crank/timing marks on cam gear/ear lobes on cam/piston at top of bore. The rotor on the distributor points towards the radiator, and at the number 1 plug outlet on the cap which also has the reference mark. I just replaced all injector clips about 3in back from the originals. I used a screw driver to my ear in order to listen to each injector to make sure they were firing. They are definitely clicking, all at the same amplitude and frequency (to the best of my hearing capacity). I can try the unplugging method too and see if I notice an issue. I've gone through the valve lash a number of times, my initial post is the measurements after the third time of going through things (going in circles😵). When I did the checks to the components, I did all the test through the ECU connector. I can check the conditions of the pins on the AFM connector to confirm they are not popping out when installed. I confirmed TVS works at all angles corresponding to the EFI-Bible. I removed the cap and made sure all contacts and moving parts were clean and free of any binding. They have some miles on them. The values in my first post were measured at the ECU connector. I agree with FP statement. I spent more time looking for a faulty AFM or other things that this might be more of the culprit. Understood on the AFM observation, thanks for clearing that up! I believe the distributor is connected directly to the intake right now. I will confirm this but it might be hooked up to one of the ports near the FPR port. In that case, the vacuum reading in the video was coming from the intake and not before the throttle plate. I will go over the vacuum lines and trace their origins as everyone has been pointing out. So right now the to-do list is: Verify vacuum line routing (Distributor) If incorrect, verify timing again (10°BTDC @ 800RPM) FPR exercise with hand vacuum pump Verify firing order (caps and plugs with pictures) 1-5-3-6-2-4 CCW Verify AFM pins not popping out when plugged in Review injectors firing unplug one at a time screw driver to ear Record video of RPM/FP/Vacuum If I am missing anything please let me know. I appreciate everyone's feedback. It is a lot to take in and I want to make sure the order of operations of the troubleshoot is correct, focusing on one thing at a time.
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