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Intermittemt miss under load

Discussion in 'General Tech and Maintenance' started by autox19, Apr 21, 2019.

  1. autox19

    autox19 Member

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    To catch up those who dont recognize me. B16. Odb0 with an obd1 dizzy and ecu. Was running crome and had the miss. Was only under vtec then under non vtec. Bought new ecu with s300. Loaded base p30. Still have the miss. New plugs and wires. Sprayed carb clean all over and cant detect a leak. Head gasket about a year ago (but only about 50 miles)

    Getting frustrated enough to just buy a new engine but seems like a sledge hammer when it might be somethig easier

    Odie
     
  2. Briansol

    Briansol Admins Admin VIP

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    do you have data logging capability.... you can maybe record the miss
     
  3. autox19

    autox19 Member

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    I did a quick look yesterday. didnt see much. With the miss I took the lean/rich conditions with a grain of salt. reading that 90% of the google searches for intermittent miss is an ignition issue, I am wondering if the Dizzy is bad. yes it is "new" (less than 100 miles) but it wasnt a really good quality one (not OEM or one of the high performance ones) The other thought was maybe the headgasket didnt seal right. but I would assume I would have cooling issues and thank god I finally got that figured out. Hard pulls and never had to turn the fan on. yes, it is manual right now. Tonight I am going to check for moisture under the cap as well as clean off the ground on the thermostat. Winter was not friendly as far as moisture is concerned. it is in a temporary tarp based garage until my real garage gets built.
    if I could figure out how to attach it here, I would include the datalog

    Odie
     
  4. Fernpatch

    Fernpatch Member

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    does it miss at idle? light load? Wot? checking inside the distributor cap for moisture/crap is a good place to start. How old is the gas in the tank? is it a light miss that you can hear but not really feel or is it a hard miss like it's running on 3 cylinders?
     
  5. autox19

    autox19 Member

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    No miss at idle or maintaining speed. Wot and light load it misses. Irregular miss no pattern so it doesnt sound like its a single cylinder. Can hear and feel. Pulled cap. No condensation or build up. Gas was new last fall ( filled up before storage) before last summer. Well it has been a 10 year project but the tank was empty until 2 years ago.

    Odie
     
  6. Fernpatch

    Fernpatch Member

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    Old gas could be the culprit. the cheapest and easiest next step to try would be topping the tank with fresh high octane fuel and run it around a while. if any improvement is noted than try to run the tank down and fill it up again with fresh fuel and see if it keeps getting better.

    If no change is noticed after getting fresh gas in the system let me know and I will put my thinking hat on again.
     
  7. autox19

    autox19 Member

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    Gas is not old. tank was empty for most of the 10 year project. was filled 2 years ago and went though about 1 tank (12 gal) since then. it was filled last fall before winter storage.

    but that doesnt mean the gas doesnt have contaminates. maybe a drain a refill might be needed, as much as a pain as it is. or maybe it would be easier to go to a fuel cel like I have wanted to. the gas tank sits behind the driver, in between 2 firewalls. behind the other fire wall is the honda's exhaust. not a fan of the tank being so close even though it is insulated well. also if I were to ever go turbo (always a thought) I would have to move the tank to the front anyway because the turbo wont fit without going into the area that the tank currently sits. So all that babbling to point out that going to a fuel cel up front will probably happen sometime.

    appreciate all the help!

    Odie
     
  8. dilbeckskate

    dilbeckskate infamous

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    im not going to say gas im going to say fresh plugs or valve adjustment , also could be dying injector
     
  9. autox19

    autox19 Member

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    interesting thought. looking back I think someone recommended valve adjustment last year I even bought one of the tools to make it easier. I think it was supposed to be a winter project last year. I think part of the reason was I did a head gasket which of course requires removing the cams. and although in theory it shouldnt matter, someone pointed out that out of many head gaskets they did, one actually had to have its valves readjusted. New NGK's late last summer. Injector.. hmm maybe new ones wouldnt be bad as who knows what these have been through.

    Odie
     
  10. dilbeckskate

    dilbeckskate infamous

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    if the cams get pulled the valves need adjusted IMO , alot of times close enough ? yes but not spec anymore
     
  11. autox19

    autox19 Member

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    going to do the valves as soon as I get a chance. good part is I will go ahead and do the retorque of the head bolts. I know there has been debate if if it is needed (arp says yes, many people say they never have had to) but if I am going to be in there already, why not.
    still in the debate of the dizzy. Xenocron, who I personally have had great service with, has a rebuild for 200. is it just a higher priced ebay item? who knows, I know they have stood by their products for me in the past. So I may just go that route to ensure it isnt dizzy related. I believe the one on there now is a cheap knock off. decided not to go with the dragon fire as I really see no useful reviews.
    going to do a few more grounds to make sure it is grounded well. thinking of making a new ground to chassis from the thermo to the body. Because this isnt a honda body, and uses a "race" harness from rywire. I might be missing a few. right now. I have ECU to ground, harness to thermo and trans to ground. Although I have had it run well once (for about 13 miles then it started to over heat and I shut it down at 220 degrees, over heating has since been fixed. started running rough before the overheat) doesnt mean the grounding was necessarily good. might have been just good enough. anyway. more efficient grounding is cheap and wont hurt

    Odie
     
  12. autox19

    autox19 Member

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    still have not gotten to the valves. I did add a few grounds, and larger gauge wires to the fuel pump. sounds a little better but still misses.
    around 18-19 seconds you can here the miss with vtec.
    Also looking at the datalog. the voltage drops during high RPM. i.e log shows 10.98 @ 7600. may be nothing, just pointing it out.

    Odie
     
  13. Fernpatch

    Fernpatch Member

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    I find the voltage reading to be interesting. low voltage could cause all kinds of drive ability problems. is there a practical way for you to rig up a volt meter to the battery that you can monitor and check against the log on another pull? I am wondering if you are fighting low system voltage from a bad alternator or if you are dealing with a localized problem with the power or ground for the ecu.

    I suppose it also could be a red herring. it's so much easier to diagnose something sitting in my shop than it is over the internet.
     
  14. autox19

    autox19 Member

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    Figured it out. Or at least got closer. Started looking at other peoples datalogs from the hondata forums. Looks like there are people whos voltage drops lower than mine. So my next thought was injector dead times. I know they vary with voltage as there is a table in hondata for it. Well my base line was a p30. Stock b16. Looked at thendead times and they were correct. Dont ask me why, because i dont know, but i decided to use the "picker" they have for certain injectors to autofill. Chose b series 240cc. Poof. 3 of the cels in the table showed they changed by going dim. Yet the numbers were the same. For giggles i saved it, uploaded it and took it for a drive. Big time miss is gone! Still not smooth but that could be tuning.

    Btw, if you have a s300, it is repeatable. Just load a base p30 and go pick b 240 injectors. You will see the same glitch

    Odie
     
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