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hunting idle issues.

Discussion in 'Civic and CRX - EF' started by hal9000, Feb 16, 2009.

  1. hal9000

    hal9000 New Member

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    I haven't driven my '88 CRX much (mostly due to the weather) after swapping out the auto trans for a manual, but I've started noticing that the idle is out of whack now. It was acting like it wasn't warming up (Idle would stay high) until yesterday, then suddenly the idle started surging between about 900-1500. I haven't burned a whole tank of gas since the swap, but it's looking as if my MPG has probably dropped quite a bit as well. I can occasionally get the idle to drop by blipping the throttle (like knocking a carbureted engine off the choke), which doesn't make any sense to me.

    To date, I have cleaned the IACV, checked for air leaks, and checked to be sure the throttle linkage/cable isn't binding. I'm not sure where to go next....I don't know much about the stock DPFI, so if anybody can give me some tips to help me find the problem I'd really appreciate the help.

    The car is a bone stock '88 CRX DX that started life as an auto and I converted to manual. (Including swapping the ECU). It summer the last time I drove it as an auto, so this problem might have been pre-existing, but I never noticed it till immediately after the swap.

    Thanks all.
     
  2. MthaFuknGreen

    MthaFuknGreen Green on the scene.

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    clean the FITV and screw the ring all the way down.
    bleed your coolant.
    if that doesnt work, replace your gaskets on your intake manifold.
    i would say just check them, but you might as well replace them.. lol
     
  3. jlicrx

    jlicrx Senior Member

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    make sure that the cooling system is completely full of coolant with no air pockets in the system - bleed the cooling system and fill it up completely - do you have a Check Engine Light showing or any codes in the ECU?
     
  4. hal9000

    hal9000 New Member

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    I'm pretty sure that the DPFI system doesn't have an FITV.... Leastways I couldn't find one (unless I was wrong about the IACV... It's bolted to the left side of the manifold, right?).

    I have been wondering if maybe there's an air bubble in the coolant jacket in the manifold. What's the best way to bleed it? The rad is full and the engine isn't running hot, but I did drain it at one point during the swap so I could replace the rad drain plug (which was damaged).

    No check engine light.... I'll have to check for engine codes. I know where the LED is, but is there anything I need to do aside from turning the ignition on or starting the engine to read the codes?

    Thanks and sorry if these sound like 101 level questions...Like I said, I don't know the specifics of this car very well yet.
     
  5. MthaFuknGreen

    MthaFuknGreen Green on the scene.

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    just turn the ignition to on to check for codes, but if theres no CEL then i dont think there will be any codes.
    i didnt think DPFI had a FITV either, i was just listing off the basics.
    theres a little bolt on the upper radiator hose housing that looks like an air nozzle. loosen that and itll let some air out.
    if that doesnt work, take the radiator cap off and turn your car on and let it warm up till the coolant/water starts to bubble. once all the bubbles are out, put the cap back on.
    if that doesnt help, bleed all the coolant out of the system and fill it back up.
     
  6. K2e2vin

    K2e2vin Senior Member

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    There should be a bleed valve/screw on top of the coolant neck on the engine where the upper radiator hose is. Also check your PCV valve; might still be good but I had one instance on a 91 Civic with DPFI where cleaning the PCV helped a bit.
     
  7. hal9000

    hal9000 New Member

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    You know, when I bought the car and did the initial service, I bought a new PCV valve, but couldn't locate locate the original one on the car so I just threw the replacement on a shelf. Where is it supposed to be located? Maybe somebody took it out completely....
     
  8. K2e2vin

    K2e2vin Senior Member

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    IIRC, it's on the runner. Maybe on the #3 runner. I remember it being a PITA because I didn't have a long-enough socket to take it off.
     
  9. hal9000

    hal9000 New Member

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    Thanks, If the weather is OK and I get home early enough I'll take a look tonight.
     
  10. 89' Project Civic

    89' Project Civic d16a6/d16y8 "mini-me"

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    Check your distributor. I was having the same issues plus loss of power and it turned out to be that I did not have the distributor set right, that will mess it right up!. GL man.
     
  11. hal9000

    hal9000 New Member

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    Well, I finally got back to this (It's been a busy few weeks) and there is no air in the cooling system. I still haven't found a PCV valve to replace either. The Dizzy has never been touched so I doubt that's causing a problem all of a sudden.

    This afternoon, I spent a few minutes unplugging sensors to see what happened and couldn't discern any major changes. The idle dropped by a few hundred (down to about 1000) when I unplugged the IACV, but aside from that nothing. Although unplugging a vacuum line (from the vacuum motor on the back of the TB) caused the car to have fits and go into what can only be a limp home mode until I shut it off for about 3 min and restarted it.

    I'm guessing it's a sensor, but I've no idea where to start in terms of diagnosing which one. Is there a chart of acceptable ranges for the stock sensors so I can check them with a meter? Better yet, are there any sensors that are particularly troublesome?

    I'm out of town again till Monday, so no time to do any more, but if anybody has any other good ideas, I'm all ears.
     
  12. MthaFuknGreen

    MthaFuknGreen Green on the scene.

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    are you throwing any codes?
     
  13. hal9000

    hal9000 New Member

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    Going to check that tonight hopefully (just got back late last night), but I don't have a good way to reference the codes... Is there a database that will help me decipher them?
     
  14. MthaFuknGreen

    MthaFuknGreen Green on the scene.

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    lol
    turn the key to the on position.
    one long flash = 10.
    two long flashes = 20 and so on..
    one short flash equals 1.
    just add the flashes together, then theyll be a short pause and another code might flash or itll just repeat the same one.
    for example, 4 long flashes and 3 short flashes is 43 Fuel Supply System
    code list.
     
  15. hal9000

    hal9000 New Member

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    Hmm, I just checked and when I turn the key on I get one short flash (assuming it's just a startup flash, but not sure), then 7 short flashes, pause, 10 short flashes, pause, 14 short flashes, pause, 16 short flashes. Short flashes are maybe 1/3 second long or so... No long flashes to compare it to though.

    So I guess that would mean codes 7, 10, 14 and 16?; TPS, IAT sensor, IAC, and bad fuel injector respectively.

    Of course It might be throwing all kinds of codes because of me unplugging things over the past few run cycles..... What's the process for clearing codes? Just unplug batt for a few minutes?
     
  16. MthaFuknGreen

    MthaFuknGreen Green on the scene.

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    disconnect the negative terminal i think for like ten seconds, but i usually just disconnect it and smoke a cigarette. or i think you can just pull the clock fuse out for 10 seconds.
    but yes, those are the numbers.
    make sure you plug in any sensors that may be disconnected while you have the negative disconnected.
     
  17. hal9000

    hal9000 New Member

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    Sensors all plugged back in already. I drive the car every few days in spite of the odd idle issues (basically whenever I don't feel like driving my truck).

    I didn't mess with the injectors, so I'm banking on that code still showing up. Although how a bad injector could trigger a fast idle I have no idea....

    Also, would a bad temp sensor or O2 sensor definitely throw a code? If so then that's great, but if they don't, then If I can find the voltage ranges the sensors are supposed to produce, I'll check them with a multimeter.
     
  18. hal9000

    hal9000 New Member

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    This is just getting silly...

    So I got home from work, disconnected the battery for about 10 min to clear the codes. Hooked it back up, checked for codes. None- Good.

    Start the car - the idle is bouncing between about 1100-1400rpm on a 1 second cycle. Hasn't done that before except once for like 5 min, and it cleared up on its own. Anyway, I drove the car around the neighborhood for about 15 min, stopped and turned it off for like 2 min then restarted it. The Idle jumped to about 2400rpm and wouldn't drop. I drove the block home and as I pulled into the driveway it started pulsing again. Turn the car off in the driveway and restart.... It starts around 2000 rpm, eventually drops to 1700 or so, and if I blip the throttle, it now drops to a steady 750. I turned the car on and off to confirm this and it's repeatable, at least for the time being....

    And of course, no new codes are being thrown.... I'm stumped. All I can think to do is start measuring the range and values of the various sensors with a meter.... IF I can find a list of acceptable ranges to compare them to.

    Any new ideas? Anybody? I'll bake cookies.
     
  19. hal9000

    hal9000 New Member

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    No more ideas then? Nobody knows where I can find the value ranges for the various temp sensors and such?
     
  20. Fernpatch

    Fernpatch Member

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    I will try and go digging through my alldata on my lunch break if I have a chance. I'll let you you know later if I can find what you need.
     
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