Replaced plugs and wires ran once for 30 seconds then nothing

Discussion in 'Gen 1 & 2 - Engine, Exhaust, Drive Line & AC syste' started by Bryan Kuban, Feb 19, 2020.

  1. Bryan Kuban

    Bryan Kuban Member

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    Frustrating late afternoon.

    I changed the plugs and wires on my 89. It went a hell of a lot smoother than I thought it would. After wiring the 1st plug I noticed the the boot didn't quite fit tight on the valve cover. I was recommended by someone in the club to get Duralast 4142 wires. I used them with NGK Iridium 5464 bkr5eix11 plugs. He even explained very well on how to run them and what to do. Was pretty easy without taking off the intake manifold. Some small odds and end vacuum lines had to be removed but nothing special and I bought a swivel magnetic socket which made things very easy. Thank you.

    I thought to myself I will just get it all done and fire it up and see what happens. If I leak some oil so be it. Ill figure it out on making a gasket or something.

    I fired it up and it ran. It always runs rough when I 1st start it up until it runs for about 1 min. Then it is fine. I went to give it some gas and give it some r's. It did fine but I didn't let it run for the full 1st min. Since I didn't it died. I went to restart it and nothing. Tried and tried again and still nothing. I even replaced the M Code and nothing.

    Any help on what to look for would be awesome.

    Thanks.
     
  2. rubydist

    rubydist SHO Master Staff Member Super Moderators

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    what are the pcm codes?
     
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  3. Bryan Kuban

    Bryan Kuban Member

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  4. luigisho

    luigisho SHO Member

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    Someone told you an IAT error code is no big deal? I've never had one and the ones I've seen on this board there was always an issue. I would guess there is something wrong with the circuit but Rubydist knows this code better than I do.
     
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  5. rubydist

    rubydist SHO Master Staff Member Super Moderators

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    Whoever told you that 21 and 24 are irrelevant has no clue what they are talking about.

    Intake air temp sensor out of range is a fatal code. I have never seen one of these engines run correctly with that code. It must be fixed or you will have no chance to make this run right. And, yes, sometimes with that code they won't run at all.

    The iat, tps and coolant temp sensor are all on the same power circuit from the pcm, iirc. Since you have codes on multiples of these on that circuit, that suggests (as luigisho has pointed out) that there is likely a problem with the wiring. I have seen opens and shorts in the harness for no apparent reason, and since you have just changed plugs and wires on this car you have jostled the wiring harness around which could have made the problem appear.

    I would start by ohming out the various parts of the circuits from the iat to the pcm, and the coolant temp sensor to the pcm and seeing where you find a short or open.
     
  6. SHOdded

    SHOdded SHO Member

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    Facebook ...
     
  7. Bryan

    Bryan Glamour Bird 1969

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    My IAT sensor took a shit on my 92 SHO as well. Car would run on start up, then a moment later would die and I had a hell of a time getting it started again. Replaced the sensor and car started right up and ran fine again. It's an easy sensor to replace and is dirt cheap. Might as well swap it out and see if it solves your problem. Also Duralast products in my opinion are cheap shit. Anything Autostupid sells I feel is not worth your dollar.
     
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  8. Bryan Kuban

    Bryan Kuban Member

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    Sorry, what is a iat sensor?
     
  9. rubydist

    rubydist SHO Master Staff Member Super Moderators

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    intake air temp sensor
     
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  10. luigisho

    luigisho SHO Member

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    It plugs into the intake air filer box. Easy to locate.
     
  11. Bryan Kuban

    Bryan Kuban Member

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    Ordered one from rockauto today. Thanks guys.
     
  12. luigisho

    luigisho SHO Member

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    That code may or may not get resolved with a new sensor -- hopefully it clears it up. Post back with results.
     
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