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na2t ran fine now running so rich gas comes out exhaust

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na2t ran fine now running so rich gas comes out exhaust

Old 07-25-2018, 07:43 PM
  #1  
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na2t ran fine now running so rich gas comes out exhaust

I'm close to finishing my 1986 na2t conversion after doing it for 3 years. I'm dying to finish it but I'm unable to figure out why it runs so rich that white smoke now comes out the downpipe and gas is dripping out. This was not an issue prior to the na2t conversion, and only presented itself after I finished. I'm 99.99999% sure the white smoke is from the massively rich mixture not burning well. It's POSSIBLE something magically fried and it's burning oil now but I find that hard to believe given I didn't touch or do anything that would have caused that.

1986 300ZX NA 5spd, all donor parts came from a 1986 300zx Turbo automatic
ECU, Injectors, Turbo manifold, Turbo swapped onto car. Using relocation pipe instead of crossmember swap

CHTS looked original. Replaced. With or without it plugged in the car runs the same. I'm getting Ohm readings testing directly from the ECU side of the harness.
ECU diagnostics complain about CHTS still, code 13
O2 sensor was known good before the swap. unplugging it made no difference in how it runs.
Swapping in the old NA ecu and it still runs like doodoo.
Pulling the spark plugs, 3 in a row were soaked in gas, didn't bother pulling the rest. conclusive that it's not a single injector sticking.

It would be completely drivable if it weren't for the embarrassing amount of smoking and I'm very concerned that the unburned fuel will catch my engine bay on fire (open downpipe until I can justify the cost of an exhaust system)

It drives but god is it too rich to do so without tearing up and killing 5 brain cells a second. It will be driving off a cliff if I can't defeat this.

I'm offering beer or bong hits if you want to give it a shot at my place in Bellevue, WA. Thanks for anything!

Last edited by Dr_Nic_T61; 07-25-2018 at 07:46 PM.
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Old 07-27-2018, 08:26 AM
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Yea sounds dangerous
Of course T & na have very different harnesses
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Old 07-27-2018, 10:56 AM
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Originally Posted by 86tcoupe View Post
Yea sounds dangerous
Of course T & na have very different harnesses
Well, two issues with that theory:

It runs the same with the old, stock, 86 NA computer. So it's not a harness compatibility issue.
The compatibility between the 86 na car and 86t ecu is ideal and the only differences don't affect how it runs once you remove all the idle control and emissions control crap

I used redz31.com for reference on interchange information.
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Old 07-28-2018, 06:53 AM
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What is the part # ?
I have a 86 t
, I have seen different a wiring harness. on na -turbo
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Old 08-03-2018, 09:29 AM
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After redoing
-injector harness and plugs
-spark plugs
-spark plug wires
-all grounds going to intake plenum
-chts and harness

And
-plugged up ALL vacuum leaks, there were a few including IACV, some under throttle body, and pcv
-changed oil cause it smelled like gas

Drove it around for a few minutes and all issues cleared up. Been driving it daily the past few days and no issues remain. I blame CHTS at first, along with spark plugs, then from it running so rich previously it got gas in the oil thinning it out causing it to burn easily.
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