300ZX (Z31) Performance / Technical Discussions related to Turbo charging, Supercharging, Engine, ECU, exhaust, and etc. performance enhancements and Techical related.

why does this happen?

Old Nov 17, 2006 | 08:22 AM
  #1  
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ern
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why does this happen?

OK I know the car will never be the same. ( I've swapped the tranny from an auto to a 5 sp and did the whole JWT 450 HP package), but when I'm in 2nd or 3rd gear with the rpms at 2500 or higher and I let off the acceleration quickly or put into netural right away to coast, all the dash lights come on and the car will stall, but if I put into gear 1-3 seconds after the lights come on i can prevent the car from stalling. However if I wait 5 secs or more then the car will stall. why why??

I bought the ECU from a yard and sent into JWT to reprogrammed
(4 bar) ....could this be the problem?

I also swapped in a pathy manifold thus removing what I thought were uneeded sensors and plugged some vacuum lines...could this be the problem?

86 turbo.

Thanks
Ernest.

Last edited by ern; Nov 17, 2006 at 08:33 AM.
Old Nov 17, 2006 | 08:32 AM
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are you completly flooring it and then just leting off. my buddies stock suby does this and its cause its a turbo car but has an external blow off valve. if you have a blow off valve its cuase you let off and the fuel mapping is throwin tons of fuel into the system the BOV let out all the pressure in your intake system and there for you just went pig rich right there and it kills your engine. and when engines stall all dash lights come on. at least in my experience. just liek before you start the car turn it to on. as to why it re stalls..... i don know
Old Nov 17, 2006 | 08:37 AM
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no I'm not flooring it, but I am going a little faster.
Old Nov 17, 2006 | 08:38 AM
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snwbrderphat540 is right. With a turbo car if the blow off isn't piped back into the intake (Bypass or recirculation) it will stall the car. I had an MR2 that the P.O. removed the bypass line and plugged the intake hole so it would sound louder and it did the same thing until I connected everything back up.
Old Nov 17, 2006 | 08:41 AM
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thanks guys!

ya my BOV isnt recirculated. Any suggestions as to a good one. I have a Turbo smart BOV right now.
Old Nov 17, 2006 | 08:48 AM
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Originally Posted by naviathan
snwbrderphat540 is right. With a turbo car if the blow off isn't piped back into the intake (Bypass or recirculation) it will stall the car. I had an MR2 that the P.O. removed the bypass line and plugged the intake hole so it would sound louder and it did the same thing until I connected everything back up.

My 280ZXT has a vented BOV. I'm running a Z31T ecu and MAF as well.... no stalling at all.
Old Nov 17, 2006 | 09:13 AM
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come to think of it I don't think I ever heard the BOV vent any air when this problems occurs (i.e I 'm not running enough boost for the pressure to build).

Again the rpms can be as low as 2500-3000 for this stupid thing to happen.

Last edited by ern; Nov 17, 2006 at 09:28 AM.
Old Nov 17, 2006 | 09:16 AM
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Then we'll need more info. Have you tried reading your plugs to see where the mixture is? Take a socket wrench with you and let it die one time then check the plugs before cranking it back up again.
Old Nov 17, 2006 | 09:28 AM
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alrighty then..... what would I see if it's rich or if it's lean?
Old Nov 17, 2006 | 09:34 AM
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Originally Posted by ern
alrighty then..... what would I see if it's rich or if it's lean?
Too rich = the plugs will be either wet or have black carbon build up.

Too lean = tips will be bright tan
Old Nov 17, 2006 | 09:41 AM
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....thanks
Old Nov 17, 2006 | 10:03 AM
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Nismo,
Eh close on the lean. Too lean will actually leave the ceramic around the base of the tip white and leave a light gray and sometimes white burn on the electrode itself. Depending on how lean it goes and for how long the electrode tips can even melt or deform. Checking the gaps can tell you whether it's deformed or not. My Harley ran lean last winter for a bit and the electrode gap opened up a full .010" wider.
Old Nov 17, 2006 | 10:09 AM
  #13  
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Originally Posted by naviathan
Nismo,
Eh close on the lean. Too lean will actually leave the ceramic around the base of the tip white and leave a light gray and sometimes white burn on the electrode itself.

Indeed, to be more specific.
Old Nov 17, 2006 | 03:35 PM
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if I floor my car then let off all the lights will come on too and the car shuts off... I dont have a BOV or anything... I just turned up the idler and it doesnt do it any more...
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