Engine dies when in neutral after going 45 mph+

[tg300zx]

I have not been able to figure this one out. After cruising at highway speeds, when I push in the clutch, and or put into neutral, the engine will die. But only if you are going over 45. Happens when exiting freeway for example. Now I noticed if a braked hard while in neutral, it will not die. This is a real head scratcher for me. I have dealt with the IACV already, I dont think that is the issue. I did repalce it with a clean on from the junkyard. Intitially the original IACV solenoids were bad, high resistance. A time of high hopes for sure. But no luck. I am now thinking maybe this is an egr issue, maybe sticking after the high speed cruise. But this seems more speed dependent than rpm... But really if you downshift, this doesnt happen. But I would like to fix this.
Thanks for any help.

Tom

[marty1mc]

Do you have a stock intake or a pop charger?

If you have a modified intake, you have to ensure there is a block for the air. On an NA or TT with a single intake, there should be a plastic dam that will bolt to the bottom of the pop charger. The stalling comes from turbulence in the MAF.

[tg300zx]

It has a stock intake, this car is all stock.
The car runs great , accelerates fine .
I did check the computer for codes and it did give me a code for both o2 sensors. I didnt expect this since the engine check light wasnt on. Is this a possible culprit? Usually when you have an o2 sensor problem the engine will run rich, and will run rough, or atleast that is what I have experienced.

[Jz32]

i no this is a little old but ..marty1mc... which plastic dam are you refering to... i tihnk im having the same problem. if im cruising around and downshift normally the idle with rest just above 1k. but after a hard acceleration in 2nd or 3rd it doesnt seem to catch itself and bounces off the 250 rpm mark once or twice n then dies. would this plastic air dam your refering cause this?,,,,

btw mine is a tt with a single cone filter

[Jehtte]

Bump for curiosity. Had this problem before swap, never did figure out what it was.

[GerryO]

Wonder if the TPS is indicating that the throttle bodies are closed, and if they could dirty and not closing completely, resulting in a leaner mixture that causes the engine to die. And how about the MAF? Braking and being in Neutral also sends different signals to the ECM, changing outupts to the Air Regulator, that will drop the idle speed when the TPS indicates that the throttle bodies are closed. New O2 sensors should improve fuel mpg.

[Jz32]

i checked the o2 sensors through the ec and both are working properly. and it only dies when moving and in neutral, not braking. does that indicate anything?

[Jz32]

i came across this link searching for a solution, maybe someone here hasnt seent his link yet .... http://www.twinturbo.net/ttnetfaq/FAQpages/stall.html

[grk nickafis]

i've posted this problem 3 or 4 times before and didn't get a response. please tell me if you fix it and what you did to make it work

[Ace2cool]

Search "flower pot mod".

[BigTDogg (MA)]

Do a vac/boost leak test to check for leaks. In addition to that, have you checked your air filter box to be sure it's not open or damaged?

I know it's a shotgun approach, but here's a list of things to check when your car hesitates

[HEC7]

I had the same problem last week car wasnt holding idle at highway speeds when I pushed in the clutch, had the idle adjusted and then tested out the car didn't shut off! Good luck...am a new z32 owner and am reading posts for some knowledge, hope this help you out!

[CrazedZ32Owner]

this might seem like a stupid question but do you have your front splash gaurd installed?? along with that is the flap inside the fascia that's supposed to hang down in front of the filter?? thats how it is supposed to be set up and have read/heard that at highway speeds w/o both of those the car can stall when going into neutral/disengaging the clutch

[mkhoid]

pcv valves stuck?

[Jz32]

iv had my Z for 2 years now.. one year with it being a DD as an NA and that whoel time i didnt have the front splash guard but i did have the 2 in the fender and never once did i have a problem with idle. once because of vaccume leaks but once thaht was fixxed it never happened again .. im only having this problem wit hthe TT motor n transmission setup i installed.... its perfectly fine crusing around but as soon as i go for some speed in 3rd or 4th thats when it cant hold the idle ill either have to feather the gas just before it hits the 1k rpm or let it decel in gear

[grk nickafis]

Flower pot mod actually worked for me. I figured Why not! 2 dollars later... no stalling!

[Jz32]

ill give that a try n ill post back

[grk nickafis]

Heres a picture of my finished product. Worst part of it was drilling into my injen filter :/ worked out great tho!

[Jz32]

i though that had to be facing te opposite direction. meanig the pot be facing the front of the car as like a shield for the cone but hey if it worked it worked

[Ace2cool]

No, he did it correctly. The point is to block the turbulent air that's going to be rushing around the airdam and mess with the MAF readings. The air will be coming from behind the filter, so that's the logical place to put it.

[Jz32]

i was looking on TT.net and a couple peoeple have the pot on the opposite side... not saying either are wrong but im confused as to which is the proper side to put the flower pot mod on. does any one have suggestions or input as to which side or the reasoning behind it? i understand it the air is more turbulant without it causing wrong reading in the mas. but thge reason behing which side to put it on... thanks a lot

[Jz32]

if i new how id post up at least 10 pictures i have of people using this flower pot mod on the opposite side

[marty1mc]

No, he did not do it correctly. The mod is to block direct air flow. The turbulence comes from direct air being forced into the MAF from the front instead of being drawn in by the motor. Here is the link to Ashley Powers (Ash) post. If you look at the last pic, you can see how it is supposed to be mounted.

http://www.twinturbo.net/net/viewmsg.as ... id=1009416

[Ace2cool]

The air will be coming from behind the filter when you don't have the OEM filter splash guard installed, so that's the logical place to put it.

Just to clear things up on what I was trying to say....

I really don't think location matters on a single pop setup, but moreso when you have the dual setups that hang down lower and are directly exposed to rushing air with nothing to "mediate" the flow. On the single pop setup, the main point is to regulate the airflow, and make it more uniform, mostly for the people who don't have the OEM splash shield. Both of my cars have the single pop, and both have the splash shield. Neither one has ever stalled out on me.