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Discussion Starter · #1 ·
So, 2003 350z 200k on body possibly less on the motor. Kinetix plenum, pop charger and ebay exhaust. Owned for about a year. Z cranks but won't start or is a really rough start. Occasionall when it does start after idling extremely rough it will suddenly smooth out and idle normally for a few seconds then it dies. Acts like it's not getting fuel or has bad gas. I've replaced cam and crank shaft sensors previously and there is no codes on scanner. Drained all the gas out and put fresh in. Fuel pump primes and plenty of fuel shot out of the line when I unhooked the regulator to check. Cranked and fired fine when spraying a little starter fluid in the throttle body...I'm lost. Not too many mechanics around here that are good with these cars or they are so busy they can't get to it...Any help would be greatly appreciated!
 

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Discussion Starter · #3 ·
Welcome- did this Z always start and run like this when your first bought it?
Hey thanks for responding and thanks for the group! No started and ran fine after purchase. Had cranking issues from crank sensor...replaced that and cam sensors ran pretty good again. Added eBay exhaust and resonated test pipes...still ran good but probably needed a tune...then it kinda stalled a little on me a couple weeks after when I was driving home...made it to the house and it hasn't run since. Seems like fuel is going into plenum from fuel reg but didn't notice much / any coming out when I disconnected driver side fuel damper.. Trying to give you as much info as possible lol. I'm no gear head I've barely changed my own oil before so I'm very ignorant about cars.. I'm enjoying learning until things like this happen lol. Thanks again!
 

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It sounds like the aftermarket exhaust and test pipes may have something to do with this, since the Z ran well before. Have you tried putting the stock parts back on to see if that solves your problem? Always look for a cause-and-effect relationship when troubleshooting.
 

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Discussion Starter · #5 ·
It sounds like the aftermarket exhaust and test pipes may have something to do with this, since the Z ran well before. Have you tried putting the stock parts back on to see if that solves your problem? Always look for a cause-and-effect relationship when troubleshooting.
I don't have them anymore....cats were shot and exhaust was too...but I do see what you mean. Although it did start and run fine after new test pipes and exhaust. But I do think it was a significant change in airflow especially since cats seemed to be clogged. So I just removed the kinetix upper plenum to look around....I unbolted it first and unsealed the gasket before removing the (vacuum hoses?) from the car...I left the larger one on passenger side attached to the plenum and removed it from the connection to the line in the engine bay and when I did air pushed out of it...I thought that was interesting because any pressure I assume would have left when I broke the seal and lifted the upper plenum. So I blew on the hose attached to the upper plenum and it hesitated before the air passed through...it still takes a little pressure to blow air through the hose but it is a pretty small hose....does this mean anything?
 

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Discussion Starter · #6 ·
I don't have them anymore....cats were shot and exhaust was too...but I do see what you mean. Although it did start and run fine after new test pipes and exhaust. But I do think it was a significant change in airflow especially since cats seemed to be clogged. So I just removed the kinetix upper plenum to look around....I unbolted it first and unsealed the gasket before removing the (vacuum hoses?) from the car...I left the larger one on passenger side attached to the plenum and removed it from the connection to the line in the engine bay and when I did air pushed out of it...I thought that was interesting because any pressure I assume would have left when I broke the seal and lifted the upper plenum. So I blew on the hose attached to the upper plenum and it hesitated before the air passed through...it still takes a little pressure to blow air through the hose but it is a pretty small hose....does this mean anything?
 

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What kind of code reader are you using? Have you tried using an alternate code reader to make sure your checks are complete? I find it hard to believe there are NO codes stored in memory with the problems you're having.
 

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Discussion Starter · #9 ·
What kind of code reader are you using? Have you tried using an alternate code reader to make sure your checks are complete. I find it hard to believe there are NO codes stored in memory with the problems you're having.
It's just a cheap craftsman scanner from napa. I did get the nats code at one point but I erased the code...I've had to wiggle/flip the key to get the light to go off...I don't know anything about stored codes? I assume if you clear them they are gone but again I know nothing really. I've been considering ordering the scanner from Z1 that is supposed to work really well with the z and can even do some system resets...like throttle body, idle etc. Do you think it could be a bad throttle body?
 

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Not sure where you live, but perhaps you can look up your local Z Car Club and see if there's anyone who has a more advanced code reader to check your car with. The Z car clubs may also have some experienced members who can help guide you through a troubleshooting process. Don't start throwing parts at the car until you get a better hands-on diagnostic started.
 

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Discussion Starter · #11 ·
Not sure where you live, but perhaps you can look up your local Z Car Club and see if there's anyone who has a more advanced code reader to check your car with. The Z car clubs may also have some experienced members who can help guide you through a troubleshooting process. Don't start throwing parts at the car until you get a better hands-on diagnostic started.
That's a good idea I'm about 2 and a half hours below Atlanta...I've considered making an appointment at Z1 and just hauling it up there.. It seems too complicated or not enough real info to diagnose through a keyboard lol but I appreciate your help. BTW I hooked the scanner back up to see if it would show me stored codes...but it said no dtc codes noticed before that when a code came up it would say pending...anyway when I hooked it up this time it showed 17 dtc codes! Lol I couldn't get it to show me a list so I ran dtc scan again and it showed 0 codes for vehicle lol...I don't know but I'll keep plugging and if I figure it out I'll update in case it may help someone else...thanks again!
 

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Discussion Starter · #13 ·
Again, I suggest getting someone local to rescan your ECM and search for codes held in memory. If there are 17 separate codes held there, you've got bigger problems brewing.
So...haven't been able to take the car anywhere yet but I bought a new scanner and I now have codes... P1121, P0223,P0123... so it looks to be throttle position sensor or electronic throttle actuator. So I'm thinking if it's not something in the wiring it could be an accelerator pedal assembly (or sensor) or the throttle body...I will try to check with voltmeter before ordering parts...any suggestions would be great I will update soon...thanks
 

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Are you sure you can't hire a trained Nissan tech to travel to you and check out your Z? Either that, or take your car to Z1. This doesn't sound like a DIY project and getting an experienced tech to do the diagnosis could save time and money.
 

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Discussion Starter · #15 ·
Are you sure you can't hire a trained Nissan tech to travel to you and check out your Z? Either that, or take your car to Z1. This doesn't sound like a DIY project and getting an experienced tech to do the diagnosis could save time and money.
Z1 isn't taking appointments until November...they are getting ready for the z nationals lol. It's really frustrating because of the way it will sometimes crank and run smoothly for a few seconds...then just die out like that. So everything (can) work right...so it seems like a signal, electric, ecu or sensor issue...not fuel pump, spark plugs or ignition/coil issue. At this point ...I hate this car. This was supposed to be a fun project for me and my son...once running good we were gonna take it to the body/paint shop and get it lookin good. I guess I live in the wrong area to have a zed without decent resources. I don't mind a challenge or spending some money...but this just isn't fun. I'm done.
 

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Sorry to hear it. Nobody ever said working on cars was easy, and it's impossible to accurately diagnose a car over a keyboard. It's why I suggested some help who could actually put their hands on the car. But if you're not having any fun and you're done- that's it.
 
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