Please help - car starts but wont run

King · 09-24-2018, 08:15 PM

PLEASE HELP.
Car Won't run correctly, Sounds like it is running on one cylinder almost. Like serious misfire. A super loped Idle.

2015. Car is modified, Full intake, catless Exhaust, and Uprev Tuned, still NA nothing crazy. Only 30k miles, maybe 8k miles with tune. No previous motor issues, just CSC.

Car was parked with 3/4 tank, running perfectly, sat for about 30 days. When I tried to start it fired and ran terribly. See first paragraph.

NO DTC Codes.
Sent it to Nissan for diagnosis. Their diagnosis was 'There are no trouble codes we can't help you.' ******* Central Valley Nissan is useless. So I paid them to install a new Crank Position Sensor, seeing some threads online about CPS not throwing a trouble code on Z's. didn't help.

When I got the car back home there was a new MAF DTC code. Replaced the MAF bank 1 just to find out the MAF code was Nissan unplugging stuff as an experiment.

I reflashed the ECU with my Uprev tune. No change. I've talked to my tuner about trouble codes being suppressed, and he has told me the only codes suppressed on this tune are for the o2's for the cat delete.

Here is an Uprev Datalog I took of the startup and several seconds of idling terrible. Maybe someone experienced can spot an obvious issue.
https://drive.google.com/open?id=10Y...Cg4H3pfr0mqCc5

I have no idea where to go from here except to jump straight to tearing the intake manifold off and checking/replacing all plugs, coils, injectors. Please anyone with similar experience with input?

Jinxx · 09-25-2018, 01:16 AM

Try flashing to stock tune ..... and if no codes are showing I would verify fuel pressure is around 52 psi .... and I would replace spark plugs and see how it does ... strange that there isn’t any codes tho .... I actually had a injector not plugged in all the way and it ran ( like crap..)without throwing a code but I would try those first

dts3 · 09-25-2018, 08:05 AM

I've never kept a car parked that long... How long does it take for that much gas to go bad?

TBatt · 09-25-2018, 09:47 AM

Quote:

Originally Posted by dts3

I've never kept a car parked that long... How long does it take for that much gas to go bad?

That depends on the gas. Different areas use different fuel treatment "packages".

I recommend checking fuel pressure too.

mults · 09-25-2018, 10:37 AM

Quote:

Originally Posted by dts3

I've never kept a car parked that long... How long does it take for that much gas to go bad?

I've had mine parked for 6 months at a time during the winter (with Sea Foam in the tank) and have NEVER had any issues starting in the spring. I would say that it takes more than a month for fresh fuel to go bad.

dts3 · 09-25-2018, 03:13 PM

Quote:

Originally Posted by mults

I've had mine parked for 6 months at a time during the winter (with Sea Foam in the tank) and have NEVER had any issues starting in the spring. I would say that it takes more than a month for fresh fuel to go bad.

That would be my assumption as well... Especially when we're talking about ~13 gallons. Just thought I'd throw that out there

SouthArk370Z · 09-25-2018, 03:19 PM

Quote:

Originally Posted by dts3

I've never kept a car parked that long... How long does it take for that much gas to go bad?

As mentioned above, it just depends. How "fresh" was the gas when you bought it? How was the car stored? Etc. If you think the gas in the tank is bad and you can safely do so, remove as much gas from the tank as you can and refill with good gas.

I suspect you have a sensor problem but couldn't even guess which one. Rather strange that no DTCs are popping up.
Edit: It might be a fuel pump problem. Search this site for "tophat", "fuel pump", etc.

King · 09-28-2018, 01:53 AM

Quote:

Originally Posted by Jinxx

Try flashing to stock tune ..... and if no codes are showing I would verify fuel pressure is around 52 psi .... and I would replace spark plugs and see how it does ...

I have a stock Tune waiting to try a reflash this weekend.

Any of you gents have any tips on checking the fuel pressure? from what i've seen searching it there isn't a simple way to check it on the z...

Jinxx · 09-28-2018, 07:41 PM

Quote:

Originally Posted by King

I have a stock Tune waiting to try a reflash this weekend.

Any of you gents have any tips on checking the fuel pressure? from what i've seen searching it there isn't a simple way to check it on the z...

There should be a block that goes under the stock regulator that would have threaded spots for guages and fuel lines ... I have the fuel return kit in mine and it came with the block ... you should be able to buy it separately .. I’m sure the guys running a wet nitrous kit would know where to find one
Here is one ... I’m sure there are others. https://autoplicity.com/261362-nitro...yABEgLJw_D_BwE

09-24-2018, 08:15 PM	#1 (permalink)
King Base Member Join Date: Oct 2016 Location: NorCal Posts: 86 Drives: 2015 370Z Pearl Rep Power: 9	Please help - car starts but wont run PLEASE HELP. Car Won't run correctly, Sounds like it is running on one cylinder almost. Like serious misfire. A super loped Idle. 2015. Car is modified, Full intake, catless Exhaust, and Uprev Tuned, still NA nothing crazy. Only 30k miles, maybe 8k miles with tune. No previous motor issues, just CSC. Car was parked with 3/4 tank, running perfectly, sat for about 30 days. When I tried to start it fired and ran terribly. See first paragraph. NO DTC Codes. Sent it to Nissan for diagnosis. Their diagnosis was 'There are no trouble codes we can't help you.' ******* Central Valley Nissan is useless. So I paid them to install a new Crank Position Sensor, seeing some threads online about CPS not throwing a trouble code on Z's. didn't help. When I got the car back home there was a new MAF DTC code. Replaced the MAF bank 1 just to find out the MAF code was Nissan unplugging stuff as an experiment. I reflashed the ECU with my Uprev tune. No change. I've talked to my tuner about trouble codes being suppressed, and he has told me the only codes suppressed on this tune are for the o2's for the cat delete. Here is an Uprev Datalog I took of the startup and several seconds of idling terrible. Maybe someone experienced can spot an obvious issue. https://drive.google.com/open?id=10Y...Cg4H3pfr0mqCc5 I have no idea where to go from here except to jump straight to tearing the intake manifold off and checking/replacing all plugs, coils, injectors. Please anyone with similar experience with input?

09-25-2018, 01:16 AM	#2 (permalink)
Jinxx Track Member Join Date: Dec 2015 Location: South Carolina Posts: 699 Drives: 2017 nismo 370z Rep Power: 3376	Try flashing to stock tune ..... and if no codes are showing I would verify fuel pressure is around 52 psi .... and I would replace spark plugs and see how it does ... strange that there isn’t any codes tho .... I actually had a injector not plugged in all the way and it ran ( like crap..)without throwing a code but I would try those first Last edited by Jinxx; 09-25-2018 at 01:19 AM.

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09-25-2018, 08:05 AM	#3 (permalink)
dts3 Track Member Join Date: May 2018 Location: Farmington Hills, MI Posts: 599 Drives: 08 Expedition Rep Power: 6765	I've never kept a car parked that long... How long does it take for that much gas to go bad?