Nissan 370Z Forum  

Strong gas smell when starting

Originally Posted by Jhill If you do an ecm reset after warm how quickly and how high (or low I guess) do the short term fuel trim jump? Meaning does

Go Back   Nissan 370Z Forum > Nissan 370Z Tech Area > Engine & Drivetrain


Like Tree12Likes

Reply
 
LinkBack Thread Tools Display Modes
Old 10-14-2017, 02:48 PM   #31 (permalink)
A True Z Fanatic
 
Z_ealot's Avatar
 
Join Date: Sep 2010
Location: Albuquerque, NM
Posts: 2,045
Drives: 09 370Z Touring/Sprt
Rep Power: 10091
Z_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond repute
Default

Quote:
Originally Posted by Jhill View Post
If you do an ecm reset after warm how quickly and how high (or low I guess) do the short term fuel trim jump? Meaning does it jump to something like -15 and keep pegging there as long term drops.
It’s been a while since i did that so i woukdnt be sure about the exact behavior it exhibited. What i can tell you about the last time i did that is that i do remember it struggling and having a rough idle after i performed an ecu reset and performed an idle air relearn, it did finally smooth out after a few minutes though.
Z_ealot is offline   Reply With Quote
Old 10-15-2017, 10:33 AM   #32 (permalink)
A True Z Fanatic
 
Z_ealot's Avatar
 
Join Date: Sep 2010
Location: Albuquerque, NM
Posts: 2,045
Drives: 09 370Z Touring/Sprt
Rep Power: 10091
Z_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond repute
Default

This is what the injectors looked like when i went to visually inspect them....


Sent from my iPhone using Tapatalk
Z_ealot is offline   Reply With Quote
Old 10-16-2017, 08:30 PM   #33 (permalink)
A True Z Fanatic
 
Z_ealot's Avatar
 
Join Date: Sep 2010
Location: Albuquerque, NM
Posts: 2,045
Drives: 09 370Z Touring/Sprt
Rep Power: 10091
Z_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond repute
Default

Quote:
Originally Posted by Jhill View Post
If you do an ecm reset after warm how quickly and how high (or low I guess) do the short term fuel trim jump? Meaning does it jump to something like -15 and keep pegging there as long term drops.
I did the best I could getting a chart of what the fuel trims are doing with what tools I have, keep in mind the blue and gray lines are short term fuel trims for banks 1 and 2 and the orange and red are the long terms, this was taken today with ambient outside temps at 92 degrees while driving normally

Z_ealot is offline   Reply With Quote
Old 10-16-2017, 09:48 PM   #34 (permalink)
Track Member
 
Join Date: Mar 2016
Location: San jose
Posts: 854
Drives: 2013 370z sport
Rep Power: 3384
Jhill has a reputation beyond reputeJhill has a reputation beyond reputeJhill has a reputation beyond reputeJhill has a reputation beyond reputeJhill has a reputation beyond reputeJhill has a reputation beyond reputeJhill has a reputation beyond reputeJhill has a reputation beyond reputeJhill has a reputation beyond reputeJhill has a reputation beyond reputeJhill has a reputation beyond repute
Default

Quote:
Originally Posted by Z_ealot View Post
I did the best I could getting a chart of what the fuel trims are doing with what tools I have, keep in mind the blue and gray lines are short term fuel trims for banks 1 and 2 and the orange and red are the long terms, this was taken today with ambient outside temps at 92 degrees while driving normally

Little hard to read, is this idling or driving? I was more just after seeing the short term % pegged - after a reset to idicate if you have an injector leaking or something else causing a large unaccounted increase in fuel. Unsure on the z but I've rarely actually had leaky injectors (maybe I'm just lucky). Your comment of it having a hard/stumbling start after reset would indicate an issue (especially if it says a hot start after reset). May be time to check fuel pressure (typical they fail low but I have on vary rare occasion had overly high pressures). Can check residual pressure at same time.
Jhill is offline   Reply With Quote
Old 10-16-2017, 10:13 PM   #35 (permalink)
A True Z Fanatic
 
Z_ealot's Avatar
 
Join Date: Sep 2010
Location: Albuquerque, NM
Posts: 2,045
Drives: 09 370Z Touring/Sprt
Rep Power: 10091
Z_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond repute
Default

Quote:
Originally Posted by Jhill View Post
Little hard to read, is this idling or driving? I was more just after seeing the short term % pegged - after a reset to idicate if you have an injector leaking or something else causing a large unaccounted increase in fuel. Unsure on the z but I've rarely actually had leaky injectors (maybe I'm just lucky). Your comment of it having a hard/stumbling start after reset would indicate an issue (especially if it says a hot start after reset). May be time to check fuel pressure (typical they fail low but I have on vary rare occasion had overly high pressures). Can check residual pressure at same time.
The peaks on the blue and gray stft are when it’s pegged at +25%, what might be interesting to you is that before i started recording the ltft was at -8% at a hot start with stft pegged at +25% for a good 10 seconds and then the engine stumbled and the fuel trims reversed with ltft shooting up to +10% and stft dropping to -15%. The graph i posted was recorded after this while i was driving in the city so it was a mix of acceleration and idling
Z_ealot is offline   Reply With Quote
Old 10-17-2017, 05:06 PM   #36 (permalink)
Track Member
 
Join Date: Mar 2016
Location: San jose
Posts: 854
Drives: 2013 370z sport
Rep Power: 3384
Jhill has a reputation beyond reputeJhill has a reputation beyond reputeJhill has a reputation beyond reputeJhill has a reputation beyond reputeJhill has a reputation beyond reputeJhill has a reputation beyond reputeJhill has a reputation beyond reputeJhill has a reputation beyond reputeJhill has a reputation beyond reputeJhill has a reputation beyond reputeJhill has a reputation beyond repute
Default

Quote:
Originally Posted by Z_ealot View Post
The peaks on the blue and gray stft are when it’s pegged at +25%, what might be interesting to you is that before i started recording the ltft was at -8% at a hot start with stft pegged at +25% for a good 10 seconds and then the engine stumbled and the fuel trims reversed with ltft shooting up to +10% and stft dropping to -15%. The graph i posted was recorded after this while i was driving in the city so it was a mix of acceleration and idling
So what's stft and ltft after full warm and leveled out, idle and like a steady cruise, no radical acceleration etc.
Jhill is offline   Reply With Quote
Old 10-17-2017, 06:27 PM   #37 (permalink)
A True Z Fanatic
 
Z_ealot's Avatar
 
Join Date: Sep 2010
Location: Albuquerque, NM
Posts: 2,045
Drives: 09 370Z Touring/Sprt
Rep Power: 10091
Z_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond repute
Default

Quote:
Originally Posted by Jhill View Post
So what's stft and ltft after full warm and leveled out, idle and like a steady cruise, no radical acceleration etc.


At idle after warming up ltft sits at -10.2% with stft fluctuating between +3% and +20%, usually i see the +20% and above after the engine is heatsoaked and idling. During cruising with rpm at a steady 2500 ltft usually sits at -3 to -5% with stft between 0 to +3%


Sent from my iPhone using Tapatalk
Z_ealot is offline   Reply With Quote
Old 10-17-2017, 07:11 PM   #38 (permalink)
Track Member
 
Join Date: Mar 2016
Location: San jose
Posts: 854
Drives: 2013 370z sport
Rep Power: 3384
Jhill has a reputation beyond reputeJhill has a reputation beyond reputeJhill has a reputation beyond reputeJhill has a reputation beyond reputeJhill has a reputation beyond reputeJhill has a reputation beyond reputeJhill has a reputation beyond reputeJhill has a reputation beyond reputeJhill has a reputation beyond reputeJhill has a reputation beyond reputeJhill has a reputation beyond repute
Default

Quote:
Originally Posted by Z_ealot View Post
At idle after warming up ltft sits at -10.2% with stft fluctuating between +3% and +20%, usually i see the +20% and above after the engine is heatsoaked and idling. During cruising with rpm at a steady 2500 ltft usually sits at -3 to -5% with stft between 0 to +3%


Sent from my iPhone using Tapatalk
Ok so your cruising numbers look good. Idle I would like a lower number but not terrible for ltft but the huge fluctuations in short term don’t look so good (although not a vq expert but that doesn’t seem great to me). How many miles on this engine? No roughness or intermittent misfires at lower RPM/idle?
Jhill is offline   Reply With Quote
Old 10-17-2017, 08:01 PM   #39 (permalink)
A True Z Fanatic
 
Z_ealot's Avatar
 
Join Date: Sep 2010
Location: Albuquerque, NM
Posts: 2,045
Drives: 09 370Z Touring/Sprt
Rep Power: 10091
Z_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond repute
Default

Quote:
Originally Posted by Jhill View Post
Ok so your cruising numbers look good. Idle I would like a lower number but not terrible for ltft but the huge fluctuations in short term don’t look so good (although not a vq expert but that doesn’t seem great to me). How many miles on this engine? No roughness or intermittent misfires at lower RPM/idle?


Just climbing up on 158,000 miles, the only roughness i encounter is when the stft pegs itself at +25% and then the engine stumbles and almost stalls and then that’s when the fuel trim numbers flip and the idle smooths out again, curiously the engine seems to act like it’s choking after this when i go to accelerate and does not really pick up power till after 5,000rpm.


Sent from my iPhone using Tapatalk
Z_ealot is offline   Reply With Quote
Old 10-17-2017, 09:22 PM   #40 (permalink)
Track Member
 
Join Date: Mar 2016
Location: San jose
Posts: 854
Drives: 2013 370z sport
Rep Power: 3384
Jhill has a reputation beyond reputeJhill has a reputation beyond reputeJhill has a reputation beyond reputeJhill has a reputation beyond reputeJhill has a reputation beyond reputeJhill has a reputation beyond reputeJhill has a reputation beyond reputeJhill has a reputation beyond reputeJhill has a reputation beyond reputeJhill has a reputation beyond reputeJhill has a reputation beyond repute
Default

Quote:
Originally Posted by Z_ealot View Post
Just climbing up on 158,000 miles, the only roughness i encounter is when the stft pegs itself at +25% and then the engine stumbles and almost stalls and then that’s when the fuel trim numbers flip and the idle smooths out again, curiously the engine seems to act like it’s choking after this when i go to accelerate and does not really pick up power till after 5,000rpm.


Sent from my iPhone using Tapatalk
How's it drive with both mafs disconnected?
Jhill is offline   Reply With Quote
Old 10-17-2017, 09:41 PM   #41 (permalink)
A True Z Fanatic
 
Z_ealot's Avatar
 
Join Date: Sep 2010
Location: Albuquerque, NM
Posts: 2,045
Drives: 09 370Z Touring/Sprt
Rep Power: 10091
Z_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond repute
Default Strong gas smell when starting

Quote:
Originally Posted by Jhill View Post
How's it drive with both mafs disconnected?


Acts like it wants to die with both disconnected at idle, rpm’s fluctuate between 1500 and 600rpm, both maf’s are new


Sent from my iPhone using Tapatalk
Z_ealot is offline   Reply With Quote
Old 10-17-2017, 09:46 PM   #42 (permalink)
Track Member
 
Join Date: Mar 2016
Location: San jose
Posts: 854
Drives: 2013 370z sport
Rep Power: 3384
Jhill has a reputation beyond reputeJhill has a reputation beyond reputeJhill has a reputation beyond reputeJhill has a reputation beyond reputeJhill has a reputation beyond reputeJhill has a reputation beyond reputeJhill has a reputation beyond reputeJhill has a reputation beyond reputeJhill has a reputation beyond reputeJhill has a reputation beyond reputeJhill has a reputation beyond repute
Default

Quote:
Originally Posted by Z_ealot View Post
Acts like it wants to die with both disconnected at idle, rpm’s fluctuate between 1500 and 600rpm, both maf’s are new


Sent from my iPhone using Tapatalk
That's odd, I haven't tested this on the Z but typically a car will default to safe mode that almost always runs smooth with no MAF reading (usually a good indicator if the MAF is bad if it's smooths out with it disconnected). I'll have to test it on mine.

Have you checked the basics like vacuum leak?
Jhill is offline   Reply With Quote
Old 10-17-2017, 10:08 PM   #43 (permalink)
A True Z Fanatic
 
Z_ealot's Avatar
 
Join Date: Sep 2010
Location: Albuquerque, NM
Posts: 2,045
Drives: 09 370Z Touring/Sprt
Rep Power: 10091
Z_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond repute
Default

Quote:
Originally Posted by Jhill View Post
That's odd, I haven't tested this on the Z but typically a car will default to safe mode that almost always runs smooth with no MAF reading (usually a good indicator if the MAF is bad if it's smooths out with it disconnected). I'll have to test it on mine.



Have you checked the basics like vacuum leak?


Triple checked and couldnt find any leaks even trying to hunt one down with soapy water. The only suspicious thing i happened to spot was what looked to be a tear in the outer part of of the intake manifold gasket.


Sent from my iPhone using Tapatalk
Z_ealot is offline   Reply With Quote
Old 10-17-2017, 10:26 PM   #44 (permalink)
Track Member
 
Join Date: Mar 2016
Location: San jose
Posts: 854
Drives: 2013 370z sport
Rep Power: 3384
Jhill has a reputation beyond reputeJhill has a reputation beyond reputeJhill has a reputation beyond reputeJhill has a reputation beyond reputeJhill has a reputation beyond reputeJhill has a reputation beyond reputeJhill has a reputation beyond reputeJhill has a reputation beyond reputeJhill has a reputation beyond reputeJhill has a reputation beyond reputeJhill has a reputation beyond repute
Default

Well I'll have to disconnect my mafs to make sure the z doesn't do something different than what I'm used to but from what I'm hearing is it's running really well at cruise load but issues at idle (where engine are most sensitive). I've seen engines with moderate leak down (valve train issues) do this but it's usually accompanied by a rougher idle and an intermittent misfire but at 158k on an engine not known to have valvetrain issues I doubt it, vacuum leaks can cause this but I would suspect your fuel trim would be going + not -, mafs acting up (typically accompanied with a dead spot in the powerband) but I'll admit none of the car lines I've worked for had dual intakes but I assume it averages
both. I will say I have had one injector have a poor spray pattern sort of have the same symptoms you describe but again a rough idle and misfire that would smooth out and run fine at cruise with more airflow/turbulence to atomize the fuel (not sure what fuel trims would be doing as it was pre obd) but this is highly unlikely i think. Slightly leaking injector but usually accompanied with a stumbling start.

Do you have a scope with amp clamp? If so scope the amperage for the injectors power wire (before it splits into parallel) and see if all the injector amperage are relitively equal.
Jhill is offline   Reply With Quote
Old 10-18-2017, 01:49 AM   #45 (permalink)
A True Z Fanatic
 
Z_ealot's Avatar
 
Join Date: Sep 2010
Location: Albuquerque, NM
Posts: 2,045
Drives: 09 370Z Touring/Sprt
Rep Power: 10091
Z_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond reputeZ_ealot has a reputation beyond repute
Default

Quote:
Originally Posted by Jhill View Post
Well I'll have to disconnect my mafs to make sure the z doesn't do something different than what I'm used to but from what I'm hearing is it's running really well at cruise load but issues at idle (where engine are most sensitive). I've seen engines with moderate leak down (valve train issues) do this but it's usually accompanied by a rougher idle and an intermittent misfire but at 158k on an engine not known to have valvetrain issues I doubt it, vacuum leaks can cause this but I would suspect your fuel trim would be going + not -, mafs acting up (typically accompanied with a dead spot in the powerband) but I'll admit none of the car lines I've worked for had dual intakes but I assume it averages

both. I will say I have had one injector have a poor spray pattern sort of have the same symptoms you describe but again a rough idle and misfire that would smooth out and run fine at cruise with more airflow/turbulence to atomize the fuel (not sure what fuel trims would be doing as it was pre obd) but this is highly unlikely i think. Slightly leaking injector but usually accompanied with a stumbling start.



Do you have a scope with amp clamp? If so scope the amperage for the injectors power wire (before it splits into parallel) and see if all the injector amperage are relitively equal.


Unfortunately a scope is one tool i dont have in my arsenal, I’ll see if i can put together a graph of what exactly it’s doing at cruise speeds as i do have another data file that i recorded over an 80 mile trip after resetting the ecu that i havent processed yet. Appreciate the help in trying to track down this issue, it has been a pain in my side for the last few months trying different things to find out what’s causing it with what little knowledge i have and every mechanic I’ve tooken it to has said there’s nothing wrong with it that they can see


Sent from my iPhone using Tapatalk
Z_ealot is offline   Reply With Quote
Reply

Bookmarks


Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
How strong is the transmission on a z? louiey370z Engine & Drivetrain 14 06-12-2015 11:42 AM
Strong Z showing at VIR this weekend takjak2 Track / Autocross / Drifting / Dragstrip 6 11-30-2011 11:37 PM
FRP? is it realy that strong? Sukh Exterior & Interior 22 01-23-2010 06:40 PM
Strong key NewlyIMPORTed Nissan 370Z General Discussions 7 06-08-2009 02:50 PM


All times are GMT -5. The time now is 03:07 AM.


Powered by vBulletin® Version 3.8.4
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Search Engine Optimization by vBSEO 3.6.0 PL2