Go Back   Infamous Nissan - Hardbody / Frontier Forums > Tech Area > Engine and Drivetrain

Reply
 
Thread Tools Display Modes
Old 02-19-2021, 02:15 AM   #1
KivPanther
Furball
 
KivPanther's Avatar
 
Join Date: Oct 2020
Location: North Carolina
Posts: 113
Vehicle: 1994 XE King Cab
Thanks: 3
Thanked 21 Times in 18 Posts
Default Stumble troubleshooting advice

I’m having a bastard of a time tracking down this intermittent stumble in my V6 so I need to pick some brains.
  • It only happens when under light acceleration or cruising; doesn’t do it coasting under power, idling, or under heavy acceleration.
  • It seems to only do it around about 3k RPM.
  • It does it both cold and hot with no seeming change in frequency.
  • It happens very quickly, often a couple times in succession. Not enough to cause the tach to jitter even.
  • It also does it while cruise is active and doesn’t seem to affect its performance.

I have replaced many vacuum hoses and couldn’t find a leak using smoke. The O2 sensor has been replaced. I cleaned the MAF while the manifold was off the truck. All the injectors are brand new and have brand new o rings and seals. The distributor is new, the spark plugs are new, and the plug wires are new. Any thoughts?
__________________

Last edited by KivPanther; 02-19-2021 at 09:47 PM.
KivPanther is offline   Reply With Quote
Old 02-19-2021, 03:10 AM   #2
Deerhurst
4/86 SE-V6 2 tone 4x4 HB
 
Deerhurst's Avatar
 
Join Date: Apr 2013
Location: Oregon
Posts: 7,445
Vehicle: 1986.5 SE-V6 4WD D21, 2003 Audi A4 Avant 3.0 Quattro
Thanks: 893
Thanked 922 Times in 840 Posts
Default

Any codes? How old are your plugs and wires?
__________________
1986.5 SE-V6 4X4 D21 Hardbody
Pacesetter Long Tube Headers
Morimoto Mini D2S HID Projectors and Hella 500s
VG33i
Deerhurst is offline   Reply With Quote
Old 02-19-2021, 03:32 AM   #3
KivPanther
Furball
 
KivPanther's Avatar
 
Join Date: Oct 2020
Location: North Carolina
Posts: 113
Vehicle: 1994 XE King Cab
Thanks: 3
Thanked 21 Times in 18 Posts
Default

No codes. Plugs and wires are brand new. NGK iridium plugs (real ones) and NGK blue wires.
__________________
KivPanther is offline   Reply With Quote
Old 02-19-2021, 03:50 AM   #4
Ftown
 
Join Date: Dec 2020
Location: Lakeland, FL
Posts: 30
Vehicle: 1995 Hardbody XE V6
Thanks: 4
Thanked 1 Time in 1 Post
Default

It happens while in cruise control? Maybe the cruise mechanism is going out. Try smoking the cruise control mechanism. It also runs off vacuum
Ftown is offline   Reply With Quote
Old 02-19-2021, 03:55 AM   #5
Ftown
 
Join Date: Dec 2020
Location: Lakeland, FL
Posts: 30
Vehicle: 1995 Hardbody XE V6
Thanks: 4
Thanked 1 Time in 1 Post
Default

Also, I'd check your injectors. I have an f150 that I chased a miss I thought was a vacuum leak. Turned out to be a bad injector
Ftown is offline   Reply With Quote
Old 02-19-2021, 05:08 AM   #6
KivPanther
Furball
 
KivPanther's Avatar
 
Join Date: Oct 2020
Location: North Carolina
Posts: 113
Vehicle: 1994 XE King Cab
Thanks: 3
Thanked 21 Times in 18 Posts
Default

Sorry, I should clarify: It doesn't happen ONLY while in cruise control, it happens ALSO while in cruise control. I actually just replaced the ASCD vacuum hose since it had rotted, but it has its own vacuum pump separate from the engine control system. The fuel injectors are, as mentioned above, all brand new, tested working, and getting pulse.
__________________
KivPanther is offline   Reply With Quote
Old 02-19-2021, 08:31 PM   #7
89'HBV6
Ol'school Geek
 
89'HBV6's Avatar
 
Join Date: Mar 2020
Location: Washington State
Posts: 520
Vehicle: 89' D21 KC SE V6 5spd 2WD - 87' D21 KC SE V6 5spd 2WD
Thanks: 534
Thanked 130 Times in 113 Posts
Default

If you replaced the vac line to the cruise, what condition was it in? Could be some smaller particulates got pulled in? ...from the inside of the old rotted hose? (thinking outloud)
89'HBV6 is offline   Reply With Quote
Old 02-19-2021, 09:46 PM   #8
KivPanther
Furball
 
KivPanther's Avatar
 
Join Date: Oct 2020
Location: North Carolina
Posts: 113
Vehicle: 1994 XE King Cab
Thanks: 3
Thanked 21 Times in 18 Posts
Default

The ASCD itself is old it in good shape. The only thing bad was the vacuum hose. Still though, since it does it regardless of whether I’m in cruise control or not I doubt it’s related.
__________________
KivPanther is offline   Reply With Quote
Thanked by:
89'HBV6 (02-19-2021)
Old 02-19-2021, 10:57 PM   #9
LugNut1990
 
LugNut1990's Avatar
 
Join Date: Jul 2015
Location: N.E. Kansas
Posts: 744
Vehicle: 1990 Nissan Hardbody
Thanks: 0
Thanked 101 Times in 89 Posts
Default

So no change between before/after the new injectors?


It seems that the problem would be more evident under hard acceleration if fuel-flow was the cause, but did you change the fuel filter too?


If it is repeatable, try cracking the gas cap open and trying it again. Might generate an error code, but is the miss gone?
__________________
Original owner
1990 Nissan Hardbody, Aztec Red
Standard cab, 4x4, KA24E, 5-speed
Intentionally near-stock
Mods: Second OEM horn, stereo/speakers/sub,
mud and snow tires, HD trailer hitch (cat 3+),
liquid bed liner, G1W dashcam
Definitely not for sale!
LugNut1990 is offline   Reply With Quote
Old 02-20-2021, 01:01 AM   #10
KivPanther
Furball
 
KivPanther's Avatar
 
Join Date: Oct 2020
Location: North Carolina
Posts: 113
Vehicle: 1994 XE King Cab
Thanks: 3
Thanked 21 Times in 18 Posts
Default

Correct; there was no change after the injectors were replaced. I did replace the fuel
filter at the same time. I had bought a new TPS but hadn’t gotten around to installing it yet since I wasn’t sure it would need it. I also haven’t been able to get the idle to drop all the way to 750 after warming up even after adjustment. I might just go ahead and swap them just in case.

I’ll give the gas cap thing a go on my way home from shift tonight and see what happens.
__________________
KivPanther is offline   Reply With Quote
Reply

Thread Tools
Display Modes

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

Forum Jump


All times are GMT. The time now is 10:14 AM.


Powered by vBulletin® Version 3.8.6
Copyright ©2000 - 2021, Jelsoft Enterprises Ltd.