Misfiring under heavy load
05-01-2007, 10:37 PM
#1
I never notice, anyway
Rennlist Member
Rennlist Member
Thread Starter
Misfiring under heavy load
I'm having problems when I get on the gas - not associated directly with boost level, but rather the amount I'm on the accelerator. I get some major misfires, sounds like a bunch of ticking noises under the hood, and a plume of black behind me. I've had this problem for a long time, but it's starting to get much worse. What can I start checking? I would assume I'm not getting spark - the plug wires are only 2 years old fwiw.
05-02-2007, 01:04 AM
#7
Burning Brakes
Join Date: Jul 2006
Location: Aurora, Colorado
Posts: 775
Likes: 0
Received 0 Likes
on
0 Posts
Mine is doing something similar. At around 5k rpms when under load it will hesitate heavily...perhaps buck, then accelerate like mad towards redline. It's the strangest damn thing. Was doing it before rebuild...is doing it now too.
Plug wires, cap and rotor are new (today). Still doing it. FPR? Shows steady Fuel pressure on the guage at idle. No idea what it's doing under boost though.
Plug wires, cap and rotor are new (today). Still doing it. FPR? Shows steady Fuel pressure on the guage at idle. No idea what it's doing under boost though.
Trending Topics
05-02-2007, 05:39 AM
#9
Originally Posted by billindenver
Mine is doing something similar. At around 5k rpms when under load it will hesitate heavily...perhaps buck, then accelerate like mad towards redline. It's the strangest damn thing. Was doing it before rebuild...is doing it now too.
Plug wires, cap and rotor are new (today). Still doing it. FPR? Shows steady Fuel pressure on the guage at idle. No idea what it's doing under boost though.
Plug wires, cap and rotor are new (today). Still doing it. FPR? Shows steady Fuel pressure on the guage at idle. No idea what it's doing under boost though.
05-02-2007, 02:15 PM
#11
Addict
Rennlist Member
Rennlist Member
I've battled the same for many months. I've replaced or swapped everything except for the TPS. I have one on order and hope to change it this weekend.
05-02-2007, 02:23 PM
#12
Addict
Rennlist Member
Rennlist Member
Join Date: Nov 2001
Location: Gloucester, Virginia
Posts: 1,488
Likes: 0
Received 3 Likes
on
3 Posts
Originally Posted by billindenver
Mine is doing something similar. At around 5k rpms when under load it will hesitate heavily...perhaps buck, then accelerate like mad towards redline. It's the strangest damn thing. Was doing it before rebuild...is doing it now too.
Plug wires, cap and rotor are new (today). Still doing it. FPR? Shows steady Fuel pressure on the guage at idle. No idea what it's doing under boost though.
Plug wires, cap and rotor are new (today). Still doing it. FPR? Shows steady Fuel pressure on the guage at idle. No idea what it's doing under boost though.
05-02-2007, 02:38 PM
#13
Administrator - "Tyson"
Lifetime Rennlist
Member
Lifetime Rennlist
Member
Originally Posted by Mike Murcia
Ticking noises = detonation = BAD! Either too much boost or bad timing.
Or if you don't fix it
About 7 years ago when I bought a 16V Scirocco for my wife it was making this weird metallic ticking noise under WOT. Not knowing what it was I stopped by a friends house, took him for a ride. He knew what that sound was, timing was WAY off, heavily advanced.
What would cause it on a 951? I have no idea.
05-02-2007, 02:40 PM
#14
Drive-by provocation guy
Rennlist Member
Rennlist Member
Join Date: Apr 2002
Location: NAS PAX River, by way of Orlando
Posts: 10,439
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by billindenver
Mine is doing something similar. At around 5k rpms when under load it will hesitate heavily...perhaps buck, then accelerate like mad towards redline. It's the strangest damn thing. Was doing it before rebuild...is doing it now too.
Plug wires, cap and rotor are new (today). Still doing it. FPR? Shows steady Fuel pressure on the guage at idle. No idea what it's doing under boost though.
Plug wires, cap and rotor are new (today). Still doing it. FPR? Shows steady Fuel pressure on the guage at idle. No idea what it's doing under boost though.
Sounds like a rich/lean spot in your fuel mapping.
Usually, if misfire issue, it only gets worse as the rpms go up and you say after 5K it is fine.