06 GT misfire mystery HELP
3/15/12, 09:39 PM
#1
Member
Thread Starter
Join Date: March 15, 2012
Posts: 14
Likes: 0
Received 0 Likes
on
0 Posts
06 GT misfire mystery HELP
2006 GT 5speed. I'm having a problem that figure put at all. Short version of the symptoms. Random cylinders misfire at idle and low to mid-ish rpm's under load, and it lopes. Burnt matches/sulphur smell from exhaust. I have checked all the plugs and coils. Checked the MAF. Changed the TPS. Changed the fuel filter. Checked all 8 injectors and they are functioning. Run injector cleaner through it (do that regularly anyways). The battery and alternator are both ok, I changed both and no difference. Air filter (KNN cold air) is fine as is the throttle body and TB motor. I feel like I'm missing something else ive checked but idk long day. Have a pressure tester so I'll check for a blockage in the exhaust tomorrow. Don't know how to check the Evap system. I only have two ideas at this point what it could be and I don't even want to think about it(2 catalytic converters $$$$). Anyone else have ideas/suggestions/help? Thanks a lot guys.
3/15/12, 11:07 PM
#5
Legacy TMS Member
Sulphur smell is the cats doing their job, maybe because the gas you're using sucks, to be frank. Put premium gas in, and do it from ANOTHER SOURCE from where you're getting it now. Until then, get some octane booster in it.
THE OTHER reason it is smelling like that is, again, it's doing it's job, but only because there's WAY too much fuel escaping the engine itself, causing the gas to burn in the cats. Sulfur smell is Hydrogen Sulfide(H2S), and it's caused by unburnt fuel in the cats. There's a leaking injector, likely, that's not closing all the way perhaps.
Beyond that, the rough running is perhaps due to the KNN filter, put the regular filter back on.
Other rough running is bad spark plugs, bad coils, bad fuel, bad fuel delivery (meaning the fuel pump, or the fuel's getting blocked in the pickup somehow), bad MAF, bad TPS, dirty throttle body, a short or faulty electricals, a bad computer, exhaust issues, timing or phasers could be messed up, bad tune, faulty connections (check firewall, check SJB, check fuse panels), air leaks in the intake...
... uh, think that's it? Most of which you already talk about, but you might want to recheck.
I know for a fact, though, that a leaky, not all closing injector can cause this exact symptom... and WILL kill the cats if not dealt with soon. HoopTBird, 1996 v6 Tbird, ran like *crap*, and exactly like this, until I swapped out all the injectors. I never found which one was dribbling, to be honest, but swapping them all out, fixed the issue. Period.
Until the cats destroyed themselves about a month later because it took too long for me figure out what was wrong with her. That hurt the pocketbook pretty nicely.
Fuel burning in the cats (as they're hot enough to do it if gas is 'poured' on them) melts the stuff inside them into a blocked up hunk of crud. Then it disintegrates a little, and plugs up the works. It's really nifty from a scientific point of view, but from fixin' the car point? Ugh.
Weird thing was, she never smelled like rotten eggs... not real sure why that was. They say that the older the cats get the less chance the catalysts do the sulfur thing...
I'd done coils, plugs, egr, all kinds of things. It was really intermittent and drove me NUTS. But now I know what it was, so that's the one I'm bettin on here, given the symptoms, coupled with the smell: It's the injectors or the computer is feeding too much fuel, or it's bad BAD gas.
THE OTHER reason it is smelling like that is, again, it's doing it's job, but only because there's WAY too much fuel escaping the engine itself, causing the gas to burn in the cats. Sulfur smell is Hydrogen Sulfide(H2S), and it's caused by unburnt fuel in the cats. There's a leaking injector, likely, that's not closing all the way perhaps.
Beyond that, the rough running is perhaps due to the KNN filter, put the regular filter back on.
Other rough running is bad spark plugs, bad coils, bad fuel, bad fuel delivery (meaning the fuel pump, or the fuel's getting blocked in the pickup somehow), bad MAF, bad TPS, dirty throttle body, a short or faulty electricals, a bad computer, exhaust issues, timing or phasers could be messed up, bad tune, faulty connections (check firewall, check SJB, check fuse panels), air leaks in the intake...
... uh, think that's it? Most of which you already talk about, but you might want to recheck.
I know for a fact, though, that a leaky, not all closing injector can cause this exact symptom... and WILL kill the cats if not dealt with soon. HoopTBird, 1996 v6 Tbird, ran like *crap*, and exactly like this, until I swapped out all the injectors. I never found which one was dribbling, to be honest, but swapping them all out, fixed the issue. Period.
Until the cats destroyed themselves about a month later because it took too long for me figure out what was wrong with her. That hurt the pocketbook pretty nicely.
Fuel burning in the cats (as they're hot enough to do it if gas is 'poured' on them) melts the stuff inside them into a blocked up hunk of crud. Then it disintegrates a little, and plugs up the works. It's really nifty from a scientific point of view, but from fixin' the car point? Ugh.Weird thing was, she never smelled like rotten eggs... not real sure why that was. They say that the older the cats get the less chance the catalysts do the sulfur thing...
I'd done coils, plugs, egr, all kinds of things. It was really intermittent and drove me NUTS. But now I know what it was, so that's the one I'm bettin on here, given the symptoms, coupled with the smell: It's the injectors or the computer is feeding too much fuel, or it's bad BAD gas.
Last edited by houtex; 3/15/12 at 11:09 PM.
3/15/12, 11:52 PM
#6
Cobra R Member
Join Date: July 27, 2011
Location: Houston, TX
Posts: 1,569
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by houtex
Sulphur smell is the cats doing their job, maybe because the gas you're using sucks, to be frank. Put premium gas in, and do it from ANOTHER SOURCE from where you're getting it now. Until then, get some octane booster in it.
THE OTHER reason it is smelling like that is, again, it's doing it's job, but only because there's WAY too much fuel escaping the engine itself, causing the gas to burn in the cats. Sulfur smell is Hydrogen Sulfide(H2S), and it's caused by unburnt fuel in the cats. There's a leaking injector, likely, that's not closing all the way perhaps.
Beyond that, the rough running is perhaps due to the KNN filter, put the regular filter back on.
Other rough running is bad spark plugs, bad coils, bad fuel, bad fuel delivery (meaning the fuel pump, or the fuel's getting blocked in the pickup somehow), bad MAF, bad TPS, dirty throttle body, a short or faulty electricals, a bad computer, exhaust issues, timing or phasers could be messed up, bad tune, faulty connections (check firewall, check SJB, check fuse panels), air leaks in the intake...
... uh, think that's it? Most of which you already talk about, but you might want to recheck.
I know for a fact, though, that a leaky, not all closing injector can cause this exact symptom... and WILL kill the cats if not dealt with soon. HoopTBird, 1996 v6 Tbird, ran like *crap*, and exactly like this, until I swapped out all the injectors. I never found which one was dribbling, to be honest, but swapping them all out, fixed the issue. Period.
Until the cats destroyed themselves about a month later because it took too long for me figure out what was wrong with her. That hurt the pocketbook pretty nicely. Fuel burning in the cats (as they're hot enough to do it if gas is 'poured' on them) melts the stuff inside them into a blocked up hunk of crud. Then it disintegrates a little, and plugs up the works. It's really nifty from a scientific point of view, but from fixin' the car point? Ugh.
Weird thing was, she never smelled like rotten eggs... not real sure why that was. They say that the older the cats get the less chance the catalysts do the sulfur thing...
I'd done coils, plugs, egr, all kinds of things. It was really intermittent and drove me NUTS. But now I know what it was, so that's the one I'm bettin on here, given the symptoms, coupled with the smell: It's the injectors or the computer is feeding too much fuel, or it's bad BAD gas.
THE OTHER reason it is smelling like that is, again, it's doing it's job, but only because there's WAY too much fuel escaping the engine itself, causing the gas to burn in the cats. Sulfur smell is Hydrogen Sulfide(H2S), and it's caused by unburnt fuel in the cats. There's a leaking injector, likely, that's not closing all the way perhaps.
Beyond that, the rough running is perhaps due to the KNN filter, put the regular filter back on.
Other rough running is bad spark plugs, bad coils, bad fuel, bad fuel delivery (meaning the fuel pump, or the fuel's getting blocked in the pickup somehow), bad MAF, bad TPS, dirty throttle body, a short or faulty electricals, a bad computer, exhaust issues, timing or phasers could be messed up, bad tune, faulty connections (check firewall, check SJB, check fuse panels), air leaks in the intake...
... uh, think that's it? Most of which you already talk about, but you might want to recheck.
I know for a fact, though, that a leaky, not all closing injector can cause this exact symptom... and WILL kill the cats if not dealt with soon. HoopTBird, 1996 v6 Tbird, ran like *crap*, and exactly like this, until I swapped out all the injectors. I never found which one was dribbling, to be honest, but swapping them all out, fixed the issue. Period.
Until the cats destroyed themselves about a month later because it took too long for me figure out what was wrong with her. That hurt the pocketbook pretty nicely.
Fuel burning in the cats (as they're hot enough to do it if gas is 'poured' on them) melts the stuff inside them into a blocked up hunk of crud. Then it disintegrates a little, and plugs up the works. It's really nifty from a scientific point of view, but from fixin' the car point? Ugh.Weird thing was, she never smelled like rotten eggs... not real sure why that was. They say that the older the cats get the less chance the catalysts do the sulfur thing...
I'd done coils, plugs, egr, all kinds of things. It was really intermittent and drove me NUTS. But now I know what it was, so that's the one I'm bettin on here, given the symptoms, coupled with the smell: It's the injectors or the computer is feeding too much fuel, or it's bad BAD gas.
3/16/12, 12:11 AM
#7
Member
Thread Starter
Join Date: March 15, 2012
Posts: 14
Likes: 0
Received 0 Likes
on
0 Posts
I agree with you Houtex there is too much fuel getting in there and it's running rich. But wouldn't one of the a specific cylinder or cylinders give me a trouble code? Maybe it is crap gas too. This sulpher smell is brand new as of today but the misfires have been getting slowly worse for 2 weeks. I have been using cheapie gas lately, so maybe just a fill up with brand name 87 Octane? I haven't flashed so I hope that's fine. What do you think?
3/16/12, 12:15 AM
#8
Cobra R Member
Join Date: July 27, 2011
Location: Houston, TX
Posts: 1,569
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by tmmanner79
I agree with you Houtex there is too much fuel getting in there and it's running rich. But wouldn't one of the a specific cylinder or cylinders give me a trouble code? Maybe it is crap gas too. This sulpher smell is brand new as of today but the misfires have been getting slowly worse for 2 weeks. I have been using cheapie gas lately, so maybe just a fill up with brand name 87 Octane? I haven't flashed so I hope that's fine. What do you think?
3/16/12, 12:44 AM
#10
Cobra R Member
Join Date: July 27, 2011
Location: Houston, TX
Posts: 1,569
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by tmmanner79
I got cheap on the gas. It's true. Any way to check/know which injectors are bad? BTW cheap is a relative term with 2 kids! Haha
3/16/12, 11:31 AM
#12
Post *****
Join Date: December 14, 2007
Location: State of Jefferson Mountains USA
Posts: 20,005
Likes: 0
Received 4 Likes
on
4 Posts
I agree with you Houtex there is too much fuel getting in there and it's running rich. But wouldn't one of the a specific cylinder or cylinders give me a trouble code? Maybe it is crap gas too. This sulpher smell is brand new as of today but the misfires have been getting slowly worse for 2 weeks. I have been using cheapie gas lately, so maybe just a fill up with brand name 87 Octane? I haven't flashed so I hope that's fine. What do you think?
Either too much fuel like you say... but the fact that cylinders aren't firing would also make you think its running rich by the increased smell of unburned fuel.
Check for codes? Doesn't autozone or somebody check for free?
Can an O2 sensor be failing?
Unhook the battery and reset the ECU?
How many miles? Have you changed the (old style) plugs yet?
Last edited by cdynaco; 3/16/12 at 11:34 AM.
3/16/12, 11:39 AM
#13
Member
Thread Starter
Join Date: March 15, 2012
Posts: 14
Likes: 0
Received 0 Likes
on
0 Posts
Cdynaco, the code it threw was "random misfire" no specific cylinder. No o2 code but idk. Have unhooked the battery numerous times while trying to figure this out and no help. About 60k miles on the orig plugs. Starting to think maybe a leaky injector or 2. Thanks for the response. Ideas?
3/16/12, 12:59 PM
#14
Cobra R Member
Join Date: July 27, 2011
Location: Houston, TX
Posts: 1,569
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by tmmanner79
Cdynaco, the code it threw was "random misfire" no specific cylinder. No o2 code but idk. Have unhooked the battery numerous times while trying to figure this out and no help. About 60k miles on the orig plugs. Starting to think maybe a leaky injector or 2. Thanks for the response. Ideas?
3/16/12, 01:04 PM
#15
A Man Just Needs Some....
Sounds like a fuel issue. Usually sulphur smell will be unburned fuel that the cats are burning. Fuel pressure gauge is probably needed. Key on engine off, let the fuel system prime with the gauge on it and see if the pressure leaks down. Also check your fuel pressure regulator, pull the vacuum hose from it and see if it's leaking fuel thru the vacuum port. O2 sensors reading incorrectly will also cause this condition.
man. Really sounds like a pay a pro diag problem but let's see if this get us anywhere. 
3/16/12, 03:09 PM
#18
Member
Thread Starter
Join Date: March 15, 2012
Posts: 14
Likes: 0
Received 0 Likes
on
0 Posts
I know I should take it to a pro, but it's a matter of pride now. Plus I'd rather get help from you fine gentlemen and drink a beer while I monkey around with the car then pay someone else $90 an hour! So thanks a lot guys!
3/16/12, 03:31 PM
#19
A Man Just Needs Some....
It's pretty tough these days without all the diag tools and really knowing the control systems. Go with what I said about the fuel system first and we will try and get you fixed.
Subscribing to thread.
Subscribing to thread.
3/16/12, 03:36 PM
#20
Post *****
Join Date: December 14, 2007
Location: State of Jefferson Mountains USA
Posts: 20,005
Likes: 0
Received 4 Likes
on
4 Posts
This guy had surging issues - apparently a tsb for 05's & 06's? New fuel pump fixed it. 
https://themustangsource.com/f637/fu...4/#post6276510
https://themustangsource.com/f637/fu...4/#post6276510