Ultra_Dog
07-02-2006, 12:27 AM
Symptoms:
1) Car runs with a decidedly apparent "Misfire"
2) Smell of gas out exhaust
3) While starting, the starter makes a regular sound, then it speeds up briefly, then normal
4) Autotap registering misfires in Cyl 6, constantly
5) Car runs very poorly, but does idle, although erratically
What is your best guess as to the problem.
zx1216
07-02-2006, 12:55 AM
it may help to know what kind of car it is and this isn't advanced tech so you will prolly be moved...
MachinistOne
07-02-2006, 01:16 AM
It's a valve problem most likely, stuck, burnt, bent...could be valve spring too.
The compression is not building and the raw fuel is coming out the pipe...
jonathan_abilene
07-02-2006, 05:00 AM
dam yer goooood
I'd check that compression
Injuneer
07-02-2006, 10:40 AM
We have "tech" forums for all the different engines..... please post V6 topics in the V6 forum. I'll move it there for you.
jonathan_abilene
07-02-2006, 02:53 PM
We have "tech" forums for all the different engines..... please post V6 topics in the V6 forum. I'll move it there for you.
Ultradog does not have a v6. Take 2 seconds to read who started the thread.
zx1216
07-02-2006, 04:47 PM
Ultradog does not have a v6. Take 2 seconds to read who started the thread.
it NEVER says what kind of car he has, maybe if he would have taken 2 seconds to read the sticky what advanced tech was for he would have placed it in the correct place to begin with:eek:
VladimirSteel
07-02-2006, 06:35 PM
one of the choices is optispark, that would be a lt1 problem, no?
1racerdude
07-02-2006, 10:47 PM
It's a valve problem most likely, stuck, burnt, bent...could be valve spring too.
The compression is not building and the raw fuel is coming out the pipe...
Do a compression test.
My money is with M1,ya got a valve problem.
If it's a high mileage engine just fix that valve that is bad Vs a complete valve job.
If ya do a complete valve job it is subject to start changing it's on oil out the exhaust.
cam25aro
07-08-2006, 10:40 PM
i had this problem with mine, it ended up being a bad coil
84firebird
07-09-2006, 12:56 AM
well the fact that the starter speeds up would suggest that the engine is getting easier to speed up, unless you have crappy ignition wiring and the power the starter sees is varying... that could be cause by crap gas not firing as well. and coil...
simplest way to run through all possibilities...
dump 'gas line antifreeze' into the tank, by the time you check everything else you bad gas problem will no longer exist
pull out your multimeter and check the coil, resistance should be really low, like under an ohm, if it's infinite resistance, then replace it.
pull your number 6 plug, you could have fouled some crap and bridged the plug, then pull another plug and cross it with a spark plug diagnosis chart
http://www.gnttype.org/techarea/engine/plugs.html
see where that leads
while you've got #6 off and another off, pull the plug wires off the distributor or optispark..? i didnt know optispark had a coil but w/e use your multimeter and make sure the plug wire resistance is within tolerance, if it's infiinity replace.
now for the important part pull your compression tester out and check 6 and other, and while you're at it, all of em
put #6 in the garbage and a new plug in its place return the other plug back to its home, and check all plugs to make sure they arent loose
if you had a crap compression test, which you probably will, my money is burnt/"stuck and really burnt" valve then....pull your passenger side valve cover and check and see if any valve is visibly burnt, or not shutting completely, and check your springs at the same time and make sure they aint broken. (if it's visibly burnt that's pretty bad you probably wont see it) if you have a bad compression test you have to tear down anyway, so you can check for burnt/bent valves then.
check for vacuum leaks, use an air leak detector spray and spray down anything that's got a vacuum on it and make sure it's all sealed bad location on a vacuum leak causes eratic idle, and it'll lean you out a bit, possibly causing a slight detonation, which to the unknowing ear may sound like a misfire (it happened)
hit your starter with a wrench, just cuz, and start it up.
now watch your thin tube headers which you installed during this tune up, and make sure they don't glow red, if one or two are glowing red, you have fuel burning in your exhaust, fix your mixture, timing and valves