LS1GTO Forums banner

21 - 40 of 51 Posts

·
Registered
Joined
·
144 Posts
I had the exact problem you are having (same codes same cylinder).

It started after my motor was rebuilt by the dealer at 10,000 miles. It took 6 months and 5 different dealers to figure it out, turns out that when the motor work was done they forgot to reset the crank position sensor.

Not sure if it is your problem, just throwing out ideas
I wonder if in my case they did not reset the sensor,they did replace it..you think my tuner can reset it or just the dealers?I took it in to have the sensor replaced, I drove home 12 miles,got ready and left for work,this is when the miss fire started,I couldnt get past 40mph,poping and jerking,went back to dealer,they said miss fire #7 and #8 and asked if I had anything done to engine,because the codes did not match stock,I had to tell them I had a dyno tune,*&%$$,warranty game started,so I called AD,tuner and they said they would take care of it so this is where I am at now,tuner said my cats were bad,waiting on my Kooks and cats.....
 

·
10's somewhere
Joined
·
63 Posts
I've had 4 coils go on me, the last one this week. Would randomly misfire for a while the be okay for weeks. Finally got bad enough to where I could get a trace on the problem. Now mind you, I've got the MSD coils and there have been issues with them. Just wanted to point out another possibility of what could cause a single cylinder randomly occuring misfire. Good luck.
 

·
Registered
Joined
·
2,730 Posts
Right after i installed my maggie i was getting some missfire on one cyl, actualy alot. I went through all my install checked all the plugs etc. Ended up being a bad coil, it was cracked with some melted plastic coming out of it. damm those things are expensive!
 

·
GONE was here FIRST!!!
Joined
·
2,115 Posts
I replaced my wires Fri and installed my plugs today and dumped in some fuel injector cleaner. Old plugs are whitish.
 

·
Registered
Joined
·
43 Posts
I have the same issue with 04 M6. In fact i was driving by Autozone and my check engine light was on...

a min. before i pulled in the light turned off. I asked them to scan it to see if something would show up. Something did show up...a Cylinder misfire - random cylinders.

It looks like i'm going to replace my plugs and wires this weekend.
 

·
GONE was here FIRST!!!
Joined
·
2,115 Posts
Leme Guess, you use octane boost...... if so then stop right away, that stuff causes nothing but problems no matter who makes it
No. Not octane boost. Gumout fuel system cleaner. But I think I am the newest member of the HEAT SOAK club. Car is sluggish at low rpm's. Accelerating up a hill from a stop is sluggish until 3K rpm then the car comes to life.
 

·
Nothing To Prove
Joined
·
112 Posts
So i am having the exact same freakin problem. except i have LT and no cats is one of my only mods, but i have alot of black smoke and crappy driving.

I just swtch out my plugs, didnt help a bit, so i guess wires are next.

Oh and my codes are ( random misfire, and bank 1 and 2 are lean)
 

·
GONE was here FIRST!!!
Joined
·
2,115 Posts
That's the thing that baffles me. I have no check eng. light whatsoever. Just sluggish performance until around 3k.
 

·
I deserve to be BLOWN!!!
Joined
·
1,481 Posts
TO be more clear so we can better diagnos problems, please put the Code in which your computer is throwing.

P0300 is Random Multiple Misfire. Computer detects misfires in different cylinders. Usually harder to diagnos as it does not point to any particular cylinder(s).

P0301 Cylinder #1
P0302 #2
P0203 #3
P0304 #4
P0305 #5
P0306 #6
P0307 #7
P0308 #8

These are a bit easier to diagnos. Other things to consider if you are having 2 or more particular cylinders ar fault. Are the two next to eachother? ie 1 and 3, 2 and 4, 3 and 5, 4 and 6 etc...
In more extreme cases, a head gasket may be in question.

One of three things are the cause for a Misfire: loss of spark; the air/fuel mixture is too far out of balance to ignite; or loss of compression/. Have you done ANY work to the car previously? Plugs, Fuel pump upgrade, Wires, tune, injectors or coilpacks?
This would be a good time to retrace your steps.

First thing that should be done is the easy stuff. When was the last time you changed your plugs? Now may be a good time to replace them anyways. Take a look at the condition of them too!

Wires. Again, these are a good investment IMO but are VERY likely to cause problems if not installed correctly. Make sure you get a couple "Snaps" when sliding them onto the Coil Pack and Plugs. If you're not sure, Keep pushing them on.

Coil packs are VERY easy to change and can be swapped over to a cylinder that's running fine. IF the problem follows the coil pack from #1 to say #2, you know you have a bad pack. Best part is it's FREE to do this.

Vacuum leaks, check all hoses, MAF sensor and intake tubing. Air coming in after your MAF can cause problems. Get some Brakleen (sp) and spray around the intake, injectors while the car is running.

02's. Before going out and buying these Costly sensors, make sure you're not having severe WOT misfiring as these only effect idle and light cruise.

Try the easy and inexpensive tips first! :patriot:
 

·
Registered
Joined
·
1,637 Posts
Check your harmonic balancer my will not go back in all the way. It was out 1/4" and the car was misfiring real bad. Now it has 1/8" left to go and not as bad misfire.
 

·
Registered
Joined
·
43 Posts
Well, I just changed out my plugs and wires... nothing changed. I still have the same problem. The plugs looked good and when i took it for a test run the check engine light came on. I maybe able to narrow it down now. I'll let you know if i find any thing out.

Kal
 

·
Finally got a Goat
Joined
·
219 Posts
Mine is going to the dealer tomorrow for 0300 Random misfire, already checked and know for sure it is not plugs or wires.
 

·
I deserve to be BLOWN!!!
Joined
·
1,481 Posts
let us know what the problem is after you get it fixed.
 

·
Registered
Joined
·
43 Posts
Well, I took my car to the dealer and wouldn't you know it... $70 later, I'm still not sure whats wrong.

They did however tell me that it could be caused by my O2 sensor and that there could be too much back pressure.

I took the car back to my place and looked into in a little further... wouldn't you know it, there really isn't any exhaust coming out the driver side exhaust. I then started to pull the exhaust and sure $hit. The driverside exhaust (front cat) is pluged.

Hopefully this helps! This really sucks cuz cats are alot of $$$!!! :(

Kal
 

·
GONE was here FIRST!!!
Joined
·
2,115 Posts
If this ish ever happens to me, my headers are goin in, cats or not.
 

·
Speed Junkie #1
Joined
·
239 Posts
Since the car only has 15k miles on it, why dont you take it to the dealer?


uhhh... STOP... dealer time. no offense to anyone's info here but if your an unmodded 06 take it somewhere when it really gets screwed up it's still on warrenty.
 

·
Registered
Joined
·
144 Posts
Well, I took my car to the dealer and wouldn't you know it... $70 later, I'm still not sure whats wrong.

They did however tell me that it could be caused by my O2 sensor and that there could be too much back pressure.

I took the car back to my place and looked into in a little further... wouldn't you know it, there really isn't any exhaust coming out the driver side exhaust. I then started to pull the exhaust and sure $hit. The driverside exhaust (front cat) is pluged.
Hopefully this helps! This really sucks cuz cats are alot of $$$!!! :(

Kal
Kal,my cats were bad so I replaced with Kooks headers and cats,1400$,my problem is going on ,not the miss fire but the crank positioning sensor,I had 2 replaced back to back,my car wont stay running so I cant get it retuned,she is at the tuners.I have less than 25000 miles and my cats were shot....I only have bolt ons,ported in take,polished throttle body,KN air,MSD wires,160 stat,Kooks system with Magnaflows,Billet shifter,Dont know how she sounds and shifts or even run yet.........
 
21 - 40 of 51 Posts
Top