The great misfire mystery
04-28-2006, 02:29 AM
#61
Registered User
Join Date: Nov 2000
Location: hell, Tx. USA
Posts: 302
Re: The great misfire mystery
Ignition Control Module, yes, it sits under the coils.
the coils connect with the ICM.
the o2 mask = o2 simulator (it tricks the computer into thinking the o2 is fine) Or you can get computer tuning to remove it
180 psi sounds barely low, might have a head gasket leak?
I did, but mine was at 90psi at the lowest
I am still getting my p0300 general misfire code. I've checked everything!!
The only thing I have left to do is get my Air-to-Fuel Ratio % back to a decent amount (through tuning)
Its running pretty lean and that'll make a misfire show up more...
Im sorry I cant help!!
the coils connect with the ICM.
the o2 mask = o2 simulator (it tricks the computer into thinking the o2 is fine) Or you can get computer tuning to remove it
180 psi sounds barely low, might have a head gasket leak?
I did, but mine was at 90psi at the lowest
I am still getting my p0300 general misfire code. I've checked everything!!
The only thing I have left to do is get my Air-to-Fuel Ratio % back to a decent amount (through tuning)
Its running pretty lean and that'll make a misfire show up more...
Im sorry I cant help!!
04-28-2006, 02:32 AM
#62
Registered User
Join Date: Nov 2000
Location: hell, Tx. USA
Posts: 302
Re: The great misfire mystery
oh yeah, I did a compression check #1 cylinder was at like 180psi, then i took it to a shop and they told me it was only 90psi!!!!!
so I brought it back home, did a compression check it was at 180psi again!
FREAKING WEIRD!!!
I took it apart and you can totally tell I had a coolant leak because the #1 cylinder is all clean as shiny. The other cylinders are black
so I brought it back home, did a compression check it was at 180psi again!
FREAKING WEIRD!!!
I took it apart and you can totally tell I had a coolant leak because the #1 cylinder is all clean as shiny. The other cylinders are black
04-28-2006, 11:46 PM
#63
Registered User
Join Date: Apr 2006
Location: Oshkosh, Wi
Posts: 167
Re: The great misfire mystery
Originally Posted by jonathan_abilene
Ignition Control Module, yes, it sits under the coils.
the coils connect with the ICM.
the o2 mask = o2 simulator (it tricks the computer into thinking the o2 is fine) Or you can get computer tuning to remove it
180 psi sounds barely low, might have a head gasket leak?
I did, but mine was at 90psi at the lowest
I am still getting my p0300 general misfire code. I've checked everything!!
The only thing I have left to do is get my Air-to-Fuel Ratio % back to a decent amount (through tuning)
Its running pretty lean and that'll make a misfire show up more...
Im sorry I cant help!!
the coils connect with the ICM.
the o2 mask = o2 simulator (it tricks the computer into thinking the o2 is fine) Or you can get computer tuning to remove it
180 psi sounds barely low, might have a head gasket leak?
I did, but mine was at 90psi at the lowest
I am still getting my p0300 general misfire code. I've checked everything!!
The only thing I have left to do is get my Air-to-Fuel Ratio % back to a decent amount (through tuning)
Its running pretty lean and that'll make a misfire show up more...
Im sorry I cant help!!
Thx
Don.
08-23-2006, 03:35 PM
#67
Registered User
Join Date: Aug 2006
Posts: 20
Re: The great misfire mystery
I had the same misfire problem. Because I didn't fix it soon enough, the catalytic converter also went bad because of bad spark plugs, so what i'm saying is not to wait.
Anyways, this is what I did to fix the misfire:
First is a tune up, change the spark plugs, spark plug wires and fuel filter. Don't buy stock parts, invest in some good plugs and wires (MSD). It ran better but still misfired. I bought some heat resistant wire sleeves and boot protectors, but my mechanic advised me to return them because they are junk. So the next step was the ignition coil pack. That was replaced and it ran like a champ, mifire was solved 100%...up until the engine blew because of a bad oil change at Valvoline...bastards. >:0
But if you did all that and it still is misfiring, I believe the fuel injectors are the last thing needing to be replaced.
Anyways, this is what I did to fix the misfire:
First is a tune up, change the spark plugs, spark plug wires and fuel filter. Don't buy stock parts, invest in some good plugs and wires (MSD). It ran better but still misfired. I bought some heat resistant wire sleeves and boot protectors, but my mechanic advised me to return them because they are junk. So the next step was the ignition coil pack. That was replaced and it ran like a champ, mifire was solved 100%...up until the engine blew because of a bad oil change at Valvoline...bastards. >:0
But if you did all that and it still is misfiring, I believe the fuel injectors are the last thing needing to be replaced.
10-04-2006, 05:08 AM
#68
Registered User
Join Date: Aug 2006
Posts: 62
Re: The great misfire mystery
This is the best read I have found for the P0300 code - it also explains ALL the other items (some pretty simple) that have been overlooked in chasing this problem
http://www.aa1car.com/p0300
http://www.aa1car.com/p0300
11-30-2006, 08:03 PM
#69
Registered User
Join Date: Nov 2006
Posts: 12
v6 3.1
Hey I have a 1991 3.1 Camaro with 281300 miles on it this misfire problem is it the same on these as the 3.8 or does anyone know? Also is there much difference in the 5.0 engine and the 5.7 stock engine? When this 3.1 blows I am wanting to switch out everything and take out the computer but if the 5.7 or 5.0 is good enough I will not have to. Any suggestions.
12-30-2006, 03:57 PM
#70
Registered User
Join Date: Dec 2006
Posts: 1
I had the same problem with my 99 3800. Last year my throttle body sensors went bad and since they are mounted in the trottle body I had to replace the entire assembly for a lot of $$$. 
Recently it had been hard to start when the engine is up to temp and it idles rough and sometimes shuts off at idle. No problems when up to speed though.
Today, it got a lot worse and I scaned a P0300 (ramdom misfire). It turns out that the middle coil pack connections were corroded. Unbolt them and cleaned the terminals with a wire brush. It is running good now.
Glad to find a solution to a problem that didn't cost me an arm and a leg!
Recently it had been hard to start when the engine is up to temp and it idles rough and sometimes shuts off at idle. No problems when up to speed though.
Today, it got a lot worse and I scaned a P0300 (ramdom misfire). It turns out that the middle coil pack connections were corroded. Unbolt them and cleaned the terminals with a wire brush. It is running good now.
Glad to find a solution to a problem that didn't cost me an arm and a leg!
01-06-2007, 05:37 PM
#71
Registered User
Join Date: Oct 2001
Location: Ft. Worth Tx, USA
Posts: 83
Hey guys, i dug this thread up, is there a writeup somewhere that is really detailed to help me fix my misfire problem. Car just went over 80k miles (1998) model.
I have plugs and plug wires to do, so any help is greatly appreciated...thanks...
I have plugs and plug wires to do, so any help is greatly appreciated...thanks...
01-09-2007, 10:20 PM
#72
Registered User
Join Date: Aug 2005
Location: West Michigan
Posts: 7
Here is a thread i made just a little while back about the problems ive been having, i have the car stored right now, with the problem NOT fixed.
Alright, for like 300-400 miles now, every so often my car bogs down really bad. I recently put a walbro intank in it, about 1000 miles ago. The first time it happend (about 400 miles ago) the ses light started blinking, and the car seemed like it was running only 3 cylinders or something. It made a funny sound like a car with a huge cam at idle or something. The first time was around like 10-20 mph. So i didnt think too much about it. The ses light went out the next time i was in the car. A few days later I was cruising like 60mph, and all the sudden it bogged for a few seconds and came back??? light and all and went away? It seems like it happends at least once a week and maybe twice.??
Before you ask, I havent used my nitrous for a long time, because i wanted to change the pump first. So I havent sprayed in prolly 2000 miles. I changed the plugs too, thinking that might help, but didnt. Im too scared to fun my nitrous becaues i dont want anything bad to happen.
Its got almost 110,000 miles on it now, and has ran good ever since i got it with 86000 on it.
UPDATE****
Since then, i got a new magnaflow cat on it, new TR6 plugs, and some seafoam ran through it. Fuel Filter isnt too old either, and a new walbro has been installed too
Im going to try the wrapping/new plug wires cause they prolly have 20,000 miles on them, and checking out the ICM???? Anything else---coil packs??
Ill keep you updated
Alright, for like 300-400 miles now, every so often my car bogs down really bad. I recently put a walbro intank in it, about 1000 miles ago. The first time it happend (about 400 miles ago) the ses light started blinking, and the car seemed like it was running only 3 cylinders or something. It made a funny sound like a car with a huge cam at idle or something. The first time was around like 10-20 mph. So i didnt think too much about it. The ses light went out the next time i was in the car. A few days later I was cruising like 60mph, and all the sudden it bogged for a few seconds and came back??? light and all and went away? It seems like it happends at least once a week and maybe twice.??
Before you ask, I havent used my nitrous for a long time, because i wanted to change the pump first. So I havent sprayed in prolly 2000 miles. I changed the plugs too, thinking that might help, but didnt. Im too scared to fun my nitrous becaues i dont want anything bad to happen.
Its got almost 110,000 miles on it now, and has ran good ever since i got it with 86000 on it.
UPDATE****
Since then, i got a new magnaflow cat on it, new TR6 plugs, and some seafoam ran through it. Fuel Filter isnt too old either, and a new walbro has been installed too
Im going to try the wrapping/new plug wires cause they prolly have 20,000 miles on them, and checking out the ICM???? Anything else---coil packs??
Ill keep you updated
01-20-2007, 09:37 AM
#73
Registered User
Join Date: Jan 2006
Posts: 32
hmmmm My problem sounds a little different then anyone elses....
When I first start my car and its cold (idleing) it runs fine, but then when it warms up a little bit (rpms are now at 1000) About every 10 seconds it will sound like its misfiring from the exhaust. It will break up. Now when i drive, anything under about 3000rpms and under 1/2 throttle it will run completly normal with no stutters or anything....but once i get about half throttle or more and over 3k it will pull then break up really bad (like someone just turned the power off) then it will pull again and keep doing it...basically it jerks in and out of power. Now, i am turbocharged and i dont have a cat so a bad cat is out of the question. I Replaced all of my spark plugs, changed my stock plug wires to MSD high currency ones, put a new fuel filter on and took out my injectors and inspected them/cleaned them. I have a inline MSD high pressure fuel pump and thats still working 100% (if you know anything about them, their so loud you can hear them working) But my intake fuel pump could also be bad. The car is in winter storage for right now and i didnt do a fuel pressure check yet however, It still has the stock coil packs (which have 102K on them...they were never changed when i had my new motor put in which currently has 26K on the clock)...So im gonna buy some AC delco performance coil packs and change those out....Im pretty sure thats the problem but not 100% positive...
also, Before i changed out the wires,plugs etc. i thought maybe i was running too lean with the turbo so i took off my BOV (which creates a boost leak so you dont build any boost) and went for a drive...so pretty much i was NA and it didnt make a difference. Car still broke up in the same area about the same throttle %...so its not turbo related
When I first start my car and its cold (idleing) it runs fine, but then when it warms up a little bit (rpms are now at 1000) About every 10 seconds it will sound like its misfiring from the exhaust. It will break up. Now when i drive, anything under about 3000rpms and under 1/2 throttle it will run completly normal with no stutters or anything....but once i get about half throttle or more and over 3k it will pull then break up really bad (like someone just turned the power off) then it will pull again and keep doing it...basically it jerks in and out of power. Now, i am turbocharged and i dont have a cat so a bad cat is out of the question. I Replaced all of my spark plugs, changed my stock plug wires to MSD high currency ones, put a new fuel filter on and took out my injectors and inspected them/cleaned them. I have a inline MSD high pressure fuel pump and thats still working 100% (if you know anything about them, their so loud you can hear them working) But my intake fuel pump could also be bad. The car is in winter storage for right now and i didnt do a fuel pressure check yet however, It still has the stock coil packs (which have 102K on them...they were never changed when i had my new motor put in which currently has 26K on the clock)...So im gonna buy some AC delco performance coil packs and change those out....Im pretty sure thats the problem but not 100% positive...
also, Before i changed out the wires,plugs etc. i thought maybe i was running too lean with the turbo so i took off my BOV (which creates a boost leak so you dont build any boost) and went for a drive...so pretty much i was NA and it didnt make a difference. Car still broke up in the same area about the same throttle %...so its not turbo related
02-14-2007, 08:30 PM
#74
Registered User
Join Date: Apr 2006
Location: Oshkosh, Wi
Posts: 167
hmmmm My problem sounds a little different then anyone elses....
When I first start my car and its cold (idleing) it runs fine, but then when it warms up a little bit (rpms are now at 1000) About every 10 seconds it will sound like its misfiring from the exhaust. It will break up. Now when i drive, anything under about 3000rpms and under 1/2 throttle it will run completly normal with no stutters or anything....but once i get about half throttle or more and over 3k it will pull then break up really bad (like someone just turned the power off) then it will pull again and keep doing it...basically it jerks in and out of power. Now, i am turbocharged and i dont have a cat so a bad cat is out of the question. I Replaced all of my spark plugs, changed my stock plug wires to MSD high currency ones, put a new fuel filter on and took out my injectors and inspected them/cleaned them. I have a inline MSD high pressure fuel pump and thats still working 100% (if you know anything about them, their so loud you can hear them working) But my intake fuel pump could also be bad. The car is in winter storage for right now and i didnt do a fuel pressure check yet however, It still has the stock coil packs (which have 102K on them...they were never changed when i had my new motor put in which currently has 26K on the clock)...So im gonna buy some AC delco performance coil packs and change those out....Im pretty sure thats the problem but not 100% positive...
also, Before i changed out the wires,plugs etc. i thought maybe i was running too lean with the turbo so i took off my BOV (which creates a boost leak so you dont build any boost) and went for a drive...so pretty much i was NA and it didnt make a difference. Car still broke up in the same area about the same throttle %...so its not turbo related
When I first start my car and its cold (idleing) it runs fine, but then when it warms up a little bit (rpms are now at 1000) About every 10 seconds it will sound like its misfiring from the exhaust. It will break up. Now when i drive, anything under about 3000rpms and under 1/2 throttle it will run completly normal with no stutters or anything....but once i get about half throttle or more and over 3k it will pull then break up really bad (like someone just turned the power off) then it will pull again and keep doing it...basically it jerks in and out of power. Now, i am turbocharged and i dont have a cat so a bad cat is out of the question. I Replaced all of my spark plugs, changed my stock plug wires to MSD high currency ones, put a new fuel filter on and took out my injectors and inspected them/cleaned them. I have a inline MSD high pressure fuel pump and thats still working 100% (if you know anything about them, their so loud you can hear them working) But my intake fuel pump could also be bad. The car is in winter storage for right now and i didnt do a fuel pressure check yet however, It still has the stock coil packs (which have 102K on them...they were never changed when i had my new motor put in which currently has 26K on the clock)...So im gonna buy some AC delco performance coil packs and change those out....Im pretty sure thats the problem but not 100% positive...
also, Before i changed out the wires,plugs etc. i thought maybe i was running too lean with the turbo so i took off my BOV (which creates a boost leak so you dont build any boost) and went for a drive...so pretty much i was NA and it didnt make a difference. Car still broke up in the same area about the same throttle %...so its not turbo related
Don
07-03-2007, 08:48 AM
#75
Registered User
Join Date: Mar 2006
Posts: 117
I think i got the misfire bug. Was told by a mechanic that i need new plugs and wires. Its going to be too much money to get it done proffesionally so i need to do it myself.
I was looking for the plugs but i can't even see the damn things. I have never worked on my camaro, only bought it a couple years ago. Never had a problem with it until now.
So are the plugs on the underside of the engine? Can the wires be replaced without taking anything apart? Am i going to have to go at this from underneath the car? Do boot covers actually help on a 99?
I've got 93,000 on the car and it ran great up until 2 weeks ago. Are the later model v6's cooler than earlier models? Will i most likely get another 90,000 out of new plugs and wires?
I was looking for the plugs but i can't even see the damn things. I have never worked on my camaro, only bought it a couple years ago. Never had a problem with it until now.
So are the plugs on the underside of the engine? Can the wires be replaced without taking anything apart? Am i going to have to go at this from underneath the car? Do boot covers actually help on a 99?
I've got 93,000 on the car and it ran great up until 2 weeks ago. Are the later model v6's cooler than earlier models? Will i most likely get another 90,000 out of new plugs and wires?