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View Full Version : MIS-FIRE!!!



pstevo8
01-20-2006, 09:01 AM
To Anybody that may know WTF this is!

I don't drive my car very much at all, maybe once like a month ago, and then again yesterday.

I have the 3037 with alcohol, boosting to 1.9 bars.

Yesterday: When running at WOT between 5 and 7k, in 3rd or 4th gear, the car will randomly mis-fire or something. It is a horrible backfire type noise and a slight hesitation when it happens. Sometimes it will be once during a pull, or sometimes two or three quick ones in a row. My alcohol is spraying, and it is holding boost fine. I am just not sure what the hell would be the cause.

My car did throw a CEL prior to me discovering this mis-fire. I am almost positive it is the P300, because of when it popped up. It happens all the time when I am just cruising.

Anybody have any ideas?

Bill

Evo442
01-20-2006, 09:12 AM
To Anybody that may know WTF this is!

I don't drive my car very much at all, maybe once like a month ago, and then again yesterday.

I have the 3037 with alcohol, boosting to 1.9 bars.

Yesterday: When running at WOT between 5 and 7k, in 3rd or 4th gear, the car will randomly mis-fire or something. It is a horrible backfire type noise and a slight hesitation when it happens. Sometimes it will be once during a pull, or sometimes two or three quick ones in a row. My alcohol is spraying, and it is holding boost fine. I am just not sure what the hell would be the cause.

My car did throw a CEL prior to me discovering this mis-fire. I am almost positive it is the P300, because of when it popped up. It happens all the time when I am just cruising.

Anybody have any ideas?

Bill

Bill - dont know if this is the same or not. After the install of my WR, when I'd accelerate hard, I'd hear this soft popping sound, once, twice or many times in a row. The car would still accelerate but it would hesitate with each pop. Held boost fine.

Talked to Pete at Works who told me that my plugs might not be holding their spark and being blown out. He told me to change plugs (which I did) and the problem went away. I'm running regular NGK plugs, not the fancy iridium ones, and it seems to work fine.

BTW, you can do a search on EvoM for "sputtering" and find some info.

hope it helps.

-david

nebolic
01-20-2006, 09:55 AM
To Anybody that may know WTF this is!

I don't drive my car very much at all, maybe once like a month ago, and then again yesterday.

I have the 3037 with alcohol, boosting to 1.9 bars.

Yesterday: When running at WOT between 5 and 7k, in 3rd or 4th gear, the car will randomly mis-fire or something. It is a horrible backfire type noise and a slight hesitation when it happens. Sometimes it will be once during a pull, or sometimes two or three quick ones in a row. My alcohol is spraying, and it is holding boost fine. I am just not sure what the hell would be the cause.

My car did throw a CEL prior to me discovering this mis-fire. I am almost positive it is the P300, because of when it popped up. It happens all the time when I am just cruising.

Anybody have any ideas?

Bill

maybe check your tune?

nebo

earlyapex
01-20-2006, 11:51 AM
1. Check your plugs. They might be fouled from the alky or just fouled from use. Also check the plug gap, they should be around .024 or .025 with the crazy amount of boost you are running it might be blowing out the spark. When is the last time you changed your plugs? You can throw in some cheap NGK BPR7ES or BPR8ES which is one step colder and might be a good idea with the amount of boost you are running.

2. If #1 doesn't work, check your coilpacks and plug wires for resistance.

3. If #1and#2 doesn't work, check for boost leaks

4. If #1,#2,#3 doesn't work you have broken pistons. :lol:

MitsuMan
01-20-2006, 12:23 PM
sounds like your getting detination to me I'd be very carfull and get your car back to the tuner to have it checked. when I was first dialing in my DSM I would sometimes have the same symptoms, at first I thought it was fuel cut but then I learned I was getting DET from too much boost.

earlyapex
01-20-2006, 12:30 PM
sounds like your getting detination to me I'd be very carfull and get your car back to the tuner to have it checked. when I was first dialing in my DSM I would sometimes have the same symptoms, at first I thought it was fuel cut but then I learned I was getting DET from too much boost.

now now, let's not jump to conclusions. Spark blow out is very common from worn or mis-gapped plugs. He can also check the plugs for detonation when he checks the gap or replaces the plugs.

White little specks on the plug strap is detonation and is bad. They should be a nice light tan color.

if the car is actually backfiring because of detonation you already have a hole in your piston.

pstevo8
01-20-2006, 01:15 PM
1. Check your plugs. They might be fouled from the alky or just fouled from use. Also check the plug gap, they should be around .024 or .025 with the crazy amount of boost you are running it might be blowing out the spark. When is the last time you changed your plugs? You can throw in some cheap NGK BPR7ES or BPR8ES which is one step colder and might be a good idea with the amount of boost you are running.

2. If #1 doesn't work, check your coilpacks and plug wires for resistance.

3. If #1and#2 doesn't work, check for boost leaks

4. If #1,#2,#3 doesn't work you have broken pistons. :lol:

i put in brand new iridiums, that are one step colder, when I had the car tuned after all of the mods. There has only been, maybe 500-1000 miles put on the car since then.

Since the "mis-fire" is so random and irregular, I would hope that it wouldn't be a hole in the piston. I would think a hole in the piston would produce more consistent back-firing.

Bill

earlyapex
01-20-2006, 01:24 PM
i put in brand new iridiums, that are one step colder, when I had the car tuned after all of the mods. There has only been, maybe 500-1000 miles put on the car since then.

Since the "mis-fire" is so random and irregular, I would hope that it wouldn't be a hole in the piston. I would think a hole in the piston would produce more consistent back-firing.

Bill

I was actually joking about the broken piston. :)

I've fouled plugs in 500 miles. Check them or swap a cheap set in there gapped to .024 to see if it fixes the problem. It's a easy,cheap, and quick check. You said you are also running one step colder which can foul out even faster.

Who tuned your car and with what? Any idea what your AFR's are at?

When you say the mis-fire is random do you mean it doesn't always happen at WOT? Does it happen more at night in the cold air or more in the middle of the day?

vboy425
02-05-2006, 10:04 PM
spark plugs. if it's misfiring at WOT, that mean your sparkplugs are tiehr bad or need to be regap

wilson1
02-05-2006, 10:15 PM
Bill,

didn't Al tuned your car when he flew in last?

Bagsik_EVOVIII
02-19-2006, 11:14 PM
I got the same problem since i GOT MY EVO. I tried doing what you guys said : change plugs to regular NGK's..same thing code 300 - multiple or random misfiring cylinders...I change my air filter and came out same thing ..I just keep reseting it...but gettin pissed off already..everytime I go over 85 to 90 mph it always come out...I was thinking about coil packs that may have a problem..I just need someone that knows more about dsm's..thanks

earlyapex
02-19-2006, 11:21 PM
I got the same problem since i GOT MY EVO. I tried doing what you guys said : change plugs to regular NGK's..same thing code 300 - multiple or random misfiring cylinders...I change my air filter and came out same thing ..I just keep reseting it...but gettin pissed off already..everytime I go over 85 to 90 mph it always come out...I was thinking about coil packs that may have a problem..I just need someone that knows more about dsm's..thanks

You get the code P0300 or you actually get real misfires on boost?

The P0300 seems to happen on alot of the evos, do a search on here and evom.net, there are a bunch of threads about it.

Bagsik_EVOVIII
02-21-2006, 09:46 AM
I check it with my OBD II scanner came out with 300..I check lil booklet with description of the codes and it was misfiring cylinders...It seems like every 100 miles it always comes out the check engine light on..

turbotiger
02-21-2006, 02:06 PM
Don't forget spark plug wires can also cause the same symptoms.