Ok, I have been getting random misfires codes for a couple of weeks and cannot seem to find the problem. It does it mainly when it is 50 degrees or colder. I have changed the plugs, wires, ran injector cleaner, checked and re-checked the injectors to make sure they are plugged in and changed the misfire detection values through edit.The car only has about 23,000 miles on it.It will miss all the way to about 3,000 rpm and then it runs fine. Any ideas? I am stumped! <img border="0" alt="[USA]" title="" src="graemlins/patriot.gif" />


<img border="0" alt="[shoot]" title="" src="graemlins/gr_guns.gif" /> Saddam

 

How long have you been running that cam?
With a 112 LSA you will definitely be getting misfires around idle, but they "should" go away before 3000!

Are they coming from random cylinders? If not try swapping coil packs around...

Faulty MAF sensor? Just a guess?

Good luck.

If you figure it out, post it!

Tommy <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

 

Well, it seems as though you've been through all the ignition. Although, I wonder if there's a bad ground somewhere.

Anyway, I was gonna suggest doing an injector cycling test. You will need a Tech2 (or similar tool) though to do this.

Essentially, you attach a fuel pressure gauge to the fuel rail. Note the pressure with the ignition on. Then have the Tech2 cycle through all 8 injectors. As each injector fires, the pressure should drop 5-10psi then rebuild after the injector fires. You should also hear the injector too. It'll repeat this process through all 8. If and when you come across one that doesn't drop pressure in the rail, that may be your smoking gun.

What kind of fuel do you use? GM does have a problem with injectors albeit this is more common on GM front wheel drive V6 vehicle's, if you use an RFG fuel, particularly Citgo, it has a tendency to corrode the pintle in the injector.

 

Something to try,thanks. I run Amoco 92 about 95% of the time. I run injector cleaner about every 5,000 miles and have changed the fuel filter twice since buying the car new. <img border="0" alt="[USA]" title="" src="graemlins/patriot.gif" />

<small>[ April 08, 2003, 09:26 AM: Message edited by: elraksaz ]</small>

 

Hey Mike, hope you figure it out.....noticed the new times <img border="0" title="" alt="[Cool]" src="gr_images/icons/cool.gif" /> ....when did you run? I haven't been out since the new setup...Mcleod MC issues.
Later,
Randy

 

I have the same problem. Not all the time, but it was real bad at the end of last seaon. It was missing like a beeyotch and wouldnt go anywhere until about 2500-3000rpm's and then it took off like a bat outta hell. Im still trying to track it down. As im sure youve heard, I already changed to the 2002 Z06 PCV valve. Got it at the dealer for 4 bucks. Now i got a air compressor line filter to take the oil out before the intake. After that, Im going to run top end cleaner through it. I notice that the pcv goes into the intake facing the #1 cyl, and thats where im getting my misfire. My juice nozzle is also on bank one side, so im thinking that that may be a cause too. just too much carbon in it??? oil isnt good for crap either. I changed the plugs about 300 miles ago, and the old ones had this crap on them, it would chip off the electrode, and if i tapped them on something, carbon would fall out. not good. so this is my potential fix. I dont think its injectors or anything, but i guess well see. Do you have autotap? i just bought efilive and i think ill check it out. its just that it doesnt happen all the time. although i logged 3 or 4 misfires on the #1 a day ago. I hate cars, but i love.

 

I have the same problem. Not all the time, but it was real bad at the end of last seaon. It was missing like a beeyotch and wouldnt go anywhere until about 2500-3000rpm's and then it took off like a bat outta hell. Im still trying to track it down. As im sure youve heard, I already changed to the 2002 Z06 PCV valve. Got it at the dealer for 4 bucks. Now i got a air compressor line filter to take the oil out before the intake. After that, Im going to run top end cleaner through it. I notice that the pcv goes into the intake facing the #1 cyl, and thats where im getting my misfire. My juice nozzle is also on bank one side, so im thinking that that may be a cause too. just too much carbon in it??? oil isnt good for crap either. I changed the plugs about 300 miles ago, and the old ones had this crap on them, it would chip off the electrode, and if i tapped them on something, carbon would fall out. not good. so this is my potential fix. I dont think its injectors or anything, but i guess well see. Do you have autotap? i just bought efilive and i think ill check it out. its just that it doesnt happen all the time. although i logged 3 or 4 misfires on the #1 a day ago. I hate cars, but i love. <img border="0" alt="[bang head]" title="" src="graemlins/gr_banghead.gif" />

 

I actually haven't tried the pcv valve. Since mine is a 2002 do you think I would already have it? It may be something to try. hopefully we can both get it figured out. <img border="0" alt="[USA]" title="" src="graemlins/patriot.gif" />

 

228/224 - 588/567 112lsa

There is where your misfire codes are coming from.

You need to have these codes deleted from the PCM with programing.

If your car is an A4, those misfire codes will also cause torque converter lock-up problems.

Ron,

 

Unfortunately I have already done that and it didn't help. Thanks for the suggestion though. <img border="0" alt="[USA]" title="" src="graemlins/patriot.gif" />

<small>[ April 10, 2003, 07:14 PM: Message edited by: elraksaz ]</small>

 

If I read this right, your not just getting codes, but true misfire. If it happens when the car is cold another guess is an air leak which is causing a lean condition, since the car needs less air when cold.

 

Misfires if real are due to being too rich.
False misfires can occur in part by :

Crank or Cam position sensors out of alignment ( use a Tech II to command a CKS relearn) Also they could be loose or damaged.

A lightweight pully put crank out of balance

Serpintine belt slipping

Cam grind causing uneven crank rotation

Wrong type of sprakplug or gap

Torque Convertor locking/unlocking whrn it should'nt

Determine if misfire is only at idle or not, is it when engine is cold or hot, tune AFR in the area it happens leaner and see if it goes away.

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by elraksaz:
<strong> Ok, I have been getting random misfires codes for a couple of weeks and cannot seem to find the problem. It does it mainly when it is 50 degrees or colder. I have changed the plugs, wires, ran injector cleaner, checked and re-checked the injectors to make sure they are plugged in and changed the misfire detection values through edit.The car only has about 23,000 miles on it.It will miss all the way to about 3,000 rpm and then it runs fine. Any ideas? I am stumped! <img border="0" alt="[USA]" title="" src="graemlins/patriot.gif" />


<img border="0" alt="[shoot]" title="" src="graemlins/gr_guns.gif" /> Saddam </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">

 

Thanks. I'll take a look at those things and hope for the best. <img border="0" alt="[cheers]" title="" src="graemlins/gr_cheers.gif" />

<img border="0" alt="[USA]" title="" src="graemlins/patriot.gif" />