SuperStock Posted August 7, 2009 Report Share Posted August 7, 2009 I was driving my truck down the highway and all of a sudden the check engine light just starts flashing for like 30 seconds? I don't know what to do should I get a code reader, will the code even show up if it's not on anymore? At idle I am getting this damn rattle NOT coming from the top of the motor, mabe the cats I have 83K on the truck? Quote Link to comment Share on other sites More sharing options...
Krambo Posted August 7, 2009 Report Share Posted August 7, 2009 A blinking CEL is typical of misfire and being that you stated you have a rattle from your cat, I feel you have all the evidence you need to diagnose a failed/clogged cat converter. Quote Link to comment Share on other sites More sharing options...
SuperStock Posted August 7, 2009 Author Report Share Posted August 7, 2009 Ok, I do have a set of MSD wires I will install tom and get new plugs, mabe a run down the highway at 130mph will fix it haha Quote Link to comment Share on other sites More sharing options...
AK04SS Posted August 7, 2009 Report Share Posted August 7, 2009 might be your plugs? i had the same thing, i thought it was a clogged cat, but i put a new set of ac delco plugs and it was good after. Quote Link to comment Share on other sites More sharing options...
SuperStock Posted August 7, 2009 Author Report Share Posted August 7, 2009 Ok sweet yea I will change the plugs and wires tomorrow morning and see what happens. Quote Link to comment Share on other sites More sharing options...
Wheatley Posted August 7, 2009 Report Share Posted August 7, 2009 just to make sure,also check all your plug wires and make sure they are not in contact with the manifolds and also make sure they are pluged in good. Quote Link to comment Share on other sites More sharing options...
SuperStock Posted August 7, 2009 Author Report Share Posted August 7, 2009 I checked them but when I replace them tomorrow I will make sure they are all on good. I still don't know whats rattling I dont see how changing the plugs and wire is going to fix that? Quote Link to comment Share on other sites More sharing options...
Fireman31 Posted August 7, 2009 Report Share Posted August 7, 2009 (edited) A flashing CEL signifies a catalyst damaging misfire, and when you see the CEL flashing you are supposed to pull over and shut the truck off immediately or severe engine damage can occur. You need to have the truck scanned to find out what codes it is throwing, but if I had to guess, you are throwing a P0420 or 430 and a P0300. A faulty cat can cause a random misfire, especially if it is almost plugged. The rattle you are hearing is the cat coming apart internally, there is an easy way to figure out which one it is.....slide under the truck and wrap on each cat with a closed fist(when cold of course), if you hear a rattle inside the cat, then it is NFG. This issue is something you need to address ASAP........ Edited August 7, 2009 by Fireman31 (see edit history) Quote Link to comment Share on other sites More sharing options...
SuperStock Posted August 8, 2009 Author Report Share Posted August 8, 2009 (edited) When it happened I never pulled over I just kept on going. Figured nothing was really wrong. I guess it's time to order the dynatech headers hu? Edited August 8, 2009 by Fast04Chevy (see edit history) Quote Link to comment Share on other sites More sharing options...
SuperStock Posted August 8, 2009 Author Report Share Posted August 8, 2009 Well I went to advance auto parts this morning they didn't have the spark plugs, and there were no codes to be found. I ordered the spark plugs on summit racing and I will get them next week, but I still have that ridiculous rattle. I hit the cats with my hand when it was cold an got nothing no rattle. I don't Know what to do at this point??? Quote Link to comment Share on other sites More sharing options...
srtSSsvt121 Posted August 12, 2009 Report Share Posted August 12, 2009 Well I went to advance auto parts this morning they didn't have the spark plugs, and there were no codes to be found. I ordered the spark plugs on summit racing and I will get them next week, but I still have that ridiculous rattle. I hit the cats with my hand when it was cold an got nothing no rattle. I don't Know what to do at this point??? I have an identical problem to yours and I can't mfigure out what it either. Don't take it to meineke though, Took it there gave me new plugs wires and coil packs $1400.00 later still doesn't work. Does your keep misfireing in early acceleration kind of sounding like its trying to switch gears? Quote Link to comment Share on other sites More sharing options...
Fireman31 Posted August 12, 2009 Report Share Posted August 12, 2009 (edited) I have an identical problem to yours and I can't mfigure out what it either. Don't take it to meineke though, Took it there gave me new plugs wires and coil packs $1400.00 later still doesn't work. Does your keep misfireing in early acceleration kind of sounding like its trying to switch gears? Take it back! All unnecessary work that you paid for, especially if the problem is still there, sounds like they don't have a clue what is wrong. I would demand my money back, or demand that they correct the problem F.O.C. It is damn near impossible for all 8 coil packs on an LS motor to go bad, unless the truck was under 5 feet of water. What codes did your truck throw? If you are having a misfire, and your trans is shifting strange, those are common signs of a bad MAF sensor...... Edited August 12, 2009 by Fireman31 (see edit history) Quote Link to comment Share on other sites More sharing options...
SuperStock Posted August 13, 2009 Author Report Share Posted August 13, 2009 Mine only flashed once at like 90 mph down the highway and that was 1 week ago it has not does it since. What should you torque the spark plugs to?? Quote Link to comment Share on other sites More sharing options...
srtSSsvt121 Posted August 13, 2009 Report Share Posted August 13, 2009 It does it at wide open throttle. then when im at a stop light then it shakes and studders when i start to accelerate how do i fix the maf sensor? Quote Link to comment Share on other sites More sharing options...
Fireman31 Posted August 13, 2009 Report Share Posted August 13, 2009 It does it at wide open throttle. then when im at a stop light then it shakes and studders when i start to accelerate how do i fix the maf sensor? What codes did it throw? Are you still running cats? The only real way to fix the MAF is to replace it. I need to know what codes you threw to have an idea of what is wrong.... Quote Link to comment Share on other sites More sharing options...
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