Engine has been running well now for about 5000 miles and and got some colder weather so I get on it off the line a bit and after a second or two it throws the engine light and I fill it let off a bit. Check for codes and I have the PO308 misfire cyl. 8. I pull cyl 8 plugs and find this So I get the closest plug I can find to replace it (same temp different plug) and it is running terrible, getting little back fires so I',m assuming that that piece either bent the exhaust valve or is stuck in the seat. What would cause that to happen
Piston slap. Over rev'd more than likely? Do you have raised shift points and raised rev limiter? That sucks man. Sorry.
I would like to see the rest of the plugs,but looking at the white tip it looks lean to me. Any power adders?
Well she was lean as hell and as burned as the electrode is, it wouldn't suprise me if you haven't hurt a piston. Take a look at all your plugs. It could be as simple as you lost a injector (clogged, failed, whatever). But I would suggest a compression and leak down test. Best of luck bud.
Well it obiously looks like you were running lean causing what we see here. the next is to find out why you are lean? I know stock lightning avoid wot blasts in cold weather because the quality of air is so good that the pcm cuts the fuel a little resulting a lean mixture... Alot of them have gotten what we see here..Some have not been so lucky and have actually kicked a rod while doing 75-120mph.. Do you have a wideband to monitor your A/F? those looks like stock plugs, perhaps consider stepping to a colder plug? I run ngk with 150 shot NX set up.. Hopefully you didnt start cracking pistons
Sorry to read this. i did a search and couldnt find a dyno sheet or hp numbers for your build. would you mind posting those? thanks
x 2 ,I saw you're thread on your build......what I didn't see is any mention of a tune.......thats an awful lot of motor for no tune.I would be willing to bet that you are running lean at WOT on all cylinders.
I am running a stock TCM so don't think there is any other way to raise shift points. Probably have a raised rev limiter but it would still shift at stock points, right? Unfortunately this happened two weeks ago and about 400 miles away from home. I have been too depressed to even bring it home yet and from what I'm hearing I'm not feeling any better. With everything else thats going on I just can't deal with it but know I have to as we only have one other vehicle to cart the family around in and some time need two. No power adders, just straight 93
Bob SVS, it was a mirror of Steve's (Sarge) tune and build with data logging and dyno to dial it in. Is there any chance this was just a weak ground strap and broke off? The engine idles pretty smooth and with out load sounds normal it was just when you start to drive that it will pop off little backfires. Also I had upgraded 42lbs injectors From HHP which I believe are off a Z06 And when I say cooler, I mean Florida cooler. Was probably 20deg difference with lower humidity I also have my last Dashhawk data logs but it won't let me post the file up here
Looks like your a/f from 4500 to 5500 is right at 13 at the tail pipe so i think thats 12.0 at the motor. Boy that cutting close.
if it's popping you have an issue.......could be a fouled plug,normally they will pop for too rich.make sure your plugs coil pack and injector is good on #8
I'm hoping that its just a little valve damage, like that peice messed up the valve on its way out or got stuck in the seat. This is what has transpired Got the code, was out of town with limited tools and resourses Pull the plugs to find that Buy two new plugs same temp but different brand because it was all I could find locally to try and get back on the road. Started it up with cyl. 8 plugs out (just idle) to see if I could shake loose what ever came off the plug, installed plugs car Idles and revs fine got to drive it and runs like crap under load and is giving small backfires and still throws the PO308 code. Left the car at my family place and has been there ever since
try swapping the coil pack with the next cylinder.....see if you get a p0306.You won't get a p030x with a hurt valve.
Well the tune was revised after that, Bob I believe said he was going to add a little fuel in to be on the safe side I've been running the revised tune since about Oct. 6 and ran my standing miles runs with it (about 5 runs) It never missed a beat and has been running well (the motor) since I installed it. If you are running lean how long would it take to see that? Wouldn't it be pretty quick after putting the tune in and going WOT? My biggest fear is that I have major damage, any damage is bad of course but the head can be pulled and fixed fairly easily but the piston........ I was afraid I would hear bad new that's why I didn't even want to post up about this (I still don't) but I gotta get this figured out.
Try the coil pack change and if you see no change, swap injectors too and see if your misfire code changes as well. I've seen these injectors take a dump before, you wouldn't be the first. Also, when you remove that injector, try not to turn it upside down, keep the fuel in it. Have a 9 volt battery and a couple jumpers ready and actuate the injector with the fuel standing in it. If it dumps fuel, you might be fine, if not, check for debree in the injector. If you need something for comparison, do the same test with one of the other injectors. I know it's not the most thorough test, but it will give you somewhat of a indication if you are having issues.
Looks like the AFR is way out of wack, the EGT's must have been through the roof. Did you run it wot for a long period of time.....
