Almost everything new, still missfires
Almost everything new, still missfires So I just got my engine rebuilt with dome pistons (forgot the CR), bored 30 over, everything done for our budget and supercharger (5 psi). We have MSD 8.5 wires, MSD coil, and opti which had problems so they gave us a reconditioned one (pretty much new) and it still will miss. We have the stock AC Delco plugs with a few thousand miles one them. Also we have a MSD 6BTM. The engine is less than a hour old and none of the wires are arcing. Any ideas why it would be missing? Needs new plugs and if so what kind? I have been recommended these for plugs
http://www.sparkplugs.com/more_info.asp?AAIA=&pid=3867
Thanks!
http://www.sparkplugs.com/more_info.asp?AAIA=&pid=3867
Thanks!
You dont want stock plugs with boost first of all.
Second does it have a tune.
Where is it missing? If it's under high load / wide open throttle / high rpm situation it could be blowing the spark out, or detonating.
Get the right plug in there and get it dyno tuned.
Second does it have a tune.
Where is it missing? If it's under high load / wide open throttle / high rpm situation it could be blowing the spark out, or detonating.
Get the right plug in there and get it dyno tuned.
We know that we need different plugs but we don't know which ones to get for our application.
As far as we know, it doesn't have a tune. We want to get it running right and fully broken in before we dyno tune it.
Well at idle it will sometime not stay steady and go up and down but it's only like 50-100 rpms. Also twice it happened when it was idling and it revs by it's self to 1500 and goes back down and the engine light comes one. When ever we are at a light and we start driving away it will backfire so I guess it's missing at idle too cause it builds up the gas and backfires. It back fires when you let of the gas and during other times too. It misses throughout the whole rpm rage. Sometimes it get better but then it will get worse right after.
you can get a tune with a dyno ..you need a basic line tune to control all the new parts you put on it..get one for pcmforless or madtuner its your choice...if it was me ill stop driving i until then...what you have now is a pitbull with no training and asking him to play with kids lol
I'm going to stick with the dyno tune.
Also forgot to say, I was driving in the rain so maybe it had something to do with that? Well today is a beautiful day so I will see how it drives now.
Also forgot to say, I was driving in the rain so maybe it had something to do with that? Well today is a beautiful day so I will see how it drives now.
You need to ditch the stock plugs ASAP. You need a plug at least one heat range colder and a smaller gap. Lots of guys prefer the NGK TR6s gapped at .035". That can easily be the cause of your issue.
Same with the tune. Was a new camshaft put in? If you're on the stock tune, that can cause issues as well.
Same with the tune. Was a new camshaft put in? If you're on the stock tune, that can cause issues as well.
You need to ditch the stock plugs ASAP. You need a plug at least one heat range colder and a smaller gap. Lots of guys prefer the NGK TR6s gapped at .035". That can easily be the cause of your issue.
Same with the tune. Was a new camshaft put in? If you're on the stock tune, that can cause issues as well.
Same with the tune. Was a new camshaft put in? If you're on the stock tune, that can cause issues as well.
The cam should be the same as the stock one. Well we have been driving without a tune for 2 years now and didn't have any problems with missing until we spun a bearing and right now. We think the MSD 6BTM box could be faulty but not to sure.
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Have you scanned for codes? The SES light is coming on for a reason. I'd scan it and see what you come up with.
A vacuum leak can also cause erratic idle and mis-firing too.
A vacuum leak can also cause erratic idle and mis-firing too.
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