ZL1Killa

iTrader: (17)

ok, the car has been running great and everything. I made my PREVIOUS 423HP and 431TQ.

we did our cam swap and its probably a coincidence, but we are getting misfires. The misfires only happen at low RPM, at higher than 1500rpm they go away completely, so electrically on the car it generates more voltage and such as rpms go up and the pulses get more frequent...so I believe my wires are just worn out.

We are not getting any crazy noises or bad valvetrain noise. The SAME plug wires have been on the car for a LONG time and we have had them off and on so many times I can't count. SO, we already replaced spark plugs and here are the OLD spark plugs.

The car has been running at a 12.2 AFR WOT, and is in normal closed loop at 14.6~15.0 AFR idle and part throttle.

It seemed to get worse, as I remember I had a sputter in the exhaust every now and then and now its pretty frequent and its tripping the misfires p0300 code in the computer.

OLD spark plugs:














THESE are 2 of my plugs and they are the TR6 plugs. I believe with my boost and AFR of only 12.2 that I'm not running cold enough to warrant running a colder plug. So I have gone with a normal plug but its gapped at .040



One of the taylor thundervolt wires fell apart on us and we substituted a stock wire for the time being. So far these thundervolts have worked great to our pulling on and pullin off. Tonight I'm going to measure the resistance of them and see whats up...maybe even rig up a test for them

as it has been a while since we replaced them, and the motor has been running fine, I believe I'm just going to go ahead and order new wires and see what happens.

jimmyblue

iTrader: (11)

If it was one or two plug wires that would show up as a
specific cylinder misfire code. More likely is that the cam has
just made the motor "trip the threshold" for declaring a misfire
(as opposed to actual misfiring). More crank ripple does this,
see it with lightweight torque converters too. If it stays just
"random" then I'd start upping the threshold values in the
misfire tables (x2 everything for starters).

ZL1Killa

iTrader: (17)

well thank you!!! it is actually ALL Of them showing as misfires. more on #5 and #7 but all of them are showing up as misfires.

will check plug wires too tho.


thanks jimmy!!

A_W_O_L

iTrader: (2)

Just a thought.....recently I read a post by RedHardSupra where guy's that are having misfires in low/idle rpms. it had to do with injector sizing. what he wrote sounds a lot like what you are describing, and since you are running a forced induction system, and changed cams... and have probly adjusted your injectors accordingly...it might be something worth looking at...

in one instance...he was describing guys that are running injectors that are sized for big boost but when in low rpm/idle the injector pw is at it's minium pw but still over fueling......here's the link below...maybe it will help, maybe not...but I think it would defiantly be worth looking in to.....

http://redhardsupra.blogspot.com/200...1_archive.html

Hope this helps.

ZL1Killa

iTrader: (17)

thanks for that info, that kind of problem is solved by modifying all the injector tables (min pulse, etc..) and me and gametech along with a bunch of others haven't officially came up with numbers but know that these values need to be modified along with having a fuel pressure regulator depending on the setup.

PERSONALLY, from prior experience with RedHardSupra aka Marcin he told me when we were trying to tune 60# injectors on my nearly stock car that my intake was too big for my motor when I was NA and it was idling rich, well the tables I talk about above need to be modified and a FPR helps. So you kind of have to know your own and talk to more than one person and see whats up.... as it is with everything.

But after Marcin told me my intake was too big for my motor because my injectors were making me idle rich, I take all he says with a grain of salt, along with some of his calculations being off by a good bit. He does have some decent write-ups but as always people need to play with things and not take peoples words unless it ends up working for them 100%

ZL1Killa

iTrader: (17)

you have efi live right? I see the misfire tables, do I modify all of them? and leave the parameters alone?

jimmyblue

iTrader: (11)

I use HPTuners but I expect it's pretty much the same except
for presentation / naming etc. Look at the cylinder mode
tables at the lower RPM and where you see "sane" values
(not 32000 or 32768) try just doubling them and see how
the rolling counts decrease; if you can tamp them down to
"barely below 0" in normal operation then you will still have
some detection ability left for if things do go bad. If counts
go down but not quite zero, double it again etc.

A_W_O_L

iTrader: (2)

Agreed...That's kind of what I was doing as I'm not having that problem and since you are seeing some of the problems he is describing I thought it would be worth mentioning if you haven't looked at that yet....

I havn't needed bigger injectors and thus no need to adjust my minimum inj. pw...I have no idea how "low you can go" with inj. pw...maybe it's a non issue on smaller injectors. Good luck, Im going to be watching this thread closly.

ZL1Killa

iTrader: (17)

k. thanks man. keep a watch on my turbo build thread too, will have numbers coming. I have already doubled the values in the table(s) on efi live under misfire.

will do a log this evening when I get home from work at 8pm or so idling and see what happens

ZL1Killa

iTrader: (17)

to catch back up, everything is running fine now. That was apparently it, however, I was also significantly lean at idle ...22:1 AFR ... so I put it to 14.7 and it was still missing so I messed with the threshold and it was fine